WorldWideScience

Sample records for rapid pressure drop

  1. Rapid intracranial pressure drop as a cause for posterior reversible encephalopathy syndrome: Two case reports.

    Science.gov (United States)

    Niwa, Ryoko; Oya, Soichi; Nakamura, Takumi; Hana, Taijun; Matsui, Toru

    2017-01-01

    Posterior reversible encephalopathy syndrome (PRES) is characterized by reversible edematous lesions on radiological examinations as well as symptoms of altered consciousness and seizures. To date, the underlying mechanism remains largely unknown. Case 1 is a 72-year-old man with a history of hypertension presented with a subarachnoid hemorrhage. Fourteen days after the successful clipping of a ruptured aneurysm; he experienced inadvertent overdrainage via the intraventricular drain. Nine hours later, he started to have seizures followed by disturbances in consciousness. An emergency magnetic resonance imaging showed multiple high-intensity lesions in the frontal, temporal, parietal, and occipital lobes, basal ganglia, brainstem, and cerebellar hemispheres bilaterally, which are compatible with typical magnetic resonance findings in PRES patients. He was treated conservatively and recovered well. Case 2 is a 68-year-old woman with a mild history of hypertension and a ventriculo-peritoneal shunt for obstructive hydrocephalus, who underwent a cysto-peritoneal shunt placement because of an enlarging symptomatic arachnoid cyst. Immediately following surgery, she experienced disturbances in consciousness and developed status epilepticus. Radiological examinations revealed remarkable shrinkage of the arachnoid cyst and multiple edematous lesions, which led us to strongly suspect PRES. With conservative treatment, her symptoms and the radiological abnormalities disappeared. Based on the previous literature and our cases, we believe that the association between rapid reduction of intracranial pressure (ICP) and the development of PRES should be recognized because most neurosurgical procedures such as craniotomy or cerebrospinal fluid diversion present a potential risk of rapid reduction of ICP.

  2. Gas Pressure-Drop Experiment

    Science.gov (United States)

    Luyben, William L.; Tuzla, Kemal

    2010-01-01

    Most chemical engineering undergraduate laboratories have fluid mechanics experiments in which pressure drops through pipes are measured over a range of Reynolds numbers. The standard fluid is liquid water, which is essentially incompressible. Since density is constant, pressure drop does not depend on the pressure in the pipe. In addition, flow…

  3. Pressure drop in contraction flow

    DEFF Research Database (Denmark)

    Rasmussen, Henrik Koblitz

    This note is a supplement to Dynamic of Polymeric Liquids (DPL) page 178. DPL gives an equation for the pressure drop in a tapered (and circular) contraction, valid only at low angles. Here the general definition of contraction flow (the Bagley correction) and a more general method to find...... the pressure drop in a contraction are given....

  4. A pressure drop model for PWR grids

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Dong Seok; In, Wang Ki; Bang, Je Geon; Jung, Youn Ho; Chun, Tae Hyun [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1998-12-31

    A pressure drop model for the PWR grids with and without mixing device is proposed at single phase based on the fluid mechanistic approach. Total pressure loss is expressed in additive way for form and frictional losses. The general friction factor correlations and form drag coefficients available in the open literatures are used to the model. As the results, the model shows better predictions than the existing ones for the non-mixing grids, and reasonable agreements with the available experimental data for mixing grids. Therefore it is concluded that the proposed model for pressure drop can provide sufficiently good approximation for grid optimization and design calculation in advanced grid development. 7 refs., 3 figs., 3 tabs. (Author)

  5. Measuring Pressure Drop Under Non Ideal Conditions

    Directory of Open Access Journals (Sweden)

    Austin M

    2014-12-01

    Full Text Available The method of measurement of the pressure drop (PD of cigarette filter rods and the draw resistance of cigarettes is defined in ISO 6565-2002 (1. This standard defines the calibration and use of a transfer standard to calibrate the measuring instrument and also defines the measurement procedure for cigarette and filter samples. The procedure described in the standard assumes that the measurement conditions are constant and that the sample is in equilibrium with the measurement environment.

  6. Reducing pressure drop in a baghouse using flow distributors

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C. [Tajen Institute of Technology, Ping-Tung Hsien (Taiwan). Dept. of Environmental Engineering and Health

    2001-10-01

    The pressure drop of ladder vanes in a baghouse could be reduced by decreasing the vane number and adjusting the inclined angle of the vane. Two types of flow distributors were utilized to test pressure drop caused by the structure of a baghouse. The pressure drops were measured by an inclined manometer under various filtration velocities. The purpose of this study is to understand the improvement effect of pressure drop saving on traditional ladder vanes. 14 refs., 6 figs.

  7. Reducing pressure drop in a baghouse using flow distributors.

    Science.gov (United States)

    Chen, C J

    2001-10-01

    The pressure drop of ladder vanes in a baghouse could be reduced by decreasing the vane number and adjusting the inclined angle of the vane. Two types of flow distributors were utilized to test pressure drop caused by the structure of a baghouse. The pressure drops were measured by an inclined manometer under various filtration velocities. The purpose of this study is to understand the improvement effect of pressure drop saving for the traditional ladder vanes. Experimental results showed that the pressure drop of the Vane 3-1 configuration (flow distributor with three vanes perpendicular to the inlet flow) was higher than that of the Empty configuration (without flow distributors). The Vane 3-1 configuration could not reduce the pressure drop because of the barrier effect. By reducing the number and adjusting the angle of the vanes, the barrier effect was decreased, and the pressure drop of the Vane 2-1 configuration was much lower than that of the Vane 3-1 configuration. The largest difference in pressure drop between Vane 2-1 and Vane 3-1 was 1.702 cm w.g. at a filtration velocity of 4.17 cm/sec and, in terms of percentage, is 18.52% corresponding to a filtration velocity of 2.25 cm/sec. The improvement effect on the pressure drop saving for Vane 3-1 was significant.

  8. Pressure drop of He II flow through a porous media

    Science.gov (United States)

    Maddocks, J. R.; van Sciver, S. W.

    The paper reports on measurements of He II pressure drop across two porous SiO2 ceramic filter materials. These materials vary only in porosity, having values of 0.94 and 0.96. The average fiber diameter in both cases is approximately 5 microns. The experiment consists of a glass tube containing a piece of this sponge in one end. The tube is rapidly displaced downward in a bath of helium and the liquid levels are allowed to equilibrate over time producing variable velocities up to 10 cm/sec. The results are compared with those previously obtained using fine mesh screens. Good qualitative agreement is observed for turbulent flow; however, the behavior in the laminar flow regime is not fully understood.

  9. Refrigeration. Two-Phase Flow. Flow Regimes and Pressure Drop

    DEFF Research Database (Denmark)

    Knudsen, Hans-Jørgen Høgaard

    2002-01-01

    The note gives the basic definitions used in two-phase flow. Flow regimes and flow regimes map are introduced. The different contributions to the pressure drop are stated together with an imperical correlation from the litterature.......The note gives the basic definitions used in two-phase flow. Flow regimes and flow regimes map are introduced. The different contributions to the pressure drop are stated together with an imperical correlation from the litterature....

  10. Reducing cyclone pressure drop with evasés

    Science.gov (United States)

    Cyclones are widely used to separate particles from gas flows and as air emissions control devices. Their cost of operation is proportional to the fan energy required to overcome their pressure drop. Evasés or exit diffusers potentially could reduce exit pressure losses without affecting collection...

  11. Estimation of pressure drop in gasket plate heat exchangers

    Directory of Open Access Journals (Sweden)

    Neagu Anisoara Arleziana

    2016-06-01

    Full Text Available In this paper, we present comparatively different methods of pressure drop calculation in the gasket plate heat exchangers (PHEs, using correlations recommended in literature on industrial data collected from a vegetable oil refinery. The goal of this study was to compare the results obtained with these correlations, in order to choose one or two for practical purpose of pumping power calculations. We concluded that pressure drop values calculated with Mulley relationship and Buonopane & Troupe correlation were close and also Bond’s equation gave results pretty close to these but the pressure drop is slightly underestimated. Kumar correlation gave results far from all the others and its application will lead to oversize. In conclusion, for further calculations we will chose either the Mulley relationship or the Buonopane & Troupe correlation.

  12. Negative Pressures and Spallation in Water Drops Subjected to Nanosecond Shock Waves.

    Science.gov (United States)

    Stan, Claudiu A; Willmott, Philip R; Stone, Howard A; Koglin, Jason E; Liang, Mengning; Aquila, Andrew L; Robinson, Joseph S; Gumerlock, Karl L; Blaj, Gabriel; Sierra, Raymond G; Boutet, Sébastien; Guillet, Serge A H; Curtis, Robin H; Vetter, Sharon L; Loos, Henrik; Turner, James L; Decker, Franz-Josef

    2016-06-02

    Most experimental studies of cavitation in liquid water at negative pressures reported cavitation at tensions significantly smaller than those expected for homogeneous nucleation, suggesting that achievable tensions are limited by heterogeneous cavitation. We generated tension pulses with nanosecond rise times in water by reflecting cylindrical shock waves, produced by X-ray laser pulses, at the internal surface of drops of water. Depending on the X-ray pulse energy, a range of cavitation phenomena occurred, including the rupture and detachment, or spallation, of thin liquid layers at the surface of the drop. When spallation occurred, we evaluated that negative pressures below -100 MPa were reached in the drops. We model the negative pressures from shock reflection experiments using a nucleation-and-growth model that explains how rapid decompression could outrun heterogeneous cavitation in water, and enable the study of stretched water close to homogeneous cavitation pressures.

  13. Determination of pressure drop across activated carbon fiber respirator cartridges.

    Science.gov (United States)

    Balanay, Jo Anne G; Lungu, Claudiu T

    2016-01-01

    Activated carbon fiber (ACF) is considered as an alternative adsorbent to granular activated carbon (GAC) for the development of thinner, lighter, and efficient respirators because of their larger surface area and adsorption capacities, thinner critical bed depth, lighter weight, and fabric form. This study aims to measure the pressure drop across different types of commercially available ACFs in respirator cartridges to determine the ACF composition and density that will result in acceptably breathable respirators. Seven ACF types in cloth (ACFC) and felt (ACFF) forms were tested. ACFs in cartridges were challenged with pre-conditioned constant air flow (43 LPM, 23°C, 50% RH) at different compositions (single- or combination-ACF type) in a test chamber. Pressure drop across ACF cartridges were obtained using a micromanometer, and compared among different cartridge configurations, to those of the GAC cartridge, and to the NIOSH breathing resistance requirements for respirator cartridges. Single-ACF type cartridges filled with any ACFF had pressure drop measurements (23.71-39.93 mmH2O) within the NIOSH inhalation resistance requirement of 40 mmH2O, while those of the ACFC cartridges (85.47±3.67 mmH2O) exceeded twice the limit due possibly to the denser weaving of ACFC fibers. All single ACFF-type cartridges had higher pressure drop compared to the GAC cartridge (23.13±1.14 mmH2O). Certain ACF combinations (2 ACFF or ACFC/ACFF types) resulted to pressure drop (26.39-32.81 mmH2O) below the NIOSH limit. All single-ACFF type and all combination-ACF type cartridges with acceptable pressure drop had much lower adsorbent weights than GAC (≤15.2% of GAC weight), showing potential for light-weight respirator cartridges. 100% ACFC in cartridges may result to respirators with high breathing resistance and, thus, is not recommended. The more dense ACFF and ACFC types may still be possibly used in respirators by combining them with less dense ACFF materials and/or by

  14. Effect of chamfer geometry on the pressure drop of perforated plates with thin orifices

    Energy Technology Data Exchange (ETDEWEB)

    Barros Filho, José A., E-mail: jabf@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear, Comissão Nacional de Energia Nuclear, Av. Pres. Antônio Carlos, 6627, 30270-901 Belo Horizonte, MG (Brazil); Santos, André A.C., E-mail: aacs@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear, Comissão Nacional de Energia Nuclear, Av. Pres. Antônio Carlos, 6627, 30270-901 Belo Horizonte, MG (Brazil); Navarro, Moysés A., E-mail: moysesnavarro@yahoo.com.br [Centro de Desenvolvimento da Tecnologia Nuclear, Comissão Nacional de Energia Nuclear, Av. Pres. Antônio Carlos, 6627, 30270-901 Belo Horizonte, MG (Brazil); Jordão, Elizabete, E-mail: bete@feq.unicamp.br [Faculdade de Engenharia Química, Universidade Estadual de Campinas – UNICAMP, Av. Albert Einstein, 500, 13.083-852 Campinas, SP (Brazil)

    2015-04-01

    Highlights: • CFD estimation of pressure drop of perforated plates with chamfered thin orifices. • Different chamfer geometric features evaluated. • Calculation validated against reduced scale experiments. - Abstract: Perforated plates with thin orifices is one of the options under considerations to be used in the debris filtering bottom end pieces for the next generation of fuel assemblies for the Brazilian nuclear plants. The increase in pressure drop can be drastically reduced by optimizing the chamfer geometries. This paper describes the development and validation of a procedure devised to use Computational Fluid Dynamics (CFD) to accurately estimate the pressure drop of water flow through perforated plates with chamfered thin orifices. The procedure comprises a scaled down calculation domain, grid configuration and a set of numerical solution parameters. The validation was performed against experiments with a set of plates with different chamfer geometric features like position (inlet, outlet and both sides), angles and sizes. Three turbulence models were evaluated with the standard k–ε giving the best result. For the range of parameters evaluated here the pressure drop decrease of a two sided chamfer plate can be estimated as a sum of both inlet and outlet chamfers individually. In both cases the pressure drop decreases rapidly for small chamfers and more slowly for larger chamfers. In the flat regions the chamfer angle has little influence at the inlet and is more important at outlet.

  15. Development of a constant surface pressure penetration langmuir balance based on axisymmetric drop shape analysis.

    Science.gov (United States)

    Wege, H A; Holgado-Terriza, J A; Cabrerizo-Vílchez, M A

    2002-05-15

    A new constant pressure pendant-drop penetration surface balance has been developed combining a pendant-drop surface balance, a rapid-subphase-exchange technique, and a fuzzy logic control algorithm. Beside the determination of insoluble monolayer compression-expansion isotherms, it allows performance of noninvasive kinetic studies of the adsorption of surfactants added to the new subphase onto the free surface and of the adsorption/penetration/reaction of the former onto/into/with surface layers, respectively. The interfacial pressure pi is a fundamental parameter in these studies: by working at constant pi one controls the height of the energy barrier to adsorption/penetration and can select different regimes and steps of the adsorption/penetration process. In our device a solution drop is formed at the tip of a coaxial double capillary, connected to a double microinjector. Drop profiles are extracted from digital drop micrographs and fitted to the equation of capillarity, yielding pi, the drop volume V, and the interfacial area A. pi is varied changing V (and hence A) with the microinjector. Control is based on a case-adaptable modulated fuzzy-logic PID algorithm able to maintain constant pi (or A) under a wide range of experimental conditions. The drop subphase liquid can be exchanged quantitatively by the coaxial capillaries. The adsorption/penetration/reaction kinetics at constant pi are then studied monitoring A(t), i.e., determining the relative area change necessary at each instant to compensate the pressure variation due to the interaction of the surfactant in the subsurface with the surface layer. A fully Windows-integrated program manages the whole setup. Examples of experimental protein adsorption and monolayer penetration kinetics are presented.

  16. Pressure Drop in Vertical Core-Annular Flow

    OpenAIRE

    Prada,José Walter Vanegas; Bannwart,Antonio Carlos

    2001-01-01

    An experimental apparatus for the study of core annular flows of heavy oil and water at room temperature has been set up and tested at laboratory scale. The test section consists of a 2.75 cm ID galvanized steel pipe. Tap water and a heavy oil (17.6 Pa.s; 963 kg/m³) were used. Pressure drop in a vertical upward test section was accurately measured for oil flow rates in the range 0.297 - 1.045 l/s and water flow rates ranging from 0.063 to 0.315 l/s. The oil-water input ratio was in the range ...

  17. Simple Model For Pressure Drop In Horizontal Core Annular Flow

    OpenAIRE

    Bannwart A.C.

    1999-01-01

    Based upon experimental data for heavy oil-water flow inside steel (26.7 mm ID) and cemented (23.9 mm ID) horizontal tubes, a very simple model for pressure drop in the core annular flow pattern was developed. The experiments were run at room temperature and the fluids used were a fuel oil (μ = 2.7 Pa.s, ρ = 989 kg/m3) and tap water, both drawn from a separator tank. First, it is shown that for both tubes the so-called 'perfect core annular flow' approach (shortly PCAF) poorly correlates the ...

  18. A Mathematical Scheme for Calculating Flows and Pressure Drops in Lit and Unlit Cigarettes

    Directory of Open Access Journals (Sweden)

    Dwyer RW

    2014-12-01

    Full Text Available A computational methodology is presented for evaluating the flows and pressure drops in both lit and unlit cigarettes. The flows and pressure drops across rows of tipping-paper perforations are considered explicitly, as are the locations and relative sizes of the ventilation holes. The flows and pressure drops across air-permeable cigarette papers are included. The influence of plugwrappermeabilities on filter ventilation is developed. Lit cigarettes are mimicked by adding a “coal” pressure drop to the upstream end of the cigarette. The computational scheme is used to predict the effects of tobacco-rod length, puff volume, and vent blocking on cigarette ventilation and pressure drop. A derivation of the pressure-drop and flow equations for a cigarette with an upstream pressure drop is included in an appendix.

  19. Evolution of pressure drop during detachment in the TCV tokamak

    Science.gov (United States)

    Fevrier, O.; Theiler, C.; Tsui, C. K.; Verhaegh, K.; Maurizio, R.; Labit, B.; Reimerdes, H.; Duval, B.; Boedo, J. A.; Lipschultz, B.; Tcv Team; Eurofusion Mst1 Team

    2017-10-01

    To ensure safe power exhaust in future fusion reactors will require, at the least, partially detached divertor operation. To further understand the dynamics of this process, we investigate detachment on TCV in a lower single-null geometry by examining the evolution of the profiles of plasma density, temperature, and pressure at the outboard midplane (``upstream'') and at the outer strikepoint (``target''). A fast reciprocating probe is plunged at different times of reproducible discharges throughout the detachment process. Its measurements are compared with target measurements from probes and infrared thermography. As expected, the roll-over of the ion flux, often used experimentally to identify detachment, coincides with a pressure drop along the field lines. This is compared quantitatively with expectations from an extended two-point model where radiation and momentum losses are evaluated from bolometry and probe data. The roll-over coincides with the onset of ``density shoulders'' at the outer midplane. These are observed in the upstream density profiles and in bolometric and AXUV measurements, that show a radiation increase at the outer midplane. The application of these findings to detachment in advanced divertor geometries will be discussed. See the author list of S. Coda et al., 2017 Nucl. Fusion 57 102011.

  20. On synthesis and optimization of steam system networks. 3. Pressure drop consideration

    CSIR Research Space (South Africa)

    Price, T

    2010-08-01

    Full Text Available the likes of pipes and heat exchangers. Pressure drop correlations are therefore needed in the form of constraints so as to incorporate this into the optimization framework. Many correlations exist in litera- ture; however, those used by Kim and Smith2....2. Piping Pressure Drop. Kim and Smith2 define the piping pressure drop according to constraint 5. This is derived from commonly used pressure drop correlations, as well as a friction factor by Hewit et al.12 to approximate the Fanning Figure 1. Typical...

  1. On the pressure drop in Plate Heat Exchangers used as desorbers in absorption chillers

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Hernando, N.; de Vega, M. [Energy System Engineering (ISE), Departamento de Ingenieria Termica y de Fluidos, Universidad Carlos III de Madrid, Avda. Universidad, 30, 28911 Leganes, Madrid (Spain); Almendros-Ibanez, J.A. [Escuela de Ingenieros Industriales de Albacete, Departamento de Mecanica Aplicada e Ingenieria de Proyectos, Universidad de Castilla La Mancha, Campus Universitario s/n, 02071 Albacete (Spain); Renewable Energy Research Institute, c/de la Investigacion s/n, 02071 Albacete (Spain); Ruiz, G. [Energy Efficiency and Renewables Department, Tecnicas Reunidas S.A., C/Arapiles No. 13, 10a, 28015 Madrid (Spain)

    2011-02-15

    The influence of the pressure drop in Plate Heat Exchangers (PHE) in the boiling temperature of LiBr-H{sub 2}O and NH{sub 3}-H{sub 2}O solutions is studied. For the NH{sub 3}-H{sub 2}O solution, the pressure drop-temperature saturation relationship estates that high pressure drops can be allowed in the solution with negligible changes in the saturation temperature, and in the PHE performance. Besides, in the case of the LiBr-H{sub 2}O solution, as the working pressure is usually very low, the analysis of the pressure drop must be taken as a main limiting parameter for the use of Plate Heat Exchangers as vapour generators. In this case, the pressure drop may considerably change the boiling temperature of the solution entering the heat exchanger and therefore a higher heating fluid temperature may be required. A guideline to design these systems is proposed. (author)

  2. Determining cyclone particle holdup by pressure Drop for a CFB boiler

    Energy Technology Data Exchange (ETDEWEB)

    Li, S.H.; Zhang, H.; Yang, H.R.; Yang, S.; Lu, J.F.; Yue, G.X. [Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing (China)

    2007-12-15

    An experimental study was conducted to assess the possibility of determining particle holdup by measuring the pressure drop of a conventional cyclone used in a circulating fluidized bed (CFB) boiler. It was found that within a wide range of inlet solid concentrations, i.e., 0.54-4.42 kg/kg-gas, the cyclone pressure drop increased linearly with inlet solid concentration at a given gas velocity, while the pressure drop between the dust exit and the vortex finder of the cyclone remained almost constant. Since particle holdup increases virtually linearly with solid flow rate, the particle holdup in the cyclone can be derived from the cyclone pressure drop, and therefore, an equation set was proposed to calculate the particle holdup from the cyclone pressure drop. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  3. Rapid determination of caffeine in one drop of beverages and foods using drop-to-drop solvent microextraction with gas chromatography/mass spectrometry.

    Science.gov (United States)

    Shrivas, Kamlesh; Wu, Hui-Fen

    2007-11-02

    A simple and rapid sample cleanup and preconcentration method for the quantitative determination of caffeine in one drop of beverages and foods by gas chromatography/mass spectrometry (GC/MS) has been proposed using drop-to-drop solvent microextraction (DDSME). The best optimum experimental conditions for DDSME were: chloroform as the extraction solvent, 5 min extraction time, 0.5 microL exposure volume of the extraction phase and no salt addition at room temperature. The optimized methodology exhibited good linearity between 0.05 and 5.0 microg/mL with correlation coefficient of 0.980. The relative standard deviation (RSD) and limits of detection (LOD) of the DDSME/GC/MS method were 4.4% and 4.0 ng/mL, respectively. Relative recovery of caffeine in beverages and foods were found to be 96.6-101%, which showing good reliability of this method. This DDSME excludes the major disadvantages of conventional method of caffeine extraction, like large amount of organic solvent and sample consumption and long sample pre-treatment process. So, this approach proves that the DDSME/GC/MS technique can be applied as a simple, fast and feasible diagnosis tool for environmental, food and biological application for extremely small amount of real sample analysis.

  4. LHe Flow Regime/Pressure Drop for D0 Solenoid at Steady State Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Rucinski, R.; /Fermilab

    1993-03-03

    This paper describes in a note taking format what was learned from several sources on two phase liquid helium flow regimes and pressure drops as applied to the D-Zero solenoid upgrade project. Calculations to estimate the steady state conditions for the D-Zero solenoid at 5, 10 and 15 g/s are also presented. For the lower flow rates a stratified type regime can be expected with a pressure drop less than 0.5 psi. For the higher flow rate a more homogeneous flow regime can be expected with a pressure drop between 0.4 to 1.5 psi.

  5. Two-phase pressure drops for CANDU fuel bundles in uncrept and crept channels

    Energy Technology Data Exchange (ETDEWEB)

    Sutradhar, S.C. [Atomic Energy of Canada Ltd., Chalk River, Ontario (Canada)

    2001-07-01

    Pressure-drop tests in Freon-134a were performed on aligned and misaligned 37-element CANDU (C6) fuel bundles in uncrept and 3% crept channels. The results indicate that the two-phase pressure-drop profiles are similar in shape, but higher in magnitude, compared with the single-phase pressure-drop profiles. The two-phase multipliers (TPMs) are a strong function of the thermodynamic quality of the fluid. The measured TPMs of the bundles in the uncrept channel are higher than those in the crept channel. The measured TPMs for the aligned bundles agree well with the Beattie correlation. (author)

  6. Effects of 4-lobe swirl-inducing pipe on pressure drop

    OpenAIRE

    George, Dickson Dungau

    2008-01-01

    This thesis describes the effects of the 4-lobe swirl-inducing pipe on pressure drops for water, sand-water slurry and carboxymethyl cellulose fluids. The pressure drops were measured for two 4-lobe swirl-inducing pipe combined, one 4-lobe swirl-inducing pipe and without swirl-inducing pipe. The swirling pipe applications were installed before a bend on radius-to-diameter (R/D) ratio of 4. The pressure drops were measured on three different locations, before and after the 4-lobe swirl-inducin...

  7. Extraction of essential oils from Algerian myrtle leaves using instant controlled pressure drop technology.

    Science.gov (United States)

    Berka-Zougali, Baya; Hassani, Aicha; Besombes, Colette; Allaf, Karim

    2010-10-01

    In the present work, the new extraction process of Détente Instantanée Contrôlée DIC (French, for instant controlled pressure drop) was studied, developed, quantitatively and qualitatively compared to the conventional hydrodistillation method for the extraction of essential oils from Algerian myrtle leaves. DIC was used as a thermomechanical treatment, DIC subjecting the product to a high-pressure saturated steam. The DIC cycle ends with an abrupt pressure drop towards vacuum, and this instantly leads to an autovaporization of myrtle volatile compounds. An immediate condensation in the vacuum tank produced a micro-emulsion of water and essential oils. Thus, an ultra-rapid cooling of residual leaves occurred, precluding any thermal degradation. An experimental protocol was designed with 3 independent variables: saturated steam pressure between 0.1 and 0.6 MPa, resulting in a temperature between 100 and 160°C, a total thermal processing time between 19 and 221 s, and between 2 and 6 DIC cycles. The essential oils yield was defined as the main dependent variable. This direct extraction gave high yields and high quality essential oil, as revealed by composition and antioxidant activity (results not shown). After this treatment, the myrtle leaves were recovered and hydrodistilled in order to quantify the essential oil content in residual DIC-treated samples. Scanning electron microscope (SEM) showed some modification of the structure with a slight destruction of cell walls after DIC treatment. Copyright © 2010 Elsevier B.V. All rights reserved.

  8. Pressure drop increase by biofilm accumulation in spiral wound RO and NF membrane systems: role of substrate concentration, flow velocity, substrate load and flow direction.

    Science.gov (United States)

    Vrouwenvelder, J S; Hinrichs, C; Van der Meer, W G J; Van Loosdrecht, M C M; Kruithof, J C

    2009-01-01

    In an earlier study, it was shown that biofouling predominantly is a feed spacer channel problem. In this article, pressure drop development and biofilm accumulation in membrane fouling simulators have been studied without permeate production as a function of the process parameters substrate concentration, linear flow velocity, substrate load and flow direction. At the applied substrate concentration range, 100-400 microg l(-1) as acetate carbon, a higher concentration caused a faster and greater pressure drop increase and a greater accumulation of biomass. Within the range of linear flow velocities as applied in practice, a higher linear flow velocity resulted in a higher initial pressure drop in addition to a more rapid and greater pressure drop increase and biomass accumulation. Reduction of the linear flow velocity resulted in an instantaneous reduction of the pressure drop caused by the accumulated biomass, without changing the biofilm concentration. A higher substrate load (product of substrate concentration and flow velocity) was related to biomass accumulation. The effect of the same amount of accumulated biomass on the pressure drop increase was related to the linear flow velocity. A decrease of substrate load caused a gradual decline in time of both biomass concentration and pressure drop increase. It was concluded that the pressure drop increase over spiral wound reverse osmosis (RO) and nanofiltration (NF) membrane systems can be reduced by lowering both substrate load and linear flow velocity. There is a need for RO and NF systems with a low pressure drop increase irrespective of the biomass formation. Current efforts to control biofouling of spiral wound membranes focus in addition to pretreatment on membrane improvement. According to these authors, adaptation of the hydrodynamics, spacers and pressure vessel configuration offer promising alternatives. Additional approaches may be replacing heavily biofouled elements and flow direction reversal.

  9. Effect of static mixer geometry on flow mixing and pressure drop in marine scr applications

    Directory of Open Access Journals (Sweden)

    Park Taewha

    2014-03-01

    Full Text Available Flow mixing and pressure drop characteristics for marine selective catalytic reduction applications were investigated numerically to develop an efficient static mixer. Two different mixers, line- and swirl-type, were considered. The effect of vane angles on the relative intensity, uniformity index, and pressure drop was investigated in a swirl-type mixer; these parameters are dramatically affected by the mixer geometry. The presence of a mixer, regardless of the mixer type, led to an improvement of approximately 20% in the mixing performance behind the mixer in comparison to not having a mixer. In particular, there was a tradeoff relationship between the uniformity and the pressure drop. Con­sidering the mixing performance and the pressure drop, the swirl-type mixer was more suitable than the line-type mixer in this study.

  10. Effect of static mixer geometry on flow mixing and pressure drop in marine scr applications

    Science.gov (United States)

    Park, Taewha; Sung, Yonmo; Kim, Taekyung; Lee, Inwon; Choi, Gyungmin; Kim, Duckjool

    2014-03-01

    Flow mixing and pressure drop characteristics for marine selective catalytic reduction applications were investigated numerically to develop an efficient static mixer. Two different mixers, line- and swirl-type, were considered. The effect of vane angles on the relative intensity, uniformity index, and pressure drop was investigated in a swirl-type mixer; these parameters are dramatically affected by the mixer geometry. The presence of a mixer, regardless of the mixer type, led to an improvement of approximately 20% in the mixing performance behind the mixer in comparison to not having a mixer. In particular, there was a tradeoff relationship between the uniformity and the pressure drop. Con­sidering the mixing performance and the pressure drop, the swirl-type mixer was more suitable than the line-type mixer in this study.

  11. Effect of static mixer geometry on flow mixing and pressure drop in marine SCR applications

    Directory of Open Access Journals (Sweden)

    Taewha Park

    2014-03-01

    Full Text Available Flow mixing and pressure drop characteristics for marine selective catalytic reduction applications were investigated numerically to develop an efficient static mixer. Two different mixers, line- and swirl-type, were considered. The effect of vane angles on the relative intensity, uniformity index, and pressure drop was investigated in a swirl-type mixer; these parameters are dramatically affected by the mixer geometry. The presence of a mixer, regardless of the mixer type, led to an improvement of approximately 20% in the mixing performance behind the mixer in comparison to not having a mixer. In particular, there was a tradeoff relationship between the uniformity and the pressure drop. Considering the mixing performance and the pressure drop, the swirl-type mixer was more suitable than the line-type mixer in this study.

  12. Two-phase pressure drop during CO{sub 2} vaporization in horizontal smooth minichannels

    Energy Technology Data Exchange (ETDEWEB)

    Pamitran, A.S.; Choi, Kwang-Il [Graduate School, Chonnam National University, San 96-1, Dunduk-Dong, Yeosu, Chonnam 550-749 (Korea); Oh, Jong-Taek [Department of Refrigeration and Air Conditioning Engineering, Chonnam National University, San 96-1, Dunduk-dong, Yeosu, Chonnam 550-749 (Korea); Oh, Hoo-Kyu [Department of Refrigeration and Air Conditioning Engineering, Pukyong National University, 100, Yongdang-dong, Nam-Ku, Busan 608-739 (Korea)

    2008-12-15

    Pressure drop experiments for a natural refrigerant vaporization of CO{sub 2} were performed in horizontal minichannels. The test section was made of stainless steel tubes with inner diameters of 1.5 mm and 3.0 mm and with lengths of 2000 and 3000 mm. This test section was uniformly heated by applying electric current directly to the tubes. Experiments were performed at inlet saturation temperatures of -10, -5 and 10 C, mass flux ranges from 200 to 600 kg m{sup -2} s{sup -1} and heat flux ranges from 10 to 30 kW m{sup -2}. The current study showed the significant effect of mass flux, tube diameter, and saturation temperature on the pressure drop. The experimental results were compared against 13 existing two-phase pressure drop prediction methods. A new pressure drop prediction method based on the Lockhart-Martinelli method was developed with 9.41% mean deviation. (author)

  13. Study on Pressure drop for Ion Exchanger in Jordan Research and Training Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Park, Ki-jung; Choi, Jungwoon; Kim, Seong-Hoon; Chi, Dae-Young; Park, Cheol [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    The Jordan Research and Training Reactor (JRTR) is currently being constructed and commissioned in the JUST (Jordan University of Science and Technology) site. The main fluid systems relevant to the JRTR have been proceeding at the Korea Atomic Energy Research Institute. In order to achieve the purpose of the pool water purification, two filters and two ion exchangers which can be to remove suspended solids and ionic impurities in the in-taken pool water have been designed. For the reliable design of this system pump, it is important to predict the pressure drop of the system equipment including the ion exchanger. In this study, the pressure drop in the ion exchanger of PWMS is predicted by using the well-known model and the results provided from manufacturing company. And, the calculated results are compared to the actual data which is measured from the ion exchanger during the PWMS commissioning. The predicted pressure drop is dominated by the resin bed as a portion of about 85% for total pressure drop. The predicted pressure drop is compared to the measured pressure drop of the ion exchanger which is installed in the JRTR, the data above 5 kg/s agree within 5% in the entire range.

  14. Sludge pipe flow pressure drop prediction using composite power ...

    African Journals Online (AJOL)

    2011-09-30

    , pressure gradient, sludge rheology. Notation ... This paper describes the application of a tech- nique presented by Garcia et al. ..... composite power law fric- tion factor correlations for laminar and turbulent gas–liquid flow in.

  15. Drops in Barometric Pressure Are Associated with Deep Intracerebral Hemorrhage.

    Science.gov (United States)

    Honig, Asaf; Eliahou, Ruth; Pikkel, Yoav Y; Leker, Ronen R

    2016-04-01

    The objective of this study is to assess the effects of changes in barometric pressure and outdoor temperature on the incidence of different subtypes of intracerebral hemorrhage (ICH). Consecutive patients with primary supratentorial ICH were included. All patients resided in the same geographic area. We compared patients with subcortical ICH to those with cortical ICH. Meteorological data were continuously accrued. High-risk ICH days were defined as those on which 1 or more patients with ICH were admitted and compared to non-high-risk days. We analyzed the relationship between spontaneous ICH location and averaged daily atmospheric pressures and temperatures. We included 206 patients (147 with deep ICH and 59 with lobar ICH). Patients with deep ICH were younger (P pressure 2 days prior to the ictus were associated with deep but not lobar ICH (P = .006). Deep ICH clustered during February months in parallel with larger changes in barometric pressures (P pressures were associated with deep but not cortical ICH, suggesting a link to hypertensive etiology. Changes in barometric pressures were also associated with higher monthly frequencies of ICH. Copyright © 2016 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  16. PDC Bit Hydraulic & Mud Rheological simulation to model pressure drop across Bit

    Directory of Open Access Journals (Sweden)

    Kai Sheng Ong

    2017-01-01

    Full Text Available During fluid flow from larger to smaller diameter pipes, a drop in pressure is experienced. High pressure drop across bit indicated high energy loss in the hydraulic system and also a setback to ROP performance. This is inefficient and pressure pumps would have to be of bigger sizing to make up for the losses. Present form of pressure drop models is in terms of mud density, flow rate, and total flow area. The objective of this paper is focused on the analysis of CFD simulation and to propose optimized parameters for improved ROP. Single phase flow study of Yield Power Law mud rheology was simulated at bottom hole of horizontal section. Parametric study on mud rheology was carried using DOE. Design points of DOE were sampled mostly using Latin Hypercube Sampling and a few by Central Composite Design. It is found that Kriging Response Surface method generated the best regression model where the predicted values are closest to the observed values and has the lowest Maximum Relative Residual (0.000336%. Inlet velocity and Power Index have significant effect on pressure drop. Consistency Index showed moderate effect while Yield Stress showed small effect to pressure drop. This research has proven that pressure loss model should take into account of mud rheology. Further research can be done with PDC bit rotation and its effect on mud behaviour.

  17. Internal rupture and rapid bouncing of impacting drops induced by submillimeter-scale textures

    Science.gov (United States)

    Zhang, Rui; Zhang, Xiwen; Hao, Pengfei; He, Feng

    2017-06-01

    We demonstrate an internal breakup mechanism for high Weber number drop impact on superhydrophobic surfaces uniformly patterned with submillimeter-scale textures, in which the liquid film ruptures from both interior and rim. The employment of submillimeter-scale posts could help decrease the critical Weber number of internal rupture, due to the small solid fraction and the large dimension ratio between primary structures and droplets. The internal rupture is found to promote more rapid drop bouncing than conventional rebound and rim breakup on superhydrophobic surfaces with small roughness, with a 10%-50% reduction of contact time. The internal rupture results from the film instability inside and the jet instability outside.

  18. Internal rupture and rapid bouncing of impacting drops induced by submillimeter-scale textures.

    Science.gov (United States)

    Zhang, Rui; Zhang, Xiwen; Hao, Pengfei; He, Feng

    2017-06-01

    We demonstrate an internal breakup mechanism for high Weber number drop impact on superhydrophobic surfaces uniformly patterned with submillimeter-scale textures, in which the liquid film ruptures from both interior and rim. The employment of submillimeter-scale posts could help decrease the critical Weber number of internal rupture, due to the small solid fraction and the large dimension ratio between primary structures and droplets. The internal rupture is found to promote more rapid drop bouncing than conventional rebound and rim breakup on superhydrophobic surfaces with small roughness, with a 10%-50% reduction of contact time. The internal rupture results from the film instability inside and the jet instability outside.

  19. Novel cyclone empirical pressure drop and emissions with heterogeneous particulate

    Science.gov (United States)

    New cyclone designs equally effective at controlling emissions that have smaller pressure losses would reduce both the financial and the environmental cost of procuring electricity. Tests were conducted with novel and industry standard 30.5 cm diameter cyclones at inlet velocities from 8 to 18 m s-...

  20. Experimental Investigation of the Effect of Particle Shape on Frictional Pressure drop in Particulate Debris Bed

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jin Ho; Kim, Eun Ho; Park, Hyun Sun [POSTECH, Pohang (Korea, Republic of)

    2014-10-15

    To ensure the long-term cooling of corium in the reactor cavity, it is important to ensure the coolant ingression into the internally heat generated corium debris bed which is governed by pressure drop in porous media. For this reason, it is necessary to understand pressure drop mechanisms in porous bed to verify the feasibility of water penetration into particulate debris bed. According to the previous investigations on molten fuel-coolant interaction (FCI) experiments, it was found that quenched particulate debris bed was composed of irregular shape particles. Therefore, empirical or semiempirical models based on the Ergun equation (Ergun, 1952) for single-phase flow in porous media composed of single sized spherical particle were developed to consider the effect of particle shape on frictional pressure drop by means of adding a shape factor or modifying the Ergun constants etc. (Leva, 1959, Handley and Heggs, 1968, Macdonald, 1979, Foumeny et al., 1996). An experimental investigate on single-phase frictional pressure drop of water in packed bed was conducted in the transparent cylindrical test section with the inner diameter of 100 mm and the height of 700 mm to study the effect of particle shape on frictional pressure drop in porous media. This paper reports the experimental data for spherical particles with the diameter of 2 mm and 5 mm and cylindrical particles with ED of 2 mm and 5 mm. And also, the experimental data compared with the models to predict frictional pressure drop in particulate bed. The conclusions are summarized as follows. As a result of the experiment to measure frictional pressure drop in particulate bed composed of cylindrical particles the models predict the experimental data well within 22.11 % except the Handley and Heggs model when ED is applied to the models.

  1. Study of nitrogen two-phase flow pressure drop in horizontal and vertical orientation

    Science.gov (United States)

    Koettig, T.; Kirsch, H.; Santandrea, D.; Bremer, J.

    2017-12-01

    The large-scale liquid argon Short Baseline Neutrino Far-detector located at Fermilab is designed to detect neutrinos allowing research in the field of neutrino oscillations. It will be filled with liquid argon and operate at almost ambient pressure. Consequently, its operation temperature is determined at about 87 K. The detector will be surrounded by a thermal shield, which is actively cooled with boiling nitrogen at a pressure of about 2.8 bar absolute, the respective saturation pressure of nitrogen. Due to strict temperature gradient constraints, it is important to study the two-phase flow pressure drop of nitrogen along the cooling circuit of the thermal shield in different orientations of the flow with respect to gravity. An experimental setup has been built in order to determine the two-phase flow pressure drop in nitrogen in horizontal, vertical upward and vertical downward direction. The measurements have been conducted under quasi-adiabatic conditions and at a saturation pressure of 2.8 bar absolute. The mass velocity has been varied in the range of 20 kg·m‑2·s‑1 to 70 kg·m‑2·s‑1 and the pressure drop data has been recorded scanning the two-phase region from vapor qualities close to zero up to 0.7. The experimental data will be compared with several established predictions of pressure drop e.g. Mueller-Steinhagen and Heck by using the void fraction correlation of Rouhani.

  2. Two-Phase Pressure Drop of a Refrigerant Flowing Vertically Downward in a Mini-channel

    Science.gov (United States)

    Miyata, Kazushi; Enoki, Koji; Mori, Hideo; Hamamoto, Yoshinori

    Experiments were performed on two-phase pressure drop of a refrigerant R-410A flowing vertically downward in small copper circular tubes with 0.5-2.0 mm I.D., and small copper rectangular and triangular tubes with 1.04 and 0.88 mm inner hydraulic equivalent diameter, respectively, for the development of a high-performance heat exchanger using small tubes or multi-port extruded tubes for air conditioning systems.Pressure drops were measured and flow patterns were observed in the range of mass flux from 30 to 400 kg/(m2s)and quality from 0.1 to 0.9 at the saturation temperature of 10 °C. Characteristics of measured pressure drops were examined for different flow channel geometries. In high quality region or relatively high mass flux condition, the frictional pressure drop was reproduced well by the Lockhart-Martinelli correlation used together with a new correlation for Chisholm's parameter C as a function of hydraulic equivalent diameter. In low mass flux and low quality region, the frictional pressure drop was also reproduced well by multiplying the Chisholm two-phase multiplier factor by modified coefficient. In addition, flow pattern was observed with 0.5 and 2.0 mm I.D circular glass tubes. Slug flow and annular flow patterns were observed at lower and higher quality, respectively.

  3. Visualization of the drop deformation and break-up process in a high pressure homogenizer

    Energy Technology Data Exchange (ETDEWEB)

    Innings, F. [Tetra Pak Processing Systems, Ruben Rausings gata, SE-221 86 Lund (Sweden); Traegaardh, C. [Lund University, Box 124, SE-221 00 Lund (Sweden)

    2005-08-01

    For the creation of sub-micron emulsions in fluids of low viscosity the high pressure homogenizer (HPH) is usually chosen. One way of obtaining deeper knowledge of exactly what happens in the active region is to visualize it. In this work, a drop deformation and break-up visualization system based on a modified Particle Image Velocimetry (PIV) system is described. The system reproduces the gap in a HPH and has been used with pressures up to 18 MPa and drops as small as 5 {mu}m. The optics of the system are analyzed taking into account limiting factors such as the lens resolving power, the focal depth, and the duration of the laser pulses. It is shown that it is possible to resolve drops down to a few {mu}m moving in excess of 100 m/s, and that the main limitations are the resolving power and in the focal depth of the objectives. Examples are shown from capillary drop creation and from the deformation and break-up of drops in a HPH. It can be concluded that in a HPH, the drops are only deformed to a limited extent in the inlet of the gap, and that all drop break-up occurs far downstream of the gap. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

  4. Nucleate boiling pressure drop in an annulus: Book 5

    Energy Technology Data Exchange (ETDEWEB)

    1992-11-01

    The application of the work described in this report is the production reactors at the Savannah River Site, and the context is nuclear reactor safety. The Loss of Coolant Accident (LOCA) scenario considered involves a double-ended break of a primary coolant pipe in the reactor. During a LOCA, the flow through portions of the reactor may reverse direction or be greatly reduced, depending upon the location of the break. The reduced flow rate of coolant (D{sub 2}O) through the fuel assembly channels of the reactor -- downflow in this situation -- can lead to boiling and to the potential for flow instabilities which may cause some of the fuel assembly channels to overheat and melt. That situation is to be avoided. The experimental approach is to provide a test annulus which simulates geometry, materials, and flow conditions in a Mark-22 fuel assembly (Coolant Channel 3) to the extent possible. The key analysis approaches are: To compare the minima in the measured demand curves with analytical criteria, in particular the Saha-Zuber (1974) model; and to compare the pressure and temperature as a function of length in the annulus with an integral model for flow boiling in a heated channel. Nineteen test series and a total of 178 tests were performed. Testing addressed the effects of: Heat flux; pressure; helium gas; power tilt; ribs; asymmetric heat flux. This document consists solely of the plato file index from 11/87 to 11/90.

  5. Single and two-phase flow pressure drop for CANFLEX bundle

    Energy Technology Data Exchange (ETDEWEB)

    Park, Joo Hwan; Jun, Ji Su; Suk, Ho Chun [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of); Dimmick, G. R.; Bullock, D. E. [Atomic Energy of Canada Limited, Ontario (Canada)

    1998-12-31

    Friction factor and two-phase flow frictional multiplier for a CANFLEX bundle are newly developed and presented in this paper. CANFLEX as a 43-element fuel bundle has been developed jointly by AECL/KAERI to provide greater operational flexibility for CANDU reactor operators and designers. Friction factor and two-phase flow frictional multiplier have been developed by using the experimental data of pressure drops obtained from two series of Freon-134a (R-134a) CHF tests with a string of simulated CANFLEX bundles in a single phase and a two-phase flow conditions. The friction factor for a CANFLEX bundle is found to be about 20% higher than that of Blasius for a smooth circular pipe. The pressure drop predicted by using the new correlations of friction factor and two-phase frictional multiplier are well agreed with the experimental pressure drop data of CANFLEX bundle within {+-} 5% error. 11 refs., 5 figs. (Author)

  6. An improved correlation of the pressure drop in stenotic vessels using Lorentz's reciprocal theorem

    Science.gov (United States)

    Ji, Chang-Jin; Sugiyama, Kazuyasu; Noda, Shigeho; He, Ying; Himeno, Ryutaro

    2015-02-01

    A mathematical model of the human cardiovascular system in conjunction with an accurate lumped model for a stenosis can provide better insights into the pressure wave propagation at pathological conditions. In this study, a theoretical relation between pressure drop and flow rate based on Lorentz's reciprocal theorem is derived, which offers an identity to describe the relevance of the geometry and the convective momentum transport to the drag force. A voxel-based simulator V-FLOW VOF3D, where the vessel geometry is expressed by using volume of fluid (VOF) functions, is employed to find the flow distribution in an idealized stenosis vessel and the identity was validated numerically. It is revealed from the correlation that the pressure drop of NS flow in a stenosis vessel can be decomposed into a linear term caused by Stokes flow with the same boundary conditions, and two nonlinear terms. Furthermore, the linear term for the pressure drop of Stokes flow can be summarized as a correlation by using a modified equation of lubrication theory, which gives favorable results compared to the numerical ones. The contribution of the nonlinear terms to the pressure drop was analyzed numerically, and it is found that geometric shape and momentum transport are the primary factors for the enhancement of drag force. This work paves a way to simulate the blood flow and pressure propagation under different stenosis conditions by using 1D mathematical model.

  7. Experimental and numerical studies on pressure drop in reverse electrodialysis: Effect of unit cell configuration

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sung Kook; Choi, Kyung Soo [Advanced Combustion Laboratory, Korea Institute of Energy Research, Daejeon (Korea, Republic of); Kim, Chan Soo; Hwang, Kyo Sik; Han, Ji Hyung; Kim, Han Ki; Jeong, Nam Jo [Jeju Global Research Center, Korea Institute of Energy Research, Jeju (Korea, Republic of)

    2016-11-15

    Experimental and numerical studies on pressure drop in Reverse electrodialysis (RED) were performed. In this study, a module with 200 unit cells is considered for the demonstration of bench-scale RED module and two different unit cell configurations are utilized. Pressure drop through the module is measured by varying flow rates. For evaluating the hydrodynamic characteristics in the unit cell, a numerical simulation is also conducted and the simplified method using a porous media model is employed to simulate the channel filled with spacer. Due to the insertion of spacer and narrow channel, great pressure loss occurs along the unit cell. Based on estimated pressure data, high pressure difference between seawater and fresh water channel takes place locally in the unit cell configuration with crossflow direction, leading to a leakage problem through the membrane and finally degradation in the output power. Consequently, it is confirmed that the unit cell configuration is one of the important design parameters in a RED module.

  8. Nucleate boiling pressure drop in an annulus: Book 7

    Energy Technology Data Exchange (ETDEWEB)

    1992-11-01

    The application of the work described in this report is the production reactors at the Savannah River Site, and the context is nuclear reactor safety. The Loss of Coolant Accident (LOCA) scenario considered involves a double-ended break of a primary coolant pipe in the reactor. During a LOCA, the flow through portions of the reactor may reverse direction or be greatly reduced, depending upon the location of the break. The reduced flow rate of coolant (D{sub 2}O) through the fuel assembly channels of the reactor -- downflow in this situation -- can lead to boiling and to the potential for flow instabilities which may cause some of the fuel assembly channels to overheat and melt. That situation is to be avoided. The experimental approach is to provide a test annulus which simulates geometry, materials, and flow conditions in a Mark-22 fuel assembly (Coolant Channel 3) to the extent possible. The annulus has a full-scale geometry, and in fat uses SRL dummy hardware for the inner annulus wall in the ribbed geometry. The materials aluminum. The annulus is uniformly heated in the axial direction, but the circumferential heat flux can be varied to provide ``power tilt`` or asymmetric heating of the inner and outer annulus walls. The test facility uses H{sub 2}O rather than D{sub 2}O, but it includes the effects of dissolved helium gas present in the reactor. The key analysis approaches are: To compare the minima in the measured demand curves with analytical criteria, in particular the Saha-Zuber (1974) model; and to compare the pressure and temperature as a function of length in the annulus with an integral model for flow boiling in a heated channel. This document consists solely of tables of temperature measurements; minima, maxima, averages and standard deviations being measured.

  9. Nucleate boiling pressure drop in an annulus: Book 4

    Energy Technology Data Exchange (ETDEWEB)

    Block, J.A.; Crowley, C.; Dolan, F.X.; Sam, R.G.; Stoedefalke, B.H.

    1992-11-01

    The application of the work described in this report is the production reactors at the Savannah River Site, and the context is nuclear reactor safety. The Loss of Coolant Accident (LOCA) scenario considered involves a double-ended break of a primary coolant pipe in the reactor. During a LOCA, the flow through portions of the reactor may reverse direction or be greatly reduced, depending upon the location of the break. The reduced flow rate of coolant (D{sub 2}O) through the fuel assembly channels of the reactor -- downflow in this situation -- can lead to boiling and to the potential for flow instabilities which may cause some of the fuel assembly channels to overheat and melt. That situation is to be avoided. The experimental approach is to provide a test annulus which simulates geometry, materials, and flow conditions in a Mark-22 fuel assembly (Coolant Channel 3) to the extent possible. The annulus has a full-scale geometry, and in fat uses SRL dummy hardware for the inner annulus wall in the ribbed geometry. The materials aluminum. The annulus is uniformly heated in the axial direction, but the circumferential heat flux can be varied to provide ``power tilt`` or asymmetric heating of the inner and outer annulus walls. The test facility uses H{sub 2}O rather than D{sub 2}O, but it includes the effects of dissolved helium gas present in the reactor. The key analysis approaches are: To compare the minima in the measured demand curves with analytical criteria, in particular the Saha-Zuber (1974) model; and to compare the pressure and temperature as a function of length in the annulus with an integral model for flow boiling in a heated channel. This document consists of data plots and summary files of temperature measurements.

  10. Nucleate boiling pressure drop in an annulus: Book 3

    Energy Technology Data Exchange (ETDEWEB)

    Block, J.A.; Crowley, C.; Dolan, F.X.; Sam, R.G.; Stoedefalke, B.H.

    1992-11-01

    The application of the work described in this report is the production reactors at the Savannah River Site, and the context is nuclear reactor safety. The Loss of Coolant Accident (LOCA) scenario considered involves a double-ended break of a primary coolant pipe in the reactor. During a LOCA, the flow through portions of the reactor may reverse direction or be greatly reduced, depending upon the location of the break. The reduced flow rate of coolant (D{sub 2}O) through the fuel assembly channels of the reactor -- downflow in this situation -- can lead to boiling and to the potential for flow instabilities which may cause some of the fuel assembly channels to overheat and melt. That situation is to be avoided. The experimental approach is to provide a test annulus which simulates geometry, materials, and flow conditions in a Mark-22 fuel assembly (Coolant Channel 3) to the extent possible. The annulus has a full-scale geometry, and in fat uses SRL dummy hardware for the inner annulus wall in the ribbed geometry. The materials aluminum. The annulus is uniformly heated in the axial direction, but the circumferential heat flux can be varied to provide ``power tilt`` or asymmetric heating of the inner and outer annulus walls. The test facility uses H{sub 2}O rather than D{sub 2}O, but it includes the effects of dissolved helium gas present in the reactor. The key analysis approaches are: To compare the minima in the measured demand curves with analytical criteria, in particular the Saha-Zuber (1974) model; and to compare the pressure and temperature as a function of length in the annulus with an integral model for flow boiling in a heated channel. This document consists of data plots and summary files of temperature measurements.

  11. Experimental and visual study on flow patterns and pressure drops in U-tubes

    Energy Technology Data Exchange (ETDEWEB)

    Da Silva Lima, J. R.

    2011-07-01

    In single- and two-phase flow heat exchangers (in particular 'coils'), besides the straight tubes there are also many singularities, in particular the 180° return bends (also called return bends or U-bends). However, contrary to the literature concerning pressure drops and heat transfer in straight tubes, where many experimental data and predicting methods are available, only a limited number of studies concerning U-bends can be found. Neither reliable experimental data nor proven prediction methods are available. Indeed, flow structure, pressure drop and heat transfer in U-bends are an old unresolved design problem in the heat transfer industry. Thus, the present study aims at providing further insight on two-phase pressure drops and flows patterns in U-bends. Based on a new type of U-bend test section, an extensive experimental study was conducted. The experimental campaign covered five test sections with three internal diameters (7.8, 10.8 and 13.4 mm), five bend diameters (24.8, 31.7, 38.1, 54.8 and 66.1 mm), tested for three orientations (horizontal, vertical upflow and vertical downflow), two fluids (R134a and R410A), two saturation temperatures (5 and 10 °C) and mass velocities ranging from 150 to 1000 kg s{sup -1} m{sup -2}. The flow pattern observations identified were stratified-wavy, slug-stratified-wavy, intermittent, annular, dryout and mist flows. The effects of the U-bend on the flow patterns were also observed. A total of 5655 pressure drop data were measured at seven different locations in the test section ( straight tubes and U-bend) providing a total of almost 40,000 data points. The straight tube data were first used to improve the actual two-phase straight tube model of Moreno-Quibén and Thome. This updated model was then used to developed a two-phase U-bend pressure drop model. Based on a comparison between experimental and predicted values, it is concluded that the new two-phase frictional pressure drop model for U

  12. A new role for reduction in pressure drop in cyclones using computational fluid dynamics techniques

    Directory of Open Access Journals (Sweden)

    Noriler D.

    2004-01-01

    Full Text Available In this work a new mechanical device to improve the gas flow in cyclones by pressure drop reduction is presented and discussed. This behavior occurs due to the effects of introducing swirling breakdown phenomenon at the inlet of the vortex finder tube. The device consists of a tube with two gas inlets in an appositive spiral flux that produces a sudden reduction in the tangential velocity peak responsible for practically 80 % of the pressure drop in cyclones. In turn, peak reduction causes a decrease in pressure drop by a breakdown of the swirling, and because of this the solid particles tend to move faster toward the wall , increasing collection efficiency. As a result of this phenomenon the overall performance of cyclones is improved. Numerical simulations with 3-D, transient, asymmetric and anisotropic turbulence closure by differential Reynolds stress for Lapple and Stairmand standard geometries of 0.3 m in diameter, show a reduction in pressure drop of 20 % and a shift of the tangential velocity peak toward the wall. All numerical experiments were carried out with a commercial CFD code showing numerical stability and good convergence rates with high-order interpolation schemes, SIMPLEC pressure-velocity coupling and other numerical features.

  13. Theoretical study of flashing and water hammer in a supercritical water cycle during pressure drop

    Energy Technology Data Exchange (ETDEWEB)

    Imre, A.R., E-mail: imre@aeki.kfki.h [Simulator Laboratory, MTA KFKI Atomic Energy Research Institute, Budapest, POB 49, H-1525 (Hungary); Barna, I.F.; Ezsoel, G. [Thermohydraulics Laboratory, MTA KFKI Atomic Energy Research Institute, Budapest, POB 49, H-1525 (Hungary); Hazi, G. [Simulator Laboratory, MTA KFKI Atomic Energy Research Institute, Budapest, POB 49, H-1525 (Hungary); Kraska, T. [Institute for Physical Chemistry, University of Cologne, Luxemburger Str. 116, D-50939 Koeln (Germany)

    2010-06-15

    During a loss of coolant accident (LOCA) the pressure of the coolant can drop significantly in the vicinity of the leak. It will be shown that unlike in pressurized water reactors (PWRs) where this pressure drop can cause only sudden vaporization - also called flashing - in supercritical water cooled reactors (SCWRs) it can cause sudden condensation (condensation-induced water hammer), too. The reason is that from supercritical state the system can go to metastable liquid as well as to metastable vapour state after LOCA. Relaxation from metastable fluid states is a fast process, followed by a local positive or negative pressure-jump, which might increase the damage around the leak. Conservative estimation will be given for the magnitude of these pressure jumps caused by the flashing or water hammer by assuming various initial pressure losses. In our calculations, three different equations of state are used: the simple van der Waals EoS; the Redlich-Kwong as an empirical development; and the more sophisticated non-cubic Deiters equation of state. These equations are able to describe metastable states qualitatively but with different accuracy. These calculations can help us to map the local immediate effect of any sudden pressure drop and therefore it can help to design better safety protocols.

  14. A Numerical Study on Heat Transfer Enhancement and Pressure drop Decrease of Heat Exchanger by Setting Inserted Plates in Duct

    OpenAIRE

    AMBARITA, Himsar; KISHINAMI, Koki; SATO, Kazuhiko; DAIMARUYA, Masashi; SUGIYAMA, Hiromu; SUZUKI, Jun

    2005-01-01

    This present paper attempts to numerically estimate heat transfer enhancement and pressure drop decrease on a duct flow system of heat exchanger. Inserted plates inside the duct flow are proposed in order to enhance heat transfer coefficient, however the inserted plates cause a significant pressure drop, In order to decrease the pressure drop, the inserted plates with slits were employed. Numerical calculations of two-dimensional, laminar, and steady state conditions of duct flow with and wit...

  15. Testing of a 4 K to 2 K heat exchanger with an intermediate pressure drop

    Energy Technology Data Exchange (ETDEWEB)

    Knudsen, Peter N. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Ganni, Venkatarao [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2015-12-01

    Most large sub-atmospheric helium refrigeration systems incorporate a heat exchanger at the load, or in the distribution system, to counter-flow the sub-atmospheric return with the super-critical or liquid supply. A significant process improvement is theoretically obtainable by handling the exergy loss across the Joule-Thompson throttling valve supplying the flow to the load in a simple but different manner. As briefly outlined in previous publications, the exergy loss can be minimized by allowing the supply flow pressure to decrease to a sub-atmospheric pressure concurrent with heat exchange flow from the load. One practical implementation is to sub-divide the supply flow pressure drop between two heat exchanger sections, incorporating an intermediate pressure drop. Such a test is being performed at Jefferson Lab's Cryogenic Test Facility (CTF). This paper will briefly discuss the theory, practical implementation and test results and analysis obtained to date.

  16. A way to reduce pressure drop in once-through micro-evaporators

    NARCIS (Netherlands)

    Rops, C.; Oosterbaan, G.; Geld, C. van der

    2014-01-01

    This investigation explores the possibilities to reduce the pressure drop of a single-channel micro-evaporator. The availability of micro-technology to create three-dimensional structures at a micro-meter scale opens opportunities to better control process conditions in once-through boilers.

  17. Numerical investigation of a thick plate restriction orifice on the pressure drop performance

    Science.gov (United States)

    Yau, K. H.; Kua, E. C.; Balvinder, S.

    2017-09-01

    This paper presents a numerical study on the thick plate restriction orifice on the pressure drop performance due to various orifice ratio, β. The restriction orifice was investigated using commercial software package namely, ANSYS. The restriction orifice was modelled using built-in modeler and simulated using Fluent module. The orifice ratio, β was varied in the range of 0.5 to 0.75. Various flow velocities were applied from 50 to 420 m/s. The fluid flow in the constriction was hydrocarbon in vapour phase. The preliminary results of discharge coefficients were compared with literature and theoretical values between a sharp-edged and thick plate orifice to show a consistent trend. The results yielded that as the Reynolds number, Re increases, the pressure drop performance increases exponentially. This is more prominent at high Re of 8.75× 106 where the pressure drop increases by 63% from the baseline of Re number, 1.08×106 based on orifice ratio of 0.75. For a hydrocarbon with low rheological properties and high Re number, the orifice ratio, β is best at higher range of 0.75 which show a pressure drop of 0.18 MPa.

  18. A new correlation of two-phase frictional pressure drop for condensing flow in pipes

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yu; Fang, Xiande, E-mail: xd_fang@yahoo.com

    2013-10-15

    Highlights: • Survey of two-phase frictional pressure drop (THFPD) experimental data of condensing flow is conducted. • Applicability of the existing THFPD correlations to condensing flow is assessed. • A new THFPD correlation for condensing flow in pipes is proposed. -- Abstract: The calculation of two-phase frictional pressure drop for condensing flow in pipes is essential in many areas. Although numerous studies concerning this issue have been conducted, an accurate correlation is still required. In this paper, an overall survey of correlations and experimental investigations of two-phase frictional pressure drop is carried out. There 525 experimental data points of 9 refrigerants are gathered from literature, with hydraulic diameter from 0.1 to 10.07 mm, mass flux from 20 to 800 kg/m{sup 2} s, and heat flux from 2 to 55.3 kW/m{sup 2}. The 29 existing correlations are evaluated against the experimental database, among which the best one has a mean absolute relative deviation (MARD) of 25.2%. Based on all the experimental data, a new correlation which has an MARD of 19.4% is proposed, improving significantly the prediction of two-phase frictional pressure drop for pipe condensing flow.

  19. Fast and Accurate Pressure-Drop Prediction in Straightened Atherosclerotic Coronary Arteries

    NARCIS (Netherlands)

    J.T.C. Schrauwen (Jelle); D. Koeze (Dion); J.J. Wentzel (Jolanda); F.N. van de Vosse (Frans); A.F.W. van der Steen (Ton); F.J.H. Gijsen (Frank)

    2014-01-01

    textabstractAtherosclerotic disease progression in coronary arteries is influenced by wall shear stress. To compute patient-specific wall shear stress, computational fluid dynamics (CFD) is required. In this study we propose a method for computing the pressure-drop in regions proximal and distal to

  20. Experimental study and analysis of the purge gas pressure drop across the pebble beds for the fusion HCPB blanket

    Energy Technology Data Exchange (ETDEWEB)

    Abou-Sena, Ali, E-mail: ali.abou-sena@kit.edu [Karlsruhe Institute of Technology (KIT), Institute for Neutron Physics and Reactor Technology, Karlsruhe (Germany); Arbeiter, Frederik; Boccaccini, Lorenzo V.; Rey, Jörg; Schlindwein, Georg [Karlsruhe Institute of Technology (KIT), Institute for Neutron Physics and Reactor Technology, Karlsruhe (Germany)

    2013-05-15

    Highlights: ► The pressure drop significantly increases with decreasing the pebbles diameter. ► The pressure drop slightly increases with increasing the packing factor. ► The pressure drop is directly proportional to pebble bed length and inlet pressure. ► Predictions of Ergun equation agree well with the measured values of pressure drop. ► The filters resistance has a small contribution to the total pressure drop. -- Abstract: The lithium ceramic and beryllium pebble beds of the breeder units (BU), in the fusion breeding blanket, are purged by helium to extract the bred tritium. Therefore, the objective of this study is to support the design of the BU purge gas system by studying the effect of pebbles diameter, packing factor, pebble bed length, and flow inlet pressure on the purge gas pressure drop. The pebble bed was formed by packing glass pebbles in a rectangular container (56 mm × 206 mm × 396 mm) and was integrated into a gas loop to be purged by helium at BU-relevant pressures (1.1–3.8 bar). To determine the pressure drop across the pebble bed, the static pressure was measured at four locations along the pebble bed as well as at the inlet and outlet locations. The results show: (i) the pressure drop significantly increases with decreasing the pebbles diameter and slightly increases with increasing the packing factor, (ii) for a constant inlet flow velocity, the pressure drop is directly proportional to the pebble bed length and inlet pressure, and (iii) predictions of Ergun's equation agree well with the experimental values of the pressure drop.

  1. Lubrication process at the wall in foam flow : application to pressure drop estimation in underbalanced drilling

    Energy Technology Data Exchange (ETDEWEB)

    Peysson, Y.; Herzhaft, B. [Institut Francais du Petrole (France)

    2005-07-01

    Underbalanced drilling (UBD) is an effective solution to prevent formation damage, differential sticking or fluid losses. Low density drilling fluids such as gas, aerated mud or foams are used for underbalanced drilling, and the pressure of the drilling fluid is maintained at a value below the formation pressure. Foam is particularly useful for drilling because of its low density and good carrying capability, but its use remains hazardous due to the incomplete knowledge of its bottom-hole properties and flowing properties. Pressure drop estimation is crucial for UBD operations. This study evaluated the pressure drop variation with the flow rate in a circular pipe for different foam qualities and formulations. Experiments conducted in a pressure and temperature circular conduct flow showed that lubrication at the wall plays a crucial role. The intrinsic viscosity of the foam can be very high leading to the development of a water layer at the wall responsible for the lubrication of the flow. A two-phase description of the system allows the analytical estimation of the pressure drop. The size of the lubricated layer was then deduced and discussion of its range of existence was presented. Main parameters of its formation were also discussed. 17 refs., 7 figs.

  2. Prediction of friction pressure drop for low pressure two-phase flows on the basis of approximate analytical models

    Science.gov (United States)

    Zubov, N. O.; Kaban'kov, O. N.; Yagov, V. V.; Sukomel, L. A.

    2017-12-01

    Wide use of natural circulation loops operating at low redused pressures generates the real need to develop reliable methods for predicting flow regimes and friction pressure drop for two-phase flows in this region of parameters. Although water-air flows at close-to-atmospheric pressures are the most widely studied subject in the field of two-phase hydrodynamics, the problem of reliably calculating friction pressure drop can hardly be regarded to have been fully solved. The specific volumes of liquid differ very much from those of steam (gas) under such conditions, due to which even a small change in flow quality may cause the flow pattern to alter very significantly. Frequently made attempts to use some or another universal approach to calculating friction pressure drop in a wide range of steam quality values do not seem to be justified and yield predicted values that are poorly consistent with experimentally measured data. The article analyzes the existing methods used to calculate friction pressure drop for two-phase flows at low pressures by comparing their results with the experimentally obtained data. The advisability of elaborating calculation procedures for determining the friction pressure drop and void fraction for two-phase flows taking their pattern (flow regime) into account is demonstrated. It is shown that, for flows characterized by low reduced pressures, satisfactory results are obtained from using a homogeneous model for quasi-homogeneous flows, whereas satisfactory results are obtained from using an annular flow model for flows characterized by high values of void fraction. Recommendations for making a shift from one model to another in carrying out engineering calculations are formulated and tested. By using the modified annular flow model, it is possible to obtain reliable predictions for not only the pressure gradient but also for the liquid film thickness; the consideration of droplet entrainment and deposition phenomena allows reasonable

  3. Measurements of the purge helium pressure drop across pebble beds packed with lithium orthosilicate and glass pebbles

    Energy Technology Data Exchange (ETDEWEB)

    Abou-Sena, Ali, E-mail: ali.abou-sena@kit.edu; Arbeiter, Frederik; Boccaccini, Lorenzo V.; Schlindwein, Georg

    2014-10-15

    Highlights: • The objective is to measure the purge helium pressure drop across various HCPB-relevant pebble beds packed with lithium orthosilicate and glass pebbles. • The purge helium pressure drop significantly increases with decreasing the pebbles diameter from one run to another. • At the same superficial velocity, the pressure drop is directly proportional to the helium inlet pressure. • The Ergun's equation can successfully model the purge helium pressure drop for the HCPB-relevant pebble beds. • The measured values of the purge helium pressure drop for the lithium orthosilicate pebble bed will support the design of the purge gas system for the HCPB breeder units. - Abstract: The lithium orthosilicate pebble beds of the Helium Cooled Pebble Bed (HCPB) blanket are purged by helium to transport the produced tritium to the tritium extraction system. The pressure drop of the purge helium has a direct impact on the required pumping power and is a limiting factor for the purge mass flow. Therefore, the objective of this study is to measure the helium pressure drop across various HCPB-relevant pebble beds packed with lithium orthosilicate and glass pebbles. The pebble bed was formed by packing the pebbles into a stainless steel cylinder (ID = 30 mm and L = 120 mm); then it was integrated into a gas loop that has four variable-speed side-channel compressors to regulate the helium mass flow. The static pressure was measured at two locations (100 mm apart) along the pebble bed and at inlet and outlet of the pebble bed. The results demonstrated that: (i) the pressure drop significantly increases with decreasing the pebbles diameter, (ii) for the same superficial velocity, the pressure drop is directly proportional to the inlet pressure, and (iii) predictions of Ergun's equation agree well with the experimental results. The measured pressure drop for the lithium orthosilicate pebble bed will support the design of the purge gas system for the HCPB.

  4. Heat transfer and pressure drop during hydrocarbon refrigerant condensation inside a brazed plate heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Longo, Giovanni A. [University of Padova, Department of Management and Engineering, Str.lla S.Nicola 3, I-36100 Vicenza (Italy)

    2010-08-15

    This paper presents the heat transfer coefficients and pressure drop measured during HC-600a, HC-290 and HC-1270 saturated vapour condensation inside a brazed plate heat exchanger: the effects of refrigerant mass flux, saturation temperature (pressure) and fluid properties are investigated. The heat transfer coefficients show weak sensitivity to saturation temperature (pressure) and great sensitivity to refrigerant mass flux and fluid properties. A transition point between gravity controlled and forced convection condensation has been found for a refrigerant mass flux around 15-18 kg m{sup -2} s{sup -1}. In the forced convection condensation region the heat transfer coefficients show a 35-40% enhancement for a 60% increase of the refrigerant mass flux. The frictional pressure drop shows a linear dependence on the kinetic energy per unit volume of the refrigerant flow. HC-1270 shows heat transfer coefficients 5% higher than HC-600a and 10-15% higher than HC-290, together with frictional pressure drop 20-25% lower than HC-290 and 50-66% lower than HC-600a. (author)

  5. Calculation of pressure drop in the developmental stages of the medaka fish heart and microvasculature

    Science.gov (United States)

    Chakraborty, Sreyashi; Vlachos, Pavlos

    2016-11-01

    Peristaltic contraction of the developing medaka fish heart produces temporally and spatially varying pressure drop across the atrioventricular (AV) canal. Blood flowing through the tail vessels experience a slug flow across the developmental stages. We have performed a series of live imaging experiments over 14 days post fertilization (dpf) of the medaka fish egg and cross-correlated the red blood cell (RBC) pattern intensities to obtain the two-dimensional velocity fields. Subsequently we have calculated the pressure field by integrating the pressure gradient in the momentum equation. Our calculations show that the pressure drop across the AV canal increases from 0.8mm Hg during 3dpf to 2.8 mm Hg during 14dpf. We have calculated the time-varying wall shear stress for the blood vessels by assuming a spatially constant velocity magnitude in each vessel. The calculated wall shear stress matches the wall shear stress sensed by human endothelial cells (10-12 dyne/sq. cm). The pressure drop per unit length of the vessel is obtained by doing a control volume analysis of flow in the caudal arteries and veins. The current results can be extended to investigate the effect of the fluid dynamic parameters on the vascular and cardiac morphogenesis.

  6. Comparison of Two Phase Pressure Drop Models in 1-D Top Flooded Debris Bed

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Moon Eon; Park, Jin Ho; Kim, Eun ho; Park, Hyun Sun [POSTECH, Pohang (Korea, Republic of)

    2016-05-15

    The dry out of coolant inside debris bed can be considered as the limitation of cooling in the conservative point of view and the heat flux through whole bed at the situation is named as Dryout Heat Flux (DHF). The modeling of DHF for debris bed started from early 1980s by several researchers. It is known that DHF mainly occurs by hydrodynamic limitation inside porous media. Therefore, there have been following attempts to capture flow resistance in porous media, precisely. Up to date, although there are about seven pressure drop models available in literatures, it is hard to find comparison of those models with a wide range of DHF experimental data. The one attempt[9] was conducted in 2013, but due to lack of consideration of the capillary pressure in his work, the DHF values that he calculated seem to be underestimated, especially in the range of the small particle diameter cases. In this research, the importance of capillary pressure in the comparison of pressure drop model with experimental data was checked and model selection among pressure drop models for the DHF calculation was also conducted. The model comparison with 108 experimental data from various conditions has been conducted and the Schmidt model shows the best agreement to the experimental data although Reed, Rahman model also show similar results.

  7. Pressure drop and temperature rise in He II flow in round tubes, Venturi flowmeters and valves

    Science.gov (United States)

    Walstrom, P. L.; Maddocks, J. R.

    1988-01-01

    Pressure drops in highly turbulent He II flow were measured in round tubes, valves, and Venturi flowmeters. Results are in good agreement with single-phase flow correlations for classical fluids. The temperature rise in flow in a round tube was measured, and found to agree well with predictions for isenthalpic expansion. Cavitation was observed in the venturis under conditions of low back pressure and high flow rate. Metastable superheating of the helium at the venturi throat was observed before the helium made a transition to saturation pressure.

  8. Effects of vascular structures on the pressure drop in stenotic coronary arteries

    Science.gov (United States)

    Kim, Jaerim; Choi, Haecheon; Kweon, Jihoon; Kim, Young-Hak; Yang, Dong Hyun; Kim, Namkug

    2016-11-01

    A stenosis, which is a narrowing of a blood vessel, of the coronary arteries restricts the flow to the heart and it may lead to sudden cardiac death. Therefore, the accurate determination of the severity of a stenosis is a critical issue. Due to the convenience of visual assessments, geometric parameters such as the diameter stenosis and area stenosis have been used, but the decision based on them sometimes under- or overestimates the functional severity of a stenosis, i.e., pressure drop. In this study, patient-specific models that have similar area stenosis but different pressure drops are considered, and their geometries are reconstructed from the coronary computed tomography angiography (CCTA). Both steady and pulsatile inflows are considered for the simulations. Comparison between two models that have a bifurcation right after a stenosis shows that the parent to daughter vessel angle results in different secondary flow patterns and wall shear stress distributions which affect the pressure downstream. Thus, the structural features of the lower and upper parts of a stenosis significantly affect the pressure drop. Supported by 20152020105600.

  9. Pressure drop and stability of flow in Archimedean spiral tube with transverse corrugations

    Directory of Open Access Journals (Sweden)

    Đorđević Milan

    2016-01-01

    Full Text Available Isothermal pressure drop experiments were carried out for the steady Newtonian fluid flow in Archimedean spiral tube with transverse corrugations. Pressure drop correlations and stability criteria for distinguishing the flow regimes have been obtained in a continuous Reynolds number range from 150 to 15 000. The characterizing geometrical groups which take into account all the geometrical parameters of Archimedean spiral and corrugated pipe has been acquired. Before performing experiments over the Archimedean spiral, the corrugated straight pipe having high relative roughness e/d = 0.129 of approximately sinusoidal type was tested in order to obtain correlations for the Darcy friction factor. Insight into the magnitude of pressure loss in the proposed geometry of spiral solar receiver for different flow rates is important because of its effect upon the efficiency of the receiver. Although flow in spiral and corrugated geometries has the advantages of compactness and high heat transfer rates, the disadvantage of greater pressure drops makes hydrodynamic studies relevant. [Projekat Ministarstva nauke Republike Srbije, br. III 42006 i br. TR 33015

  10. Evaporation Heat Transfer and Pressure Drop of HCFC 22 Inside an Internally Grooved Horizontal Tube

    Science.gov (United States)

    Kido, Osao; Taniguchi, Mitsunori; Taira, Teruhiko; Uehara, Haruo

    The evaporation heat heat transfer and pressure drop inside seven kinds of grooved horizontal tubes with 7.0 mm outside diameter and 60 to 100 grooves with 0.15 to 0.21 mm in height and 3 to 18 degree of lead angle, were obtained. The test section, 300 mm in length, was heated by condensing CFC 114 vapor on the outside of tube. HCFC 22 was used as a working fluid. Evaporating pressure was 0.49MPa, heat flux was 9.3 kW/ m2, vapor quality was varied from 0.1 to 0.9, and mass velocity was varied from 86 to 345 kg/(m2s). The empirical correlations to predict heat transfer coefficient and pressure drop were proposed. Increasing the modified bond number, the heat transfer coefficient decreases in the range of the modified bond number experimented. Pressure drop isn't influenced by the groove geometries except for lead angle.

  11. Heat Transfer and Pressure Drop in Concentric Annular Flows of Binary Inert Gas Mixtures

    Science.gov (United States)

    Reid, R. S.; Martin, J. J.; Yocum, D. J.; Stewart, E. T.

    2007-01-01

    Studies of heat transfer and pressure drop of binary inert gas mixtures flowing through smooth concentric circular annuli, tubes with fully developed velocity profiles, and constant heating rate are described. There is a general lack of agreement among the constant property heat transfer correlations for such mixtures. No inert gas mixture data exist for annular channels. The intent of this study was to develop highly accurate and benchmarked pressure drop and heat transfer correlations that can be used to size heat exchangers and cores for direct gas Brayton nuclear power plants. The inside surface of the annular channel is heated while the outer surface of the channel is insulated. Annulus ratios range 0.5 spacer ribs, or other surfaces.

  12. Filter efficiency and pressure drop calculations through two and three dimensional fiber arrays

    Energy Technology Data Exchange (ETDEWEB)

    Bergman, W.; Corey, I.; Speck, D.

    1994-04-01

    We have used a commercially available fluid dynamics code, NEKTON version 2.85, and the Langevin particle equation of motion to compute the particle capture efficiency and pressure drop through selected two- and three-dimensional fiber arrays. The approach we used was to first compute the air velocity vector field throughout a defined region containing the fiber matrix. The particle capture in the fiber matrix is then computed by superimposing the Langevin particle equation of motion over the flow velocity field. Using the Langevin equation combines the particle Brownian motion, inertia and interception mechanisms in a single equation. In contrast, most previous investigations treat the different capture mechanisms separately. We have computed the particle capture efficiency and the pressure drop through a 2-D and two 3-D fiber matrix elements.

  13. Non-newtonian flow and pressure drop of pineapple juice in a plate heat exchanger

    Directory of Open Access Journals (Sweden)

    R. A. F. Cabral

    2010-12-01

    Full Text Available The study of non-Newtonian flow in plate heat exchangers (PHEs is of great importance for the food industry. The objective of this work was to study the pressure drop of pineapple juice in a PHE with 50º chevron plates. Density and flow properties of pineapple juice were determined and correlated with temperature (17.4 < T < 85.8ºC and soluble solids content (11.0 < Xs < 52.4 ºBrix. The Ostwald-de Waele (power law model described well the rheological behavior. The friction factor for non-isothermal flow of pineapple juice in the PHE was obtained for diagonal and parallel/side flow. Experimental results were well correlated with the generalized Reynolds number (20 < Re g < 1230 and were compared with predictions from equations from the literature. The mean absolute error for pressure drop prediction was 4% for the diagonal plate and 10% for the parallel plate.

  14. Pressure Drop Experiments on a Flow Channel Filled with Catalysts for Nuclear Hydrogen Production System

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sungdeok; Kim, C. S.; Kim, M. H.; Kim, Y. W. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Seo, D. U.; Park, G. C. [Seoul National Univ., Seoul (Korea, Republic of)

    2014-05-15

    The Korea Atomic Energy Research Institute (KAERI) has developed a hybrid-design decomposer to withstand severe operating conditions. Hong and Seo have been studying a two-dimensional numerical analysis for a catalyst channel line-up with a 3mm ball shaped catalyst. They compared their CFD results to many widespread correlations developed for porous media such as those by Carman, Ergun, and Zhavoronkov as well as Susskind and Becker and Reichelt including a pebble-bed nuclear reactor design correlation. They concluded that the validation should be accomplished by the experiments for a catalyst channel simulating the channel of the PHE. In this paper, we discuss the pressure drop experiments on a flow channel filled with ball shaped catalysts. The test section simulates a single channel of the PHE secondary side plate-fin channel. The experimental results compared well with the known pressure drop correlations and a numerical analysis, respectively. We discussed an experimental validation of a pressure drop correlations and 2D CFD analysis on a flow channel filled with catalysts in the channel. The results of the pressure drop measurements are compared with the results obtained using well-known empirical correlations and 2D CFD analysis. From the comparison results, the validity of all the correlations and 2D numerical analysis is not satisfactory. There are two kind of reasons are presumed. While the general packed channel has radially infinite and complete circular cross section, the catalyst channel has radially finite with a very narrow width and irregular wavy cross section. Another reason is presumed to be because the inordinate large void fraction in the catalyst channel which is beyond the application range on void fraction in the empirical correlations.

  15. Heat Transfer and Pressure Drop Characteristics in Straight Microchannel of Printed Circuit Heat Exchangers

    Directory of Open Access Journals (Sweden)

    Jang-Won Seo

    2015-05-01

    Full Text Available Performance tests were carried out for a microchannel printed circuit heat exchanger (PCHE, which was fabricated with micro photo-etching and diffusion bonding technologies. The microchannel PCHE was tested for Reynolds numbers in the range of 100‒850 varying the hot-side inlet temperature between 40 °C–50 °C while keeping the cold-side temperature fixed at 20 °C. It was found that the average heat transfer rate and heat transfer performance of the countercurrrent configuration were 6.8% and 10%‒15% higher, respectively, than those of the parallel flow. The average heat transfer rate, heat transfer performance and pressure drop increased with increasing Reynolds number in all experiments. Increasing inlet temperature did not affect the heat transfer performance while it slightly decreased the pressure drop in the experimental range considered. Empirical correlations have been developed for the heat transfer coefficient and pressure drop factor as functions of the Reynolds number.

  16. Experimental and numerical study of the pressure drop for ITER blanket shield block

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Min-Su; Kim, Sawoong; Jung, Hun-Chea; Shim, Hee-Jin; Ahn, Hee-Jae

    2016-11-01

    Highlights: • The results of the experiment and the numerical analysis are compared. • The numerical analysis results are lower than the experimental results. • The margin of the pressure drop is suggested. - Abstract: The blanket shield block (SB) is located inside the ITER vacuum chamber, and the main function is to provide the thermal and nuclear shielding to the vacuum vessel and external components. The SB is foreseen to undergo a significant heat load which is a body load throughout the whole thickness of the SB under normal operation conditions. Therefore, the cooling configuration in SB should be designed very carefully based on the various experiences. The pressure drop in the cooling design is one of the most important factors to balance a water distribution of overall blanket cooling system. In order to verify the pressure drop characteristic and validate the design methodology of SB, experiment and numerical analysis are performed and compared their results. These results would be a benchmarking of the numerical results with experimental results to assess the gap between calculations and experiments.

  17. Heat transfer and pressure drop in rectangular channels with crossing fins (a Review)

    Science.gov (United States)

    Sokolov, N. P.; Polishchuk, V. G.; Andreev, K. D.; Rassokhin, V. A.; Zabelin, N. A.

    2015-06-01

    Channels with crossing finning find wide use in the cooling paths of high-temperature gas turbine blade systems. At different times, different institutions carried out experimental investigations of heat transfer and pressure drop in channels with coplanar finning of opposite walls for obtaining semiempirical dependences of Nusselt criteria (dimensionless heat-transfer coefficients) and pressure drop coefficients on the operating Reynolds number and relative geometrical parameters (or their complexes). The shape of experimental channels, the conditions of experiments, and the used variables were selected so that they would be most suited for solving particular practical tasks. Therefore, the results obtained in processing the experimental data have large scatter and limited use. This article considers the results from experimental investigations of different authors. In comparing the results, additional calculations were carried out for bringing the mathematical correlations to the form of dependences from the same variables. Generalization of the results is carried out. In the final analysis, universal correlations are obtained for determining the pressure drop coefficients and Nusselt number values for the flow of working medium in channels with coplanar finning.

  18. On the Impact of Particulate Matter Distribution on Pressure Drop of Wall-Flow Particulate Filters

    Directory of Open Access Journals (Sweden)

    Vicente Bermúdez

    2017-03-01

    Full Text Available Wall-flow particulate filters are a required exhaust aftertreatment system to abate particulate matter emissions and meet current and incoming regulations applying worldwide to new generations of diesel and gasoline internal combustion engines. Despite the high filtration efficiency covering the whole range of emitted particle sizes, the porous substrate constitutes a flow restriction especially relevant as particulate matter, both soot and ash, is collected. The dependence of the resulting pressure drop, and hence the fuel consumption penalty, on the particulate matter distribution along the inlet channels is discussed in this paper taking as reference experimental data obtained in water injection tests before the particulate filter. This technique is demonstrated to reduce the particulate filter pressure drop without negative effects on filtration performance. In order to justify these experimental data, the characteristics of the particulate layer are diagnosed applying modeling techniques. Different soot mass distributions along the inlet channels are analyzed combined with porosity change to assess the new properties after water injection. Their influence on the subsequent soot loading process and regeneration is assessed. The results evidence the main mechanisms of the water injection at the filter inlet to reduce pressure drop and boost the interest for control strategies able to force the re-entrainment of most of the particulate matter towards the inlet channels’ end.

  19. THE EXPERIMENTAL AND NUMERICAL ANALYSIS OF TURBULENT FLOW PRESSURE DROP OF HELICAL SQUARE DUCT

    Directory of Open Access Journals (Sweden)

    Okyar KAYA

    2004-02-01

    Full Text Available In this study, the pressure drop of helical square duct which has 8x8 mm dimension, a pitch of b =12 mm was investigated both experimentally and numerically with the similar experimental boundary conditions. SIMPLE algorithm, PRESTO pressure-velocity interpolation option, RNG k-? turbulent model and Gauss Siedel iteration method were used in numerical computations which were done by FLUENT® programme. As a result it was understood that the maximum difference between numerical and experimental data is about 5 %. The experimental and numerical results were compared and validated with the results in the literature.

  20. Flow of Hydrolysed Polyacrylamide Mother Liquor through Filter Bag: Detecting the Effects of Formulation and Process Properties on Pressure Drop

    Directory of Open Access Journals (Sweden)

    Zi-Ming Feng

    2016-01-01

    Full Text Available Hydrolysed polyacrylamide (HPAM mother liquor is mainly used to extract oil. The HPAM solution is needed to filter the impurity using a bag filter before it is injected into the oil well. Therefore, the pressure drop of HPAM mother liquor must be less than 0.02 MPa in the processing of impurity filtration. The influence factors on pressure drop need to be researched. In this work, the computational fluid dynamics program (CFD was used to research some key influence factors on pressure drop, such as porosity, outlet pressure of filter, inlet flow rate and viscosity of mother liquor. The simulation results indicated that with increasing porosity, outlet pressure, inlet flow rate and mother liquor viscosity, the pressure drop had increased after flowing through the filter bag.

  1. Estimating the irreversible pressure drop across a stenosis by quantifying turbulence production using 4D Flow MRI.

    Science.gov (United States)

    Ha, Hojin; Lantz, Jonas; Ziegler, Magnus; Casas, Belen; Karlsson, Matts; Dyverfeldt, Petter; Ebbers, Tino

    2017-04-20

    The pressure drop across a stenotic vessel is an important parameter in medicine, providing a commonly used and intuitive metric for evaluating the severity of the stenosis. However, non-invasive estimation of the pressure drop under pathological conditions has remained difficult. This study demonstrates a novel method to quantify the irreversible pressure drop across a stenosis using 4D Flow MRI by calculating the total turbulence production of the flow. Simulation MRI acquisitions showed that the energy lost to turbulence production can be accurately quantified with 4D Flow MRI within a range of practical spatial resolutions (1-3 mm; regression slope = 0.91, R2 = 0.96). The quantification of the turbulence production was not substantially influenced by the signal-to-noise ratio (SNR), resulting in less than 2% mean bias at SNR > 10. Pressure drop estimation based on turbulence production robustly predicted the irreversible pressure drop, regardless of the stenosis severity and post-stenosis dilatation (regression slope = 0.956, R2 = 0.96). In vitro validation of the technique in a 75% stenosis channel confirmed that pressure drop prediction based on the turbulence production agreed with the measured pressure drop (regression slope = 1.15, R2 = 0.999, Bland-Altman agreement = 0.75 ± 3.93 mmHg).

  2. Changes in center of pressure displacement with the use of a foot drop stimulator in individuals with stroke.

    Science.gov (United States)

    Nolan, Karen J; Yarossi, Mathew; Mclaughlin, Patrick

    2015-08-01

    Center of pressure measured during gait can provide information about underlying control mechanisms and the efficacy of a foot drop stimulator. This investigation evaluated changes in center of pressure displacement in individuals with stroke with and without a foot drop stimulator. Individuals with stroke-related foot drop (n=11) using a foot drop stimulator and healthy controls (n=11). Walking speed and bilateral center of pressure variables: 1) net displacement; 2) position and maximum displacement; and 3) mean velocity during walking. On the affected limb with the foot drop stimulator as compared to the affected limb without the foot drop stimulator: 1) increased anterior/posterior maximum center of pressure excursion 8% during stance; 2) center of pressure at initial contact was 6% more posterior; 3) medial/lateral mean, maximum and minimum center of pressure position during stance all significantly decreased; 4) anterior/posterior net displacement increased during stance and single support; and 5) anterior/posterior velocity of the center of pressure increased during stance. Individuals with stroke using a foot drop stimulator contacted the ground more posterior at initial contact and utilized more of the anterior/posterior plantar surface of the foot on the affected limb during stance. With the foot drop stimulator there was a shift in center of pressure toward the medial side possibly indicating an improvement in equinovarus gait where there is a tendency to load the lateral foot throughout stance. For individuals with stroke a foot drop stimulator can improve displacement of the center of pressure which indicates improved forward progression and stability during walking. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Clinical outcomes of combined flow-pressure drop measurements using newly developed diagnostic endpoint: Pressure drop coefficient in patients with coronary artery dysfunction

    Science.gov (United States)

    Effat, Mohamed A; Peelukhana, Srikara Viswanath; Banerjee, Rupak K

    2016-01-01

    AIM: To combine pressure and flow parameter, pressure drop coefficient (CDP) will result in better clinical outcomes in comparison to the fractional flow reserve (FFR) group. METHODS: To test this hypothesis, a comparison was made between the FFR 27.9 groups in this study, for the major adverse cardiac events [major adverse cardiac events (MACE): Primary outcome] and patients’ quality of life (secondary outcome). Further, a comparison was also made between the survival curves for the FFR 27.9 groups. Two-tailed χ2 test proportions were performed for the comparison of primary and secondary outcomes. Kaplan-Meier survival analysis was performed to compare the survival curves of FFR 27.9 groups (MedcalcV10.2, Mariakerke, Belgium). Results were considered statistically significant for P 27.9 group (8.57%, 2 out of 35). Noteworthy is the reduction in the %MACE in the CDP > 27.9 group, in comparison to the FFR 27.9 groups. Survival analysis results suggest that the survival time for the CDP > 27.9 group (n = 35) is significantly higher (P = 0.048) in comparison to the survival time for the FFR < 0.75 group (n = 20). The results remained similar for a FFR = 0.80 cut-off. CONCLUSION: Based on the above, CDP could prove to be a better diagnostic end-point for clinical revascularization decision-making in the cardiac catheterization laboratories. PMID:27022460

  4. Hereditary Neuropathy with Liability to Pressure Palsy: A Recurrent and Bilateral Foot Drop Case Report

    Directory of Open Access Journals (Sweden)

    Filipa Flor-de-Lima

    2013-01-01

    Full Text Available Hereditary neuropathy with liability to pressure palsy is characterized by acute, painless, recurrent mononeuropathies secondary to minor trauma or compression. A 16-year-old boy had the first episode of right foot drop after minor motorcycle accident. Electromyography revealed conduction block and slowing velocity conduction of the right deep peroneal nerve at the fibular head. After motor rehabilitation, he fully recovered. Six months later he had the second episode of foot drop in the opposite site after prolonged squatting position. Electromyography revealed sensorimotor polyneuropathy of left peroneal, sural, posterior tibial, and deep peroneal nerves and also of ulnar, radial, and median nerves of both upper limbs. Histological examination revealed sensory nerve demyelination and focal thickenings of myelin fibers. The diagnosis of hereditary neuropathy with liability to pressure palsy was confirmed by PMP22 deletion of chromosome 17p11.2. He started motor rehabilitation and avoidance of stressing factors with progressive recovery. After one-year followup, he was completely asymptomatic. Recurrent bilateral foot drop history, “sausage-like” swellings of myelin in histological examination, and the results of electromyography led the authors to consider the diagnosis despite negative family history. The authors highlight this rare disease in pediatric population and the importance of high index of clinical suspicion for its diagnosis.

  5. Investigations on mixture preparation for two phase adiabatic pressure drop of R134a flowing in 5 mm diameter channel

    Science.gov (United States)

    Muszyński, Tomasz; Andrzejczyk, Rafał; Dorao, Carlos A.

    2017-09-01

    The article presents detailed two-phase adiabatic pressure drops data for refrigerant R134a. Study cases have been set for a mass flux varying from 200 to 400 kg/m2s, at the saturation temperature of 19.4 °C. Obtained experimental data was compared with the available correlations from the literature for the frictional pressure drop during adiabatic flow. Influence of mixture preparation on pressure drop was investigated, for varying inlet subcooling temperature in the heated section. The flow patterns have also been obtained by means of a high-speed camera placed in the visualization section and compared with literature observations.

  6. The influence of the equivalent hydraulic diameter on the pressure drop prediction of annular test section

    Science.gov (United States)

    Al-Kayiem, A. H. H.; Ibrahim, M. A.

    2015-12-01

    The flow behaviour and the pressure drop throughout an annular flow test section was investigated in order to evaluate and justify the reliability of experimental flow loop for wax deposition studies. The specific objective of the present paper is to assess and highlight the influence of the equivalent diameter method on the analysis of the hydrodynamic behaviour of the flow and the pressure drop throughout the annular test section. The test section has annular shape of 3 m length with three flow passages, namely; outer thermal control jacket, oil annular flow and inner pipe flow of a coolant. The oil annular flow has internal and external diameters of 0.0422 m and 0.0801 m, respectively. Oil was re-circulated in the annular passage while a cold water-glycol mixture was re-circulated in the inner pipe counter currently to the oil flow. The experiments were carried out at oil Reynolds number range of 2000 to 17000, covering laminar, transition and turbulent flow regimes. Four different methods of equivalent diameter of the annulus have been considered in this hydraulic analysis. The correction factor model for frictional pressure drop was also considered in the investigations. All methods addressed the high deviation of the prediction from the experimental data, which justified the need of a suitable pressure prediction correlation for the annular test section. The conventional hydraulic diameter method is a convenient substitute for characterizing physical dimension of a non-circular duct, and it leads to fairly good correlation between turbulent fluid flow and heat transfer characteristic of annular ducts.

  7. Double Contact During Drop Impact on a Solid Under Reduced Air Pressure

    KAUST Repository

    Li, Erqiang

    2017-11-20

    Drops impacting on solid surfaces entrap small bubbles under their centers, owing to the lubrication pressure which builds up in the thin intervening air layer. We use ultrahigh-speed interference imaging, at 5 Mfps, to investigate how this air layer changes when the ambient air pressure is reduced below atmospheric. Both the radius and the thickness of the air disc become smaller with reduced air pressure. Furthermore, we find the radial extent of the air disc bifurcates, when the compressibility parameter exceeds similar to 25. This bifurcation is also imprinted onto some of the impacts, as a double contact. In addition to the central air disc inside the first ring contact, this is immediately followed by a second ring contact, which entraps an outer toroidal strip of air, which contracts into a ring of bubbles. We find this occurs in a regime where Navier slip, due to rarefied gas effects, enhances the rate gas can escape from the path of the droplet.

  8. Double Contact During Drop Impact on a Solid Under Reduced Air Pressure

    Science.gov (United States)

    Li, Er Qiang; Langley, Kenneth R.; Tian, Yuan Si; Hicks, Peter D.; Thoroddsen, Sigurdur T.

    2017-11-01

    Drops impacting on solid surfaces entrap small bubbles under their centers, owing to the lubrication pressure which builds up in the thin intervening air layer. We use ultrahigh-speed interference imaging, at 5 Mfps, to investigate how this air layer changes when the ambient air pressure is reduced below atmospheric. Both the radius and the thickness of the air disc become smaller with reduced air pressure. Furthermore, we find the radial extent of the air disc bifurcates, when the compressibility parameter exceeds ˜25 . This bifurcation is also imprinted onto some of the impacts, as a double contact. In addition to the central air disc inside the first ring contact, this is immediately followed by a second ring contact, which entraps an outer toroidal strip of air, which contracts into a ring of bubbles. We find this occurs in a regime where Navier slip, due to rarefied gas effects, enhances the rate gas can escape from the path of the droplet.

  9. Analysis of regurgitation, mean systolic pressure drop and energy losses for two artificial aortic valves.

    Science.gov (United States)

    Sakhaeimanesh, A A; Morsi, Y S

    1999-01-01

    The work reported here is related to the hydrodynamic performance of a Jellyfish valve and St Vincent valve in terms of total energy losses, mean systolic pressure drop and regurgitation. The in vitro experimental investigation was conducted at cardiac outputs of 3.5, 4.5 and 6.51 min-1 across the two valves and under pulsatile flow condition. It was found that the closure volume of the St Vincent valve was about 2.5 times higher than that of the Jellyfish valve. The total back flow losses on the other hand were found to be in the range of 36.5 to 107.1 and 85.5 to 192.5 mJ for the Jellyfish valve and St Vincent valve respectively. Moreover, the mean systolic pressure drop of the St Vincent valve was found to be higher than that of the Jellyfish valve. However, for all the operating conditions tested here, the Jellyfish valve showed superior hydrodynamic performance in terms of backflow and mean systolic pressure as well as energy losses.

  10. Pressure drop correlation for air/water two-phase flow in horizontal helicoidal pipes

    Energy Technology Data Exchange (ETDEWEB)

    Ebadian, M.A.; Dong, Z.F.; Awwad, A.; Xin, R.C. [Florida International Univ., Miami, FL (United States)

    1995-10-01

    In this paper, an experimental investigation is reported for air/water two-phase flow in horizontal helicoidal pipes. The helicoidal pipes are constructed of Tygon tubing with varying inside diameters of 12.7 mm, 19.1 mm, 25.4 mm, and 38.1 mm wrapped around two different cylindrical concrete forms with outside diameters of 304.8 mm and 609.6 mm each. Also, the helix angle of each helicoidal pipe varies up to 20 degrees. The experiments are conducted for superficial water velocity in the range of U{sub L} = 0.008 {minus} 2.2 m/s and superficial air velocity in the range of U{sub G} = 0.2 {minus} 50 m/s. The pressure drop of the two-phase flow is measured and the data are correlated. It was found that the Lockhart-Martinelli correlation for a straight pipe can represent the data for a helicoidal pipe only in the cases of a high rate of flow; nevertheless, the pressure drop relates strongly to the superficial air/water velocity when the flow rate is lower. The helix angle has almost no effect on the pressure drop, although the pipe and coil diameters have certain effects in low rates of flow. Correlations for two-phase flow in each of the horizontal helicoidal pipes have been established based on the present data. Helicoidal pipes are used extensively in compact heat exchangers, boilers, refrigerators, nuclear reactors, chemical plants, as well as the food, drug, and cryogenics industries.

  11. Experimental study on the two-phase pressure drop in copper foams

    Science.gov (United States)

    Ji, Xianbing; Xu, Jinliang

    2012-01-01

    Experiments were performed to study pressure drops in copper foams embedded in a rectangular copper channel. De-ionized water was used as the working fluid with mass fluxes of 30-200 kg/m2 s, and inlet temperature of 40-80°C. The copper foam has the porosity of 0.88 and the pore densities of 30, 60 and 90 ppi (pores per inch). Both single-phase liquid flow and boiling two-phase flow are studied. Effects of mass fluxes, vapor mass qualities, and average pore diameters of metallic foams are investigated. It is found that friction factors for the single-phase liquid flow are mainly dependent on the Reynolds number and the average pore diameter of metallic foams. The friction factors are decreased with increases in the Reynolds numbers, and will approach 0.22 at high Reynolds numbers. For the boiling two-phase flow, two-phase pressure drops are increased with increases in the outlet vapor mass qualities, mass fluxes, and ppi values. The two-phase multiplier is increased with increases in the outlet vapor mass qualities and mass fluxes, and it is decreased with increases in the Martinelli parameter and will attain a constant value depending on the mass fluxes. The larger the mass fluxes, the larger the constant value is. An experimental correlation considering the effects of vapor mass qualities, mass fluxes, and average pore diameters of metallic foams is recommended, showing good accuracy to predict the two-phase pressure drops in metallic foams.

  12. Geometry-based pressure drop prediction in mildly diseased human coronary arteries.

    Science.gov (United States)

    Schrauwen, J T C; Wentzel, J J; van der Steen, A F W; Gijsen, F J H

    2014-06-03

    Pressure drop (△p) estimations in human coronary arteries have several important applications, including determination of appropriate boundary conditions for CFD and estimation of fractional flow reserve (FFR). In this study a △p prediction was made based on geometrical features derived from patient-specific imaging data. Twenty-two mildly diseased human coronary arteries were imaged with computed tomography and intravascular ultrasound. Each artery was modelled in three consecutive steps: from straight to tapered, to stenosed, to curved model. CFD was performed to compute the additional △p in each model under steady flow for a wide range of Reynolds numbers. The correlations between the added geometrical complexity and additional △p were used to compute a predicted △p. This predicted △p based on geometry was compared to CFD results. The mean △p calculated with CFD was 855±666Pa. Tapering and curvature added significantly to the total △p, accounting for 31.4±19.0% and 18.0±10.9% respectively at Re=250. Using tapering angle, maximum area stenosis and angularity of the centerline, we were able to generate a good estimate for the predicted △p with a low mean but high standard deviation: average error of 41.1±287.8Pa at Re=250. Furthermore, the predicted △p was used to accurately estimate FFR (r=0.93). The effect of the geometric features was determined and the pressure drop in mildly diseased human coronary arteries was predicted quickly based solely on geometry. This pressure drop estimation could serve as a boundary condition in CFD to model the impact of distal epicardial vessels. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. The impact of mass flow and masking on the pressure drop of air filter in heavy-duty diesel engine

    Directory of Open Access Journals (Sweden)

    Gorji-Bandpy Mofid

    2012-04-01

    Full Text Available This paper presents a computational fluid dynamics (CFD calculation approach to predict and evaluate the impact of the mass-flow inlet on the pressure drop of turbocharger`s air filtfer in heavy-duty diesel engine. The numerical computations were carried out using a commercial CFD program whereas the inlet area of the air filter consisted of several holes connected to a channel. After entering through the channel, the air passes among the holes and enters the air filter. The effect of masking holes and hydraulic diameter is studied and investigated on pressure drop. The results indicate that pressure drop increase with decreasing of hydraulic diameter and masking of the holes has considerable affect on the pressure drop.

  14. Effects of instant controlled pressure drop process on physical and sensory properties of puffed wheat snack.

    Science.gov (United States)

    Yağcı, Sibel

    2017-04-01

    In this study, research on the development of a puffed wheat snack using the instant controlled pressure drop (DIC) process was carried out. Snack products were produced by expanding moistened wheat under various DIC processing conditions in order to obtain adequate puffing, followed by drying in a hot air dryer. The effects of operational variables such as wheat initial moisture content (11-23% w/w, wet basis), processing pressure (3-5 × 10 2 kPa) and processing time (3-11 min) on the physical (density, color and textural characteristics) and sensory properties of the product were investigated. The physical properties of the wheat snack were most affected by changes in processing pressure, followed by processing time and wheat moisture content. Increasing processing pressure and time often improved expansion and textural properties but led to darkening of the raw wheat color. The most acceptable snack in terms of physical properties was obtained at the lowest wheat moisture content. Sensory analysis suggested that consumer acceptability was optimal for wheat snacks produced at higher processing pressure, medium processing time and lower moisture content. The most desirable conditions for puffed wheat snack production using the DIC process were determined as 11% (w/w) of wheat moisture content, 5 × 10 2 kPa of processing pressure and 7 min of processing time. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  15. Dysfunctional vestibular system causes a blood pressure drop in astronauts returning from space.

    Science.gov (United States)

    Hallgren, Emma; Migeotte, Pierre-François; Kornilova, Ludmila; Delière, Quentin; Fransen, Erik; Glukhikh, Dmitrii; Moore, Steven T; Clément, Gilles; Diedrich, André; MacDougall, Hamish; Wuyts, Floris L

    2015-12-16

    It is a challenge for the human body to maintain stable blood pressure while standing. The body's failure to do so can lead to dizziness or even fainting. For decades it has been postulated that the vestibular organ can prevent a drop in pressure during a position change--supposedly mediated by reflexes to the cardiovascular system. We show--for the first time--a significant correlation between decreased functionality of the vestibular otolith system and a decrease in the mean arterial pressure when a person stands up. Until now, no experiments on Earth could selectively suppress both otolith systems; astronauts returning from space are a unique group of subjects in this regard. Their otolith systems are being temporarily disturbed and at the same time they often suffer from blood pressure instability. In our study, we observed the functioning of both the otolith and the cardiovascular system of the astronauts before and after spaceflight. Our finding indicates that an intact otolith system plays an important role in preventing blood pressure instability during orthostatic challenges. Our finding not only has important implications for human space exploration; they may also improve the treatment of unstable blood pressure here on Earth.

  16. Pressure drop and mass transfer in two-pass ribbed channels

    Science.gov (United States)

    Chandra, P. R.; Han, J. C.

    1989-01-01

    The combined effects of the sharp 180-deg turn and of the rib configuration on the pressure drop and mass transfer characteristics in a two-pass square channel with a pair of opposite rib-roughened walls (to simulate turbine airfoil cooling passages) were determined for a Reynolds number range of 10,000-60,000. Heat transfer enhancements were compared for the first pass and for the two-pass channel with the sharp 180-deg turn. Correlations for the fully-developed friction factors and loss coefficients were obtained.

  17. Rapidly solidified Ag-Cu eutectics: A comparative study using drop-tube and melt fluxing techniques

    Science.gov (United States)

    Yu, Y.; Mullis, A. M.; Cochrane, R. F.

    2016-03-01

    A comparative study of rapid solidification of Ag-Cu eutectic alloy processed via melt fluxing and drop-tube techniques is presented. A computational model is used to estimate the cooling rate and undercooling of the free fall droplets as this cannot be determined directly. SEM micrographs show that both materials consist of lamellar and anomalous eutectic structures. However, below the critical undercooling the morphologies of each are different in respect of the distribution and volume of anomalous eutectic. The anomalous eutectic in flux- undercooled samples preferentially forms at cell boundaries around the lamellar eutectic in the cell body. In drop-tube processed samples it tends to distribute randomly inside the droplets and at much smaller volume fractions. That the formation of the anomalous eutectic can, at least in part, be suppressed in the drop-tube is strongly suggestive that the formation of anomalous eutectic occurs via remelting process, which is suppressed by rapid cooling during solidification.

  18. Shapes and Fissility of Highly Charged and Rapidly Rotating Levitated Liquid Drops

    Science.gov (United States)

    Liao, L.; Hill, R. J. A.

    2017-09-01

    We use diamagnetic levitation to investigate the shapes and the stability of free electrically charged and spinning liquid drops of volume ˜1 ml. In addition to binary fission and Taylor cone-jet fission modes observed at low and high charge density, respectively, we also observe an unusual mode which appears to be a hybrid of the two. Measurements of the angular momentum required to fission a charged drop show that nonrotating drops become unstable to fission at the amount of charge predicted by Lord Rayleigh. This result is in contrast to the observations of most previous experiments on fissioning charged drops, which typically exhibit fission well below Rayleigh's limit.

  19. Boiling on a tube bundle: heat transfer, pressure drop and flow patterns

    Energy Technology Data Exchange (ETDEWEB)

    Royen Van, E.

    2011-11-15

    The complexity of two-phase flow boiling on a tube bundle presents many challenges to the understanding of the physical phenomena taking place. It is important to quantify these numerous heat flow mechanisms in order to better describe the performance of tube bundles as a function of the operational conditions. In the present study, the bundle boiling facility at the Laboratory of Heat and Mass Transfer (LTCM) was modified to obtain high-speed videos to characterise the two-phase regimes and some bubble dynamics of the boiling process. It was then used to measure heat transfer on single tubes and in bundle boiling conditions. Pressure drop measurements were also made during adiabatic and diabatic bundle conditions. New enhanced boiling tubes from Wolverine Tube Inc. (Turbo-B5) and the Wieland-Werke AG (Gewa-B5) were investigated using R134a and R236fa as test fluids. The tests were carried out at saturation temperatures T{sub sat} of 5 °C and 15 °C, mass flow rates from 4 to 35 kg/m{sup 2}s and heat fluxes from 15 to 70 kW/m{sup 2}, typical of actual operating conditions. The flow pattern investigation was conducted using visual observations from a borescope inserted in the middle of the bundle. Measurements of the light attenuation of a laser beam through the intertube two-phase flow and local pressure fluctuations with piezo-electric pressure transducers were also taken to further help in characterising the complex flow. Pressure drop measurements and data reduction procedures were revised and used to develop new, improved frictional pressure drop prediction methods for adiabatic and diabatic two-phase conditions. The physical phenomena governing the enhanced tube evaporation process and their effects on the performance of tube bundles were investigated and insight gained. A new method based on a theoretical analysis of thin film evaporation was used to propose a new correlating parameter. A large new database of local heat transfer coefficients were obtained

  20. Extraction of essential oil from Bunium Persicum (Boiss.) by instant controlled pressure drop (DIC).

    Science.gov (United States)

    Feyzi, Elnaz; Eikani, Mohammad H; Golmohammad, Fereshteh; Tafaghodinia, Bahram

    2017-12-29

    Essential oils extraction from Bunium Persicum (Boiss) was performed using instant controlled pressure drop (in French: Détente Instantanée Contrôlée or DIC) thechnology and optimum extraction conditions were obtained. Response surface methodology (RSM) was used to determine the optimal conditions and the results were 20s heating time, 3.5bar pressure, 0.44mm particle diameter and 9 cycles. Essential oils extraction was also compared with Hydrodistillation (HD), ultrasound-assisted extraction (UAE) and Soxhlet (SOX) extraction. Results show higher efficiency of the DIC than other methods and more oxygenated components were observed. Impact of DIC, HD, UAE and SOX on the morphological structure of the plant was studied by SEM. Antioxidant activity and total phenolic content (TPC) of the extract were determined and comapred by HD. Results show that DIC facilitates achieving to higher TPC and more antioxidant activity. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Boiling Heat Transfer and Pressure Drop of Non-Azeotropic Mixtures Inside a Horizontal Grooved Tube

    Science.gov (United States)

    Kajikawa, Satoru; Ayukawa, Kyozo; Sogo, Motosuke; Okita, Yuji

    The evaporation of HCFC141b, HFC152a and HFC23, and non-azeotropic refrigerant mixture used at the very low temperature refrigeration system is experimentally studied in a horizontal spirally grooved tube with corrugation. The experiments were conducted at 0.03 to 0.47MPa of boiling pressure, 100 kg/(m2s) of mass flux, 1 to 15 kW/ m2 of heat flux, -26 to 21 °C of refrigerant temperature and 11.4 mm of average inner diameter. It is concluded that boiling heat transfer coefficients of single-refrigerant are higher than these of non-azeotropic refrigerant mixture. And dimensionless correlation of the heat transfer coefficirnts, i.e. Lockhart-Martinelli parameters agreed with equation (10) within the limit of ±40 percent. Pressure drops of these refrigerant mixture depend on its liquid density and flow pattern.

  2. Two-phase flow and pressure drop in flow passages of compact heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Wambsganss, M.W.; Jendrzejczyk, J.A.; France, D.M.

    1992-02-01

    Two-phase flow experiments were performed with air/water mixtures in a small rectangular channel measuring 9.52 {times} 1.59 mm (aspects ratio equal to 6), for applications to compact heat exchangers. Pressure drop and flow pattern definition data were obtained over a large range of mass qualities (0.0002 to 1), and in the case of flow pattern data, a large range of mass fluxes (50 to 2,000 kg/m{sup 2}s). A flow pattern map, based on visual observations and photographs of the flow patterns, is presented and compared with a map developed for a rectangular channel of the same aspect ratio but with dimensions twice those of the test channel, and with a map developed for a circular tube with the same hydraulic diameter of 3 mm. Pressure drop data are presented as a function of both mass quality and Martinelli parameter and are compared with state-of-the-art correlations and a modified Chisholm correlation. 13 refs.

  3. Two-phase flow and pressure drop in flow passages of compact heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Wambsganss, M.W.; Jendrzejczyk, J.A.; France, D.M.

    1992-01-01

    Two-phase flow experiments were performed with air/water mixtures in a small rectangular channel measuring 9.52 {times} 1.59 mm (aspects ratio equal to 6), for applications to compact heat exchangers. Pressure drop and flow pattern definition data were obtained over a large range of mass qualities (0.0002 to 1), and in the case of flow pattern data, a large range of mass fluxes (50 to 2,000 kg/m{sup 2}s). A flow pattern map, based on visual observations and photographs of the flow patterns, is presented and compared with a map developed for a rectangular channel of the same aspect ratio but with dimensions twice those of the test channel, and with a map developed for a circular tube with the same hydraulic diameter of 3 mm. Pressure drop data are presented as a function of both mass quality and Martinelli parameter and are compared with state-of-the-art correlations and a modified Chisholm correlation. 13 refs.

  4. Influence of peak inspiratory flow rates and pressure drops on inhalation performance of dry powder inhalers.

    Science.gov (United States)

    Hira, Daiki; Okuda, Tomoyuki; Ichihashi, Mika; Mizutani, Ayano; Ishizeki, Kazunori; Okada, Toyoko; Okamoto, Hirokazu

    2012-01-01

    The aim of this study was to reveal the relationship between human inspiratory flow patterns and the concomitant drops in pressure in different inhalation devices, and the influence of the devices on inhalation performance. As a model formulation for inhalers, a physically mixed dry powder composed of salbutamol sulfate and coarse lactose monohydrate was selected. The drops in pressure at 28.3 L/min of three inhalation devices, Single-type, Dual-type, and Reverse-type, was 1.0, 5.1, and 8.7 kPa, respectively. Measurements of human inspiratory patterns revealed that although the least resistant device (Single) had large inter- and intra-individual variation of peak flow rate (PFR), the coefficients of variation of PFR of the three devices were almost the same. In tests with a human inspiratory flow simulator in vitro, inhalation performance was higher, but the variation in inhalation performance in the range of human flow patterns was wider, for the more resistant device. To minimize the intra- and inter-individual variation in inhalation performance for the model formulation in this study, a formulation design that allows active pharmaceutical ingredient to detach from the carrier with a lower inhalation flow rate is needed.

  5. a Comprehensive Model for Capillary Pressure Difference across a Drop/bubble Flowing Through a Constricted Capillary

    Science.gov (United States)

    Liang, Mingchao; Wei, Junhong; Han, Hongmei; Fu, Chengguo; Liu, Jianjun

    2015-09-01

    The capillary pressure is one of the crucial parameters in many science and engineering applications such as composite materials, interface science, chemical engineering, oil exploration, etc. The drop/bubble formation and its mechanisms that affect the permeability of porous media have steadily attracted much attention in the past. When a drop/bubble moves from a larger capillary to a smaller one, it is often obstructed by an additional pressure difference caused by the capillary force. In this paper, a comprehensive model is derived for the capillary pressure difference when a drop/bubble flows through a constricted capillary, i.e. a geometrically constricted passage with an abrupt change in radius. The proposed model is expressed as a function of the smaller capillary radius, pore-throat ratio, contact angle, surface tension and length of the drop/bubble in the smaller capillary. The model predictions are compared with the available experimental data, and good agreement is found between them.

  6. Diagnostic performance of pressure drop coefficient in relation to fractional flow reserve and coronary flow reserve.

    Science.gov (United States)

    Kolli, Kranthi K; Arif, Imran; Peelukhana, Srikara V; Succop, Paul; Back, Lloyd H; Helmy, Tarek A; Leesar, Massoud A; Effat, Mohamed A; Banerjee, Rupak K

    2014-05-01

    Functional assessment of coronary lesion severity during cardiac catheterization is conducted using diagnostic parameters like fractional flow reserve (FFR; pressure derived) and coronary flow reserve (CFR; flow derived). However, the complex hemodynamics of stenosis might not be sufficiently explained by either pressure or flow alone, particularly in the case of intermediate stenosis. CDP (ratio of pressure drop across a stenosis to distal dynamic pressure), a non-dimensional index derived from fundamental fluid dynamic principles based on a combination of intracoronary pressure and flow, may improve the functional assessment of coronary lesion severity. We performed a meta-analysis of seven studies, retrieved from MEDLINE and PubMed, comparing the results of FFR and CFR of the same lesions. Two studies reported functional measurements (pressure and flow) obtained in individual patients. Five studies reported two-dimensional plots of FFR vs. CFR. The FFR and CFR data were digitized and corresponding functional measurements were extracted using the reported mean values of hemodynamic data from each of the five studies. The receiver operating characteristic (ROC) curve was used to identify the optimal cut-off point of CDP, which corresponds to the clinically used cut-off values (FFR = 0.80, FFR = 0.75, and CFR = 2.0). CDP correlated significantly with FFR (r = 0.78; P27.1 and CDP >27.9, respectively. CDP, a functional parameter based on both intracoronary pressure and flow measurements, has close agreement (area under the ROC curve = 89%) with FFR, the most frequently used method for evaluation of coronary stenosis severity.

  7. Optimal operation of rapid pressure swing adsorption with slop recycling

    NARCIS (Netherlands)

    Betlem, Bernardus H.L.; Gotink, R.W.M.; Bosch, H.

    1998-01-01

    Rapid pressure swing adsorption (RPSA) is a cyclic process operating, basically, in three phases: a pressurization, a delay, and a depressurization phase. A new, modified operation is suggested by the addition of either a raffinate recycle phase or an extract recycle phase, during which raffinate

  8. A numerical model for pressure drop and flow distribution in a solar collector with U-connected absorber pipes

    DEFF Research Database (Denmark)

    Bava, Federico; Furbo, Simon

    2016-01-01

    increased, but remained within the accuracy of the differential pressure sensor. The flow distribution was mainly affected by the flow regime in the manifolds. Turbulent regime throughout the manifolds entailed a more uniform distribution across the absorber pipes compared to laminar regime. The comparison......This study presents a numerical model calculating the pressure drop and flow distribution in a solar collector with U-type harp configuration in isothermal conditions. The flow maldistribution in the absorber pipes, caused by the different hydraulic resistances, was considered to evaluate...... at different flow rates and temperatures for water and water/propylene glycol mixture. For collector pressure drops higher than 1.4 kPa, the relative difference between the model and measurements was within 5% for water and 7% for water/propylene glycol mixture. For lower pressure drops the relative difference...

  9. Measurement and correlation of frictional pressure drop of refrigerant-based nanofluid flow boiling inside a horizontal smooth tube

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Hao; Ding, Guoliang; Jiang, Weiting; Hu, Haitao [Institute of Refrigeration and Cryogenics, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240 (China); Gao, Yifeng [International Copper Association Shanghai Office, 381 Huaihaizhong Road, Shanghai 200020 (China)

    2009-11-15

    The objective of this paper is to investigate the effect of nanoparticle on the frictional pressure drop characteristics of refrigerant-based nanofluid flow boiling inside a horizontal smooth tube, and to present a correlation for predicting the frictional pressure drop of refrigerant-based nanofluid. R113 refrigerant and CuO nanoparticle were used for preparing refrigerant-based nanofluid. Experimental conditions include mass fluxes from 100 to 200 kg m{sup -2} s{sup -1}, heat fluxes from 3.08 to 6.16 kW m{sup -2}, inlet vapor qualities from 0.2 to 0.7, and mass fractions of nanoparticles from 0 to 0.5 wt%. The experimental results show that the frictional pressured drop of refrigerant-based nanofluid increases with the increase of the mass fraction of nanoparticles, and the maximum enhancement of frictional pressure drop is 20.8% under above conditions. A frictional pressure drop correlation for refrigerant-based nanofluid is proposed, and the predictions agree with 92% of the experimental data within the deviation of {+-}15%. (author)

  10. Pressure drop and heat transfer during two-phase flow vaporization of propane in horizontal smooth minichannels

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kwang-Il; Pamitran, A.S. [Graduate School, Chonnam National University, San 96-1, Dunduk-Dong, Yeosu, Chonnam 550-749 (Korea); Oh, Jong-Taek [Department of Refrigeration and Air Conditioning Engineering, Chonnam National University, San 96-1, Dunduk-dong, Yeosu, Chonnam 550-749 (Korea); Saito, Kiyoshi [Department of Applied Mechanics and Aerospace Engineering, Waseda University, 1-104, Totsuka-machi, Shinjuku-ku, Tokyo 169-8050 (Japan)

    2009-08-15

    This study examined the two-phase flow boiling pressure drop and heat transfer for propane, as a long term alternative refrigerant, in horizontal minichannels. The pressure drop and local heat transfer coefficients were obtained for heat fluxes ranging from 5-20 kW m{sup -2}, mass fluxes ranging from 50-400 kg m{sup -2} s{sup -1}, saturation temperatures of 10, 5 and 0 C, and quality up to 1.0. The test section was made of stainless steel tubes with inner diameters of 1.5 mm and 3.0 mm, and lengths of 1000 mm and 2000 mm, respectively. The present study showed the effect of mass flux, heat flux, inner tube diameter and saturation temperature on pressure drop and heat transfer coefficient. The experimental results were compared against several existing pressure drop and heat transfer coefficient prediction methods. Because the study on evaporation with propane in minichannels was limited, new correlations of pressure drop and boiling heat transfer coefficient were developed in this present study. (author)

  11. Flow patterns and pressure drop in air/water two-phase flow in horizontal helicoidal pipes

    Energy Technology Data Exchange (ETDEWEB)

    Awwad, A.; Xin, R.C.; Dong, Z.F.; Ebadian, M.A. [Florida International Univ., Miami, FL (United States). Dept. of Mechanical Engineering; Soliman, H.M. [Univ. of Manitoba, Winnipeg, Manitoba (Canada). Dept. of Mechanical Engineering

    1995-12-01

    An experimental investigation is conducted for air/water two-phase flow in horizontal helicoidal pipes. The helicoidal pipes are constructed of 25.4 mm I.D. Tygon tubing wrapped around cylindrical concrete forms with outside diameters of 62 cm and 124 cm. The helix angles of the helicoidal pipes vary from 1 to 20 deg. The experiments are performed for superficial water velocity in a range of U{sub L} = 0.008 {approximately} 2.2 m/s and for superficial air velocity in a range of U{sub G} = 0.2 {approximately} 50 m/s. The flow patterns are discerned and recorded photographically. The pressure drop of the air/water two-phase flow in the coils is measured and the Lockhart-Martinelli approach is used to analyze the data. The results are presented in the form of frictional pressure drop multipliers versus the Lockhart-Martinelli parameter. It was found that the flow patterns differ greatly from those of the straight pipe, and that the frictional pressure drop multipliers depend on both the Lockhart-Martinelli parameter and the flow rates. The correlation of the frictional pressure drop has been provided based on the current data. Furthermore, it was also found that the helix angle of the helicoidal pipe had almost no effect on the air/water two-phase flow pressure drop in the present experimental ranges.

  12. Pressure Drop in Cold Water Flow in Beds Packed with Several Kinds of Crushed Ice.

    Science.gov (United States)

    Yanadori, Michio; Ohira, Akiyoshi

    This paper deals with the pressure drop in cold water flow in the beds packed with crushed ice. 1n each case, ice-packed beds were filled with sevral kinds of crushed ice, and friction-loss coefficients were examined. The following results were obtained. (1) The friction factor of rectangular-type ice-packed beds is smaller than that of ideal sphere beds by about 1/4 to 1/2. (2) The friction factor of small-stone-type ice-packed beds is about twice as large as that of ideal sphere beds. (3) It is difficult to compare the flow model of water in restricted channel of particle-type ice-packed beds with that of ideal packed beds.

  13. Pressure drop measurement for flow-measuring dummy fuel assemblies in HANARO core

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Heon Il; Chae, Hee Taek; Chung, Heung June [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1996-06-01

    In order to characterize the flow distribution of HANARO core, flow-rate measuring dummy fuel assemblies (instrumented dummy fuel assemblies) were to be used in the HANARO commissioning. To do this instrumented dummy fuel assemblies were developed and the calibration tests were conducted in the thermal-hydraulic laboratory. Through this experiment the correlations for 6 instrumented dummy fuel assemblies were derived. The measured total pressure drop for the 36-element dummy fuel assembly was 211 kPa, which meets the design requirement, 209 kPa {+-} 5%. The form loss coefficients for the spacers were re-evaluated and the new correlation was obtained. 7 tabs., 13 figs., 2 refs. (Author).

  14. CFD Analysis of the Effect of Elbow Radius on Pressure Drop in Multiphase Flow

    Directory of Open Access Journals (Sweden)

    Quamrul H. Mazumder

    2012-01-01

    Full Text Available Computational fluid dynamics (CFD analysis was performed in four different 90 degree elbows with air-water two-phase flows. The inside diameters of the elbows were 6.35 mm and 12.7 mm with radius to diameter ratios ( of 1.5 to 3. The pressure drops at two different upstream and downstream locations were investigated using empirical, experimental, and computational methods. The combination of three different air velocities, ranging from 15.24 to 45.72 m/sec, and nine different water velocities, in the range of 0.1–10.0 m/s, was used in this study. CFD analysis was performed using the mixture model and a commercial code, FLUENT. The comparison of CFD predictions with experimental data and empirical model outputs showed good agreement.

  15. Geothermal Two-Phase Wellbore Flow: Pressure Drop Correlations and Flow Pattern Transitions

    Energy Technology Data Exchange (ETDEWEB)

    Ambastha, A.K.; Gudmundsson, J.S.

    1986-01-21

    In this paper we present some basic concepts of two-phase flow and review the Orkiszewski (1967) correlations which have been suggested by various investigators to perform well for geothermal wellbore flow situations. We also present a flow regime map based on the transition criteria used by Orkiszewski (1967) and show that most geothermal wells flow under slug flow regime. We have rearranged bubble- to slug-flow transition criterion used by Orkiszewski (1967) to show that the transition depends on the dimensionless pipe diameter number in addition to dimensionless liquid and gas velocity numbers. Our aim is also to identify what research may lead to improvements in two-phase pressure drop calculations for geothermal wellbore flow.

  16. FLUID-STRUCTURE INTERACTION IN A U-TUBE WITH SURFACE ROUGHNESS AND PRESSURE DROP

    Directory of Open Access Journals (Sweden)

    GYUN-HO GIM

    2014-10-01

    Full Text Available In this research, the surface roughness affecting the pressure drop in a pipe used as the steam generator of a PWR was studied. Based on the CFD (Computational Fluid Dynamics technique using a commercial code named ANSYS-FLUENT, a straight pipe was modeled to obtain the Darcy frictional coefficient, changed with a range of various surface roughness ratios as well as Reynolds numbers. The result is validated by the comparison with a Moody chart to set the appropriate size of grids at the wall for the correct consideration of surface roughness. The pressure drop in a full-scale U-shaped pipe is measured with the same code, correlated with the surface roughness ratio. In the next stage, we studied a reduced scale model of a U-shaped heat pipe with experiment and analysis of the investigation into fluid-structure interaction (FSI. The material of the pipe was cut from the real heat pipe of a material named Inconel 690 alloy, now used in steam generators. The accelerations at the fixed stations on the outer surface of the pipe model are measured in the series of time history, and Fourier transformed to the frequency domain. The natural frequency of three leading modes were traced from the FFT data, and compared with the result of a numerical analysis for unsteady, incompressible flow. The corresponding mode shapes and maximum displacement are obtained numerically from the FSI simulation with the coupling of the commercial codes, ANSYS-FLUENT and TRANSIENT_STRUCTURAL. The primary frequencies for the model system consist of three parts: structural vibration, BPF(blade pass frequency of pump, and fluid-structure interaction.

  17. Fluid-structure interaction in u-tube with surfce roughness and pressure drop

    Energy Technology Data Exchange (ETDEWEB)

    Gim, Gyun Ho; Chang, Se Myoung; Lee, Sin Young [Mechanical Engineering, Kunsan National University, Gunsan (Korea, Republic of); Jang, Gang Won [Faculty of Mechanical and Aerospace Engineering, Sejong University, Seoul (Korea, Republic of)

    2014-10-15

    In this research, the surface roughness affecting the pressure drop in a pipe used as the steam generator of a PWR was studied. Based on the CFD (Computational Fluid Dynamics) technique using a commercial code named ANSYS-FLUENT, a straight pipe was modeled to obtain the Darcy frictional coefficient, changed with a range of various surface roughness ratios as well as Reynolds numbers. The result is validated by the comparison with a Moody chart to set the appropriate size of grids at the wall for the correct consideration of surface roughness. The pressure drop in a full-scale U-shaped pipe is measured with the same code, correlated with the surface roughness ratio. In the next stage, we studied a reduced scale model of a U-shaped heat pipe with experiment and analysis of the investigation into fluid-structure interaction (FSI). The material of the pipe was cut from the real heat pipe of a material named Inconel 690 alloy, now used in steam generators. The accelerations at the fixed stations on the outer surface of the pipe model are measured in the series of time history, and Fourier transformed to the frequency domain. The natural frequency of three leading modes were traced from the FFT data, and compared with the result of a numerical analysis for unsteady, incompressible flow. The corresponding mode shapes and maximum displacement are obtained numerically from the FSI simulation with the coupling of the commercial codes, ANSYS-FLUENT and TRANSIENT{sub S}TRUCTURAL. The primary frequencies for the model system consist of three parts: structural vibration, BPF(blade pass frequency) of pump, and fluid-structure interaction.

  18. Boiling Heat Transfer and Pressure Drop of a Refrigerant Flowing Vertically Downward in a Small Diameter Tube

    Science.gov (United States)

    Miyata, Kazushi; Mori, Hideo; Ohishi, Katsumi; Tanaka, Hirokazu

    Experiments were performed on boiling heat transfer and pressure drop of a refrigerant R410A flowing vertically downward in a copper smooth tube of 1.0 mm inside diameter for the development of a high-performance heat exchanger using small diameter tubes for air conditioning systems. Local heat transfer coefficients were measured in a range of mass fluxes from 30 to 200 kg/(m2•s), heat fluxes from 1 to 16 kW/m2 and quality from 0.1 to over 1 at evaporation temperature of 10°C. Pressure drops were measured and flow patterns were observed at mass fluxes from 30 to 200 kg/(m2•s) and quality from 0.1 to 0.9. The characteristics of frictional pressure drop, heat transfer coefficient and dryout qualities were clarified by comparing the measurements with the data for the vertically upward flow previously obtained.

  19. Pressure Drop and Catalytic Dehydrogenation of NaBH{sub 4} Solution Across Pin Fin Structures in a Microchannel Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Ki Moon [Korea Institute of Industrial Technology, Cheonan (Korea, Republic of); Choi, Seok Hyun [Key Valve Technologies Ltd., Siheung (Korea, Republic of); Lee, Hee Joon [Kookmin Univ., Seoul (Korea, Republic of)

    2017-06-15

    Dehydrogenation from the hydrolysis of a sodium borohydride (NaBH{sub 4}) solution has been of interest owing to its high theoretical hydrogen storage capacity (10.8 wt.%) and potentially safe operation. An experimental study has been performed on the catalytic reaction rate and pressure drop of a NaBH4 solution over both a single microchannel with a hydraulic diameter of 300 μm and a staggered array of micro pin fins in the microchannel with hydraulic diameter of 50 μm. The catalytic reaction rates and pressure drops were obtained under Reynolds numbers from 1 to 60 and solution concentrations from 5 to 20 wt.%. Moreover, reacting flows were visualized using a high-speed camera with a macro zoom lens. As a result, both the amount of hydrogenation and pressure drop are 2.45 times and 1.5 times larger in a pin fin microchannel array than in a single microchannel, respectively.

  20. A systematic search of sudden pressure drops on Gale crater during two Martian years derived from MSL/REMS data

    Science.gov (United States)

    Ordonez-Etxeberria, Iñaki; Hueso, Ricardo; Sánchez-Lavega, Agustín

    2018-01-01

    The Mars Science Laboratory (MSL) rover carries a suite of meteorological detectors that constitute the Rover Environmental Monitoring Station (REMS) instrument. REMS investigates the meteorological conditions at Gale crater by obtaining high-frequency data of pressure, air and ground temperature, relative humidity, UV flux at the surface and wind intensity and direction with some limitations in the wind data. We have run a search of atmospheric pressure drops of short duration (warm vortices and dust devils. Previous systematic searches of warm vortices from REMS pressure data (Kahanpää et al., 2016; Steakley and Murphy, 2016) cover about one Martian year. We show that sudden pressure drops are twice more abundant in the second Martian year [sols 671-1339] than in the first one analyzed in previous works. The higher number of detections could be linked to a combination of different topography, higher altitudes (120 m above the landing site) and true inter-annual meteorological variability. We found 1129 events with a pressure drop larger than 0.5 Pa. Of these, 635 occurred during the local daytime (∼56%) and 494 were nocturnal. The most intense pressure drop (4.2 Pa) occurred at daytime on sol 1417 (areocentric solar longitude Ls = 195°) and was accompanied by a simultaneous decrease in the UV signal of 7.1%, pointing to a true dust devil. We also discuss similar but less intense simultaneous pressure and UV radiation drops that constitute 0.7% of all daytime events. Most of the intense daytime pressure drops with variations larger than 1.0 Pa occur when the difference between air and ground temperature is larger than 15 K. Statistically, the frequency of daytime pressure drops peaks close to noon (12:00-13:00 Local True Solar Time or LTST) with more events in spring and summer (Ls from 180° to 360°). The nocturnal sudden pressure drops concentrate in the 20:00-23:00 LTST time interval and they only occur in spring and summer. We interpret these nocturnal

  1. Association between portal vein pressure drop gradient after transjugular intrahepatic portosystemic shunt and clinical prognosis

    Directory of Open Access Journals (Sweden)

    XU Zhengguo

    2016-12-01

    Full Text Available ObjectiveTo investigate the association between portal vein pressure drop gradient in patients with cirrhotic portal hypertension treated by transjugular intrahepatic portosystemic shunt (TIPS and clinical prognosis, as well as the ideal range of portal vein pressure drop. MethodsA total of 58 patients who underwent TIPS in Xinqiao Hospital of Third Military Medical University from November 2013 to December 2015 were enrolled. All the patients underwent TIPS and embolization of the gastric coronary vein and the short gastric veins, and the change intervals of portal vein pressure gradient were monitored. The follow-up time ranged from 3 days to 2 years, and the association of portal vein pressure drop gradient with postoperative liver function, splenic function, rebleeding rate, hepatic encephalopathy, and portal hypertensive gastrointestinal diseases was analyzed. The paired t-test was used for comparison of parameters before and after treatment. ResultsThe patients had a significant reduction in liver function on day 3 after surgery. At 2 month after surgery, the levels of TBil was rised and had significant changes[(49.81±27.82μmol/L vs (31.64±17.67 μmol/L,t=5.372,P<0.001]. At 6 months after surgery, red blood cell count and platelet count had no significant changes,but,white blood cell count was reduced[(3.79±1.37)×109/L vs (4.57±2.24×109/L,t=2.835,P=0.006]. There was a 23% reduction in portal vein pressure after surgery (from 30.62±3.56 mmHg before surgery to 21.21±2.90 mmHg after surgery, t=23.318,P<0.001. All the patients had varying degrees of relief of gastrointestinal symptoms associated with portal vein hypertension, such as abdominal distension, poor appetite, and diarrhea. Of all patients, none experienced in-stent restenosis or occlusion and 13 experienced hepatic encephalopathy after surgery, which tended to occur at the time when postoperative portal vein pressure was reduced to 14.7-25.7 mmHg, i

  2. Pressure measurements in a rapidly sheared turbulent wall layer

    Science.gov (United States)

    Diwan, Sourabh; Morrison, Jonathan

    2014-11-01

    The aim of the present work is to improve understanding of the role of pressure fluctuations in the generation of coherent structures in wall-bounded turbulent flows, with particular regard to the rapid and slow source terms. The work is in part motivated by the recent numerical simulations of Sharma et al. (Phy. Fluids, 23, 2011), which showed the importance of pressure fluctuations (and their spatial gradients) in the dynamics of large-scale turbulent motions. Our experimental design consists of first generating a shearless boundary layer in a wind tunnel by passing a grid-generated turbulent flow over a moving floor whose speed is matched to the freestream velocity, and then shearing it rapidly by passing it over a stationary floor further downstream. Close to the leading edge of the stationary floor, the resulting flow is expected to satisfy the approximations of the Rapid Distortion Theory and therefore would be an ideal candidate for studying linear processes in wall turbulence. We carry out pressure measurements on the wall as well as within the flow - the former using surface mounted pressure transducers and the latter using a static pressure probe similar in design to that used by Tsuji et al. (J. Fluid. Mech. 585, 2007). We also present a comparison between the rapidly sheared flow and a more conventional boundary layer subjected to a turbulent free stream. We acknowledge the financial support from EPSRC (Grant No. EP/I037938).

  3. Possibilities of mine gases outflow prediction during pressure drops considering abandoned shaft located in old coal mining area

    Energy Technology Data Exchange (ETDEWEB)

    Wrona, P. [Silesian University of Technology, Gleiwitz (Poland). Inst. of Geotechnology, Mining Geophysics and Ecology of Industrial Areas

    2005-09-01

    There are abandoned mine shafts, small shafts and drifts located in an old, shallow coal mining area at the slope of Zabrze Dome. Creation of voids and connections with abandoned excavations hasn't been avoided during liquidation of these constructions. Mine gas outflow can create a hazard for people's safety, so it may be helpful to be able to predict volume flow of out flowing gases. One of the abandoned shafts has been selected to conduct extensive measurements of volume flow of mine gases during pressure drops. One case has been selected to perform a comparison between measured and calculated results. Calculated results have been obtained with application of Torricelli's model of gas outflow phenomena from a tank. Pressure drops are considered as the external input functions (the extortions) with quantity of volume flow in the abandoned shaft as the response. The coal shaft must have sufficient volume of voids and a leaky lock. The case of the extortion which is built of pressure drop and pressure buildup is discussed, too. The loop characteristic as the result of the extortion may indicate the existence of volume flow in a hysteresis curve. Mine gases volume flow from abandoned mine shaft depends on time of pressure drop and pressure changes rate. Concentration of CO{sub 2} in mine gases out flowing from abandoned mine shafts located at the slope of Zabrze Dome exceeded 10%. Concentration of CO{sub 2} depends on time of pressure drop, too. The model could be a useful and very simple tool to perform predictions for gas hazard estimations. (orig.)

  4. Characterization of interfacial waves and pressure drop in horizontal oil-water core-annular flows

    Science.gov (United States)

    Tripathi, Sumit; Tabor, Rico F.; Singh, Ramesh; Bhattacharya, Amitabh

    2017-08-01

    We study the transportation of highly viscous furnace-oil in a horizontal pipe as core-annular flow (CAF) using experiments. Pressure drop and high-speed images of the fully developed CAF are recorded for a wide range of flow rate combinations. The height profiles (with respect to the centerline of the pipe) of the upper and lower interfaces of the core are obtained using a high-speed camera and image analysis. Time series of the interface height are used to calculate the average holdup of the oil phase, speed of the interface, and the power spectra of the interface profile. We find that the ratio of the effective velocity of the annular fluid to the core velocity, α , shows a large scatter. Using the average value of this ratio (α =0.74 ) yields a good estimate of the measured holdup for the whole range of flow rate ratios, mainly due to the low sensitivity of the holdup ratio to the velocity ratio. Dimensional analysis implies that, if the thickness of the annular fluid is much smaller than the pipe radius, then, for the given range of parameters in our experiments, the non-dimensional interface shape, as well as the non-dimensional wall shear stress, can depend only on the shear Reynolds number and the velocity ratio. Our experimental data show that, for both lower and upper interfaces, the normalized power spectrum of the interface height has a strong dependence on the shear Reynolds number. Specifically, for low shear Reynolds numbers, interfacial modes with large wavelengths dominate, while, for large shear Reynolds numbers, interfacial modes with small wavelengths dominate. Normalized variance of the interface height is higher at lower shear Reynolds numbers and tends to a constant with increasing shear Reynolds number. Surprisingly, our experimental data also show that the effective wall shear stress is, to a large extent, proportional to the square of the core velocity. Using the implied scalings for the holdup ratio and wall shear stress, we can derive

  5. Rapid Assessment of Protected area Pressures and Threats in ...

    African Journals Online (AJOL)

    Regular evaluation of protected area operations can enable policy makers develop strategic responses to pervasive management problems. Pressures and threats in seven National Parks of the National Park Service (NPS) were therefore assessed using the Rapid Assessment and Prioritization of Protected Area ...

  6. Influence of Peer Pressure on Secondary School Students Drop out in Rongo Sub-County, Migori County, Kenya

    Science.gov (United States)

    Omollo, Atieno Evaline; Yambo, Onyango J. M.

    2017-01-01

    The purpose of this study was to establish the influence of peer pressure on secondary school students' drop out in Rongo Sub-County, Migori County, Kenya. The statement of the problem showed that the sub-county had a dropout rate of 43 percent as compared to the neighboring sub counties like Uriri, Awendo, Nyatike, Kuria and Migori which had 25,…

  7. Experimental study of a cocurrent upflow packed bed bubble column reactor: pressure drop, holdup and interfacial area

    NARCIS (Netherlands)

    Molga, E.J.; Westerterp, K.R.

    1997-01-01

    Gas¿liquid interfacial areas have been determined by means of chemically enhanced absorption of CO2 into DEA in a packed bed bubble column reactor with an inner diameter of 156 mm. The influence of the gas velocity and particle diameter on the interfacial areas, pressure drops and liquid holdups has

  8. Burn-out, Circumferential Film Flow Distribution and Pressure Drop for an Eccentric Annulus with Heated Rod

    DEFF Research Database (Denmark)

    Andersen, P. S.; Jensen, A.; Mannov, G.

    1974-01-01

    Measurements of (1) burn-out, (2) circumferential film flow distribution, and (3) pressure drop in a 17 × 27.2 × 3500 mm concentric and eccentric annulus geometry are presented. The eccentric displacement was varied between 0 and 3 mm. The working fluid was water. Burn-out curves at 70 bar...... flow variation on burn-out is discussed....

  9. Pressure drop calculation using a one-dimensional mathematical model for two-phase flow through an orifice

    DEFF Research Database (Denmark)

    Petkov, K.P.; Puton, M; Madsen, Søren Peder

    2014-01-01

    A model based on a homogeneous formulation of the governing differential equations (Navier-Stokes equations) describing the process of pressure drop in a simplified geometry of an expansion valve is investigated and simulated. Numerical solutions are compared to experimental results. The model...

  10. Boiling Heat Transfer and Pressure Drop of a Refrigerant Flowing Vertically Upward in a Small Diameter Tube

    Science.gov (United States)

    Miyata, Kazushi; Mori, Hideo; Ohishi, Katsumi; Tanaka, Hirokazu

    In the present study, experiments were performed to examine characteristics of flow boiling heat transfer and pressure drop of a refrigerant R410A flowing vertically upward in a copper smooth tube with 1.0 mm inside diameter for the development of a high-performance heat exchanger using small diameter tubes for air conditioning systems. Local heat transfer coefficients were measured in a range of mass fluxes from 30 to 200 kg/(m2•s), heat fluxes from 1 to 16 kW/m2 and qualities from 0.1 to over 1 at evaporation temperature of 10°C, and pressure drops were also measured at mass fluxes of 100 and 200 kg/(m2•s) and qualities from 0.1 to 0.9. Three types of flow pattern were observed in the tube: A slug, a slug-annular and an annular flow. Based on the measurements, the characteristics of frictional pressure drop, heat transfer coefficient and dryout qualities were clarified. The measured pressure drop and heat transfer coefficient were compared with correlations.

  11. Pressure Drop of Hybrid Heat Exchanger for SO{sub 3} Decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chan Soo; Seo, Dong Un; Yoo, Tae Ho; Hong, Sung Deok; Kim, Yong Wan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2011-05-15

    A sulfur trioxide decomposer is one of the main technical challenges in the development of a nuclear hydrogen production system using SI cycle or hybrid sulfur cycle. Kim et al. developed a hybrid heat exchanger for the sulfur trioxide decomposition to withstand its severe operating conditions. The operation conditions include the high temperature over 850 .deg. C, the large pressure difference over 1 MPa, and the corrosive working fluid with the sulfuric acid gas mixture. The surface contacted with the process gas is coated with the corrosion resistant silicon carbide. Ion beam mixing technology with nitrogen ions is applied to reduce the thermal stress through the mixed interface between the coating layer and the base material. The base material of the heat exchanger is heat-resistant super alloy such as Hastelloy X. The hot gas channel plate and the process gas channel plate are joined by Park et al.'s diffusion bonding process. Kim et al. performed the sensitivity analysis of the thermo-chemical design of the hybrid-concept sulfur trioxide decomposer to determine the operation condition of the laboratory scale decomposer. The feasibility test results of the heat exchanger showed the surface enhancement effect on the corrosion-resistance in the sulfuric acid gas condition. Song et al. provided the thermal structural analysis results to install the laboratory-scale heat exchanger to maintain the structural integrity at the experimental condition. In this study, we obtained the experimental results for the pressure drop of the laboratory-scale hybrid heat exchanger

  12. Comparative study of heat transfer and pressure drop during flow boiling and flow condensation in minichannels

    Directory of Open Access Journals (Sweden)

    Mikielewicz Dariusz

    2014-09-01

    Full Text Available In the paper a method developed earlier by authors is applied to calculations of pressure drop and heat transfer coefficient for flow boiling and also flow condensation for some recent data collected from literature for such fluids as R404a, R600a, R290, R32,R134a, R1234yf and other. The modification of interface shear stresses between flow boiling and flow condensation in annular flow structure are considered through incorporation of the so called blowing parameter. The shear stress between vapor phase and liquid phase is generally a function of nonisothermal effects. The mechanism of modification of shear stresses at the vapor-liquid interface has been presented in detail. In case of annular flow it contributes to thickening and thinning of the liquid film, which corresponds to condensation and boiling respectively. There is also a different influence of heat flux on the modification of shear stress in the bubbly flow structure, where it affects bubble nucleation. In that case the effect of applied heat flux is considered. As a result a modified form of the two-phase flow multiplier is obtained, in which the nonadiabatic effect is clearly pronounced.

  13. Heat transfer and pressure drop characteristics of nanofluids in a plate heat exchanger.

    Science.gov (United States)

    Kwon, Y H; Kim, D; Li, C G; Lee, J K; Hong, D S; Lee, J G; Lee, S H; Cho, Y H; Kim, S H

    2011-07-01

    In this paper, the heat transfer characteristics and pressure drop of the ZnO and Al2O3 nanofluids in a plate heat exchanger were studied. The experimental conditions were 100-500 Reynolds number and the respective volumetric flow rates. The working temperature of the heat exchanger was within 20-40 degrees C. The measured thermophysical properties, such as thermal conductivity and kinematic viscosity, were applied to the calculation of the convective heat transfer coefficient of the plate heat exchanger employing the ZnO and Al2O3 nanofluids made through a two-step method. According to the Reynolds number, the overall heat transfer coefficient for 6 vol% Al2O3 increased to 30% because at the given viscosity and density of the nanofluids, they did not have the same flow rates. At a given volumetric flow rate, however, the performance did not improve. After the nanofluids were placed in the plate heat exchanger, the experimental results pertaining to nanofluid efficiency seemed inauspicious.

  14. Instant controlled pressure drop extraction of lavandin essential oils: fundamentals and experimental studies.

    Science.gov (United States)

    Besombes, Colette; Berka-Zougali, Baya; Allaf, Karim

    2010-10-29

    Détente Instantanée contrôlée (DIC), French for Instant Controlled Pressure Drop, was performed on laboratory apparatus as well as on a pilot plant for proving its feasibility, and identifying the optimized processing conditions and recognizing the energy consumption and the quantity of water used for such an operation. GC-MS and SPME analysis of the extracts and residue material were carried out to assess the extracts and solid residues. The lavandin essential oils obtained by using the new DIC extraction process was studied, modeled and quantitatively and qualitatively compared to the conventional hydrodistillation method. The most important differences between the two essential oils were reflected in the yields, with 4.25 as against 2.3 g EO/100 g of raw matter, and in the extraction time, with 480 s as against some hours for respectively the DIC and the hydrodistillation operations. These differences have been previewed through the fundamental analysis. They can normally explain the great decreasing of energy consumption to be 662 kWh/t of raw material. The amount of water to be added was about 42 kg water/t of raw material. Copyright © 2010 Elsevier B.V. All rights reserved.

  15. The numerical investigation of heat transfer and pressure drop of turbulent flow in a triangular microchannel

    Science.gov (United States)

    Rezaei, Omid; Akbari, Omid Ali; Marzban, Ali; Toghraie, Davood; Pourfattah, Farzad; Mashayekhi, Ramin

    2017-09-01

    In this presentation, the flow and heat transfer inside a microchannel with a triangular section, have been numerically simulated. In this three-dimensional simulation, the flow has been considered turbulent. In order to increase the heat transfer of the channel walls, the semi-truncated and semi-attached ribs have been placed inside the channel and the effect of forms and numbers of ribs has been studied. In this research, the base fluid is Water and the effect of volume fraction of Al2O3 nanoparticles on the amount of heat transfer and physics of flow have been investigated. The presented results are including of the distribution of Nusselt number in the channel, friction coefficient and Performance Evaluation Criterion of each different arrangement. The results indicate that, the ribs affect the physics of flow and their influence is absolutely related to Reynolds number of flow. Also, the investigation of the used semi-truncated and semi-attached ribs in Reynolds number indicates that, although heat transfer increases, but more pressure drop arises. Therefore, in this method, in order to improve the heat transfer from the walls of microchannel on the constant heat flux, using the pump is demanded.

  16. Investigation of the different base fluid effects on the nanofluids heat transfer and pressure drop

    Science.gov (United States)

    Bayat, Javad; Nikseresht, Amir Hossein

    2011-09-01

    A numerical study of laminar forced convective flows of three different nanofluids through a horizontal circular tube with a constant heat flux condition has been performed. The effect of Al2O3 volume concentration 0 ≤ φ ≤ 0.09 in the pure water, water-ethylene glycol mixture and pure ethylene glycol as base fluids, and Reynolds number of 100 ≤ Re ≤ 2,000 for different power inputs in the range of 10 ≤ Q( W) ≤ 400 have been investigated. In this study, all of the nanofluid properties are temperature and nanoparticle volume concentration dependent. The governing equations have been solved using finite volume approach with the SIMPLER algorithm. The results indicate an increase in the averaged heat transfer coefficient with increasing the mass of ethylene glycol in the water base fluid, solid concentration and Reynolds number. From the investigations it can be inferred that, the pressure drop and pumping power in the nanofluids at low solid volumetric concentration (φ rate with lower wall shear stress with the use of proper nanofluids.

  17. Measurement of heat transfer and pressure drop in rectangular channels with turbulence promoters

    Science.gov (United States)

    Han, J. C.; Park, J. S.; Ibrahim, M. Y.

    1986-01-01

    Periodic rib turbulators were used in advanced turbine cooling designs to enhance the internal heat transfer. The objective of the present project was to investigate the combined effects of the rib angle of attack and the channel aspect ratio on the local heat transfer and pressure drop in rectangular channels with two opposite ribbed walls for Reynolds number varied from 10,000 to 60,000. The channel aspect ratio (W/H) was varied from 1 to 2 to 4. The rib angle of attack (alpha) was varied from 90 to 60 to 45 to 30 degree. The highly detailed heat transfer coefficient distribution on both the smooth side and the ribbed side walls from the channel sharp entrance to the downstream region were measured. The results showed that, in the square channel, the heat transfer for the slant ribs (alpha = 30 -45 deg) was about 30% higher that of the transverse ribs (alpha = 90 deg) for a constant pumping power. However, in the rectangular channels (W/H = 2 and 4, ribs on W side), the heat transfer at alpha = 30 -45 deg was only about 5% higher than 90 deg. The average heat transfer and friction correlations were developed to account for rib spacing, rib angle, and channel aspect ratio over the range of roughness Reynolds number.

  18. Antimicrobial nanoparticle-coated electrostatic air filter with high filtration efficiency and low pressure drop.

    Science.gov (United States)

    Sim, Kyoung Mi; Park, Hyun-Seol; Bae, Gwi-Nam; Jung, Jae Hee

    2015-11-15

    In this study, we demonstrated an antimicrobial nanoparticle-coated electrostatic (ES) air filter. Antimicrobial natural-product Sophora flavescens nanoparticles were produced using an aerosol process, and were continuously deposited onto the surface of air filter media. For the electrostatic activation of the filter medium, a corona discharge electrification system was used before and after antimicrobial treatment of the filter. In the antimicrobial treatment process, the deposition efficiency of S. flavescens nanoparticles on the ES filter was ~12% higher than that on the pristine (Non-ES) filter. In the evaluation of filtration performance using test particles (a nanosized KCl aerosol and submicron-sized Staphylococcus epidermidis bioaerosol), the ES filter showed better filtration efficiency than the Non-ES filter. However, antimicrobial treatment with S. flavescens nanoparticles affected the filtration efficiency of the filter differently depending on the size of the test particles. While the filtration efficiency of the KCl nanoparticles was reduced on the ES filter after the antimicrobial treatment, the filtration efficiency was improved after the recharging process. In summary, we prepared an antimicrobial ES air filter with >99% antimicrobial activity, ~92.5% filtration efficiency (for a 300-nm KCl aerosol), and a ~0.8 mmAq pressure drop (at 13 cm/s). This study provides valuable information for the development of a hybrid air purification system that can serve various functions and be used in an indoor environment. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Experimental Investigation of the Effect of Spherical Particle Size Distribution on Frictional Pressure drop in Particulate Debris Bed

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jin Ho; Kim, Eunho; Park, Hyun Sun [POSTECH, Daejeon (Korea, Republic of)

    2015-10-15

    It is important to ensure the coolant ingression into the internally heat generated debris bed which is governed by pressure drop in debris bed to assure the long-term cooling of debris bed on the cavity floor. For this reason, it is necessary to understand the pressure drop mechanism in porous bed that can be characterized by physical parameters that include porosity, particle morphology, particle size distribution etc. According to previous investigations on molten fuel coolant interaction (FCI) experiment, the settled particulate debris bed after fuel-coolant interaction were stratified and it was composed of multi-sized particles with irregular shape. (Karbojian et al., 2009; Magallon, 2006). Among these characteristics of debris bed, this study focused on the effect of particle size distribution on frictional pressure drop in bed. The experiment using single-phase water was conducted to investigate the effect of spherical particle size distribution on frictional pressure drop in mixed bed. This study reports the experimental data for measured frictional pressure drops in bed according to the particle Reynolds number. It is composed of multi-sized spherical particles whose sizes are varied from 1 mm to 10 mm. Besides, the experimental data is compared to the Ergun equation with the mean particle diameters (mass, area, length, and number mean diameters). The results of this study are also compared to those of KTH published in 2011. The conclusions are summarized as follows. The calculated mean particle diameters can be changed according to chosen particle sizes and those mass fractions even though the cumulative mass fractions are almost similar trend. As results of obtaining the effective diameter in mixed using measured frictional pressure drops and the Ergun equation, it is close to the length mean diameter when the particle Reynolds number is lower than 7, however, it has the value between the length mean diameter and the area mean diameter when the particle

  20. MHD pressure drop characteristics in a three-surface-multi-layered channel under a strong magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Aoyagi, M., E-mail: mao@karma.qse.tohoku.ac.jp [Department of Quantum Science and Energy Engineering, School of Engineering, Tohoku University, 6-6-01-2 Aramaki-Aoba, Aoba-ku, Sendai 980-8579 (Japan); Ito, S.; Hashizume, H. [Department of Quantum Science and Energy Engineering, School of Engineering, Tohoku University, 6-6-01-2 Aramaki-Aoba, Aoba-ku, Sendai 980-8579 (Japan); Muroga, T. [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan)

    2010-12-15

    A three-surface-multi-layered channel is one of the possible methods for reducing the magnetohydrodynamic (MHD) pressure drop in a Li/V blanket. In this study, experimental and numerical evaluations of the liquid metal MHD flow in a three-surface-multi-layered channel were conducted to confirm the extent of MHD pressure reduction in the channel. The MHD flow was tested using a Bi-Sn eutectic alloy (MHD liquid) and an open annular channel under up to 5 T magnetic field. Experimentally determined pressure drops differed from those predicted by numerical analysis. This may be as a result of an increase in the friction force caused by an oxide appearing on the liquid free surface and a decrease in the electromagnetic force owing to the formation of a contact resistance between the Bi-Sn alloy and the bottom wall of the stainless steel channel.

  1. CFD analysis of pressure drop across grid spacers in rod bundles compared to correlations and heavy liquid metal experimental data

    Energy Technology Data Exchange (ETDEWEB)

    Batta, A., E-mail: batta@kit.edu; Class, A.G., E-mail: class@kit.edu

    2017-02-15

    Early studies of the flow in rod bundles with spacer grids suggest that the pressure drop can be decomposed in contributions due to flow area variations by spacer grids and frictional losses along the rods. For these shape and frictional losses simple correlations based on theoretical and experimental data have been proposed. In the OECD benchmark study LACANES it was observed that correlations could well describe the flow behavior of the heavy liquid metal loop including a rod bundle with the exception of the core region, where different experts chose different pressure-loss correlations for the losses due to spacer grids. Here, RANS–CFD simulations provided very good data compared to the experimental data. It was observed that the most commonly applied Rehme correlation underestimated the shape losses. The available correlations relate the pressure drop across a grid spacer to the relative plugging of the spacer i.e. solidity e{sub max}. More sophisticated correlations distinct between spacer grids with round or sharp leading edge shape. The purpose of this study is to (i) show that CFD is suitable to predict pressure drop across spacer grids and (ii) to access the generality of pressure drop correlations. By verification and validation of CFD results against experimental data obtained in KALLA we show (i). The generality (ii) is challenged by considering three cases which yield identical pressure drop in the correlations. First we test the effect of surface roughness, a parameter not present in the correlations. Here we compare a simulation assuming a typical surface roughness representing the experimental situation to a perfectly smooth spacer surface. Second we reverse the flow direction for the spacer grid employed in the experiments which is asymmetric. The flow direction reversal is chosen for convenience, since an asymmetric spacer grid with given blockage ratio, may result in different flow situations depending on flow direction. Obviously blockage

  2. Effect Of Cuo-Distilled Water Based Nanofluids On Heat Transfer Characteristics And Pressure Drop Characteristics.

    Directory of Open Access Journals (Sweden)

    SANDEEP KUMAR

    2014-09-01

    Full Text Available In this paper, the heat transfer and pressure drop characteristics of the distilled water and the copper oxide-distilled water based nanofluid flowing in a horizontal circular pipe under constant heat flux condition are studied. Copper oxide nanoparticles of 40nm size are dispersed in distilled water using sodium dodecyl sulphate as surfactant and sonicated the nanofluid for three hour. Both surfactant and sonication increases the stability of the nanofluid. The nanofluids are made in three different concentration i.e. 0.1 Vol. %, 0.25 Vol. % and 0.50 Vol. %. The thermal conductivity is measured by KD2 PRO, density with pycnometer, viscosity with Brookfield LVDV-III rheometer. The results show that the thermal conductivity increases with both temperature and concentration. The viscosity and density increases with concentration but decreases with temperature. The specific heat is calculated by model and it decreases with concentration. The experimental local Nusselt number of distilled water is compared with local Nusselt number obtained by the well known shah equation for laminar flow under constant heat flux condition for validation of the experimental set up. The relative error is 4.48 % for the Reynolds number 750.9. The heat transfer coefficient increases with increase in both flow rate and concentration. It increases from 14.33 % to 46.1 % when the concentration is increased from 0.1 Vol. % to 0.5 Vol. % at 20 LPH flow rate. Friction factor decreases with increase in flow rate. It decreases 66.54 % when the flow rate increases from 10 LPH to 30 LPH for 0.1 Vol. %.

  3. THE INTERACTION OF LIQUID DROPS WITH A ROTATING GAS STREAM WITHIN A RAPIDLY REVOLVING ANNULAR ENCLOSURE

    Directory of Open Access Journals (Sweden)

    A. AROUSSI

    2006-12-01

    Full Text Available The flow phenomena occurring around a rotating shaft are extremely complex and are a common feature in turbomachinery such as the bearing chambers of aero engines. As the liquid jet impinges onto the shaft, circumferential streams of lubricating liquid droplets centrifuge away from the rotor surface and impinge onto the inner circumference of the stationary case. A further break-up of drops occurred whilst rotating around the shaft before impacting on to the casing surface. Non-intrusive laser techniques have been employed to aid the visualisation processes and the analysis of the flow phenomena occurring within the rotating annular enclosure. Results reveal that, the liquid flow conditions and the shaft rotation regimes, along with the aerodynamic movement of the air circulating around the shaft influence the dynamics of the droplets and consequently the lubrication processes within the bearing chambers.

  4. Experimental investigation of the two-phase flow regimes and pressure drop in horizontal mini-size rectangular test section

    Science.gov (United States)

    Elazhary, Amr Mohamed; Soliman, Hassan M.

    2012-10-01

    An experimental study was conducted in order to investigate two-phase flow regimes and fully developed pressure drop in a mini-size, horizontal rectangular channel. The test section was machined in the form of an impacting tee junction in an acrylic block (in order to facilitate visualization) with a rectangular cross-section of 1.87-mm height on 20-mm width on the inlet and outlet sides. Pressure drop measurement and flow regime identification were performed on all three sides of the junction. Air-water mixtures at 200 kPa (abs) and room temperature were used as the test fluids. Four flow regimes were identified visually: bubbly, plug, churn, and annular over the ranges of gas and liquid superficial velocities of 0.04 ≤ JG ≤ 10 m/s and 0.02 ≤ JL ≤ 0.7 m/s, respectively, and a flow regime map was developed. Accuracy of the pressure-measurement technique was validated with single-phase, laminar and turbulent, fully developed data. Two-phase experiments were conducted for eight different inlet conditions and various mass splits at the junction. Comparisons were conducted between the present data and former correlations for the fully developed two-phase pressure drop in rectangular channels with similar sizes. Wide deviations were found among these correlations, and the correlations that agreed best with the present data were identified.

  5. Investigation of thermal behaviour, pressure drop, and pumping power in a Cu nanofluid-filled solar flat-plate collector

    Directory of Open Access Journals (Sweden)

    Shamshirgaran S. Reza

    2017-01-01

    Full Text Available The evaluations of the performance of solar flat-plate collectors are reported in the literature. A computer program developed by MATLAB has been applied for modelling the performance of a solar collector under steady state laminar conditions. Results demonstrate that Cu-water nanofluid would be capable of boosting the thermal efficiency of the collector by 2.4% at 4% volume concentration in the case of using Cunanofluid instead of just water as the working fluid. It is noteworthy that, dispersing the nanoparticles into the water results in a higher pressure drop and, therefore, a higher power consumption for pumping the nanofluid within the collector. It has been estimated for the collector understudy, that the increase in the pressure drop and pumping power to be around 30%.

  6. Two Phase Flow Modeling: Summary of Flow Regimes and Pressure Drop Correlations in Reduced and Partial Gravity

    Science.gov (United States)

    Balasubramaniam, R.; Rame, E.; Kizito, J.; Kassemi, M.

    2006-01-01

    The purpose of this report is to provide a summary of state-of-the-art predictions for two-phase flows relevant to Advanced Life Support. We strive to pick out the most used and accepted models for pressure drop and flow regime predictions. The main focus is to identify gaps in predictive capabilities in partial gravity for Lunar and Martian applications. Following a summary of flow regimes and pressure drop correlations for terrestrial and zero gravity, we analyze the fully developed annular gas-liquid flow in a straight cylindrical tube. This flow is amenable to analytical closed form solutions for the flow field and heat transfer. These solutions, valid for partial gravity as well, may be used as baselines and guides to compare experimental measurements. The flow regimes likely to be encountered in the water recovery equipment currently under consideration for space applications are provided in an appendix.

  7. Characteristics of two-phase flow pattern transitions and pressure drop of five refrigerants in horizontal circular small tubes

    Energy Technology Data Exchange (ETDEWEB)

    Pamitran, A.S. [Department of Mechanical Engineering, University of Indonesia, Kampus Baru UI, Depok 16424 (Indonesia); Choi, Kwang-Il [Graduate School, Chonnam National University, San 96-1, Dunduk-Dong, Yeosu, Chonnam 550-749 (Korea); Oh, Jong-Taek [Department of Refrigeration and Air Conditioning Engineering, Chonnam National University, San 96-1, Dunduk-Dong, Yeosu, Chonnam 550-749 (Korea); Hrnjak, Pega [Department of Mechanical Science and Engineering, ACRC, University of Illinois at Urbana-Champaign, 1206 West Green Street, Urbana, IL 61801 (United States)

    2010-05-15

    An experimental investigation on the characteristics of two-phase flow pattern transitions and pressure drop of R-22, R-134a, R-410A, R-290 and R-744 in horizontal small stainless steel tubes of 0.5, 1.5 and 3.0 mm inner diameters is presented. Experimental data were obtained over a heat flux range of 5-40 kW/m{sup 2}, mass flux range of 50-600 kg/(m{sup 2} s), saturation temperature range of 0-15 C, and quality up to 1.0. Experimental data were evaluated with Wang et al. and Wojtan et al. [Wang, C.C., Chiang, C.S., Lu, D.C., 1997. Visual observation of two-phase flow pattern of R-22, R-134a, and R-407C in a 6.5-mm smooth tube. Exp. Therm. Fluid Sci. 15, 395-405; Wojtan, L., Ursenbacher, T., Thome, J.R., 2005. Investigation of flow boiling in horizontal tubes: part I - a new diabatic two-phase flow pattern map. Int. J. Heat Mass Transfer 48, 2955-2969.] flow pattern maps. The effects of mass flux, heat flux, saturation temperature and inner tube diameter on the pressure drop of the working refrigerants are reported. The experimental pressure drop was compared with the predictions from some existing correlations. A new two-phase pressure drop model that is based on a superposition model for two-phase flow boiling of refrigerants in small tubes is presented. (author)

  8. Flow Boiling Pressure Drop and Heat Transfer of Refrigerants in Multi-microchannel Evaporators under Steady and Transient States

    OpenAIRE

    Huang, Houxue

    2016-01-01

    Multi-microchannel evaporators used for the cooling of high heat flux electronics have been of interest to both industry and academia for more than a decade. Such interest has sparked a large number of research studies on the flow boiling pressure drop and heat transfer in multi-microchannel evaporators. However, there are still several aspects that need to be addressed in order to better understand the complicated flow boiling process taking place in such micro-evaporators. Firstly, the me...

  9. Smooth- and enhanced-tube heat transfer and pressure drop : Part II. The role of transition to turbulent flow.

    Energy Technology Data Exchange (ETDEWEB)

    Obot, N. T.; Das, L.; Rabas, T. J.

    2000-11-14

    The objectives of this presentation are two-fold: first, to demonstrate the connection between the attainable coefficients and transition to turbulent flow by using the transition-based corresponding states method to generalize results obtained with smooth tubes and enhanced tubes, and second, to provide guidelines on the calculation of heat transfer coefficients from pressure-drop data and vice versa by using the transition concept or the functional law of corresponding states.

  10. On axial temperature gradients due to large pressure drops in dense fluid chromatography.

    Science.gov (United States)

    Colgate, Sam O; Berger, Terry A

    2015-03-13

    The effect of energy degradation (Degradation is the creation of net entropy resulting from irreversibility.) accompanying pressure drops across chromatographic columns is examined with regard to explaining axial temperature gradients in both high performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC). The observed effects of warming and cooling can be explained equally well in the language of thermodynamics or fluid dynamics. The necessary equivalence of these treatments is reviewed here to show the legitimacy of using whichever one supports the simpler determination of features of interest. The determination of temperature profiles in columns by direct application of the laws of thermodynamics is somewhat simpler than applying them indirectly by solving the Navier-Stokes (NS) equations. Both disciplines show that the preferred strategy for minimizing the reduction in peak quality caused by temperature gradients is to operate columns as nearly adiabatically as possible (i.e. as Joule-Thomson expansions). This useful fact, however, is not widely familiar or appreciated in the chromatography community due to some misunderstanding of the meaning of certain terms and expressions used in these disciplines. In fluid dynamics, the terms "resistive heating" or "frictional heating" have been widely used as synonyms for the dissipation function, Φ, in the NS energy equation. These terms have been widely used by chromatographers as well, but often misinterpreted as due to friction between the mobile phase and the column packing, when in fact Φ describes the increase in entropy of the system (dissipation, ∫TdSuniv>0) due to the irreversible decompression of the mobile phase. Two distinctly different contributions to the irreversibility are identified; (1) ΔSext, viscous dissipation of work done by the external surroundings driving the flow (the pump) contributing to its warming, and (2) ΔSint, entropy change accompanying decompression of

  11. Numerical studies on heat transfer and pressure drop characteristics of flat finned tube bundles with various fin materials

    Science.gov (United States)

    Peng, Y.; Zhang, S. J.; Shen, F.; Wang, X. B.; Yang, X. R.; Yang, L. J.

    2017-11-01

    The air-cooled heat exchanger plays an important role in the field of industry like for example in thermal power plants. On the other hand, it can be used to remove core decay heat out of containment passively in case of a severe accident circumstance. Thus, research on the performance of fins in air-cooled heat exchangers can benefit the optimal design and operation of cooling systems in nuclear power plants. In this study, a CFD (Computational Fluid Dynamic) method is implemented to investigate the effects of inlet velocity, fin spacing and tube pitch on the flow and the heat transfer characteristics of flat fins constructed of various materials (316L stainless steel, copper-nickel alloy and aluminium). A three dimensional geometric model of flat finned tube bundles with fixed longitudinal tube pitch and transverse tube pitch is established. Results for the variation of the average convective heat transfer coefficient with respect to cooling air inlet velocity, fin spacing, tube pitch and fin material are obtained, as well as for the pressure drop of the cooling air passing through finned tube. It is shown that the increase of cooling air inlet velocity results in enhanced average convective heat transfer coefficient and decreasing pressure drop. Both fin spacing and tube pitch engender positive effects on pressure drop and have negative effects on heat transfer characteristics. Concerning the fin material, the heat transfer performance of copper-nickel alloy is superior to 316L stainless steel and inferior to aluminium.

  12. Turbulent heat transfer characteristics and pressure drop in swirling flow at upstream and downstream of an abrupt expansion

    Science.gov (United States)

    Zohir, A. E.

    2012-03-01

    This investigation is aimed at studying the heat transfer characteristics and pressure drop for turbulent airflow in a sudden expansion pipe equipped with propeller swirl generator. The investigation is performed for the Reynolds number ranging from 10,000 to 41,000 under a uniform heat flux condition. The experiments are conducted for three locations for the propeller fan upstream the sudden expansion and three locations downstream the sudden expansion ( N = 5 blades and blade angle of 45°). The influences of using a freely rotating propeller on heat transfer enhancement and pressure drop are reported. The experimental results indicate that inserting the propeller downstream of the tube provides considerable improvement of the heat transfer rate higher than inserting the propeller upstream the tube. The increase in pressure drop resulting from using the propeller upstream is found to be higher than the downstream swirler. The maximum performance enhancement for the downstream swirler is about 326% while it is about 213% for upstream one. Correlations for relative mean Nusselt number and enhancement performance are presented for different fan locations and different Reynolds numbers.

  13. Flow boiling heat transfer and pressure drop of pure HFC-152a in a horizontal mini-channel

    Energy Technology Data Exchange (ETDEWEB)

    Hamdar, M.; Zoughaib, A.; Clodic, D. [Ecole des Mines de Paris, Center for Energy and Processes, 60, boulevard Saint-Michel, F 75272 Paris Cedex 06 (France)

    2010-05-15

    This study investigates boiling heat transfer and two-phase pressure drop of HFC-152a in a horizontal square mini-channel of 1 mm in diameter. Convection heat fluxes were obtained using an inverse heat transfer method. Tests were performed at a nearly constant system pressure of 600 kPa and under saturated conditions. Local heat transfer coefficients were determined as a function of vapor quality along the length of the test section. Tests were carried out for mass flux ranging from 200 to 600 kg/m{sup 2}s and for heat flux ranging from 10 to 60 kW/m{sup 2}. Experimental results were compared to predictive models from the literature for two-phase flow pressure drop and boiling heat transfer. The correlation of was found to give a good agreement for prediction of mini-channel frictional pressure losses. The heat transfer mechanism was found to be dominated by nucleate boiling, and the heat transfer coefficient independent of vapor quality and mass flux. A new correlation for Nusselt number was developed based on the correlation, which was able to predict the present experimental data with respective average and maximum absolute deviations of 3.7% and 11%. (author)

  14. Effect of an instantaneous controlled pressure drop on in vitro allergenicity to lupins (Lupinus albus var Multolupa).

    Science.gov (United States)

    Guillamón, Eva; Burbano, Carmen; Cuadrado, Carmen; Muzquiz, Mercedes; Pedrosa, Mercedes M; Sánchez, Mónica; Cabanillas, Beatriz; Crespo, Jesus F; Rodriguez, Julia; Haddad, Joseph; Haddad, Joshep; Allaf, Karim; Allaf, Karin

    2008-01-01

    Lupin seed flour has been reported as a causative agent of allergic reactions, especially in patients with allergy to peanut. Previous studies have demonstrated that autoclave treatment can considerably reduce the allergenicity of lupins. The aim of this work was to evaluate the effect of instantaneous controlled pressure drop (détente instantanée contrôlée, DIC) treatment on lupin in vitro allergenicity. Lupin cotyledons were subjected to instantaneous controlled pressure drop at several pressure and time conditions (3, 4.5 and 6 bar for 1, 2 and 3 min, respectively). Immunoreactivity to raw and DIC-treated extracts was evaluated by Western blot using a serum pool from 19 sensitized patients. Depending on the operating parameters used during DIC treatment, a reduction in protein solubility of lupin seed was observed. Moreover, drastic modifications in protein profiles were observed after DIC treatment by SDS-PAGE analysis. Western blot experiments showed that the decreases in IgE binding to lupin proteins were associated with the increases in steam pressure and time treatment, and binding was completely abolished by DIC at 6 bar for 3 min. The results suggest that DIC treatment could produce a reduction in lupin allergenicity. 2007 S. Karger AG, Basel

  15. Sensitivity Analysis and Accuracy of a CFD-TFM Approach to Bubbling Bed Using Pressure Drop Fluctuations.

    Science.gov (United States)

    Tricomi, Leonardo; Melchiori, Tommaso; Chiaramonti, David; Boulet, Micaël; Lavoie, Jean Michel

    2017-01-01

    Based upon the two fluid model (TFM) theory, a CFD model was implemented to investigate a cold multiphase-fluidized bubbling bed reactor. The key variable used to characterize the fluid dynamic of the experimental system, and compare it to model predictions, was the time-pressure drop induced by the bubble motion across the bed. This time signal was then processed to obtain the power spectral density (PSD) distribution of pressure fluctuations. As an important aspect of this work, the effect of the sampling time scale on the empirical power spectral density (PSD) was investigated. A time scale of 40 s was found to be a good compromise ensuring both simulation performance and numerical validation consistency. The CFD model was first numerically verified by mesh refinement process, after what it was used to investigate the sensitivity with regards to minimum fluidization velocity (as a calibration point for drag law), restitution coefficient, and solid pressure term while assessing his accuracy in matching the empirical PSD. The 2D model provided a fair match with the empirical time-averaged pressure drop, the relating fluctuations amplitude, and the signal's energy computed as integral of the PSD. A 3D version of the TFM was also used and it improved the match with the empirical PSD in the very first part of the frequency spectrum.

  16. Sensitivity Analysis and Accuracy of a CFD-TFM Approach to Bubbling Bed Using Pressure Drop Fluctuations

    Directory of Open Access Journals (Sweden)

    Leonardo Tricomi

    2017-06-01

    Full Text Available Based upon the two fluid model (TFM theory, a CFD model was implemented to investigate a cold multiphase-fluidized bubbling bed reactor. The key variable used to characterize the fluid dynamic of the experimental system, and compare it to model predictions, was the time-pressure drop induced by the bubble motion across the bed. This time signal was then processed to obtain the power spectral density (PSD distribution of pressure fluctuations. As an important aspect of this work, the effect of the sampling time scale on the empirical power spectral density (PSD was investigated. A time scale of 40 s was found to be a good compromise ensuring both simulation performance and numerical validation consistency. The CFD model was first numerically verified by mesh refinement process, after what it was used to investigate the sensitivity with regards to minimum fluidization velocity (as a calibration point for drag law, restitution coefficient, and solid pressure term while assessing his accuracy in matching the empirical PSD. The 2D model provided a fair match with the empirical time-averaged pressure drop, the relating fluctuations amplitude, and the signal’s energy computed as integral of the PSD. A 3D version of the TFM was also used and it improved the match with the empirical PSD in the very first part of the frequency spectrum.

  17. Sensitivity Analysis and Accuracy of a CFD-TFM Approach to Bubbling Bed Using Pressure Drop Fluctuations

    Science.gov (United States)

    Tricomi, Leonardo; Melchiori, Tommaso; Chiaramonti, David; Boulet, Micaël; Lavoie, Jean Michel

    2017-01-01

    Based upon the two fluid model (TFM) theory, a CFD model was implemented to investigate a cold multiphase-fluidized bubbling bed reactor. The key variable used to characterize the fluid dynamic of the experimental system, and compare it to model predictions, was the time-pressure drop induced by the bubble motion across the bed. This time signal was then processed to obtain the power spectral density (PSD) distribution of pressure fluctuations. As an important aspect of this work, the effect of the sampling time scale on the empirical power spectral density (PSD) was investigated. A time scale of 40 s was found to be a good compromise ensuring both simulation performance and numerical validation consistency. The CFD model was first numerically verified by mesh refinement process, after what it was used to investigate the sensitivity with regards to minimum fluidization velocity (as a calibration point for drag law), restitution coefficient, and solid pressure term while assessing his accuracy in matching the empirical PSD. The 2D model provided a fair match with the empirical time-averaged pressure drop, the relating fluctuations amplitude, and the signal’s energy computed as integral of the PSD. A 3D version of the TFM was also used and it improved the match with the empirical PSD in the very first part of the frequency spectrum. PMID:28695119

  18. Heat transfer, pressure drop and void fraction in two- phase, two-component flow in a vertical tube

    Science.gov (United States)

    Sujumnong, Manit

    1998-09-01

    There are very few data existing in two-phase, two- component flow where heat transfer, pressure drop and void fraction have all been measured under the same conditions. Such data are very valuable for two-phase heat-transfer model development and for testing existing heat-transfer models or correlations requiring frictional pressure drop (or wall shear stress) and/or void fraction. An experiment was performed which adds markedly to the available data of the type described in terms of the range of gas and liquid flow rates and liquid Prandtl number. Heat transfer and pressure drop measurements were taken in a vertical 11.68-mm i.d. tube for two-phase (gas-liquid) flows covering a wide range of conditions. Mean void fraction measurements were taken, using quick- closing valves, in a 12.7-mm i.d. tube matching very closely pressures, temperatures, gas-phase superficial velocities and liquid-phase superficial velocities to those used in the heat-transfer and pressure-drop experiments. The gas phase was air while water and two aqueous solutions of glycerine (59 and 82% by mass) were used as the liquid phase. In the two-phase experiments the liquid Prandtl number varied from 6 to 766, the superficial liquid velocity from 0.05 to 8.5 m/s, and the superficial gas velocity from 0.02 to 119 m/s. The measured two-phase heat-transfer coefficients varied by a factor of approximately 1000, the two-phase frictional pressure drop ranged from small negative values (in slug flow) to 93 kPa and the void fraction ranged from 0.01 to 0.99; the flow patterns observed included bubble, slug, churn, annular, froth, the various transitions and annular-mist. Existing heat-transfer models or correlations requiring frictional pressure drop (or wall shear stress) and/or void fraction were: tested against the present data for mean heat-transfer coefficients. It was found that the methods with more restrictions (in terms of the applicable range of void fraction, liquid Prandtl number or liquid

  19. International Space Station (ISS) Bacterial Filter Elements (BFEs): Filter Efficiency and Pressure Drop Testing of Returned Units

    Science.gov (United States)

    Green, Robert D.; Agui, Juan H.; Vijayakumar, R.; Berger, Gordon M.; Perry, Jay L.

    2017-01-01

    The air quality control equipment aboard the International Space Station (ISS) and future deep space exploration vehicles provide the vital function of maintaining a clean cabin environment for the crew and the hardware. This becomes a serious challenge in pressurized space compartments since no outside air ventilation is possible, and a larger particulate load is imposed on the filtration system due to lack of sedimentation. The ISS Environmental Control and Life Support (ECLS) system architecture in the U.S. Segment uses a distributed particulate filtration approach consisting of traditional High-Efficiency Particulate Air (HEPA) filters deployed at multiple locations in each U.S. Seg-ment module; these filters are referred to as Bacterial Filter Elements, or BFEs. In our previous work, we presented results of efficiency and pressure drop measurements for a sample set of two returned BFEs with a service life of 2.5 years. In this follow-on work, we present similar efficiency, pressure drop, and leak tests results for a larger sample set of six returned BFEs. The results of this work can aid the ISS Program in managing BFE logistics inventory through the stations planned lifetime as well as provide insight for managing filter element logistics for future exploration missions. These results also can provide meaningful guidance for particulate filter designs under consideration for future deep space exploration missions.

  20. Impact of organic nutrient load on biomass accumulation, feed channel pressure drop increase and permeate flux decline in membrane systems

    KAUST Repository

    Bucs, Szilard

    2014-12-01

    The influence of organic nutrient load on biomass accumulation (biofouling) and pressure drop development in membrane filtration systems was investigated. Nutrient load is the product of nutrient concentration and linear flow velocity. Biofouling - excessive growth of microbial biomass in membrane systems - hampers membrane performance. The influence of biodegradable organic nutrient load on biofouling was investigated at varying (i) crossflow velocity, (ii) nutrient concentration, (iii) shear, and (iv) feed spacer thickness. Experimental studies were performed with membrane fouling simulators (MFSs) containing a reverse osmosis (RO) membrane and a 31 mil thick feed spacer, commonly applied in practice in RO and nanofiltration (NF) spiral-wound membrane modules. Numerical modeling studies were done with identical feed spacer geometry differing in thickness (28, 31 and 34 mil). Additionally, experiments were done applying a forward osmosis (FO) membrane with varying spacer thickness (28, 31 and 34 mil), addressing the permeate flux decline and biofilm development. Assessed were the development of feed channel pressure drop (MFS studies), permeate flux (FO studies) and accumulated biomass amount measured by adenosine triphosphate (ATP) and total organic carbon (TOC).Our studies showed that the organic nutrient load determined the accumulated amount of biomass. The same amount of accumulated biomass was found at constant nutrient load irrespective of linear flow velocity, shear, and/or feed spacer thickness. The impact of the same amount of accumulated biomass on feed channel pressure drop and permeate flux was influenced by membrane process design and operational conditions. Reducing the nutrient load by pretreatment slowed-down the biofilm formation. The impact of accumulated biomass on membrane performance was reduced by applying a lower crossflow velocity and/or a thicker and/or a modified geometry feed spacer. The results indicate that cleanings can be delayed

  1. Numerical Analysis of the Pressure Drop on a Flow Channel Filled with Catalysts for Nuclear Hydrogen Production System

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sung Deok; Kim, C. S.; Kim, M. H.; Kim, Y. W. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Seo, D. U.; Park, G. C. [Seoul National Univ., Seoul (Korea, Republic of)

    2013-10-15

    Designing a process heat exchanger (PHE) is one of the main technical challenges in the development of a nuclear hydrogen production system. The PHE provides an interface between the helium gas and the sulfuric acid gas. The SO3 gas is heated and decomposed into SO2 and O2 in the PHE. For this reason, PHE is also called a sulfur trioxide decomposer. The Korea Atomic Energy Research Institute (KAERI) has developed a hybrid-design decomposer to withstand severe operating conditions. Figure 1 shows the layout of the PHE which has a hybrid form of its flow channel geometry; there is a printed-circuit form on the primary helium side and a plate-fin form on the secondary SO3 side. There are many widespread correlations for the porous media such as the Carman, Ergun, Zhavoronkov et al., Susskind and Becker and Reichelt correlation. In the nuclear field, the KTA correlation was developed for a reactor core design for a high-temperature gas-cooled reactor. In this paper, we discussed a numerical analysis and validation of a pressure drop on a SO3 flow channel filled with various sized catalysts. We discussed a numerical analysis and validation of a pressure drop on a flow channel filled with catalysts in the channel. The results of the pressure drop simulation are compared with the results obtained using well-known empirical correlations. From the comparison results, the validity of the two-dimensional numerical analysis is not shown. The main reason may be due to a discord of the channel geometry and the extreme irregularity in the size of the catalyst. It should be accomplished by comparing its results with the experimental data, yet there are no experimental data available up to now.

  2. Impact of biofilm accumulation on transmembrane and feed channel pressure drop: Effects of crossflow velocity, feed spacer and biodegradable nutrient

    KAUST Repository

    Dreszer, C.

    2014-03-01

    Biofilm formation causes performance loss in spiral-wound membrane systems. In this study a microfiltration membrane was used in experiments to simulate fouling in spiral-wound reverse osmosis (RO) and nanofiltration (NF) membrane modules without the influence of concentration polarization. The resistance of a microfiltration membrane is much lower than the intrinsic biofilm resistance, enabling the detection of biofilm accumulation in an early stage. The impact of biofilm accumulation on the transmembrane (biofilm) resistance and feed channel pressure drop as a function of the crossflow velocity (0.05 and 0.20ms-1) and feed spacer presence was studied in transparent membrane biofouling monitors operated at a permeate flux of 20Lm-2h-1. As biodegradable nutrient, acetate was dosed to the feed water (1.0 and 0.25mgL-1 carbon) to enhance biofilm accumulation in the monitors. The studies showed that biofilm formation caused an increased transmembrane resistance and feed channel pressure drop. The effect was strongest at the highest crossflow velocity (0.2ms-1) and in the presence of a feed spacer. Simulating conditions as currently applied in nanofiltration and reverse osmosis installations (crossflow velocity 0.2ms-1 and standard feed spacer) showed that the impact of biofilm formation on performance, in terms of transmembrane and feed channel pressure drop, was strong. This emphasized the importance of hydrodynamics and feed spacer design. Biomass accumulation was related to the nutrient load (nutrient concentration and linear flow velocity). Reducing the nutrient concentration of the feed water enabled the application of higher crossflow velocities. Pretreatment to remove biodegradable nutrient and removal of biomass from the membrane elements played an important part to prevent or restrict biofouling. © 2013 Elsevier Ltd.

  3. Scoping Experiments for Pressure Drop Measurement for the Ex-Vessel Debris Bed Coolability in Severe Accidents

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jin Ho; Kim, Eun Ho; Park, Hyun Sun [POSTECH, Pohang (Korea, Republic of); Kim, Moo Hwan [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of); Ma, Weimin; Bechta, Sevostian [Nuclear Power Safety Division, Stockholm (Sweden)

    2014-05-15

    To ensure the long-term cooling of corium in the reactor cavity, it is important to ensure the coolant ingression into the internally heat generated corium debris bed governed by pressure drop in the porous media. According to the previous investigations on molten fuel-coolant interactions (FCIs) experiments, the debris beds are expected to form channels in the bed due to intensive boiling and flow. And also, it was found that quenched particulate debris bed was composed of multi-sized (0∼10 mm), irregular shape particles and it has a micro/macro inhomogeneity such as axially and radially stratified debris bed, where a layer of smaller particles covers the main bed part. In this particulate debris bed with the internal heat generation by decay heat, not only co- but also counter-current two-phase flow may be occurred by the water inflow through sides of bed combined with steam outflow to top of bed. To investigate the effect of each characteristics of heterogeneous debris bed expected in real severe accident scenarios on pressure drop with various conditions, an experimental facility called as PICASSO (Pressure drop Investigation and Coolability ASSessment through Observation) facility was constructed. With the experimental facility, the scoping test was conducted as injecting upward air flow into the bottom of particle bed composed of 2 mm, 5 mm spherical SUJ-2 balls respectively, and the experimental data compared with Ergun equation. As a result of the single phase flow experiment using air, Ergun equation predicts the experimental data for the spherical particles with the diameter of 2 mm and 5 mm with a mean deviation of 14.62 %.

  4. Convective heat transfer and pressure drop of aqua based TiO2 nanofluids at different diameters of nanoparticles: Data analysis and modeling with artificial neural network

    Science.gov (United States)

    Hemmat Esfe, Mohammad; Nadooshan, Afshin Ahmadi; Arshi, Ali; Alirezaie, Ali

    2018-03-01

    In this study, experimental data related to the Nusselt number and pressure drop of aqueous nanofluids of Titania is modeled and estimated by using ANN with 2 hidden layers and 8 neurons in each layer. Also in this study the effect of various effective variables in the Nusselt number and pressure drop is surveyed. This study indicated that the neural network modeling has been able to model experimental data with great accuracy. The modeling regression coefficient for the data of Nusselt number and relative pressure drop is 99.94% and 99.97% respectively. Besides, it represented that the increment of the Reynolds number and concentration made the increment of Nusselt number and pressure drop of aqueous nanofluid.

  5. THE EFFECTS OF SWIRL GENERATOR HAVING WINGS WITH HOLES ON HEAT TRANSFER AND PRESSURE DROP IN TUBE HEAT EXCHANGER

    Directory of Open Access Journals (Sweden)

    Zeki ARGUNHAN

    2006-02-01

    Full Text Available This paper examines the effect of turbulance creators on heat transfer and pressure drop used in concentric heat exchanger experimentaly. Heat exchanger has an inlet tube with 60 mm in diameter. The angle of swirl generators wings is 55º with each wing which has single, double, three and four holes. Swirl generators is designed to easily set to heat exchanger entrance. Air is passing through inner tube of heat exhanger as hot fluid and water is passing outer of inner tube as cool fluid.

  6. Rapid Heat Treatment of Aluminum High-Pressure Diecastings

    Science.gov (United States)

    Lumley, R. N.; Polmear, I. J.; Curtis, P. R.

    2009-07-01

    Recently, it has been demonstrated that common high-pressure diecasting (HPDC) alloys, such as those based on the Al-Si-Cu and Al-Si-Mg-(Cu) systems, may be successfully heat treated without causing surface blistering or dimensional instability. In some compositions, the capacity to exploit age hardening may allow the proof stress values to be doubled when compared to the as-cast condition. This heat treatment procedure involves the use of severely truncated solution treatment cycles conducted at lower than normal temperatures, followed by quenching and natural or artificial aging. The potential therefore exists to develop and evaluate secondary HPDC alloys designed specifically for rapid heat treatment, while still displaying high castability. This article reports results of an experimental program in which responses of various alloy compositions to age hardening have been investigated with the primary aim of further reducing the duration and cost of the heat treatment cycle while maintaining high tensile properties. Composition ranges have been established for which values of 0.2 pct proof stress exceeding 300 MPa ( i.e., increases of ~100 pct above as-cast values) can be achieved using a procedure that involves a total time for solution treatment plus age hardening of only 30 minutes. This rapid aging behavior is shown to be related to precipitation of the complex Q' phase, which forms primarily when Mg contents of the alloys are above ~0.2 wt pct.

  7. Association of systolic blood pressure drop with intravenous administration of itraconazole in children with hemato-oncologic disease.

    Science.gov (United States)

    Lee, Hyeong Jin; Lee, Bongjin; Park, June Dong; Jeong, Hyung Joo; Choi, Yu Hyeon; Ju, Hee Young; Hong, Che Ry; Lee, Ji Won; Kim, Hyery; Suh, Dong In; Park, Kyung Duk; Kang, Hyoung Jin; Shin, Hee Young; Ahn, Hyo Seop

    2015-01-01

    Although few adverse effects have been reported for itraconazole, a widely used antifungal therapy for febrile neutropenia, we found intravenous (IV) itraconazole to be associated with serious cases of blood pressure (BP) drop. We therefore evaluated the incidence and risk factors for BP drop during IV administration of the drug. We reviewed the medical records of children with hemato-oncologic disease who were treated with IV itraconazole from January 2012 to December 2013. By analyzing systolic BP (SBP) measurements made from 4 hours before through to 4 hours after itraconazole administration, we evaluated the changes in SBP and the risk factors for an SBP drop, especially clinically meaningful (≥ 20%) drops. Itraconazole was administered 2,627 times to 180 patients. The SBP during the 4 hours following itraconazole administration was lower than during the 4 hours before administration (104 [53.0-160.33 mmHg] versus 105 [59.8-148.3 mmHg]; Pdrop was seen in 5.37% (141 out of 2,627) of the administrations, and the use of inotropics (odds ratio [OR] 6.70, 95% confidence interval [CI] 3.22-13.92; P<0.001), reducing the dose of inotropics (OR 8.08; 95% CI 1.39-46.94; P=0.02), CRRT (OR 3.10, 95% CI 1.41-6.81; P=0.005), and bacteremia (OR 2.70, 95% CI 1.32-5.51; P=0.007) were risk factors, while age was a protective factor (OR 0.93, 95% CI 0.89-0.97; P<0.001). A decrease in SBP was associated with IV administration of itraconazole. It was particularly significant in younger patients with bacteremia using inotropic agents and during application of CRRT. Careful attention to hypotension is warranted during IV administration of itraconazole in this group of patients.

  8. Transient integral boundary layer method to calculate the translesional pressure drop and the fractional flow reserve in myocardial bridges

    Science.gov (United States)

    Bernhard, Stefan; Möhlenkamp, Stefan; Tilgner, Andreas

    2006-01-01

    Background The pressure drop – flow relations in myocardial bridges and the assessment of vascular heart disease via fractional flow reserve (FFR) have motivated many researchers the last decades. The aim of this study is to simulate several clinical conditions present in myocardial bridges to determine the flow reserve and consequently the clinical relevance of the disease. From a fluid mechanical point of view the pathophysiological situation in myocardial bridges involves fluid flow in a time dependent flow geometry, caused by contracting cardiac muscles overlying an intramural segment of the coronary artery. These flows mostly involve flow separation and secondary motions, which are difficult to calculate and analyse. Methods Because a three dimensional simulation of the haemodynamic conditions in myocardial bridges in a network of coronary arteries is time-consuming, we present a boundary layer model for the calculation of the pressure drop and flow separation. The approach is based on the assumption that the flow can be sufficiently well described by the interaction of an inviscid core and a viscous boundary layer. Under the assumption that the idealised flow through a constriction is given by near-equilibrium velocity profiles of the Falkner-Skan-Cooke (FSC) family, the evolution of the boundary layer is obtained by the simultaneous solution of the Falkner-Skan equation and the transient von-Kármán integral momentum equation. Results The model was used to investigate the relative importance of several physical parameters present in myocardial bridges. Results have been obtained for steady and unsteady flow through vessels with 0 – 85% diameter stenosis. We compare two clinical relevant cases of a myocardial bridge in the middle segment of the left anterior descending coronary artery (LAD). The pressure derived FFR of fixed and dynamic lesions has shown that the flow is less affected in the dynamic case, because the distal pressure partially recovers

  9. Compensation for the Effects of Ambient Conditions on the Calibration of Multi-Capillary Pressure Drop Standards

    Directory of Open Access Journals (Sweden)

    Colard S

    2014-12-01

    Full Text Available Cigarette draw resistance and filter pressure drop (PD are both major physical parameters for the tobacco industry. Therefore these parameters must be measured reliably. For these measurements, specific equipment calibrated with PD transfer standards is used. Each transfer standard must have a known and stable PD value, such standards usually being composed of several capillary tubes associated in parallel. However, PD values are modified by ambient conditions during calibration of such standards, i.e. by temperature and relative humidity (RH of air, and atmospheric pressure. In order to reduce the influence of these ambient factors, a simplified model was developed for compensating the effects of ambient conditions on the calibration of multi-capillary PD standards.

  10. Condensation heat transfer and pressure drop of R-410A in flat aluminum multi-port tubes

    Science.gov (United States)

    Kim, Nae-Hyun

    2018-02-01

    Brazed heat exchangers with aluminum flat multi-port tubes are being used as condensers of residential air-conditioners. In this study, R-410A condensation tests were conducted in four multi-port tubes having a range of hydraulic diameter (0.78 ≤ Dh ≤ 0.95 mm). The test range covered the mass flux from 100 to 400 kg/m2 s and the heat flux at 3 kW/m2, which are typical operating conditions of residential air conditioners. Results showed that both the heat transfer coefficient and the pressure drop increased as the hydraulic diameter decreased. The effect of hydraulic diameter on condensation heat transfer was much larger than the predictions of existing correlations for the range of investigation. Comparison of the data with the correlations showed that some macro-channel tube correlations and mini-channel tube correlations reasonably predicted the heat transfer coefficient. However, macro-channel correlations highly overpredicted the pressure drop data.

  11. Study of Wettability Effect on Pressure Drop and Flow Pattern of Two-Phase Flow in Rectangular Microchannel

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Chi Woong; Yu, Dong In; Kim, Moo Hwan [Pohang University of Science and Technology, Pohang (Korea, Republic of)

    2009-12-15

    Wettability is a critical parameter in micro-scale two-phase system. Several previous results indicate that wettability has influential affect on two-phase flow pattern in a microchannel. However, previous studies conducted using circular microtube, which was made by conventional fabrication techniques. Although most applications for micro thermal hydraulic system has used a rectangular microchannel, data for the rectangular microchannel is totally lack. In this study, a hydrophilic rectangular microchannel was fabricated using a photosensitive glass. And a hydrophobic rectangular microchannel was prepared using silanization of glass surfaces with OTS (octa-dethy1-trichloro-siliane). Experiments of two-phase flow in the hydrophilic and the hydrophobic rectangular microchannels were conducted using water and nitrogen gas. Visualization of two-phase flow pattern was carried out using a high-speed camera and a long distance microscope. Visualization results show that the wettability was important for two-phase flow pattern in rectangular microchannel. In addition, two-phase frictional pressure drop was highly related with flow patterns. Finally, Two-phase frictional pressure drop was analyzed with flow patterns.

  12. Pressure-Drop Coefficients for Cushioning System of Hydraulic Cylinder With Grooved Piston: A Computational Fluid Dynamic Simulation

    Directory of Open Access Journals (Sweden)

    Robert Castilla

    2017-10-01

    Full Text Available Cushioning is an important aspect in hydraulic cylinder performance. The piston has to be decelerated before it strikes the end cap in order to avoid stresses in the cylinder components and reduce vibration that can be transmitted to the machine. One of the least-studied methods is internal cushioning by grooves in the piston. In this method, the flow is throttled with adequately designed grooves when the piston reaches the outlet port position. The purpose of the present work is to present a method to estimate the pressure-drop coefficients for a certain design of piston grooves in order to provide a model to develop a dynamic system simulation of the cushion system. The method is based on a computational fluid dynamic simulation of flow through piston grooves to the outlet port for each piston’s static position. The results are compared with experimental measurements, and a correction, based on Reynolds number, is proposed. Good agreement, below 16%, was obtained for all the positions but particularly for the last grooves, for which the numerical result’s deviation to the experimental measurements was less than 10%. In general, the numerical simulation tended to underestimate the pressure drop for the first grooves and overestimate the calculation for the last grooves.

  13. In vitro comparison of Günther Tulip and Celect filters: testing filtering efficiency and pressure drop.

    Science.gov (United States)

    Nicolas, M; Malvé, M; Peña, E; Martínez, M A; Leask, R

    2015-02-05

    In this study, the trapping ability of the Günther Tulip and Celect inferior vena cava filters was evaluated. Thrombus capture rates of the filters were tested in vitro in horizontal position with thrombus diameters of 3 and 6mm and tube diameter of 19mm. The filters were tested in centered and tilted positions. Sets of 30 clots were injected into the model and the same process was repeated 20 times for each different condition simulated. Pressure drop experienced along the system was also measured and the percentage of clots captured was recorded. The Günther Tulip filter showed superiority in all cases, trapping almost 100% of 6mm clots both in an eccentric and tilted position and trapping 81.7% of the 3mm clots in a centered position and 69.3% in a maximum tilted position. The efficiency of all filters tested decreased as the size of the embolus decreased and as the filter was tilted. The injection of 6 clots raised the pressure drop to 4.1mmHg, which is a reasonable value that does not cause the obstruction of blood flow through the system. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Experimental and numerical investigation of pressure drop and heat transfer coefficient in converging-diverging microchannel heat sink

    Science.gov (United States)

    Chakravarthii, M. K. Dheepan; Mutharasu, D.; Shanmugan, S.

    2017-07-01

    The major challenge in microelectronic chips is to eliminate the generated heat for stable and reliable operation of the devices. Microchannel heat sinks are efficient method to dissipate high heat flux. The pressure drop and heat transfer coefficient are the important parameters which determine the thermal-hydraulic performance of the microchannel heat sink. In this study, a converging-diverging (CD) microchannel heat sink was experimentally investigated for the variation of pressure drop and heat transfer coefficient. De-ionized water was considered as the working fluid. Experiments were conducted for single phase fluid flow with mass flow rate and heat flux ranging from 0.001232 to 0.01848 kg/s and 10-50 W/cm2 respectively. The fluid and solid temperature were measured to calculate the heat transfer coefficients. Numerical results were computed using the CFD software and validated against the experimental results. The CD microchannel possesses high heat transfer coefficient than the straight microchannels. Theoretical correlations were proposed for comparing the experimental Nusselt number of CD microchannel. Evaluation of thermal-hydraulic performance of CD microchannel is important to quantify its applications in electronics cooling.

  15. Feasibility of granular bed filtration of an aerosol of ultrafine metallic particles including a pressure drop regeneration system.

    Science.gov (United States)

    Bémer, D; Wingert, L; Morele, Y; Subra, I

    2015-09-01

    A process for filtering an aerosol of ultrafine metallic particles (UFP) has been designed and tested, based on the principle of a multistage granular bed. The filtration system comprised a succession of granular beds of varying thickness composed of glass beads of different diameters. This system allows the pressure drop to be regenerated during filtration ("on-line" mode) using a vibrating probe. Tests monitoring the pressure drop were conducted on a "10-L/min" low airflow rate device and on a "100-m(3)/hr" prototype. Granular bed unclogging is automated on the latter. The cyclic operation and filtration performances are similar to that of filter medium-based industrial dust collectors. Filtration of ultrafine metallic particles generated by different industrial processes such as arc welding, metal cutting, or spraying constitutes a difficult problem due to the high filter clogging properties of these particles and to the high temperatures generally encountered. Granular beds represent an advantageous means of filtering these aerosols with difficult properties.

  16. Moisture transfer and pressure drop of humidifying elements made of non-woven fabric (Rayon/PET)

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Nae-Hyun [Incheon National University, Incheon (Korea, Republic of)

    2017-06-15

    In modern buildings, humidity control is an essential constituent of the building management, where spray-type humidifying element is widely used. For the spray-type element, there is a concern about the durability and the resistance to formation of mold. In this study, we made new humidifying elements were made using non-woven fabric rayon/PET and investigated the moisture transfer and pressure drop characteristics. Samples consisted of two different rayon compositions (30 % and 50 %). From the results the sample with 50 % rayon and 50 % PET showed superior moisture transfer performance than the sample with 50 % Kraft fiber and 50 % PET, probably due to better water absorption characteristics of rayon over Kraft fiber. However, pressure drop of the rayon/PET sample was larger than Kraft fiber/PET sample due to increased surface roughness. The moisture transfer performance of the rayon/PET sample deteriorated as the rayon content decreased. The efficiency (j{sub m}/{sup f}1/3) was the largest for rayon/PET (5:5) sample, followed by Kraft fiber/PET and rayon/PET (3:7) sample. The efficiency of commercially available Glasdek was much lower than other samples.

  17. Al-Coated Conductive Fibrous Filter with Low Pressure Drop for Efficient Electrostatic Capture of Ultrafine Particulate Pollutants.

    Science.gov (United States)

    Choi, Dong Yun; Jung, Soo-Ho; Song, Dong Keun; An, Eun Jeong; Park, Duckshin; Kim, Tae-Oh; Jung, Jae Hee; Lee, Hye Moon

    2017-05-17

    Here, we demonstrate a new strategy of air filtration based on an Al-coated conductive fibrous filter for high efficient nanoparticulate removals. The conductive fibrous filter was fabricated by a direct decomposition of Al precursor ink, AlH3{O(C4H9)2}, onto surfaces of a polyester air filter via a cost-effective and scalable solution-dipping process. The prepared conductive filters showed a low sheet resistance (conductive filters exhibited excellent performances in terms of the pressure drop (∼4.9 Pa at 10 cm s-1), quality factor (∼2.2 Pa-1 at 10 cm s-1), and dust holding capacity (12.5 μg mm-2). After being cleaned by water, the filtration efficiency and pressure drop of the conductive filter was perfectly recovered, which indicates its good recyclability. It is expected that these promising features make the conductive fibrous filter have a great potential for use in low-cost and energy-efficient air cleaning devices as well as other relevant research areas.

  18. Effect of guidewire on contribution of loss due to momentum change and viscous loss to the translesional pressure drop across coronary artery stenosis: An analytical approach

    Directory of Open Access Journals (Sweden)

    Back Lloyd H

    2011-06-01

    Full Text Available Abstract Background Guidewire (GW size and stenosis dimensions are the two major factors affecting the translesional pressure drop. Studying the combined effect of these parameters on the mean pressure drop (Δp across the stenosis is of high practical importance. Methods In this study, time averaged mass and momentum conservation equations are solved analytically to obtain pressure drop-flow, Δp-Q, curves for three different percentage area blockages corresponding to moderate (64%, intermediate (80%, and severe (90% stenoses. Stenosis is considered to be axisymmetric consisting of three different sections namely converging, throat, and diverging regions. Analytical expressions for pressure drop are obtained for each of these regions separately. Using this approach, effects of lesion length and GW insertion on the mean translesional pressure drop and its component (loss due to momentum change and viscous loss are analyzed. Results and Conclusion It is observed that for a given percent area stenosis (AS, increase in the throat length only increases the viscous loss. However, increase in the severity of stenosis and GW insertion increase both loss due to momentum change and viscous loss. GW insertion has greater contribution to the rise in viscous loss (increase by 2.14 and 2.72 times for 64% and 90% AS, respectively than loss due to momentum change (1.34% increase for 64% AS and 25% decrease for 90% AS. It also alters the hyperemic pressure drop in moderate (48% increase to intermediate (30% increase stenoses significantly. However, in severe stenoses GW insertion has a negligible effect (0.5% increase on hyperemic translesional pressure drop. It is also observed that pressure drop in a severe stenosis is less sensitive to lesion length variation (4% and 14% increase in Δp for without and with GW, respectively as compared to intermediate (10% and 30% increase in Δp for without and with GW, respectively and moderate stenoses (22% and 48

  19. Effect of instant controlled pressure drop on IgE antibody reactivity to peanut, lentil, chickpea and soybean proteins.

    Science.gov (United States)

    Cuadrado, Carmen; Cabanillas, Beatriz; Pedrosa, Mercedes M; Muzquiz, Mercedes; Haddad, Joseph; Allaf, Karim; Rodriguez, Julia; Crespo, Jesus F; Burbano, Carmen

    2011-01-01

    The use of legume seeds is being expanded in the food industry due to their excellent nutritional and technological properties. However, legumes have been considered causative agents of allergic reactions through ingestion. Previous studies indicated that processing methods combining heat and steam pressure, such as instant controlled pressure drop (DIC®), could decrease allergenicity. The aim of this study was to investigate the impact of DIC treatment on peanut, lentil, chickpea and soybean IgE antibody reactivity. Peanut, lentil, chickpea and soybean seeds were subjected to DIC treatment at different pressure and time conditions (3 and 6 bar for 1 and 3 min). Control (raw) and DIC-treated extracts were analyzed by SDS-PAGE and immunoblotting using a serum pool from sensitized patients. DIC treatment did not affect the total protein content of legume seeds. Nevertheless, modifications of protein profiles after DIC showed a general decrease in IgE binding to legume proteins that was correlated to a higher steam pressure and longer treatment. The immunoreactivity of soybean proteins was almost abolished with treatment at 6 bar for 3 min. The results demonstrated that DIC treatment produces a reduction in the overall in vitro IgE binding of peanut, lentil and chickpea and a drastic reduction in soybean immunoreactivity. Copyright © 2011 S. Karger AG, Basel.

  20. High-Lift Low Reynolds Number Aerofoils With Specified Pressure Drop for Ducted Wind Turbine

    NARCIS (Netherlands)

    Tang, J.; van Bussel, G.J.W.

    2017-01-01

    A new high-lift aerofoil modification for the duct has been developed and will be experimentally tested in a small wind tunnel. Aerofoils for such wind tunnel ducts typically operate in the low Reynolds number range from 2 × 105 to 6 × 105. The effect of a duct and of rotor on power and pressure

  1. Experimental studies on the enhanced flow boiling heat transfer and pressure drop of organic fluid with high saturation temperature in vertical porous coated tube

    Science.gov (United States)

    Yang, Dong; Shen, Zhi; Chen, Tingkuan; Zhou, Chenn Q.

    2013-07-01

    The characteristics of flow boiling heat transfer and pressure drop of organic fluid with high saturation temperature in a vertical porous coated tube are experimentally studied in this paper. The experiments are performed at evaporation pressure of 0.16-0.31MPa, mass flux of 390-790kg/m2s, and vapor quality of 0.06-0.58. The variations of heat transfer coefficient and pressure drop with vapor quality are measured and compared to the results of smooth tube. Boiling curves are generated at mass flux of 482 and 675kg/m2s. The experimental results indicate that the heat transfer coefficients of the porous tube are 1.8-3.5 times those of smooth tube, and that the frictional pressure drops of the porous tube are 1.1-2.9 times those of smooth tube. The correlations for heat transfer coefficient and frictional pressure drop are derived, in which the effect of fluid molecular weight is included. The experiments show that significant heat transfer enhancement is accompanied by a little pressure drop penalty, the application of the porous coated tube is promising in the process industries.

  2. An analytical model for droplet separation in vane separators and measurements of grade efficiency and pressure drop

    Energy Technology Data Exchange (ETDEWEB)

    Koopman, Hans K., E-mail: hans.koopman@siemens.com [Siemens AG, Energy Sector, Power Generation Freyeslebenstrasse 1, 91052 Erlangen (Germany); Köksoy, Çağatay; Ertunç, Özgür; Lienhart, Hermann; Hedwig, Heinz; Delgado, Antonio [Institute of Fluid Mechanics, Friedrich-Alexander University, Erlangen-Nuremberg Cauerstrasse 4, 91058 Erlangen (Germany)

    2014-09-15

    Highlights: • An analytical model for efficiency is extended with additional geometrical features. • A simplified and a novel vane separator design are investigated experimentally. • Experimental results are significantly affected by re-entrainment effects. • Outlet droplet size spectra are accurately predicted by the model. • The improved grade efficiency doubles the pressure drop. - Abstract: This study investigates the predictive power of analytical models for the droplet separation efficiency of vane separators and compares experimental results of two different vane separator geometries. The ability to predict the separation efficiency of vane separators simplifies their design process, especially when analytical research allows the identification of the most important physical and geometrical parameters and can quantify their contribution. In this paper, an extension of a classical analytical model for separation efficiency is proposed that accounts for the contributions provided by straight wall sections. The extension of the analytical model is benchmarked against experiments performed by Leber (2003) on a single stage straight vane separator. The model is in very reasonable agreement with the experimental values. Results from the analytical model are also compared with experiments performed on a vane separator of simplified geometry (VS-1). The experimental separation efficiencies, computed from the measured liquid mass balances, are significantly below the model predictions, which lie arbitrarily close to unity. This difference is attributed to re-entrainment through film detachment from the last stage of the vane separators. After adjustment for re-entrainment effects, by applying a cut-off filter to the outlet droplet size spectra, the experimental and theoretical outlet Sauter mean diameters show very good agreement. A novel vane separator geometry of patented design (VS-2) is also investigated, comparing experimental results with VS-1

  3. Investigation of heat transfer and pressure drop of CO(2) two-phase flow in a horizontal minichannel

    CERN Document Server

    Wu, J; Haug, F; Franke, C; Bremer, J; Eisel, T; Koettig, T

    2011-01-01

    An innovative cooling system based on evaporative CO(2) two-phase flow is under investigation for the tracker detectors upgrade at CERN (European Organization for Nuclear Research). The radiation hardness and the excellent thermodynamic properties emphasize carbon dioxide as a cooling agent in the foreseen minichannels. A circular stainless steel tube in horizontal orientation with an inner diameter of 1.42 mm and a length of 0.3 m has been used as a test section to perform the step-wise scanning of the vapor quality in the entire two-phase region. To characterize the heat transfer and the pressure drop depending on the vapor quality in the tube, measurements have been performed by varying the mass flux from 300 to 600 kg/m(2) s, the heat flux from 7.5 to 29.8 kW/m(2) and the saturation temperature from -40 to 0 degrees C (reduced pressures from 0.136 to 0.472). Heat transfer coefficients between 4 kW/m(2) K and 28 kW/m(2) K and pressure gradients up to 75 kPa/m were registered. The measured data was analyzed...

  4. Pressure Drop Versus Flow Rate Analysis of the Limited Streamer Tube Gas System of the BaBar Muon Detector Upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Yi, M.

    2004-09-03

    It has been proposed that Limited Streamer Tubes (LST) be used in the current upgrade of the muon detector in the BaBar detector. An LST consists of a thin silver plated wire centered in a graphite-coated cell. One standard LST tube consists of eight such cells, and two or three such tubes form an LST module. Under operation, the cells are filled with a gas mixture of CO{sub 2}, argon and isobutane. During normal operation of the detector, the gas will be flushed out of the system at a constant low rate of one volume change per day. During times such as installation, however, it is often desired to flush and change the LST gas volumes very rapidly, leading to higher than normal pressure which may damage the modules. This project studied this pressure as a function of flow rate and the number of modules that are put in series in search of the maximal safe flow rate at which to flush the modules. Measurements of pressure drop versus flow rate were taken using a flow meter and a pressure transducer on configurations of one to five modules put in series. Minimal Poly-Flo tubing was used for all connections between test equipment and modules. They contributed less than 25% to all measurements. A ratio of 0.00022 {+-} 0.00001 mmHg per Standard Cubic Centimeter per Minute (SCCM) per module was found, which was a slight overestimate since it included the contributions from the tubing connections. However, for the purpose of finding a flow rate at which the modules can be safely flushed, this overestimate acts as a safety cushion. For a standard module with a volume of 16 liters and a known safe overpressure of 2 inches of water, the ratio translates into a flow rate of 17000 {+-} 1000SCCM and a time requirement of 56 {+-} 5 seconds to flush an entire module.

  5. Computational investigation of heat transfer and pressure drop in a typical louver fin-and-tube heat exchanger for various louver angles and fin pitches

    Directory of Open Access Journals (Sweden)

    Okbaz Abdulkerim

    2017-01-01

    Full Text Available In this study 3-D numerical simulations on heat transfer and pressure drop characteristics for a typical louver fin-and- double-row tube heat exchanger were carried out. The heat transfer improvement and the corresponding pressure drop amounts were investigated depending on louver angles, fin pitch and Reynolds number, and reported in terms of Colburn j-factor and Fanning friction factor f. The heat transfer improvement and the corresponding pressure drop amounts were investigated depending on louver angles between 20° ≤Ө≤ 30°, louver pitch of Lp=3.8 mm and frontal velocities of U between 1.22 m/s - 3 m/s. In addition, flow visualization of detailed flow features results, such as velocity vectors, streamlines and temperature counters have been shown to understand heat transfer enhancement mechanism. The present results indicated that louver angle and fin pitch noticeably affected the thermal and hydraulic performance of heat exchanger. It has been seen that increasing louver angle, increases thermal performance while decreasing hydraulic performance associated to pressure drop for fin pitches of 3.2 mm and 2.5 mm. Fin pitch determines the flow behaviour that for fin pitch of 2 mm, increasing louver angle decreased heat transfer and pressure drop. Velocity vectors and streamlines give considerable information about the flow whether it is duct directed or louver directed. For all conditions the flow is louver directed.

  6. Dynamics of diffusivity and pressure drop in flow-through and parallel-flow bioreactors during tissue regeneration.

    Science.gov (United States)

    Podichetty, Jagdeep T; Dhane, Dhananjay V; Madihally, Sundararajan V

    2012-07-01

    In this study, transport characteristics in flow-through and parallel-flow bioreactors used in tissue engineering were simulated using computational fluid dynamics. To study nutrient distribution and consumption by smooth muscle cells colonizing the 100 mm diameter and 2-mm thick scaffold, effective diffusivity of glucose was experimentally determined using a two-chambered setup. Three different concentrations of chitosan-gelatin scaffolds were prepared by freezing at -80°C followed by lyophilization. Experiments were performed in both bioreactors to measure pressure drop at different flow rates. At low flow rates, experimental results were in agreement with the simulation results for both bioreactors. However, increase in flow rate beyond 5 mL/min in flow-through bioreactor showed channeling at the circumference resulting in lower pressure drop relative to simulation results. The Peclet number inside the scaffold indicated nutrient distribution within the flow-through bioreactor to be convection-dependent, whereas the parallel-flow bioreactor was diffusion-dependent. Three alternative design modifications to the parallel-flow were made by (i) introducing an additional inlet and an outlet, (ii) changing channel position, and (iii) changing the hold-up volume. Simulation studies were performed to assess the effect of scaffold thickness, cell densities, and permeability. These new designs improved nutrient distribution for 2 mm scaffolds; however, parallel-flow configuration was found to be unsuitable for scaffolds more than 4-mm thick, especially at low porosities as tissues regenerate. Furthermore, operable flow rate in flow-through bioreactors is constrained by the mechanical strength of the scaffold. In summary, this study showed limitations and differences between flow-through and parallel-flow bioreactors used in tissue engineering. Copyright © 2012 American Institute of Chemical Engineers (AIChE).

  7. Carbon dioxide heat transfer coefficients and pressure drops during flow boiling: Assessment of predictive methods

    Energy Technology Data Exchange (ETDEWEB)

    Mastrullo, R.; Mauro, A.W.; Rosato, A. [D.E.TE.C., Facolta di Ingegneria, Universita degli Studi di Napoli Federico II, p.le Tecchio 80, 80125 Napoli (Italy); Vanoli, G.P. [Dipartimento di Ingegneria, Universita degli Studi del Sannio, corso Garibaldi 107, Palazzo dell' Aquila Bosco Lucarelli, 82100 Benevento (Italy)

    2010-09-15

    Among the alternatives to the HCFCs and HFCs, carbon dioxide emerged as one of the most promising environmentally friendly refrigerants. In past years many works were carried out about CO{sub 2} flow boiling and very different two-phase flow characteristics from conventional fluids were found. In order to assess the best predictive methods for the evaluation of CO{sub 2} heat transfer coefficients and pressure gradients in macro-channels, in the current article a literature survey of works and a collection of the results of statistical comparisons available in literature are furnished. In addition the experimental data from University of Naples are used to run a deeper analysis. Both a statistical and a direct comparison against some of the most quoted predictive methods are carried out. Methods implemented both for low-medium pressure refrigerants and specifically developed for R744 are used in the comparison. Some general indications about the choice of the predictive methods dependently on the operating conditions are given. (author)

  8. Experimental study of single-phase pressure drops in coarse particle beds

    Energy Technology Data Exchange (ETDEWEB)

    Clavier, R., E-mail: remi.clavier@irsn.fr [IRSN Cadarache, Saint Paul-lez-Durance (France); Chikhi, N., E-mail: nourdine.chikhi@irsn.fr [IRSN Cadarache, Saint Paul-lez-Durance (France); Fichot, F., E-mail: florian.fichot@irsn.fr [IRSN Cadarache, Saint Paul-lez-Durance (France); Quintard, M., E-mail: Michel.Quintard@imft.fr [Université de Toulouse, Allée Camille Soula, F-31400 Toulouse (France); INPT, UPS, Allée Camille Soula, F-31400 Toulouse (France); IMFT (Institut de Mécanique des Fluides de Toulouse), Allée Camille Soula, F-31400 Toulouse (France); CNRS, F-31400 Toulouse (France)

    2017-02-15

    Motivated by uncertainty reduction in nuclear debris beds coolability, experiments have been conducted on the CALIDE facility in order to investigate single-phase pressure losses in representative debris beds, i.e., high sphericity (>80%) particle beds with small size dispersion (from 1 mm to 10 mm), for which no validated model exists. In this paper, experimental results are presented and analyzed in order to identify a simple correlation for single-phase flow pressure losses generated in this kind of porous media in reflooding flowing conditions, which cover Darcy to weakly turbulent regimes. In the literature, it has been observed that their behavior can be accurately described by a Darcy–Forchheimer law, involving the sum of a linear term and a quadratic non-linear deviation, with respect to the filtration velocity. Expressions for the coefficients of the linear and quadratic terms are determined by assessing the possibility to evaluate equivalent diameters, i.e., characteristic lengths allowing correct predictions of the linear and quadratic terms by the Ergun equation. It has been observed that the Sauter diameter of particles allows a very precise prediction of the linear term, while the quadratic term can be predicted using the product of the Sauter diameter and a sphericity coefficient as an equivalent diameter.

  9. Association of systolic blood pressure drop with intravenous administration of itraconazole in children with hemato-oncologic disease

    Directory of Open Access Journals (Sweden)

    Lee HJ

    2015-12-01

    Full Text Available Hyeong Jin Lee,1,* Bongjin Lee,2,* June Dong Park,2 Hyung Joo Jeong,2 Yu Hyeon Choi,2 Hee Young Ju,1 Che Ry Hong,1 Ji Won Lee,1 Hyery Kim,1 Dong In Suh,3 Kyung Duk Park,1 Hyoung Jin Kang,1 Hee Young Shin,1 Hyo Seop Ahn1 1Department of Pediatrics, Cancer Research Institute, 2Division of Pediatric Intensive Care, Department of Pediatrics, 3Division of Pulmonology, Department of Pediatrics, Seoul National University College of Medicine, Seoul National University, Seoul, South Korea *These authors contributed equally to this work Purpose: Although few adverse effects have been reported for itraconazole, a widely used antifungal therapy for febrile neutropenia, we found intravenous (IV itraconazole to be associated with serious cases of blood pressure (BP drop. We therefore evaluated the incidence and risk factors for BP drop during IV administration of the drug.Materials and methods: We reviewed the medical records of children with hemato-oncologic disease who were treated with IV itraconazole from January 2012 to December 2013. By analyzing systolic BP (SBP measurements made from 4 hours before through to 4 hours after itraconazole administration, we evaluated the changes in SBP and the risk factors for an SBP drop, especially clinically meaningful (≥20% drops.Results: Itraconazole was administered 2,627 times to 180 patients. The SBP during the 4 hours following itraconazole administration was lower than during the 4 hours before administration (104 [53.0–160.33 mmHg] versus 105 [59.8–148.3 mmHg]; P<0.001. The decrease in SBP was associated with the application of continuous renal replacement therapy (CRRT (P=0.012 and the use of inotropic (P=0.005 and hypotensive drugs (P=0.021. A clinically meaningful SBP drop was seen in 5.37% (141 out of 2,627 of the administrations, and the use of inotropics (odds ratio [OR] 6.70, 95% confidence interval [CI] 3.22–13.92; P<0.001, reducing the dose of inotropics (OR 8.08; 95% CI 1.39–46.94; P=0

  10. Numerical simulation of effect of catalyst wire-mesh pressure drop characteristics on flow distribution in catalytic parallel plate steam reformer

    DEFF Research Database (Denmark)

    Sigurdsson, Haftor Örn; Kær, Søren Knudsen

    2012-01-01

    , is considered to investigate the effect of catalyst wire-mesh pressure drop characteristics on flow distribution in the CPHE reformer. Flow distribution in a CPHE reformer is rarely uniform due to inlet and exhaust manifold design. Poorly-designed manifolds may lead to severe flow maldistribution, flow reversal...... source to account for the pressure drop. The numerical model is verified experimentally, numerical and experimental results are found to be in good agreement. The study shows that severe flow maldistribution exists in the current reformer stack. At nominal load some channels in the CPHE reformer receive...... up to four times the average mass flow, while other channels have reversed flow. Flow maldistribution and flow reversal can be improved significantly by increasing the pressure drop characteristics of the catalyst wire-mesh....

  11. Effect of Suction Nozzle Pressure Drop on the Performance of an Ejector-Expansion Transcritical CO2 Refrigeration Cycle

    Directory of Open Access Journals (Sweden)

    Zhenying Zhang

    2014-08-01

    Full Text Available The basic transcritical CO2 systems exhibit low energy efficiency due to their large throttling loss. Replacing the throttle valve with an ejector is an effective measure for recovering some of the energy lost in the expansion process. In this paper, a thermodynamic model of the ejector-expansion transcritical CO2 refrigeration cycle is developed. The effect of the suction nozzle pressure drop (SNPD on the cycle performance is discussed. The results indicate that the SNPD has little impact on entrainment ratio. There exists an optimum SNPD which gives a maximum recovered pressure and COP under a specified condition. The value of the optimum SNPD mainly depends on the efficiencies of the motive nozzle and the suction nozzle, but it is essentially independent of evaporating temperature and gas cooler outlet temperature. Through optimizing the value of SNPD, the maximum COP of the ejector-expansion cycle can be up to 45.1% higher than that of the basic cycle. The exergy loss of the ejector-expansion cycle is reduced about 43.0% compared with the basic cycle.

  12. Effect of filtration velocity and filtration pressure drop on the bag-cleaning performance of a pulse-jet baghouse

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, C.J.; Tsai, M.L.; Lu, H.C.

    2000-01-01

    In this study the filtration velocity and filtration pressure drop at the beginning of bag cleaning were used as experimental parameters to evaluate the bag-cleaning performance of a pulse-jet baghouse. The effective residual pressure loss was used to indicate the cleaning performance after bag cleaning. Two different test dusts, fly ash and limestone, were used. The critical cleaning indices under different operation conditions for bag cleaning were also investigated. A critical average pulse overpressure was found to exist beyond which bag-cleaning performance did not improve much. It was found the filter's final filtration resistance is an important parameter to decide whether a Venturi is necessary for a good bag-cleaning performance or not. Use of a Venturi was found to increase the average pulse overpressure for a system with a filter's final resistance coefficient greater than about 500 Pa{center{underscore}dot}s/cm. However, no Venturi is recommended when the filter's final resistance coefficient is smaller than 500 Pa{center{underscore}dot}s/cm.

  13. Effect of Channel Orientation and Rib Pitch-to-Height Ratio on Pressure Drop in a Rotating Square Channel with Ribs on Two Opposite Surfaces

    Directory of Open Access Journals (Sweden)

    Prabhu S. V.

    2005-01-01

    Full Text Available The effect of channel orientation and rib pitch-to-height ratio on the pressure drop distribution in a rib-roughened channel is an important issue in turbine blade cooling. The present investigation is a study of the overall pressure drop distribution in a square cross-sectioned channel, with rib turbulators, rotating about an axis normal to the free stream. The ribs are configured in a symmetric arrangement on two opposite surfaces with a rib angle of 90 ∘ to the mainstream flow. The study has been conducted for three Reynolds numbers, namely, 13 000, 17 000, and 22 000 with the rotation number varying from 0– 0.38 . Experiments have been carried out for various rib pitch-to-height ratios ( P/e with a constant rib height-to-hydraulic diameter ratio ( e/D of 0.1 . The test section in which the ribs are placed on the leading and trailing surfaces is considered as the base case ( orientation angle= 0 ∘ , Coriolis force vector normal to the ribbed surfaces. The channel is turned about its axis in steps of 15 ∘ to vary the orientation angle from 0 ∘ to 90 ∘ . The overall pressure drop does not change considerably under conditions of rotation for the base case. However, for the other cases tested, it is observed that the overall pressure drop increases with an increase in the rotation number for a given orientation angle and also increases with an increase in the orientation angle for a given rotation number. This change is attributed to the variation in the separation zone downstream of the ribs due to the presence of the Coriolis force—local pressure drop data is presented which supports this idea. At an orientation angle of 90 ∘ (ribs on the top and bottom surfaces, Coriolis force vector normal to the smooth surfaces, the overall pressure drop is observed to be maximum during rotation. The overall pressure drop for a case with a rib pitch-to-height ratio of 5 on both surfaces is found to be the highest

  14. Define and Quantify the Physics of Air Flow, Pressure Drop and Aerosol Collection in Nuclear Grade HEPA Filters

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Murray E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-02-23

    Objective: Develop a set of peer-review and verified analytical methods to adjust HEPA filter performance to different flow rates, temperatures and altitudes. Experimental testing will measure HEPA filter flow rate, pressure drop and efficiency to verify the analytical approach. Nuclear facilities utilize HEPA (High Efficiency Particulate Air) filters to purify air flow for workspace ventilation. However, the ASME AG-1 technical standard (Code on Nuclear Air and Gas Treatment) does not adequately describe air flow measurement units for HEPA filter systems. Specifically, the AG-1 standard does not differentiate between volumetric air flow in ACFM (actual cubic feet per minute)compared to mass flow measured in SCFM (standard cubic feet per minute). More importantly, the AG-1 standard has an overall deficiency for using HEPA filter devices at different air flow rates, temperatures, and altitudes. Technical Approach: The collection efficiency and pressure drops of 18 different HEPA filters will be measured over a range of flow rates, temperatures and altitudes. The experimental results will be compared to analytical scoping calculations. Three manufacturers have allocated six HEPA filters each for this effort. The 18 filters will be tested at two different flow rates, two different temperatures and two different altitudes. The 36 total tests will be conducted at two different facilities: the ATI Test facilities (Baltimore MD) and the Los Alamos National Laboratory (Los Alamos NM). The Radiation Protection RP-SVS group at Los Alamos has an aerosol wind tunnel that was originally designed to evaluate small air samplers. In 2010, modifications were started to convert the wind tunnel for HEPA filter testing. (Extensive changes were necessary for the required aerosol generators, HEPA test fixtures, temperature control devices and measurement capabilities.) To this date, none of these modification activities have been funded through a specific DOE or NNSA program. This is

  15. The respective effect of under-rib convection and pressure drop of flow fields on the performance of PEM fuel cells

    Science.gov (United States)

    Wang, Chao; Zhang, Qinglei; Shen, Shuiyun; Yan, Xiaohui; Zhu, Fengjuan; Cheng, Xiaojing; Zhang, Junliang

    2017-03-01

    The flow field configuration plays an important role on the performance of proton exchange membrane fuel cells (PEMFCs). For instance, channel/rib width and total channel cross-sectional area determine the under-rib convection and pressure drop respectively, both of which directly influence the water removal, in turn affecting the oxygen supply and cathodic oxygen reduction reaction. In this study, effects of under-rib convection and pressure drop on cell performance are investigated experimentally and numerically by adjusting the channel/rib width and channel cross-sectional area of flow fields. The results show that the performance differences with various flow field configurations mainly derive from the oxygen transport resistance which is determined by the water accumulation degree, and the cell performance would benefit from the narrower channels and smaller cross sections. It reveals that at low current densities when water starts to accumulate in GDL at under-rib regions, the under-rib convection plays a more important role in water removal than pressure drop does; in contrast, at high current densities when water starts to accumulate in channels, the pressure drop dominates the water removal to facilitate the oxygen transport to the catalyst layer.

  16. The respective effect of under-rib convection and pressure drop of flow fields on the performance of PEM fuel cells

    Science.gov (United States)

    Wang, Chao; Zhang, Qinglei; Shen, Shuiyun; Yan, Xiaohui; Zhu, Fengjuan; Cheng, Xiaojing; Zhang, Junliang

    2017-01-01

    The flow field configuration plays an important role on the performance of proton exchange membrane fuel cells (PEMFCs). For instance, channel/rib width and total channel cross-sectional area determine the under-rib convection and pressure drop respectively, both of which directly influence the water removal, in turn affecting the oxygen supply and cathodic oxygen reduction reaction. In this study, effects of under-rib convection and pressure drop on cell performance are investigated experimentally and numerically by adjusting the channel/rib width and channel cross-sectional area of flow fields. The results show that the performance differences with various flow field configurations mainly derive from the oxygen transport resistance which is determined by the water accumulation degree, and the cell performance would benefit from the narrower channels and smaller cross sections. It reveals that at low current densities when water starts to accumulate in GDL at under-rib regions, the under-rib convection plays a more important role in water removal than pressure drop does; in contrast, at high current densities when water starts to accumulate in channels, the pressure drop dominates the water removal to facilitate the oxygen transport to the catalyst layer. PMID:28251983

  17. Numerical Study on Bubble Dynamics and Two-Phase Frictional Pressure Drop of Slug Flow Regime in Adiabatic T-junction Square Microchannel

    Directory of Open Access Journals (Sweden)

    K. Kishor

    2017-10-01

    Full Text Available In this study, bubble dynamics and frictional pressure drop associated with gas liquid two-phase slug flow regime in adiabatic T-junction square microchannel has been investigated using CFD. A comprehensive study on the mechanism of bubble formation via squeezing and shearing regime is performed. The randomness and recirculation profiles observed in the squeezing regime are significantly higher as compared to the shearing regime during formation of the slug. Further, effects of increasing gas velocity on bubble length are obtained at fixed liquid velocities and simulated data displayed good agreement with available correlations in literature. The frictional pressure drop for slug flow regime from simulations are also obtained and evaluated against existing separated flow models. A regression correlation has also been developed by modifying C-parameter using separated flow model, which improves the prediction of two-phase frictional pressure drop data within slug flow region, with mean absolute error of 10 %. The influences of fluid properties such as liquid viscosity and surface tension on the two-phase frictional pressure drop are also investigated and compared with developed correlation. The higher liquid viscosity and lower surface tension value resulted in bubble formation via shearing regime.

  18. Steady RANS methodology for calculating pressure drop in an in-line molten salt compact crossflow heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Carasik, Lane B.; Shaver, Dillon R.; Hassan, Yassin A.; Haefner, Jonah B.

    2017-11-01

    The development of molten salt cooled reactors (MSR) and fluoride-salt cooled high temperature reactors (FHR) requires the use of advanced design tools for the primary heat exchanger design. Due to geometric and flow characteristics, compact (pitch to diameter ratios equal to or less than 1.25) heat exchangers with a crossflow flow arrangement can become desirable for these reactors. Unfortunately, the available experimental data is limited for compact tube bundles or banks in crossflow. Computational Fluid Dynamics can be used to alleviate the lack of experimental data in these tube banks. Previous computational efforts have been primarily focused on large S/D ratios (larger than 1.4) using unsteady Reynolds averaged Navier-Stokes and Large Eddy Simulation frameworks. These approaches are useful, but have large computational requirements that make comprehensive design studies impractical. A CFD study was conducted with steady RANS in an effort to provide a starting point for future design work. The study was performed for an in-line tube bank geometry with FLiBe (LiF-BeF2), a frequently selected molten salt, as the working fluid. Based on the estimated pressure drops, the pressure and velocity distributions in the domain, an appropriate meshing strategy was determined and presented. Periodic boundaries in the spanwise direction transverse flow were determined to be an appropriate boundary condition for reduced computational domains. The domain size was investigated and a minimum of 2-flow channels for a domain is recommended to ensure the behavior is accounted for. Lastly, the standard low Re κ-ε (Lien) turbulence model was determined to be the most appropriate for steady RANS of this case at the time of writing.

  19. Anisotropy effects on convective heat transfer and pressure drop in Kelvin’s open-cell foams

    Science.gov (United States)

    Iasiello, M.; Bianco, N.; Chiu, W. K. S.; Naso, V.

    2017-11-01

    Open-cell foams have the potential to offer heat transfer enhancement in many applications, such as heat exchangers, solar air receivers, porous burners, thanks to their high heat transfer surface to volume ratio and to tortuosity, that promotes the internal flow mixing. Their microstructural transport features are affected by foam anisotropy, and could play an important role not only because manufacturing processes can stretch the cells along a preferential direction, but also because modern techniques allow for the customization of the foam cell shape. However, structural anisotropy in open cell foams has been scarcely investigated. In this paper, anisotropy effects on convective heat transfer and pressure drop in Kelvin’s open-cell foams are analyzed. Since Kelvin’s model is geometrically regular, anisotropy has been investigated by stretching the foam along three orthogonal directions, at equal cell volume. Governing mass, momentum and energy equations have been solved using a finite element method. Results are presented for different fluid inlet velocities and cell sizes along three orthogonal stretching directions. They show that anisotropy affects the velocity and temperature fields, and, consequently, the permeability, inertial factor and volumetric heat transfer coefficients.

  20. Delineation of epicardial stenosis in patients with microvascular disease using pressure drop coefficient: A pilot outcome study.

    Science.gov (United States)

    Hebbar, Ullhas Udaya; Effat, Mohamed A; Peelukhana, Srikara V; Arif, Imran; Banerjee, Rupak K

    2017-12-26

    To investigate the patient-outcomes of newly developed pressure drop coefficient (CDP) in diagnosing epicardial stenosis (ES) in the presence of concomitant microvascular disease (MVD). Patients from our clinical trial were divided into two subgroups with: (1) cut-off of coronary flow reserve (CFR) 27.9 groups for assessing major adverse cardiac events (MACE: Primary outcome). Comparisons were also made between the survival curves for FFR 27.9 groups. Two tailed chi-squared and Fischer's exact tests were performed for comparison of the primary outcomes, and the log-rank test was used to compare the Kaplan-Meier survival curves. P 27.9 group (7.7%, 2/26) was lower than FFR 27.9 group (12.5%, 2/16) was lower than FFR 27.9 group ( n = 26) when compared with FFR 27.9 group ( n = 16) showed higher survival times compared to FFR group ( n = 11); P = 0.58. CDP correlated significantly with HMR and resulted in better %MACE as well as survival rates in comparison to FFR. These positive trends demonstrate that CDP could be a potential diagnostic endpoint for delineating MVD with or without ES.

  1. Study of heat transfer and pressure drop characteristics of air heat exchanger using PCM for free cooling applications

    Directory of Open Access Journals (Sweden)

    Kalaiselvam Sivakumar

    2016-01-01

    Full Text Available Free cooling is the process of storing the cool energy available in the night ambient air and using it during the day. The heat exchanger used in this work is a modular type which is similar to the shell and tube heat exchanger. The shell side is filled with Phase Change Materials (PCM and air flow is through the tubes in the module. The modules of the heat exchanger are arranged one over other with air spacers in between each module. The air space provided in between the module in-creases the retention time of the air for better heat transfer. Transient Computational Fluid Dynamics modeling is carried out for single air passage in a modular heat exchanger. It shows that the PCM phase transition time in the module in which different shape of fins is adopted. The module with rectangular fins has 17.2 % reduction in solidification compared with the plain module. Then steady state numerical analysis is accomplished to the whole module having the fin of high heat transfer, so that pressure drop, flow and thermal characteristics across the module and the air spacers are deter-mined for various air inlet velocities of 0.4 to 1.6 m/s. To validate the computational results, experiments are carried out and the agreement was found to be good.

  2. Study of the Pressure Drop and Flow Field in Standard Gas Cyclone Models Using the Granular Model

    Directory of Open Access Journals (Sweden)

    Nabil Kharoua

    2011-01-01

    Full Text Available A particle-laden flow inside solid gas cyclones has been studied using computational fluid dynamics (CFD. The effects of high temperatures and different particle loadings have been investigated. The Reynolds stress (RSM model-predicted results, in the case of pure gas, are within engineering accuracy even at high temperatures. Using the granular mixture model for the cases of particle-laden flow, discrepancies occurred at relatively high loadings (up to 0.5 kg/m3. Since the pressure drop is strongly related to the friction inside the cyclone body, the concept of entropy generation has been employed to detect regions of high frictional effects. Friction has been observed to be important at the vortex finder wall, the bottom of the conical-part wall, and the interface separating the outer and the core streams. The discrepancies between the present numerical simulation and the experimental results taken from the existing literature, which are caused by the mixture and turbulence models simplifying assumptions, are discussed in this paper.

  3. Bubble and drop interfaces

    CERN Document Server

    Miller

    2011-01-01

    The book aims at describing the most important experimental methods for characterizing liquid interfaces, such as drop profile analysis, bubble pressure and drop volume tensiometry, capillary pressure technique, and oscillating drops and bubbles. Besides the details of experimental set ups, also the underlying theoretical basis is presented in detail. In addition, a number of applications based on drops and bubbles is discussed, such as rising bubbles and the very complex process of flotation. Also wetting, characterized by the dynamics of advancing contact angles is discussed critically. Spec

  4. Twenty-Four-Hour Variation of Intraocular Pressure in Primary Open-Angle Glaucoma Treated with Triple Eye Drops

    Directory of Open Access Journals (Sweden)

    Yoshinori Itoh

    2017-01-01

    Full Text Available Objectives. To evaluate 24-hour intraocular pressure (IOP variation in patients with primary open-angle glaucoma (POAG treated with triple eye drops. Subjects and Methods. The IOP was measured in 74 eyes in 74 POAG patients (seated on triple therapy (PG analogue, β-blocker, carbonic anhydrase inhibitor at about every 3 hours. Results. The peak IOP was 13.5 ± 3.1 at 1:00, and the trough IOP was at 12.6 ± 2.4 mmHg at 7:00. The IOP at 7:00 was significantly lower than that at 10:00, 1:00, and 3:00 (p<0.05. Based on the time of the peak IOP, we classified the patients into two groups: diurnal (28 eyes and nocturnal types (37 eyes. There was significant difference at the spherical equivalent between diurnal and nocturnal types (p=0.014. To assess the influence of reflective error, we conducted subanalysis for two groups: high myopic (26 eyes, ≤−6D and low/nonmyopic (24 eyes, ≥−2D groups. In the low/nonmyopia group, the IOP was significantly higher at 1:00 and 3:00 than at 13:00, 16:00, and 7: 00 (p<0.05. Conclusion. The mean of IOP elevated outside of clinic hour in the POAG patients on triple therapy. The low/nonmyopia patient should be carefully treated because the IOP of the patients at night elevated significantly.

  5. Pressure drop-flow rate curves for single-phase steam in Combustion Engineering type steam generator U-tubes during severe accidents

    Energy Technology Data Exchange (ETDEWEB)

    Fynan, Douglas A.; Ahn, Kwang-Il, E-mail: kiahn@kaeri.re.kr

    2016-12-15

    Highlights: • Pressure drop-flow rate curves for superheated steam in U-tubes were generated. • Forward flow of hot steam is favored in the longer and taller U-tubes. • Reverse flow of cold steam is favored in short U-tubes. • Steam generator U-tube bundle geometry and tube diameter are important. • Need for correlation development for natural convention heat transfer coefficient. - Abstract: Characteristic pressure drop-flow rate curves are generated for all row numbers of the OPR1000 steam generators (SGs), representative of Combustion Engineering (CE) type SGs featuring square bend U-tubes. The pressure drop-flow rate curves are applicable to severe accident natural circulations of single-phase superheated steam during high pressure station blackout sequences with failed auxiliary feedwater and dry secondary side which are closely related to the thermally induced steam generator tube rupture event. The pressure drop-flow rate curves which determine the recirculation rate through the SG tubes are dependent on the tube bundle geometry and hydraulic diameter of the tubes. The larger CE type SGs have greater variation of tube length and height as a function of row number with forward flow of steam favored in the longer and taller high row number tubes and reverse flow favored in the short low row number tubes. Friction loss, natural convection heat transfer coefficients, and temperature differentials from the primary to secondary side are dominant parameters affecting the recirculation rate. The need for correlation development for natural convection heat transfer coefficients for external flow over tube bundles currently not modeled in system codes is discussed.

  6. Characterisation of heat transfer and pressure drop in condensation processes within mini-channel tubes with last generation of refrigerant fluids

    Science.gov (United States)

    Lopez Belchi, D. Alejandro

    Heat exchanger developments are driven by energetic efficiency increase and emissionreduction. To reach the standards new system are required based on mini-channels. Mini-channels can be described as tubes with one or more ports extruded in aluminiumwith hydraulic diameter are in the range of 0.2 to 3 mm. Its use in refrigeration systemsfor some years ago is a reality thanks to the human ability to made micro-scale systems.Some heat exchanger enterprises have some models developed specially for their use inautomotive sector, cooling sector, and industrial refrigeration without having a deepknowledge of how these reduced geometries affect the most important parameters suchas pressure drop and the heat transfer coefficient. To respond to this objective, an exhaustive literature review of the last two decades hasbeen performed to determinate the state of the research. Between all the publications,several models have been selected to check the predicting capacities of them becausemost of them were developed for single port mini-channel tubes. Experimentalmeasurements of heat transfer coefficient and frictional pressure drop were recorded inan experimental installation built on purpose at the Technical University of Cartagena.Multiple variables are recorded in this installation in order to calculate local heattransfer coefficient in two-phase condensing flow within mini-channels. Both pressure drop and heat transfer coefficient experimental measurements arecompared to the previously mentioned models. Most of them capture the trend correctlybut others fail predicting experimental data. These differences can be explained by theexperimental parameters considered during the models development. In some cases themodels found in the literature were developed specific conditions, consequently theirpredicting capacities are restricted. As main contributions, this thesis provides new modelling tools for mini-channelscondensing pressure drop and heat transfer coefficient

  7. Novel Combined Freeze-Drying and Instant Controlled Pressure Drop Drying for Restructured Carrot-Potato Chips: Optimized by Response Surface Method

    OpenAIRE

    Yi, Jianyong; Hou, Chunhui; Bi, Jinfeng; Zhao, Yuanyuan; Peng, Jian; Liu, Changjin

    2018-01-01

    Combined freeze-drying and instant controlled pressure drop process (FD-DIC) for restructured carrot-potato chips was developed and its processing conditions were optimized using response surface methodology (RSM) with the purpose of improving the quality of products and reducing energy consumption. Three critical variables including the amount of carrot, the moisture content of the partially dried product before DIC treatment, and equilibrium temperature of DIC for the restructured chips wer...

  8. A Discussion about the Methodology to Validate the Correlations of Heat Transfer Coefficients and Pressure Drop during the Condensation in a Finned-Tube Heat Exchanger

    OpenAIRE

    Pisano, Alessandro; Martinez-Ballester, Santiago; Corberán, José M.; Hidalgo Monpeán, Fernando; Illán Gómez, Ferdando; García Cascales, J-Ramón

    2014-01-01

    As already demonstrated by others authors, when the performance of a heat exchanger is analyzed, a semi-empirical model allows getting good prediction of the experimental results provided that it is accompanied by the application of the suitable correlations for calculating heat transfer coefficients (HTC) and pressure drop (PD) in both refrigerant and air side. Many correlations for calculating these coefficients are available in literature, therefore choose the more suitable of them turns o...

  9. CFD - neutronic coupled calculation of a quarter of a simplified PWR fuel assembly including spacer pressure drop and turbulence enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Pena, C.; Pellacani, F.; Macian Juan, R., E-mail: carlos.pena@ntech.mw.tum.de, E-mail: pellacani@ntech.mw.tum.de, E-mail: macian@ntech.mw.tum.de [Technische Universitaet Muenchen, Garching (Germany). Ntech Lehrstuhl fuer Nukleartechnik; Chiva, S., E-mail: schiva@emc.uji.es [Universitat Jaume I, Castellon de la Plana (Spain). Dept. de Ingenieria Mecanica y Construccion; Barrachina, T.; Miro, R., E-mail: rmiro@iqn.upv.es, E-mail: tbarrachina@iqn.upv.es [Universitat Politecnica de Valencia (ISIRYM/UPV) (Spain). Institute for Industrial, Radiophysical and Environmental Safety

    2011-07-01

    been developed for calculation and synchronization purposes. The data exchange is realized by means of the Parallel Virtual Machine (PVM) software package. In this contribution, steady-state and transient results of a quarter of PWR fuel assembly with cold water injection are presented and compared with obtained results from a RELAP5/PARCS v2.7 coupled calculation. A simplified model for the spacers has been included. A methodology has been introduced to take into account the pressure drop and the turbulence enhancement produced by the spacers. (author)

  10. Carbon dioxide and R410A flow boiling heat transfer, pressure drop, and flow pattern in horizontal tubes at low temperatures

    Science.gov (United States)

    Park, Chang Yong

    Carbon dioxide (CO2) has been seriously considered as an alternate refrigerant for HCFC and HFC fluids, due to the increasing interest of environmentally safe refrigerants in air-conditioning and refrigeration systems. In this study, CO2 flow boiling heat transfer coefficients and pressure drop are measured in macro-scale (6.1 and 3.5 mm) tubes at evaporation temperatures of -15 and -30°C. The measured results show that the nucleate boiling is a main heat transfer mechanism in the 6.1 mm tube and the contribution of convective boiling becomes greater with the decrease of tube diameters and the increase of mass fluxes. The surface roughness of the 6.1 and 3.5 mm tube are presented by SEM and AFM images and surface profiles, and it is shown that the rougher surface of the 6.1 mm tube can affect the flow boiling heat transfer. The CO2 heat transfer coefficients and pressure drop are measured in a mini-scale (0.89 mm) multi-ported tube at the evaporation temperature of -30°C. Also, R410A and R22 flow boiling heat transfer coefficients and pressure drop in a macro-scale (6.1 mm) tube were measured, and they are compared with CO2. This comparison presents that the CO2 flow boiling heat transfer coefficients are higher than R410A and R22 at low vapor qualities, and CO2 pressure drop is significantly lower than R410A and R22. This advantageous characteristic for CO2 could be explained by properties such as surface tension, reduced pressure, and the density ratio of liquid to vapor. The prediction of heat transfer coefficients and pressure drop was performed by general correlations and the calculation results are compared with measured values. Two-phase flow patterns were visualized for CO2 and R410A in the 6 and 3 mm glass tubes, and they are compared with the Weisman et al. and the Wojtan et al. flow pattern maps. The flow pattern maps can determine the flow patterns relatively well, except the transition from intermittent to annular flow.

  11. A critical review of forced convection heat transfer and pressure drop of Al2O3, TiO2 and CuO nanofluids

    Science.gov (United States)

    Khurana, Deepak; Choudhary, Rajesh; Subudhi, Sudhakar

    2017-01-01

    Nanofluid is the colloidal suspension of nanosized solid particles like metals or metal oxides in some conventional fluids like water and ethylene glycol. Due to its unique characteristics of enhanced heat transfer compared to conventional fluid, it has attracted the attention of research community. The forced convection heat transfer of nanofluid is investigated by numerous researchers. This paper critically reviews the papers published on experimental studies of forced convection heat transfer and pressure drop of Al2O3, TiO2 and CuO based nanofluids dispersed in water, ethylene glycol and water-ethylene glycol mixture. Most of the researchers have shown a little rise in pressure drop with the use of nanofluids in plain tube. Literature has reported that the pumping power is appreciably high, only at very high particle concentration i.e. more than 5 %. As nanofluids are able to enhance the heat transfer at low particle concentrations so most of the researchers have used less than 3 % volume concentration in their studies. Almost no disagreement is observed on pressure drop results of different researchers. But there is not a common agreement in magnitude and mechanism of heat transfer enhancement. Few studies have shown an anomalous enhancement in heat transfer even at low particle concentration. On the contrary, some researchers have shown little heat transfer enhancement at the same particle concentration. A large variation (2-3 times) in Nusselt number was observed for few studies under similar conditions.

  12. A numerical investigation of γ-Al2O3-water nanofluids heat transfer and pressure drop in a shell and tube heat exchanger

    Directory of Open Access Journals (Sweden)

    P. Shahmohammadi

    2016-01-01

    Full Text Available The effect of γ-Al2O3 nanoparticles on heat transfer rate, baffle spacing and pressure drop in the shell side of small shell and tube heat exchangers was investigated numerically under turbulent regime. γ-Al2O3-water nanofluids and pure water were used in the shell side and the tube side of heat exchangers, respectively. Since the properties of γ-Al2O3-water nanofluids were variable, they were defined using the user define function. The results revealed that heat transfer and pressure drop were increased with mass flow rate as well as baffle numbers. Adding nanoparticles to the based fluid did not have a significant effect on pressure drop in the shell side. The best heat transfer performance of heat exchangers was for γ-Al2O3-water 1 vol.% and higher nanoparticles concentration was not suitable. The suitable baffle spacing was 43.4% of the shell diameter, showing a good agreement with Bell-Delaware method.

  13. Water holdup estimation from pressure drop measurements in oil-water two-phase flows by means of the two-fluid model

    Science.gov (United States)

    Colombo, L. P. M.; Guilizzoni, M.; Sotgia, G.; Babakhani Dehkordi, P.; Lucchini, A.

    2017-11-01

    The Two-Fluid Model (TFM) has been applied to determine water holdup from pressure drop measurements for core-annular flows in horizontal pipes. The fluids are Milpar 220 oil (ρo=890 kg/m3, μo=0.832 Pa·s at 20 °C) and tap water (μw=1.026×10-3 Pa·s at 20 °C). The investigated volume flow rates range from 2 to 6 m3/h, for water, and from 1 to 3.5 m3/h, for oil, respectively. The results are in very good agreement with available experimental data from the literature and a simple correlation between water holdup and water input fraction has been benchmarked to the overall data set. Eventually, the TFM endowed with the holdup correlation has been adopted to predict the pressure drop with quite satisfactory results: 98% of data fall within a percentage error of ±10%, 99% of the data fall within ±15%, and all the data are predicted within ±20%. On the other hand, the mean absolute relative error for the pressure drop reduction factor is 5.5%.

  14. Rapid control prototyping for cylinder pressure indication; Rapid Control Prototyping fuer Zylinderdruckindizierung

    Energy Technology Data Exchange (ETDEWEB)

    Pfluger, Jan [RWTH Aachen Univ. (Germany). Lehrstuhl fuer Verbrennungskraftmaschinen; Andert, Jakob [FEV GmbH, Aachen (Germany). Fahrzeugelektronik/E-Mobilitaet; Ross, Holger; Mertens, Frank [dSpace GmbH, Paderborn (Germany). Rapid Control Prototyping Systems

    2012-11-15

    Cylinder-pressure-based controls that allow cycle-synchronous reactions to events in the combustion chamber are a particularly promising possibility further optimising engine combustion processes. However, the requirements of real-time cylinder indication are fast pushing today's systems up against their limits. The Institute for Combustion Engines at RWTH Aachen University and dSpace together developed a high performance prototype for online indication with cycle-synchronous combustion control. (orig.)

  15. Pressure and Quantity Thresholds for Ignition of Oil Contamination by Rapid Pressurization in Oxygen Systems

    Science.gov (United States)

    Tapia, Susana; Smith, Sarah; Peralta, Steve; Stoltzfus, Joel

    2009-01-01

    This slide presentation reviews the problem and solution of oil contamination and increased ignition hazard in oxygen systems. The experiments that were used are reviewed, and the contamination level threshold and the oxygen pressure threshold are reviewed.

  16. Studies of Drop/Drop and Drop/Interface Impact

    Science.gov (United States)

    Lowengrub, John; Cristini, Vittorio; Kim, Jun-Seok; Zheng, Xiaoming; Mohammed-Kassim, Zulfaa; Longmire, Ellen

    2003-11-01

    In this talk, we will study the impact and coalescence of liquid drops using a physically-based numerical model that allows seamless transitions in interface topologies combined with adaptive mesh refinement. By using a mesh size that is adaptive to the length scales associated to the lubrication pressure generated by interfaces in near contact, we accurately describe the near contact motion and recover the predictions of asymptotic analyses. We compare simulation results to recent experiments performed by Mohamed-Kassim and Longmire. The effects of multiple drops, van der Waal forces and surfactants will also be considered.

  17. An experimental study on single phase convection heat transfer and pressure drop in two brazed plate heat exchangers with different chevron shapes and hydraulic diameters

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Man Bae; Park, Chang Yong [Seoul National University of Science and Technology, Seoul (Korea, Republic of)

    2017-05-15

    An experimental study on heat transfer and pressure drop characteristics was performed at single phase flow in two Brazed plate heat exchangers (BPHEs) with different geometries. The corrugation density of one of the BPHE (Type II) was two times as high as that of the other BPHE (Type I). The hydraulic diameter of the type II BPHE was 2.13 mm, which was 38 % smaller than that of the type I BPHE. Also, the cross section shape of the flow channels for the type II BPHE was different from that for conventional BPHEs due to the unusual corrugation patterns and brazing points. The experimental conditions for temperatures were varied from 4.6 °C to 49.1 °C, and for mass flow rates were changed from 0.07 kg/s to 1.24 kg/s. The measured results showed that pressure drop in the type II BPHE was about 110 % higher than that in the type I BPHE. Nu of the type II was higher than that of the type I BPHE and the enhancement became larger with the increase of Re at the ranges above 800. New correlations for fF and Nu were proposed by this study and their prediction accuracy could be improved by considering the surface enlargement factor in the correlations. The performance evaluation of the two BPHEs was performed by (j/f{sub F}1{sup /3}) which represented the ratio of heat transfer and pressure drop performance. Also, a new parameter, the capacity compactness of PHE, was proposed and it presented the PHE capacity per unit volume and unit log mean temperature difference. The comparison showed that the two BPHEs had similar values of the (j/f{sub F}1{sup /3}), whereas they had significantly different values of the capacity compactness. The capacity compactness of the type II BPHE was 1.5 times higher than that for the type I BPHE.

  18. Rapid label-free identification of Klebsiella pneumoniae antibiotic resistant strains by the drop-coating deposition surface-enhanced Raman scattering method

    Science.gov (United States)

    Cheong, Youjin; Kim, Young Jin; Kang, Heeyoon; Choi, Samjin; Lee, Hee Joo

    2017-08-01

    Although many methodologies have been developed to identify unknown bacteria, bacterial identification in clinical microbiology remains a complex and time-consuming procedure. To address this problem, we developed a label-free method for rapidly identifying clinically relevant multilocus sequencing typing-verified quinolone-resistant Klebsiella pneumoniae strains. We also applied the method to identify three strains from colony samples, ATCC70063 (control), ST11 and ST15; these are the prevalent quinolone-resistant K. pneumoniae strains in East Asia. The colonies were identified using a drop-coating deposition surface-enhanced Raman scattering (DCD-SERS) procedure coupled with a multivariate statistical method. Our workflow exhibited an enhancement factor of 11.3 × 106 to Raman intensities, high reproducibility (relative standard deviation of 7.4%), and a sensitive limit of detection (100 pM rhodamine 6G), with a correlation coefficient of 0.98. All quinolone-resistant K. pneumoniae strains showed similar spectral Raman shifts (high correlations) regardless of bacterial type, as well as different Raman vibrational modes compared to Escherichia coli strains. Our proposed DCD-SERS procedure coupled with the multivariate statistics-based identification method achieved excellent performance in discriminating similar microbes from one another and also in subtyping of K. pneumoniae strains. Therefore, our label-free DCD-SERS procedure coupled with the computational decision supporting method is a potentially useful method for the rapid identification of clinically relevant K. pneumoniae strains.

  19. Ionic-liquid-assisted microwave distillation coupled with headspace single-drop microextraction followed by GC-MS for the rapid analysis of essential oil in Dryopteris fragrans.

    Science.gov (United States)

    Jiao, Jiao; Gai, Qing-Yan; Wang, Wei; Luo, Meng; Zhao, Chun-Jian; Fu, Yu-Jie; Ma, Wei

    2013-12-01

    A rapid, green and effective miniaturized sample preparation technique, ionic-liquid-assisted microwave distillation coupled with headspace single-drop microextraction was developed for the extraction of essential oil from dried Dryopteris fragrans. 1-Ethyl-3-methylimidazolium acetate was the optimal ionic liquid as the destruction agent of plant cell walls and microwave absorption was medium. n-Heptadecane (2.0 μL) was adopted as the suspended microdrop solvent in the headspace for the extraction and concentration of essential oil. The optimal parameters of the proposed method were an irradiation power of 300 W, sample mass of 0.9 g, mass ratio of ionic liquids to sample of 2.8, extraction temperature of 79°C, and extraction time of 3.6 min. In comparison to the previous reports, the proposed technique could equally monitor all the essential oil components with no significant differences in a simple way, which was more rapid and required a much lower amount of sample. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Three-phase pressure drop in heavy oil, water and gas flow in a horizontal pipe for application in heavy oil transportation

    Energy Technology Data Exchange (ETDEWEB)

    Trevisan, Francisco E.; Bannwart, Antonio Carlos [Universidade Estadual de Campinas, SP (Brazil)

    2003-07-01

    A significant extent of the Brazilian oil reserves consists of heavy oil, and its importance and economic value have been increasing in the last years. However, these oils, besides their elevated densities (API degree lower than 20), have viscosities higher than 100 mPa.s , which makes it more difficult to transport them through pipelines. A solution for this problem is the injection of water in the pipe, in such a way to reduce friction and, consequently, the energy expend for a given oil flow rate. The two-phase flow of heavy oil and water has been the object of a number of recent studies, and concepts such as the core-flow technology can be useful for heavy oil transportation. But in production operations, gas is also present, initially dissolved in the oil phase then leaving the solution to form a free gas phase if the pressure is below the bubble point pressure. Thus the study of three-phase flow of heavy oil, water and gas is in order. The present paper presents the three-phase flow pressure drop measured in a horizontal glass tube of 2.84 cm i.d. at several combinations of the individual flow rates. Initially, for the development of the experiment, two-phase flow of heavy oil-water and gas-water were studied to establish the flow rate ranges that cover the main patterns already known. The superficial velocities used varied from 0.04 to 0.5 m/s for water, 0.04 to 9.0 m/s for gas and 0.02 to 1.2 m/s for oil. For each test run, the three-phase flow pressure drop was determined with the help of absolute and differential pressure transducers. The results are shown in the form of maps in terms of superficial velocities. (author)

  1. Foot Drop

    Science.gov (United States)

    ... Seizures Information Page Fibromuscular Dysplasia Information Page Foot Drop Information Page Friedreich's Ataxia Information Page Gaucher Disease Information Page Generalized Gangliosidoses Information Page Gerstmann's Syndrome ...

  2. Continuous positive airway pressure (CPAP) changes in bariatric surgery patients undergoing rapid weight loss.

    Science.gov (United States)

    Lankford, D Alan; Proctor, Charles D; Richard, Robert

    2005-03-01

    Obstructive sleep apnea (OSA) is a common condition in morbidly obese patients, with the reported prevalence ranging from 12-78%. There is increasing recognition of the need to diagnose and treat/manage OSA both preoperatively and postoperatively. Nasal CPAP is the preferred treatment of OSA; however, weight loss is associated with a reduction in required pressures. We evaluated the CPAP pressure requirements in a group of patients undergoing rapid weight loss following Roux-en-Y gastric bypass. 15 patients who had been diagnosed with OSA before surgery were retrospectively evaluated. All patients had demonstrated compliance on home CPAP therapy, were minimally 3 months post-surgery and had follow-up reports that their CPAP was less effective. We obtained data on age, sex, weight, BMI, and apnea/hypopnea index (AHI). Optimal CPAP pressure was obtained initially through attended in-laboratory complex polysomnography. Follow-up CPAP pressure was obtained using an auto-titrating PAP device at home. These data were used to evaluate the pressure changes that accompanied weight loss. This group of patients had lost an average of 44.5 +/- 19.4 kg. Four patients had achieved their goal weight. Their starting CPAP pressures averaged 11 +/- 3.0 cm H2O, with a range of 7-18 cm H2O. Follow-up CPAP pressures averaged 9 +/- 2.7 cm H2O, with a range of 4-12 cm H2O, representing an overall reduction of 18%. The subgroup of patients who had achieved goal weight had a pressure reduction of 22% (9 +/- 2.0 to 7 +/- 1.0 cm H2O). CPAP pressure requirements change considerably in bariatric surgery patients undergoing rapid weight loss. Auto-titrating PAP devices have promise for facilitating the management of CPAP therapy during this time. Consideration should also be given to the use of autotitrating PAP units as the treatment of choice in these patients.

  3. Investigation of the pressure drop inside a rectangular channel with a built-in U-shaped tube bundle heat exchanger

    Directory of Open Access Journals (Sweden)

    Xi-yue Liu

    2017-01-01

    Full Text Available A simplified approach which utilizes an isotropic porous medium model has been widely adopted for modeling the flow through a compact heat exchanger. With respect to situations where the compact heat exchangers are partially installed inside a channel, such as the application of recuperators in an intercooled recuperative engine, the use of an isotropic porous medium model needs to be carefully assessed because the flow passing through the heat exchanger is very complicated. For this purpose, in this study the isotropic porous medium model is assessed together with specific pressure–velocity relationships for flow field modeling inside a rectangular channel with a built-in double-U-shaped tube bundle heat exchanger. Firstly, experiments were conducted using models to investigate the relationship between the pressure drop and the inlet velocity for a specific heat exchanger with different installation angles inside a rectangular channel. Secondly, a series of numerical computations were carried out using the isotropic porous medium model and the pressure–velocity relationship was then modified by introducing correction coefficients empirically. Finally, a three-dimensional (3-D direct computation was made using a computational fluid dynamics (CFD method for the comparison of detailed flow fields. The results suggest that the isotropic porous medium model is capable of making precise pressure drop predictions given the reasonable pressure–velocity relationship but is unable to precisely simulate the detailed flow features.

  4. Flow boiling heat transfer and pressure drop analysis of R134a in a brazed heat exchanger with offset strip fins

    Science.gov (United States)

    Amaranatha Raju, M.; Ashok Babu, T. P.; Ranganayakulu, C.

    2017-10-01

    The saturated flow boiling heat transfer and friction analysis of R 134a were experimentally analyzed in a brazed plate fin heat exchanger with offset strip fins. Experiments were performed at mass flux range of 50-82 kg/m2 s, heat flux range of 14-22 kW/m2 and quality of 0.32-0.75. The test section consists of three fins, one refrigerant side fin in which the boiling heat transfer was estimated and two water side fins. These three fins are stacked, held together and vacuum brazed to form a plate fin heat exchanger. The refrigerant R134a flowing in middle of the test section was heated using hot water from upper and bottom sides of the test section. The temperature and mass flow rates of water circuit is controlled to get the outlet conditions of refrigerant R134a. Two-phase flow boiling heat transfer and frictional coefficient was estimated based on experimental data for offset strip fin geometry and presented in this paper. The effects of mass flux, heat flux and vapour quality on heat transfer coefficient and pressure drop were investigated. Two-phase local boiling heat transfer coefficient is correlated in terms of Reynolds number factor F, and Martinelli parameter X. Pressure drop is correlated in terms of two-phase frictional multiplier ϕ f , and Martinelli parameter X.

  5. A method for rapid measurement of intrarenal and other tissue pressures.

    Science.gov (United States)

    SWANN, H G; MONTGOMERY, A V; DAVIS, J C; MICKLE, E R

    1950-12-01

    A rapid method for measuring tissue pressures has been designed. A pressure of 250 mm. Hg is imposed on a manometer. Then the system is allowed to discharge into a needle cannula inserted in the tissue. The manometer forces out fluid (about 10 c.mm.) until the pressure within it is the same as that within the tissue. Records of the pressure changes are made. Each observation takes about a minute. The method gives results that are closely comparable with other reports of tissue pressures. With this method, the pressure in the following organs of dogs was found to be: kidney, 26 mm. Hg, cerebral cortex, 0 to 5 mm., muscle, 1 to 10 mm., spleen, S to 16 mm., subcutaneous tissue, 0 to 3 mm., and liver -2 to 14 mm. The reliability of the method was tested on the kidneys of decerebrate dogs. Measurements were found to be the same within narrow limits over a period of an hour; they were the same when taken simultaneously in different regions of the same kidney or in opposite kidneys. They were independent of the volume of fluid forced into the tissue. Similar pressures were observed with 1 or 5 or 10 holes bored in the shaft of the cannulating needle. The intrarenal pressure was also measured by inserting a needle cannula into the tissue and then allowing the pressure to reach equilibrium passively with a manometer. This method gave similar results. The intrarenal pressure has now found to be the same when measured by three different technics.

  6. A drop in the pond: the effect of rapid mass-loss on the dynamics and interaction rate of collisionless particles

    Science.gov (United States)

    Penoyre, Zephyr; Haiman, Zoltán

    2018-01-01

    In symmetric gravitating systems experiencing rapid mass-loss, particle orbits change almost instantaneously, which can lead to the development of a sharply contoured density profile, including singular caustics for collisionless systems. This framework can be used to model a variety of dynamical systems, such as accretion discs following a massive black hole merger and dwarf galaxies following violent early star formation feedback. Particle interactions in the high-density peaks seem a promising source of observable signatures of these mass-loss events (i.e. a possible EM counterpart for black hole mergers or strong gamma-ray emission from dark matter annihilation around young galaxies), because the interaction rate depends on the square of the density. We study post-mass-loss density profiles, both analytic and numerical, in idealized cases and present arguments and methods to extend to any general system. An analytic derivation is presented for particles on Keplerian orbits responding to a drop in the central mass. We argue that this case, with initially circular orbits, gives the most sharply contoured profile possible. We find that despite the presence of a set of singular caustics, the total particle interaction rate is reduced compared to the unperturbed system; this is a result of the overall expansion of the system dominating over the steep caustics. Finally, we argue that this result holds more generally, and the loss of central mass decreases the particle interaction rate in any physical system.

  7. Rapid analysis of Fructus forsythiae essential oil by ionic liquids-assisted microwave distillation coupled with headspace single-drop microextraction followed by gas chromatography-mass spectrometry.

    Science.gov (United States)

    Jiao, Jiao; Ma, Dan-Hui; Gai, Qing-Yan; Wang, Wei; Luo, Meng; Fu, Yu-Jie; Ma, Wei

    2013-12-04

    A rapid, green and effective miniaturized sample preparation and analytical technique, i.e. ionic liquids-assisted microwave distillation coupled with headspace single-drop microextraction (ILAMD-HS-SDME) followed by gas chromatography-mass spectrometry (GC-MS) was developed for the analysis of essential oil (EO) in Fructus forsythiae. In this work, ionic liquids (ILs) were not only used as the absorption medium of microwave irradiation but also as the destruction agent of plant cell walls. 1-Ethyl-3-methylimidazolium acetate ([C2mim]OAc) was chosen as the optimal ILs. Moreover, n-heptadecane (2.0 μL) was selected as the appropriate suspended solvent for the extraction and concentration of EO. Extraction conditions of the proposed method were optimized using the relative peak area of EO constituents as the index, and the optimal operational parameters were obtained as follows: irradiation power (300 W), sample mass (0.7 g), mass ratio of ILs to sample (2.4), temperature (78°C) and time (3.4 min). In comparison to previous reports, the proposed method was faster and required smaller sample amount but could equally monitor all EO constituents with no significant differences. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Experimental Study of Pressure Drop and Wall Shear Stress Characteristics of γ /Al2O3-Water Nanofluid in a Circular pipe under Turbulent flow induced vibration.

    Directory of Open Access Journals (Sweden)

    Adil Abbas AL-Moosawy

    2016-09-01

    Full Text Available Experimental study of γ /Al2O3 with mean diameter of less than 50 nm was dispersed in the distilled water that flows through a pipe consist of five sections as work station ,four sections made of carbon steel metal and one sections made of Pyrex glass pipe, with five nanoparticles volume concentrations of 0%,0.1%,0.2%,0.3%,and 0.4% with seven different volume flow rates 100, 200 , 300, 400, 500, 600 ,and 700ℓ/min were investigated to calculated pressure distribution for the cases without rubber ,with 3mm rubber and with 6mm rubber used to support the pipe. Reynolds number was between 20000 and 130000. Frequency value through pipe was measured for all stations of pipe for all cases. The results show that the pressure drop and wall shear stress of the nanofluid increase by increasing the nanoparticles volume concentrations or Reynolds number, the values of frequency through the pipe increase continuously when wall shear stress increases and the ratio of increment increases as nanofluid concentrations increase. Increasing of vibration frequency lead to increasing the friction factor between the pipe and the wall and thus increasing in pressure drop. Several equations between the wall shear stress and frequency for all volume concentration and for three cases without rubber, with rubber has 3mm thickness ,and with rubber has 6mm thickness. Finally, the results led to that γ /Al2O3 could function as a good and alternative conventional working fluid in heat transfer applications. A good agreement is seen between the experimental and those available in the literature

  9. Analysis of Heat Transfer and Pressure Drop for a Gas Flowing Through a set of Multiple Parallel Flat Plates at High Temperatures

    Science.gov (United States)

    Einstein, Thomas H.

    1961-01-01

    Equations were derived representing heat transfer and pressure drop for a gas flowing in the passages of a heater composed of a series of parallel flat plates. The plates generated heat which was transferred to the flowing gas by convection. The relatively high temperature level of this system necessitated the consideration of heat transfer between the plates by radiation. The equations were solved on an IBM 704 computer, and results were obtained for hydrogen as the working fluid for a series of cases with a gas inlet temperature of 200 R, an exit temperature of 5000 0 R, and exit Mach numbers ranging from 0.2 to O.8. The length of the heater composed of the plates ranged from 2 to 4 feet, and the spacing between the plates was varied from 0.003 to 0.01 foot. Most of the results were for a five- plate heater, but results are also given for nine plates to show the effect of increasing the number of plates. The heat generation was assumed to be identical for each plate but was varied along the length of the plates. The axial variation of power used to obtain the results presented is the so-called "2/3-cosine variation." The boundaries surrounding the set of plates, and parallel to it, were assumed adiabatic, so that all the power generated in the plates went into heating the gas. The results are presented in plots of maximum plate and maximum adiabatic wall temperatures as functions of parameters proportional to f(L/D), for the case of both laminar and turbulent flow. Here f is the Fanning friction factor and (L/D) is the length to equivalent diameter ratio of the passages in the heater. The pressure drop through the heater is presented as a function of these same parameters, the exit Mach number, and the pressure at the exit of the heater.

  10. Rapidly tuning miniature transversely excited atmospheric-pressure CO2 laser.

    Science.gov (United States)

    Qu, Yanchen; Ren, Deming; Hu, Xiaoyong; Liu, Fengmei; Zhao, Jingshan

    2002-08-20

    An experimental study of a rapidly tuning miniature transversely excited atmospheric-pressure CO2 laser is reported. To rapidly shift laser wavelengths over selected transitions in the 9-11 microm wavelength region, we have utilized a high-frequency stepping motor and a diffraction grating. The laser is highly automated with a monolithic microprocessor controlled laser line selection. For the achievement of stable laser output, a system of laser excitation with a voltage of 10 kV, providing effective surface corona preionization and allowing one to work at various gas pressures, is utilized. Laser operation at 59 emission lines of the CO2 molecule rotational transition is obtained and at 51 lines, the pulse energy of laser radiation exceeds 30 mJ. The system can be tuned between two different rotational lines spanning the wavelength range from 9.2 to 10.8 microm within 10 ms.

  11. An experimental analysis of flow boiling and pressure drop in a brazed plate heat exchanger for organic Rankine cycle power systems

    DEFF Research Database (Denmark)

    Desideri, Adriano; Zhang, Ji; Kærn, Martin Ryhl

    2017-01-01

    Organic Rankine cycle power systems for low quality waste heat recovery applications can play a major role in achieving targets of increasing industrial processes efficiency and thus reducing the emissions of greenhouse gases. Low capacity organic Rankine cycle systems are equipped with brazed...... and pressure drop during vaporization at typical temperatures for low quality waste heat recovery organic Rankine cycle systems are presented for the working fluids HFC-245fa and HFO-1233zd. The experiments were carried out at saturation temperatures of 100°C, 115°C and 130°C and inlet and outlet qualities...... plate heat exchangers which allows for efficient heat transfer with a compact design. Accurate heat transfer correlations characterizing these devices are required from the design phase to the development of model-based control strategies. In this paper, the experimental heat transfer coefficient...

  12. Drag with external and pressure drop with internal flows: a new and unifying look at losses in the flow field based on the second law of thermodynamics

    Science.gov (United States)

    Herwig, Heinz; Schmandt, Bastian

    2013-10-01

    Internal and external flows are characterized by friction factors and drag coefficients, respectively. Their definitions are based on pressure drop and drag force and thus are very different in character. From a thermodynamics point of view in both cases dissipation occurs which can uniformly be related to the entropy generation in the flow field. Therefore we suggest to account for losses in the flow field by friction factors and drag coefficients that are based on the overall entropy generation due to the dissipation in the internal and external flow fields. This second law analysis (SLA) has been applied to internal flows in many studies already. Examples of this flow category are given together with new cases of external flows, also treated by the general SLA-approach.

  13. Experimental analysis on pressure drop and heat transfer of a terminal fan-coil unit with ice slurry as cooling medium

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Seara, Jose; Diz, Ruben; Uhia, Francisco J.; Dopazo, J. Alberto [Area de Maquinas y Motores Termicos, E.T.S. de Ingenieros Industriales, University of Vigo, Campus Lagoas-Marcosende No 9, 36310 Vigo (Spain)

    2010-09-15

    This paper is concerned with the experimental analysis of a standard terminal fan-coil unit with ice slurry as coolant. The ice slurry was produced from an ethylene glycol 10 wt% aqueous solution. The pressure drop measurements are presented as a function of volumetric flow rate, ice concentration and Reynolds number. The experimental friction factors are obtained and discussed. The fan-coil capacity was experimentally determined for chilled water and melting ice slurry with inlet ice fractions around 5, 10, 15 and 20 wt%, considering in each case three different fan rotation velocities. The fan-coil capacity is higher with melting ice slurry than with chilled water by factors between 3.7 and 4.9. The heat transfer analysis realizes that the air side thermal resistance controls the heat transfer process. Experimental results for the melt off rate of ice in the fan coil and the superheating at the fan-coil outlet are shown and discussed. (author)

  14. Smooth- and enhanced-tube heat transfer and pressure drop : Part I. Effect of Prandtl number with air, water, and glycol/water mixtures.

    Energy Technology Data Exchange (ETDEWEB)

    Obot, N. T.; Das, L.; Rabas, T. J.

    2000-11-14

    An extensive experimental investigation was carried out to determine the pressure drop and heat transfer characteristics in laminar, transitional, and turbulent flow through one smooth tube and twenty-three enhanced tubes. The working fluids for the experiments were air, water, ethylene glycol, and ethylene glycol/water mixtures; Prandtl numbers (Pr) ranged from 0.7 to 125.3. The smooth-tube experiments were carried out with Pr values of 0.7, 6.8, 24.8, 39.1, and 125.3; Pr values of 0.7, 6.8, and 24.8 were tested with enhanced tubes. Reynolds number (Re) range (based on the maximum internal diameter of a tube) was 200 to 55,000, depending on Prandtl number and tube geometry. The results are presented and discussed in this paper.

  15. Rapid extraction and determination of amphetamines in human urine samples using dispersive liquid-liquid microextraction and solidification of floating organic drop followed by high performance liquid chromatography.

    Science.gov (United States)

    Ahmadi-Jouibari, Toraj; Fattahi, Nazir; Shamsipur, Mojtaba

    2014-06-01

    A novel, rapid, simple and sensitive dispersive liquid-liquid microextraction method based on the solidification of floating organic drop (DLLME-SFO) combined with high-performance liquid chromatography-ultraviolet detection (HPLC-UV) was used to determine amphetamine and methamphetamine in urine samples. The factors affecting the extraction efficiency of DLLME-SFO such as the kind and volume of the extraction and the disperser solvents, effect of concentration of K2CO3 and extraction time were investigated and the optimal extraction conditions were established. Under the optimum conditions (extraction solvent: 30.0μl 1-undecanol; disperser solvent: 300μl acetonitrile; buffer concentration: 2% (w/v) K2CO3 and extraction time: 1min), calibration curves are linear in the range of 10-3000μgl(-1) and limit of detections (LODs) are in the range of 2-8μgl(-1). The relative standard deviations (RSDs) for 100μgl(-1) of amphetamine and methamphetamine in diluted urine are in the range of 6.2-7.8% (n=7). The method was successfully applied for the determination of amphetamine and methamphetamine in the actual urine samples. The relative recoveries of urine samples spiked with amphetamine and methamphetamine are 87.8-113.2%. The obtained results show that DLLME-SFO combined with HPLC-UV is a fast and simple method for the determination of amphetamine and methamphetamine in urine. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Enhancing Heat Transfer of Drag-Reducing Surfactant Solution by an HEV Static Mixer with Low Pressure Drop

    Directory of Open Access Journals (Sweden)

    Haifeng Shi

    2011-01-01

    Full Text Available A novel high-efficiency vortex (HEV static mixer was used to locally enhance the heat transfer coefficient of a drag-reducing fluid, Ethoquad O/12 (EO12 (3 mM with sodium salicylate (NaSal (5 mM. Significant enhancement of heat transfer coefficients was observed. The Nusselt numbers were three to five times those of normal drag-reducing flow without mixer and were close to those of water at high Reynolds number with only modest energy penalty. In contrast, a Helix static mixer increased Nusselt number slightly with very high pressure loss. A performance number was used for comparisons among the HEV static mixer, the Helix static mixer, and water without mixer. The HEV static mixer had a performance number comparable to that of water. The enhanced heat transfer by the HEV static mixer resulted from streamwise vortices generated by the inclined tabs, which increased the convective heat transfer in the radial direction.

  17. The Pressure Drop Model of Liquid Flow with Wall Mass Transfer in Horizontal Wellbore with Perforated Completion

    Directory of Open Access Journals (Sweden)

    Ping Yue

    2014-01-01

    Full Text Available The fluids in horizontal wells can exhibit complicated flow behaviors with wall mass transfer, partly due to the interaction between the main flow and the radial influx along the wellbore and the completion parameters used. This paper presents a novel regression model established based on the experiment data retrieved from the available literatures to determine the apparent friction factor for a single phase wellbore flow. The proposed model has the potential to be readily applicable to different perforation parameters, such as shot phasing and shot density. Compared with other models in the same practical example which is offered by Ouyang et al., the model of this paper to calculate the wellbore pressure is applicable and reasonable. This new model can be easily incorporated into reservoir simulators or analytical reservoir and horizontal wellbore inflow coupling models.

  18. Empirical Correlations and CFD Simulations of Vertical Two-Phase Gas-Liquid (Newtonian and Non-Newtonian) Flow Compared Against Experimental Data of Void Fraction and Pressure Drop

    DEFF Research Database (Denmark)

    Ratkovich, Nicolas Rios; Bentzen, Thomas Ruby; Majumder, S.K.

    2012-01-01

    measurements, the CFD results and the empirical relationships. In terms of void fraction, for Newtonian and non-Newtonian liquids, the empirical correlations perform much worse than the CFD simulations, error of 48 and 25 %, respectively, against the experimental data. In terms of pressure drop, for Newtonian...... and non-Newtonian liquids, the empirical correlations perform much worse than the CFD simulations, error of 29 and 19 %, respectively, against the experiment data. This shows that CFD can be used to predict relatively well void fraction and pressure drop compared against empirical correlations...... pressure drop using computational fluid dynamics (CFD) and compared directly with experimental measurements and empirical relationships found in literature. A vertical tube of 3.4 m with an internal diameter of 0.1905 m was used. Superficial liquid and gas velocities ranged from 0.32 to 2.34 and from 0...

  19. Experimental investigation of heat transfer and pressure drop characteristics of water and glycol-water mixture in multi-port serpentine microchannel slab heat exchangers

    Science.gov (United States)

    Khan, Md Mesbah-ul Ghani

    Microchannels have several advantages over traditional large tubes. Heat transfer using microchannels recently have attracted significant research and industrial design interests. Open literatures leave with question on the applicability of classical macroscale theory in microchannels. Better understanding of heat transfer in various microchannel geometries and building experimental database are continuously urged. The purpose of this study is to contribute the findings and data to this emerging area through carefully designed and well controlled experimental works. The commercially important glycol-water mixture heat transfer fluid and multiport slab serpentine heat exchangers are encountered in heating and cooling areas, e.g. in automotive, aircraft, and HVAC industries. For a given heat duty, the large diameter tubes experience turbulent flow whereas the narrow channels face laminar flow and often developing flow. Study of low Reynolds number developing glycol-water mixture laminar flow in serpentine microchannel heat exchanger with parallel multi-port slab is not available in the open literature. Current research therefore experimentally investigates glycol-water mixture and water in simultaneously developing laminar flows. Three multiport microchannel heat exchangers; straight and serpentine slabs, are used for each fluid. Friction factors of glycol-water mixture and water flows in straight slabs are higher than conventional fully developed laminar flow. If a comprehensive pressure balance is introduced, the results are well compared with conventional Poiseuille theory. Similar results are found in serpentine slab. The pressure drop for the straight core is the highest, manifolds are the intermediate, and serpentine is the least; which are beneficial for heat exchangers. The heat transfer results in serpentine slab for glycol-water mixture and water are higher and could not be compared with conventional fully developed and developing flow correlations. New

  20. Rapid inactivation of Penicillium digitatum spores using high-density nonequilibrium atmospheric pressure plasma

    Science.gov (United States)

    Iseki, Sachiko; Ohta, Takayuki; Aomatsu, Akiyoshi; Ito, Masafumi; Kano, Hiroyuki; Higashijima, Yasuhiro; Hori, Masaru

    2010-04-01

    A promising, environmentally safe method for inactivating fungal spores of Penicillium digitatum, a difficult-to-inactivate food spoilage microorganism, was developed using a high-density nonequilibrium atmospheric pressure plasma (NEAPP). The NEAPP employing Ar gas had a high electron density on the order of 1015 cm-3. The spores were successfully and rapidly inactivated using the NEAPP, with a decimal reduction time in spores (D value) of 1.7 min. The contributions of ozone and UV radiation on the inactivation of the spores were evaluated and concluded to be not dominant, which was fundamentally different from the conventional sterilizations.

  1. System for Rapid, Precise Modulation of Intraocular Pressure, toward Minimally-Invasive In Vivo Measurement of Intracranial Pressure.

    Directory of Open Access Journals (Sweden)

    Max A Stockslager

    Full Text Available Pathologic changes in intracranial pressure (ICP are commonly observed in a variety of medical conditions, including traumatic brain injury, stroke, brain tumors, and glaucoma. However, current ICP measurement techniques are invasive, requiring a lumbar puncture or surgical insertion of a cannula into the cerebrospinal fluid (CSF-filled ventricles of the brain. A potential alternative approach to ICP measurement leverages the unique anatomy of the central retinal vein, which is exposed to both intraocular pressure (IOP and ICP as it travels inside the eye and through the optic nerve; manipulating IOP while observing changes in the natural pulsations of the central retinal vein could potentially provide an accurate, indirect measure of ICP. As a step toward implementing this technique, we describe the design, fabrication, and characterization of a system that is capable of manipulating IOP in vivo with <0.1 mmHg resolution and settling times less than 2 seconds. In vitro tests were carried out to characterize system performance. Then, as a proof of concept, we used the system to manipulate IOP in tree shrews (Tupaia belangeri while video of the retinal vessels was recorded and the caliber of a selected vein was quantified. Modulating IOP using our system elicited a rapid change in the appearance of the retinal vein of interest: IOP was lowered from 10 to 3 mmHg, and retinal vein caliber sharply increased as IOP decreased from 7 to 5 mmHg. Another important feature of this technology is its capability to measure ocular compliance and outflow facility in vivo, as demonstrated in tree shrews. Collectively, these proof-of-concept demonstrations support the utility of this system to manipulate IOP for a variety of useful applications in ocular biomechanics, and provide a framework for further study of the mechanisms of retinal venous pulsation.

  2. Decreasing pressure ulcer risk during hospital procedures: a rapid process improvement workshop.

    Science.gov (United States)

    Haugen, Vicki; Pechacek, Judy; Maher, Travis; Wilde, Joy; Kula, Larry; Powell, Julie

    2011-01-01

    A 300-bed acute care community hospital used a 2-day "Rapid Process Improvement Workshop" to identify factors contributing to facility-acquired pressure ulcers (PU). The Rapid Process Improvement Workshop included key stakeholders from all procedural areas providing inpatient services and used standard components of rapid process improvement: data analysis, process flow charting, factor identification, and action plan development.On day 1, the discovery process revealed increased PU risk related to prolonged immobility when transporting patients for procedures, during imaging studies, and during the perioperative period. On day 2, action plans were developed that included communication of PU risk or presence of an ulcer,measures to shorten procedure times when clinically appropriate, implementation of prevention techniques during procedures, and recommendations for mattress upgrades. In addition, educational programs about PU prevention were developed, schedules for presentations were established, and an online power point presentation was completed and placed in a learning management system module. Finally, our nursing department amended a hospital wide handoff communication tool to include skin status and PU risk level. This tool is used in all patient handoff situations, including nonnursing departments such as radiology. Patients deemed at risk for ulcers were provided "Braden Risk" armbands to enhance interdepartmental awareness.

  3. Modeling cavitation in a rapidly changing pressure field - application to a small ultrasonic horn.

    Science.gov (United States)

    Žnidarčič, Anton; Mettin, Robert; Dular, Matevž

    2015-01-01

    Ultrasonic horn transducers are frequently used in applications of acoustic cavitation in liquids. It has been observed that if the horn tip is sufficiently small and driven at high amplitude, cavitation is very strong, and the tip can be covered entirely by the gas/vapor phase for longer time intervals. A peculiar dynamics of the attached cavity can emerge with expansion and collapse at a self-generated frequency in the subharmonic range, i.e. below the acoustic driving frequency. The term "acoustic supercavitation" was proposed for this type of cavitation Žnidarčič et al. (2014) [1]. We tested several established hydrodynamic cavitation models on this problem, but none of them was able to correctly predict the flow features. As a specific characteristic of such acoustic cavitation problems lies in the rapidly changing driving pressures, we present an improved approach to cavitation modeling, which does not neglect the second derivatives in the Rayleigh-Plesset equation. Comparison with measurements of acoustic supercavitation at an ultrasonic horn of 20kHz frequency revealed a good agreement in terms of cavity dynamics, cavity volume and emitted pressure pulsations. The newly developed cavitation model is particularly suited for simulation of cavitating flow in highly fluctuating driving pressure fields. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Heat transfer and pressure drop characteristics of the tube bank fin heat exchanger with fin punched with flow redistributors and curved triangular vortex generators

    Science.gov (United States)

    Liu, Song; Jin, Hua; Song, KeWei; Wang, LiangChen; Wu, Xiang; Wang, LiangBi

    2017-10-01

    The heat transfer performance of the tube bank fin heat exchanger is limited by the air-side thermal resistance. Thus, enhancing the air-side heat transfer is an effective method to improve the performance of the heat exchanger. A new fin pattern with flow redistributors and curved triangular vortex generators is experimentally studied in this paper. The effects of the flow redistributors located in front of the tube stagnation point and the curved vortex generators located around the tube on the characteristics of heat transfer and pressure drop are discussed in detail. A performance comparison is also carried out between the fins with and without flow redistributors. The experimental results show that the flow redistributors stamped out from the fin in front of the tube stagnation points can decrease the friction factor at the cost of decreasing the heat transfer performance. Whether the combination of the flow redistributors and the curved vortex generators will present a better heat transfer performance depends on the size of the curved vortex generators. As for the studied two sizes of vortex generators, the heat transfer performance is promoted by the flow redistributors for the fin with larger size of vortex generators and the performance is suppressed by the flow redistributors for the fin with smaller vortex generators.

  5. Evaluation of browning ratio in an image analysis of apple slices at different stages of instant controlled pressure drop-assisted hot-air drying (AD-DIC).

    Science.gov (United States)

    Gao, Kun; Zhou, Linyan; Bi, Jinfeng; Yi, Jianyong; Wu, Xinye; Zhou, Mo; Wang, Xueyuan; Liu, Xuan

    2017-06-01

    Computer vision-based image analysis systems are widely used in food processing to evaluate quality changes. They are able to objectively measure the surface colour of various products since, providing some obvious advantages with their objectivity and quantitative capabilities. In this study, a computer vision-based image analysis system was used to investigate the colour changes of apple slices dried by instant controlled pressure drop-assisted hot air drying (AD-DIC). The CIE L* value and polyphenol oxidase activity in apple slices decreased during the entire drying process, whereas other colour indexes, including CIE a*, b*, ΔE and C* values, increased. The browning ratio calculated by image analysis increased during the drying process, and a sharp increment was observed for the DIC process. The change in 5-hydroxymethylfurfural (5-HMF) and fluorescent compounds (FIC) showed the same trend with browning ratio due to Maillard reaction. Moreover, the concentrations of 5-HMF and FIC both had a good quadratic correlation (R2  > 0.998) with the browning ratio. Browning ratio was a reliable indicator of 5-HMF and FIC changes in apple slices during drying. The image analysis system could be used to monitor colour changes, 5-HMF and FIC in dehydrated apple slices during the AD-DIC process. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  6. Performance Analysis of an Evaporator for a Diesel Engine–Organic Rankine Cycle (ORC Combined System and Influence of Pressure Drop on the Diesel Engine Operating Characteristics

    Directory of Open Access Journals (Sweden)

    Chen Bei

    2015-06-01

    Full Text Available The main purpose of this research is to analyze the performance of an evaporator for the organic Rankine cycle (ORC system and discuss the influence of the evaporator on the operating characteristics of diesel engine. A simulation model of fin-and-tube evaporator of the ORC system is established by using Fluent software. Then, the flow and heat transfer characteristics of the exhaust at the evaporator shell side are obtained, and then the performance of the fin-and-tube evaporator of the ORC system is analyzed based on the field synergy principle. The field synergy angle (β is the intersection angle between the velocity vector and the temperature gradient. When the absolute values of velocity and temperature gradient are constant and β < 90°, heat transfer enhancement can be achieved with the decrease of the β. When the absolute values of velocity and temperature gradient are constant and β >90°, heat transfer enhancement can be achieved with the increase of the β. Subsequently, the influence of the evaporator of the ORC system on diesel engine performance is studied. A simulation model of the diesel engine is built by using GT–Power software under various operating conditions, and the variation tendency of engine power, torque, and brake specific fuel consumption (BSFC are obtained. The variation tendency of the power output and BSFC of diesel engine–ORC combined system are obtained when the evaporation pressure ranges from 1.0 MPa to 3.5 MPa. Results show that the field synergy effect for the areas among the tube bundles of the evaporator main body and the field synergy effect for the areas among the fins on the windward side are satisfactory. However, the field synergy effect in the areas among the fins on the leeward side is weak. As a result of the pressure drop caused by the evaporator of the ORC system, the diesel engine power and torque decreases slightly, whereas the BSFC increases slightly with the increase of exhaust back

  7. Acute pressure on the sciatic nerve results in rapid inhibition of the wide dynamic range neuronal response

    Directory of Open Access Journals (Sweden)

    Wang Wenxue

    2012-12-01

    Full Text Available Abstract Background Acute pressure on the sciatic nerve has recently been reported to provide rapid short-term relief of pain in patients with various pathologies. Wide dynamic range (WDR neurons transmit nociceptive information from the dorsal horn to higher brain centers. In the present study, we examined the effect of a 2-min application of sciatic nerve pressure on WDR neuronal activity in anesthetized male Sprague–Dawley rats. Results Experiments were carried out on 41 male Sprague–Dawley albino rats weighing 160–280 grams. Dorsal horn WDR neurons were identified on the basis of characteristic responses to mechanical stimuli applied to the cutaneous receptive field. Acute pressure was applied for 2 min to the sciatic nerve using a small vascular clip. The responses of WDR neurons to three mechanical stimuli applied to the cutaneous receptive field were recorded before, and 2, 5 and 20 min after cessation of the 2-min pressure application on the sciatic nerve. Two-min pressure applied to the sciatic nerve caused rapid attenuation of the WDR response to pinching, pressure and brushing stimuli applied to the cutaneous receptive field. Maximal attenuation of the WDR response to pinching and pressure was noted 5 min after release of the 2-min pressure on the sciatic nerve. The mean firing rate decreased from 31.7±1.7 Hz to 13±1.4 Hz upon pinching (p p p Conclusions Our results indicate that acute pressure applied to the sciatic nerve exerts a rapid inhibitory effect on the WDR response to both noxious and innocuous stimuli. Our results may partially explain the rapid analgesic effect of acute sciatic nerve pressure noted in clinical studies, and also suggest a new model for the study of pain.

  8. An Empirical Method Permitting Rapid Determination of the Area, Rate and Distribution of Water-Drop Impingement on an Airfoil of Arbitrary Section at Subsonic Speeds

    Science.gov (United States)

    Bergrun, N. R.

    1951-01-01

    An empirical method for the determination of the area, rate, and distribution of water-drop impingement on airfoils of arbitrary section is presented. The procedure represents an initial step toward the development of a method which is generally applicable in the design of thermal ice-prevention equipment for airplane wing and tail surfaces. Results given by the proposed empirical method are expected to be sufficiently accurate for the purpose of heated-wing design, and can be obtained from a few numerical computations once the velocity distribution over the airfoil has been determined. The empirical method presented for incompressible flow is based on results of extensive water-drop. trajectory computations for five airfoil cases which consisted of 15-percent-thick airfoils encompassing a moderate lift-coefficient range. The differential equations pertaining to the paths of the drops were solved by a differential analyzer. The method developed for incompressible flow is extended to the calculation of area and rate of impingement on straight wings in subsonic compressible flow to indicate the probable effects of compressibility for airfoils at low subsonic Mach numbers.

  9. Investigations of levitated helium drops

    Science.gov (United States)

    Whitaker, Dwight Lawrence

    1999-11-01

    We report on the development of two systems capable of levitating drops of liquid helium. Helium drops of ˜20 mum have been levitated with the radiation pressure from two counter-propagating Nd:YAG laser beams. Drops are produced with a submerged piezoelectric transducer, and could be held for up to three minutes in our optical trap. Calculations show that Brillouin and Raman scattering of the laser light in the liquid helium produces a negligible rate of evaporation of the drop. Evaporation caused by the enhanced vapor pressure of the curved drop surfaces appears to be a significant effect limiting the drop lifetimes. Helium drops as large as 2 cm in diameter have been suspended in the earth's gravitational field with a magnetic field. A commercial superconducting solenoid provides the necessary field, field-gradient product required to levitate the drops. Drops are cooled to 0.5 K with a helium-3 refrigerator, and can be held in the trap indefinitely. We have found that when two or more drops are levitated in the same magnetic trap, the drops often remain in a state of apparent contact without coalescing. This effect is a result of the evaporation of liquid from between the two drops, and is found to occur only for normal fluid drops. We can induce shape oscillations in charged, levitated drops with an applied ac electric field. We have measured the resonance frequencies and damping rates for the l = 2 mode of oscillation as function of temperature. We have also developed a theory to describe the small amplitude shape oscillations of a He II drop surrounded by its saturated vapor. In our theory, we have considered two sets of boundary conditions---one where the drop does not evaporate and another in which the liquid and vapor are in thermodynamic equilibrium. We have found that both solutions give a frequency that agrees well with experiment, but that the data for the damping rate agree better with the solution without evaporation.

  10. Short-term effects of sports taping on navicular height, navicular drop and peak plantar pressure in healthy elite athletes: A within-subject comparison.

    Science.gov (United States)

    Kim, Taegyu; Park, Jong-Chul

    2017-11-01

    Medial tibial stress syndrome (MTSS) is one of the most common exercise-induced leg pain. The navicular drop (ND) was identified as a risk factor for MTSS. This study aimed to evaluate the short-term effects of sports taping applied to the supporting lower leg during sitting, standing, walking, and jogging to restrict the ND in healthy elite athletes.Twenty-four healthy elite athletes without a history of exercise-induced pain or injuries in the lower limbs participated in this study (median age: 21.00 years; 1st--3rd quartiles; 19.25-22.00). The 4 taping conditions were used: rigid taping (RT), kinesiology taping (KT), placebo taping (PT), and non-taping (NT). The order of taping techniques was randomly assigned. Normalized navicular height (NH), ND, and normalized ND evaluated using 3-dimensional motion analysis, and normalized peak plantar pressure (PP) were compared in 4 taping conditions during sitting, standing, walking, and jogging.During sitting, the normalized NH of RT is higher than that of NT, KT, and PT (χ = 17.30, P = .001), while during jogging, the normalized NH of RT is higher than that of NT and PT (χ = 10.55, P = .014). The normalized peak PP of NT is higher than that of PT (χ = 8.871, P = .031) in the lateral midfoot region.This study showed the RT technique maintained NH during sitting and jogging, and the RT technique could be an effective preventive and treatment strategy for MTSS.

  11. Thermodynamic and fluid mechanic analysis of rapid pressurization in a dead-end tube

    Science.gov (United States)

    Leslie, Ian H.

    1989-01-01

    Three models have been applied to very rapid compression of oxygen in a dead-ended tube. Pressures as high as 41 MPa (6000 psi) leading to peak temperatures of 1400 K are predicted. These temperatures are well in excess of the autoignition temperature (750 K) of teflon, a frequently used material for lining hoses employed in oxygen service. These findings are in accord with experiments that have resulted in ignition and combustion of the teflon, leading to the combustion of the stainless steel braiding and catastrophic failure. The system analyzed was representative of a capped off-high-pressure oxygen line, which could be part of a larger system. Pressurization of the larger system would lead to compression in the dead-end line, and possible ignition of the teflon liner. The model consists of a large plenum containing oxygen at the desired pressure (500 to 6000 psi). The plenum is connected via a fast acting valve to a stainless steel tube 2 cm inside diameter. Opening times are on the order of 15 ms. Downstream of the valve is an orifice sized to increase filling times to around 100 ms. The total length from the valve to the dead-end is 150 cm. The distance from the valve to the orifice is 95 cm. The models describe the fluid mechanics and thermodynamics of the flow, and do not include any combustion phenomena. A purely thermodynamic model assumes filling to be complete upstream of the orifice before any gas passes through the orifice. This simplification is reasonable based on experiment and computer modeling. Results show that peak temperatures as high as 4800 K can result from recompression of the gas after expanding through the orifice. An approximate transient model without an orifice was developed assuming an isentropic compression process. An analytical solution was obtained. Results indicated that fill times can be considerably shorter than valve opening times. The third model was a finite difference, 1-D transient compressible flow model. Results from

  12. Impact of ultra-viscous drops: air-film gliding and extreme wetting

    KAUST Repository

    Langley, Kenneth

    2017-01-23

    A drop impacting on a solid surface must push away the intervening gas layer before making contact. This entails a large lubricating air pressure which can deform the bottom of the drop, thus entrapping a bubble under its centre. For a millimetric water drop, the viscous-dominated flow in the thin air layer counteracts the inertia of the drop liquid. For highly viscous drops the viscous stresses within the liquid also affect the interplay between the drop and the gas. Here the drop also forms a central dimple, but its outer edge is surrounded by an extended thin air film, without contacting the solid. This is in sharp contrast with impacts of lower-viscosity drops where a kink in the drop surface forms at the edge of the central disc and makes a circular contact with the solid. Larger drop viscosities make the central air dimple thinner. The thin outer air film subsequently ruptures at numerous random locations around the periphery, when it reaches below 150 nm thickness. This thickness we measure using high-speed two-colour interferometry. The wetted circular contacts expand rapidly, at orders of magnitude larger velocities than would be predicted by a capillary-viscous balance. The spreading velocity of the wetting spots is independent of the liquid viscosity. This may suggest enhanced slip of the contact line, assisted by rarefied-gas effects, or van der Waals forces in what we call extreme wetting. Myriads of micro-bubbles are captured between the local wetting spots.

  13. CFD- and Bernoulli-based pressure drop estimates: A comparison using patient anatomies from heart and aortic valve segmentation of CT images.

    Science.gov (United States)

    Weese, Jürgen; Lungu, Angela; Peters, Jochen; Weber, Frank M; Waechter-Stehle, Irina; Hose, D Rodney

    2017-06-01

    An aortic valve stenosis is an abnormal narrowing of the aortic valve (AV). It impedes blood flow and is often quantified by the geometric orifice area of the AV (AVA) and the pressure drop (PD). Using the Bernoulli equation, a relation between the PD and the effective orifice area (EOA) represented by the area of the vena contracta (VC) downstream of the AV can be derived. We investigate the relation between the AVA and the EOA using patient anatomies derived from cardiac computed tomography (CT) angiography images and computational fluid dynamic (CFD) simulations. We developed a shape-constrained deformable model for segmenting the AV, the ascending aorta (AA), and the left ventricle (LV) in cardiac CT images. In particular, we designed a structured AV mesh model, trained the model on CT scans, and integrated it with an available model for heart segmentation. The planimetric AVA was determined from the cross-sectional slice with minimum AV opening area. In addition, the AVA was determined as the nonobstructed area along the AV axis by projecting the AV leaflet rims on a plane perpendicular to the AV axis. The flow rate was derived from the LV volume change. Steady-state CFD simulations were performed on the patient anatomies resulting from segmentation. Heart and valve segmentation was used to retrospectively analyze 22 cardiac CT angiography image sequences of patients with noncalcified and (partially) severely calcified tricuspid AVs. Resulting AVAs were in the range of 1-4.5 cm2 and ejection fractions (EFs) between 20 and 75%. AVA values computed by projection were smaller than those computed by planimetry, and both were strongly correlated (R2 = 0.995). EOA values computed via the Bernoulli equation from CFD-based PD results were strongly correlated with both AVA values (R2 = 0.97). EOA values were ∼10% smaller than planimetric AVA values. For EOA values < 2.0 cm2 , the EOA was up to ∼15% larger than the projected AVA. The presented segmentation algorithm

  14. Pressure applied by the healthcare staff on a cricoids cartilage simulator during Sellick's maneuver in rapid sequence intubation

    NARCIS (Netherlands)

    J.A. Calvache (Jose Andrés); L.C.B. Sandoval (Luz); W.A. Vargas (William Andres)

    2013-01-01

    textabstractBackground: Sellick's maneuver or cricoid pressure is a strategy used to prevent bronchoaspiration during the rapid intubation sequence. Several studies have described that the force required for an adequate maneuver is of 2.5-3.5 kg. The purpose of this paper was to determine the force

  15. Acute pressure on the sciatic nerve results in rapid inhibition of the wide dynamic range neuronal response.

    Science.gov (United States)

    Wang, Wenxue; Tan, Wei; Luo, Danping; Lin, Jianhua; Yu, Yaoqing; Wang, Qun; Zhao, Wangyeng; Wu, Buling; Chen, Jun; He, Jiman

    2012-12-04

    Acute pressure on the sciatic nerve has recently been reported to provide rapid short-term relief of pain in patients with various pathologies. Wide dynamic range (WDR) neurons transmit nociceptive information from the dorsal horn to higher brain centers. In the present study, we examined the effect of a 2-min application of sciatic nerve pressure on WDR neuronal activity in anesthetized male Sprague-Dawley rats. Experiments were carried out on 41 male Sprague-Dawley albino rats weighing 160-280 grams. Dorsal horn WDR neurons were identified on the basis of characteristic responses to mechanical stimuli applied to the cutaneous receptive field. Acute pressure was applied for 2 min to the sciatic nerve using a small vascular clip. The responses of WDR neurons to three mechanical stimuli applied to the cutaneous receptive field were recorded before, and 2, 5 and 20 min after cessation of the 2-min pressure application on the sciatic nerve. Two-min pressure applied to the sciatic nerve caused rapid attenuation of the WDR response to pinching, pressure and brushing stimuli applied to the cutaneous receptive field. Maximal attenuation of the WDR response to pinching and pressure was noted 5 min after release of the 2-min pressure on the sciatic nerve. The mean firing rate decreased from 31.7±1.7 Hz to 13±1.4 Hz upon pinching (p < 0.001), from 31.2±2.3 Hz to 10.9±1.4 Hz (p < 0.001) when pressure was applied, and from 18.9±1.2 Hz to 7.6±1.1 Hz (p < 0.001) upon brushing. Thereafter, the mean firing rates gradually recovered. Our results indicate that acute pressure applied to the sciatic nerve exerts a rapid inhibitory effect on the WDR response to both noxious and innocuous stimuli. Our results may partially explain the rapid analgesic effect of acute sciatic nerve pressure noted in clinical studies, and also suggest a new model for the study of pain.

  16. Deagglomeration and mixing via the rapid expansion of high pressure and supercritical suspensions

    Science.gov (United States)

    To, Daniel

    Nano-materials are the focus of many research activities due to the desirable properties imparted from their small grain size and high interfacial surface area. However, these materials are highly cohesive powders in the dry state and typically form large agglomerates, leading to a diminished surface area or even grain growth, which minimizes the effectiveness of these nanomaterials. This dissertation addresses the issue of mixing nanopowders constituents by deagglomerating them and achieving simultaneous mixing so that even after inevitable reagglomeration, the effectiveness of large interfacial surface area may be preserved. Nano-particle mixtures were prepared using the environmentally benign dry mixing methods of Stirring in Supercritical Fluids and the Rapid Expansion of High Pressure and Supercritical Suspensions (REHPS). Stirring in Supercritical Fluids was capable of producing course scale nano-particle mixtures that were comparable to mixtures produced with more traditional liquid solvents, without the necessity of filtration and caking issues that are typically associated with them. The REHPS process was capable of producing high-quality mixtures on the sub-micron scale, and was made far superior when the nano-powders were first pre-mixed by stirring to decrease inhomogeneity of the feed. It was also shown that in general, conditions that enhanced turbulent shear stress, and thereby deagglomeration, also enhanced mixing, however this effect could be obscured by inhomogeneities introduced by the feed mixtures. Previous authors have suggested that the primary deagglomeration mechanism is the explosive expansion of the carbon dioxide from within the agglomerate as it transitions from a high pressure to an ambient environment. In this study two other deagglomeration mechanisms were proposed, namely intense turbulent shear stress imparted by the fluid in the nozzle and impaction with the Mach disc near the exit of the nozzle. Explosive expansion was observed

  17. Effects of Rapid Vaccine Injection Without Aspiration and Applying Manual Pressure Before Vaccination on Pain and Crying Time in Infants.

    Science.gov (United States)

    Göl, İlknur; Altuğ Özsoy, Süheyla

    2017-04-01

    To compare effects of rapid injection without aspiration and 10-second manual pressure before injection on pain severity and crying time in 4- to 6-month-old infants given the vaccine DTaP/IPV/Hib. This is a randomized double-blind controlled study. The study population included all the infants presenting for DTaP/IPV/Hib to two family health centers between April and August in 2015. The study sample included 128 infants based on confidence interval of 95% and statistical power of 80%. The sample was divided into four groups: manual pressure, rapid injection without aspiration, manual pressure combined with rapid injection without aspiration, and control groups. There were 32 infants in each group. Gender was adjusted in all groups. Stratified and block randomizations were used. Pain severity scores and crying time during and after the injections were significantly lower in the three intervention groups than in the control group (p = .001). The lowest increase in the mean heart rate during and after the injections occurred in the rapid injection without aspiration group (p injections was significantly lower in this group than in the other groups (p injection without aspiration group had low oxygen saturation levels starting before the injections. In fact, mean oxygen saturations did not change across time. This suggests that lower oxygen saturation in the rapid injection without aspiration group cannot be due to vaccines or the techniques used. Manual pressure and rapid injection without aspiration are effective and useful in relief of pain and reduction of crying time due to vaccine injections in 4- to 6-month-old infants. © 2017 Sigma Theta Tau International.

  18. The dynamic pressure response to rapid dilatation of the resting urethra in healthy women

    DEFF Research Database (Denmark)

    Bagi, P; Thind, P; Colstrup, H

    1993-01-01

    The urethral pressure response to a sudden forced dilatation was studied at the bladder neck, in the high-pressure zone and in the distal urethra in ten healthy female volunteers. The pressure response was fitted with a double exponential function of the form Pt = Pequ + P alpha e-t/tau alpha + P...... tissues were computed. The results showed significant differences along the urethra, with the high-pressure zone showing the highest maximum and equilibrium pressures, fastest pressure decay and highest elastic coefficient. The pressure response represents an integrated stress response from...... a detailed assessment of static and dynamic urethral responses to dilatation which can be applied as an experimental simulation of urine ingression, and is therefore presumed to be of value in the evaluation of normal and pathological urethral sphincter function....

  19. Thermally moderated hollow fiber sorbent modules in rapidly cycled pressure swing adsorption mode for hydrogen purification

    KAUST Repository

    Lively, Ryan P.

    2012-10-01

    We describe thermally moderated multi-layered pseudo-monolithic hollow fiber sorbents entities, which can be packed into compact modules to provide small-footprint, efficient H2 purification/CO2 removal systems for use in on-site steam methane reformer product gas separations. Dual-layer hollow fibers are created via dry-jet, wet-quench spinning with an inner "active" core of cellulose acetate (porous binder) and zeolite NaY (69 wt% zeolite NaY) and an external sheath layer of pure cellulose acetate. The co-spun sheath layer reduces the surface porosity of the fiber and was used as a smooth coating surface for a poly(vinyl-alcohol) post-treatment, which reduced the gas permeance through the fiber sorbent by at least 7 orders of magnitude, essentially creating an impermeable sheath layer. The interstitial volume between the individual fibers was filled with a thermally-moderating paraffin wax. CO2 breakthrough experiments on the hollow fiber sorbent modules with and without paraffin wax revealed that the "passively" cooled paraffin wax module had 12.5% longer breakthrough times than the "non-isothermal" module. The latent heat of fusion/melting of the wax offsets the released latent heat of sorption/desorption of the zeolites. One-hundred rapidly cycled pressure swing adsorption cycles were performed on the "passively" cooled hollow fiber sorbents using 25 vol% CO2/75 vol% He (H2 surrogate) at 60 °C and 113 psia, resulting in a product purity of 99.2% and a product recovery of 88.1% thus achieving process conditions and product quality comparable to conventional pellet processes. Isothermal and non-isothermal dynamic modeling of the hollow fiber sorbent module and a traditional packed bed using gPROMS® indicated that the fiber sorbents have sharper fronts (232% sharper) and longer adsorbate breakthrough times (66% longer), further confirming the applicability of the new fiber sorbent approach for H2 purification. © 2012, Hydrogen Energy Publications, LLC

  20. Dilating Eye Drops

    Science.gov (United States)

    ... Frequently Asked Questions Español Condiciones Chinese Conditions Dilating Eye Drops En Español Read in Chinese What are dilating eye drops? Dilating eye drops contain medication to enlarge ( ...

  1. The Rapid Inactivation of Porcine Skin by Applying High Hydrostatic Pressure without Damaging the Extracellular Matrix

    Directory of Open Access Journals (Sweden)

    Naoki Morimoto

    2015-01-01

    Full Text Available We previously reported that high hydrostatic pressure (HHP of 200 MPa for 10 minutes could induce cell killing. In this study, we explored whether HHP at 200 MPa or HHP at lower pressure, in combination with hyposmotic distilled water (DW, could inactivate the skin, as well as cultured cells. We investigated the inactivation of porcine skin samples 4 mm in diameter. They were immersed in either a normal saline solution (NSS or DW, and then were pressurized at 100 and 200 MPa for 5, 10, 30, or 60 min. Next, we explored the inactivation of specimens punched out from the pressurized skin 10 × 2 cm in size. The viability was evaluated using a WST-8 assay and an outgrowth culture. The histology of specimens was analyzed histologically. The mitochondrial activity was inactivated after the pressurization at 200 MPa in both experiments, and no outgrowth was observed after the pressurization at 200 MPa. The arrangement and proportion of the dermal collagen fibers or the elastin fibers were not adversely affected after the pressurization at 200 MPa for up to 60 minutes. This study showed that a HHP at 200 MPa for 10 min could inactivate the skin without damaging the dermal matrix.

  2. The rapid inactivation of porcine skin by applying high hydrostatic pressure without damaging the extracellular matrix.

    Science.gov (United States)

    Morimoto, Naoki; Mahara, Atsushi; Shima, Kouji; Ogawa, Mami; Jinno, Chizuru; Kakudo, Natsuko; Kusumoto, Kenji; Fujisato, Toshia; Suzuki, Shigehiko; Yamaoka, Tetsuji

    2015-01-01

    We previously reported that high hydrostatic pressure (HHP) of 200 MPa for 10 minutes could induce cell killing. In this study, we explored whether HHP at 200 MPa or HHP at lower pressure, in combination with hyposmotic distilled water (DW), could inactivate the skin, as well as cultured cells. We investigated the inactivation of porcine skin samples 4 mm in diameter. They were immersed in either a normal saline solution (NSS) or DW, and then were pressurized at 100 and 200 MPa for 5, 10, 30, or 60 min. Next, we explored the inactivation of specimens punched out from the pressurized skin 10×2 cm in size. The viability was evaluated using a WST-8 assay and an outgrowth culture. The histology of specimens was analyzed histologically. The mitochondrial activity was inactivated after the pressurization at 200 MPa in both experiments, and no outgrowth was observed after the pressurization at 200 MPa. The arrangement and proportion of the dermal collagen fibers or the elastin fibers were not adversely affected after the pressurization at 200 MPa for up to 60 minutes. This study showed that a HHP at 200 MPa for 10 min could inactivate the skin without damaging the dermal matrix.

  3. Use of molecular beacons for the rapid analysis of DNA damage induced by exposure to an atmospheric pressure plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Kurita, Hirofumi, E-mail: kurita@ens.tut.ac.jp, E-mail: mizuno@ens.tut.ac.jp; Miyachika, Saki; Yasuda, Hachiro; Takashima, Kazunori; Mizuno, Akira, E-mail: kurita@ens.tut.ac.jp, E-mail: mizuno@ens.tut.ac.jp [Department of Environmental and Life Sciences, Toyohashi University of Technology, Aichi 441-8580 (Japan)

    2015-12-28

    A rapid method for evaluating the damage caused to DNA molecules upon exposure to plasma is demonstrated. Here, we propose the use of a molecular beacon for rapid detection of DNA strand breaks induced by atmospheric pressure plasma jet (APPJ) irradiation. Scission of the molecular beacon by APPJ irradiation leads to separation of the fluorophore-quencher pair, resulting in an increase in fluorescence that directly correlates with the DNA strand breaks. The results show that the increase in fluorescence intensity is proportional to the exposure time and the rate of fluorescence increase is proportional to the discharge power. This simple and rapid method allows the estimation of DNA damage induced by exposure to a non-thermal plasma.

  4. The dynamic pressure response to rapid dilatation of the resting urethra in healthy women

    DEFF Research Database (Denmark)

    Bagi, P; Thind, P; Colstrup, H

    1993-01-01

    beta e-t/tau beta, where Pequ, P alpha and P beta are constants, and tau alpha and tau beta are time constants; this equation has previously been demonstrated to describe the pressure decay following dilatation. On the basis of a theoretical model the elastic and viscous constants for the urethral......The urethral pressure response to a sudden forced dilatation was studied at the bladder neck, in the high-pressure zone and in the distal urethra in ten healthy female volunteers. The pressure response was fitted with a double exponential function of the form Pt = Pequ + P alpha e-t/tau alpha + P...... a detailed assessment of static and dynamic urethral responses to dilatation which can be applied as an experimental simulation of urine ingression, and is therefore presumed to be of value in the evaluation of normal and pathological urethral sphincter function....

  5. Partial coalescence from bubbles to drops

    KAUST Repository

    Zhang, F. H.

    2015-10-07

    The coalescence of drops is a fundamental process in the coarsening of emulsions. However, counter-intuitively, this coalescence process can produce a satellite, approximately half the size of the original drop, which is detrimental to the overall coarsening. This also occurs during the coalescence of bubbles, while the resulting satellite is much smaller, approximately 10 %. To understand this difference, we have conducted a set of coalescence experiments using xenon bubbles inside a pressure chamber, where we can continuously raise the pressure from 1 up to 85 atm and thereby vary the density ratio between the inner and outer fluid, from 0.005 up to unity. Using high-speed video imaging, we observe a continuous increase in satellite size as the inner density is varied from the bubble to emulsion-droplet conditions, with the most rapid changes occurring as the bubble density grows up to 15 % of that of the surrounding liquid. We propose a model that successfully relates the satellite size to the capillary wave mode responsible for its pinch-off and the overall deformations from the drainage. The wavelength of the primary wave changes during its travel to the apex, with the instantaneous speed adjusting to the local wavelength. By estimating the travel time of this wave mode on the bubble surface, we also show that the model is consistent with the experiments. This wavenumber is determined by both the global drainage as well as the interface shapes during the rapid coalescence in the neck connecting the two drops or bubbles. The rate of drainage is shown to scale with the density of the inner fluid. Empirically, we find that the pinch-off occurs when 60 % of the bubble fluid has drained from it. Numerical simulations using the volume-of-fluid method with dynamic adaptive grid refinement can reproduce these dynamics, as well as show the associated vortical structure and stirring of the coalescing fluid masses. Enhanced stirring is observed for cases with second

  6. Heat transfer and pressure drop when flow boiling of CO{sub 2}-oil-mixtures; Waermeuebergang und Druckverlust beim Stroemungssieden von CO{sub 2}-Oel-Gemischen

    Energy Technology Data Exchange (ETDEWEB)

    Wetzel, Markus; Dietrich, Benjamin; Wetzel, Thomas [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany). Inst. fuer Thermische Verfahrenstechnik

    2012-07-01

    The contribution under consideration describes experimental results for the heat transfer and pressure drop when flow boiling of CO{sub 2} and CO{sub 2}-oil mixtures. A comparison of these data with current correlations from the literature shall present the accuracy of the evaluation of the technical evaporator critically, and demonstrate the need for further research. Due to the required oil lubrication, for technical compression chillers, the refrigerant oil is also a part of the circulatory fluid. Thereby, the material properties of the fluid (density, viscosity, surface tension, thermal conductivity, specific heat capacity) can be significantly affected. These characteristics affect both, the form of the flow (for example, foaming, enhanced wall wetting), and the heat transfer as well as the pressure drop. The change of the material properties particularly is affected by the oil content. When flow boiling, an oil concentration of 1 wt.% already may result in a significantly different behavior in comparison to the pure refrigerant. In this case, the oil content may amount up to 8 wt.% in industrial refrigeration systems. The experiments on heat transfer and pressure drop were carried out on a pilot plant at the Institute of Thermal Process Engineering of the Karlsruhe Institute of Technology (Karlsruhe, Federal Republic of Germany). The fluid (CO{sub 2} or CO{sub 2}-oil mixture) circulates in a horizontal cycle consisting of four pre-evaporators in order to adjust the vapor content, the measurement path with a subsequent protective heat section for the determination of heat transfer and pressure loss under isothermal wall boundary condition, a sight glass to determine the flow pattern and a brine-cooled condenser for back-condensation of CO{sub 2} and adjustment of temperature and pressure. The discontinuous feeding of oil is carried out on an oil circuit, and the oil content is determined gravimetrically by sampling. The measurement section consists of a nickel

  7. Injector Element which Maintains a Constant Mean Spray Angle and Optimum Pressure Drop During Throttling by Varying the Geometry of Tangential Inlets

    Science.gov (United States)

    Trinh, Huu P. (Inventor); Myers, William Neill (Inventor)

    2014-01-01

    A method for determining the optimum inlet geometry of a liquid rocket engine swirl injector includes obtaining a throttleable level phase value, volume flow rate, chamber pressure, liquid propellant density, inlet injector pressure, desired target spray angle and desired target optimum delta pressure value between an inlet and a chamber for a plurality of engine stages. The tangential inlet area for each throttleable stage is calculated. The correlation between the tangential inlet areas and delta pressure values is used to calculate the spring displacement and variable inlet geometry. An injector designed using the method includes a plurality of geometrically calculated tangential inlets in an injection tube; an injection tube cap with a plurality of inlet slots slidably engages the injection tube. A pressure differential across the injector element causes the cap to slide along the injection tube and variably align the inlet slots with the tangential inlets.

  8. Possibility for rapid generation of high-pressure phases in single-crystal silicon by fast nanoindentation

    Science.gov (United States)

    Huang, Hu; Yan, Jiwang

    2015-11-01

    High-pressure phases of silicon such as Si-XII/Si-III exhibit attractive optical, electrical and chemical properties, but until now, it has been technologically impossible to produce a significant quantity of Si-XII or Si-III. In this study, to explore the possibility of generating high-pressure silicon phases efficiently, comparative nanoindentation experiments were conducted. Effects of the loading rate, unloading rate and maximum indentation load were investigated, and key factors affecting the high-pressure phase formation were identified. A new nanoindentation protocol is proposed that introduces an intermediate holding stage into the unloading process. The resulting end phases under the indent were detected by a laser micro-Raman spectrometer and compared with those formed in conventional nanoindentation. The results indicate that high-pressure phases Si-XII and Si-III were successfully formed during the intermediate holding stage even with a very high loading/unloading rate. This finding demonstrates the possibility of rapid production of high-pressure phases of silicon through fast mechanical loading and unloading.

  9. Flow boiling heat transfer and pressure drop characteristics of R134a, R1234yf and R1234ze in a plate heat exchanger for organic Rankine cycle units

    DEFF Research Database (Denmark)

    Zhang, Ji; Desideri, Adriano; Kærn, Martin Ryhl

    2017-01-01

    . This paper is aimed at obtaining flow boiling heat transfer and pressure drop characteristics in a plate heat exchanger under the working conditions prevailing in the evaporator of organic Rankine cycle units. Two hydrofluoroolefins R1234yf and R1234ze, and one hydrofluorocarbon R134a, were selected......The optimal design of the evaporator is one of the key issues to improve the efficiency and economics of organic Rankine cycle units. The first step in studying the evaporator design is to understand the thermal-hydraulic performance of the working fluid in the evaporator of organic Rankine cycles......, respectively. The working conditions covered relatively high saturation temperatures (corresponding reduced pressures of 0.35-0.74), which are prevailing in organic Rankine cycles yet absent in the open literature. The experimental data were compared with existing correlations, and new correlations were...

  10. Ultra-rapid microwave variable pressure-induced histoprocessing : Description of a new tissue processor

    NARCIS (Netherlands)

    Visinoni, F; Milios, J; Leong, ASY; Boon, ME; Kok, LP; Malcangi, F

    We describe a new method of ultra-rapid histoprocessing that reduces the processing times for needle and endoscopic biopsies to 30 min and that of other surgical biopsy tissue blocks of up to 4 mm thick to 120 min. The MicroMED U R M Histoprocessor, which combines microwave irradiation with precise

  11. Characterization of metal powder based rapid prototyping components under aluminium high pressure die casting process conditions

    CSIR Research Space (South Africa)

    Pereira, MFVT

    2009-11-01

    Full Text Available used in metal high pressure die casting toolsets. The specimens were subjected to a program of cyclic immersion in molten aluminium alloy and cooling in water based die release medium. The heat checking and soldering phenomena were analyzed through...

  12. Experimental investigation of heat transfer and pressure drop characteristics of non-Newtonian nanofluids flowing in the shell-side of a helical baffle heat exchanger with low-finned tubes

    Science.gov (United States)

    Tan, Yunkai; He, Zhenbin; Xu, Tao; Fang, Xiaoming; Gao, Xuenong; Zhang, Zhengguo

    2017-09-01

    An aqueous solution of Xanthan Gum (XG) at a weight fraction as high as 0.2% was used as the base liquid, the stable MWCNTs-dispersed non-Newtonian nanofluids at different weight factions of MWCNTs was prepared. The base fluid and all nanofluids show pseudoplastic (shear-thinning) rheological behavior. Experiments were performed to compare the shell-side forced convective heat transfer coefficient and pressure drop of non-Newtonian nanofluids to those of non-Newtonian base fluid in an integrally helical baffle heat exchanger with low-finned tubes. The experimental results showed that the enhancement of the convective heat transfer coefficient increases with an increase in the Peclet number and the nanoparticle concentration. For nanofluids with 1.0, 0.5 and 0.2 wt% of multi-walled carbon nanotubes (MWCNTs), the heat transfer coefficients respectively augmented by 24.3, 13.2 and 4.7% on average and the pressure drops become larger than those of the base fluid. The comprehensive thermal performance factor is higher than one and increases with an increasing weight fraction of MWCNTs. A remarkable heat transfer enhancement in the shell side of helical baffle heat exchanger with low-finned tubes can be obtained by adding MWCNTs into XG aqueous solution based on thermal resistance analysis. New correlations have been suggested for the shell-side friction coefficient and the Nusselt numbers of non-Newtonian nanofluids and give very good agreement with experimental data.

  13. Star-shaped oscillations of Leidenfrost drops

    Science.gov (United States)

    Ma, Xiaolei; Liétor-Santos, Juan-José; Burton, Justin C.

    2017-03-01

    We experimentally investigate the self-sustained, star-shaped oscillations of Leidenfrost drops. The drops levitate on a cushion of evaporated vapor over a heated, curved surface. We observe modes with n =2 -13 lobes around the drop periphery. We find that the wavelength of the oscillations depends only on the capillary length of the liquid and is independent of the drop radius and substrate temperature. However, the number of observed modes depends sensitively on the liquid viscosity. The dominant frequency of pressure variations in the vapor layer is approximately twice the drop oscillation frequency, consistent with a parametric forcing mechanism. Our results show that the star-shaped oscillations are driven by capillary waves of a characteristic wavelength beneath the drop and that the waves are generated by a large shear stress at the liquid-vapor interface.

  14. Eye Drop Tips

    Science.gov (United States)

    ... Involved News About Us Donate In This Section Eye Drop Tips en Español email Send this article ... the reach of children. Steps For Putting In Eye Drops: Start by tilting your head backward while ...

  15. Rapid Atmospheric-Pressure-Plasma-Jet Processed Porous Materials for Energy Harvesting and Storage Devices

    Directory of Open Access Journals (Sweden)

    Jian-Zhang Chen

    2015-01-01

    Full Text Available Atmospheric pressure plasma jet (APPJ technology is a versatile technology that has been applied in many energy harvesting and storage devices. This feature article provides an overview of the advances in APPJ technology and its application to solar cells and batteries. The ultrafast APPJ sintering of nanoporous oxides and 3D reduced graphene oxide nanosheets with accompanying optical emission spectroscopy analyses are described in detail. The applications of these nanoporous materials to photoanodes and counter electrodes of dye-sensitized solar cells are described. An ultrashort treatment (1 min on graphite felt electrodes of flow batteries also significantly improves the energy efficiency.

  16. Rapid analysis of the essential oil components of dried Zanthoxylum bungeanum Maxim by Fe2O3-magnetic-microsphere-assisted microwave distillation and simultaneous headspace single-drop microextraction followed by GC-MS.

    Science.gov (United States)

    Ye, Qing

    2013-06-01

    In this work, microwave distillation assisted by Fe2 O3 magnetic microspheres (FMMS) and headspace single-drop microextraction were combined, and developed for determination of essential oil compounds in dried Zanthoxylum bungeanum Maxim (ZBM). The FMMS were used as microwave absorption solid medium for dry distillation of dried ZBM. Using the proposed method, isolation, extraction, and concentration of essential oil compounds can be carried out in a single step. The experimental parameters including extraction solvent, solvent volume, microwave power, irradiation time, and the amount of added FMMS, were studied. The optimal analytical conditions were: 2.0 μL decane as the extraction solvent, microwave power of 300 W, irradiation time of 2 min, and the addition of 0.1 g FMMS to ZBM. The method precision was from 4 to 10%. A total of 52 compounds were identified by the proposed method. The conventional steam distillation method was also used for the analysis of essential oil in dried ZBM and only 31 compounds were identified by steam distillation method. It was found that the proposed method is a simple, rapid, reliable, and solvent-free technique for the determination of volatile compounds in Chinese herbs. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Lateral flow assay with pressure meter readout for rapid point-of-care detection of disease-associated protein.

    Science.gov (United States)

    Lin, Bingqian; Guan, Zhichao; Song, Yanling; Song, Eunyeong; Lu, Zifei; Liu, Dan; An, Yuan; Zhu, Zhi; Zhou, Leiji; Yang, Chaoyong

    2018-02-26

    Paper-based assays such as lateral flow assays are good candidates for portable diagnostics owing to their user-friendly format and low cost. In terms of analytical detection, lateral flow assays usually require dedicated instruments to obtain quantitative results. Here we demonstrate a lateral flow assay with handheld pressure meter readout for the rapid detection of disease-related protein with high sensitivity and selectivity. Based on the pressure change produced by the catalytic reaction of Pt nanoparticles related to the concentration of the target, a quantitative reaction platform was established. During the lateral flow assay, the Pt nanoparticles are aggregated in the test line to form a gray band by biomolecular recognition and finally convert the recognition signal into highly sensitive pressure readout for quantitative analysis. Without sophisticated instrumentation and complicated operations, the whole detection process can be completed within 20 minutes. The limit of detection for myoglobin (2.9 ng mL -1 in diluted serum samples) meets the requirements of clinical monitoring. With the advantages of low cost, ease of operation, high sensitivity and selectivity, the method represents a versatile platform for point-of-care testing of disease biomarkers.

  18. Payments for carbon sequestration to alleviate development pressure in a rapidly urbanizing region

    Science.gov (United States)

    Smith, Jordan W.; Dorning, Monica; Shoemaker, Douglas A.; Méley, Andréanne; Dupey, Lauren; Meentemeyer, Ross K.

    2017-01-01

    The purpose of this study was to determine individuals' willingness to enroll in voluntary payments for carbon sequestration programs through the use of a discrete choice experiment delivered to forest owners living in the rapidly urbanizing region surrounding Charlotte, North Carolina. We examined forest owners' willingness to enroll in payments for carbon sequestration policies under different levels of financial incentives (annual revenue), different contract lengths, and different program administrators (e.g., private companies versus a state or federal agency). We also examined the influence forest owners' sense of place had on their willingness to enroll in hypothetical programs. Our results showed a high level of ambivalence toward participating in payments for carbon sequestration programs. However, both financial incentives and contract lengths significantly influenced forest owners' intent to enroll. Neither program administration nor forest owners' sense of place influenced intent to enroll. Although our analyses indicated that payments from carbon sequestration programs are not currently competitive with the monetary returns expected from timber harvest or property sales, certain forest owners might see payments for carbon sequestration programs as a viable option for offsetting increasing tax costs as development encroaches and property values rise.

  19. A Rapid Deposition of Fluorine Doped Zinc Oxide Using the Atmospheric Pressure Chemical Vapour Deposition Method

    Science.gov (United States)

    Najafi, Navid; Rozati, S. M.

    2018-03-01

    Fluorine-doped zinc oxide (FZO) (ZnO:F) thin films were manufactured by atmospheric pressure chemical vapor deposition (APCVD) on glass substrates using zinc acetate dihydrate [C4H6O4Zn·2H2O, ZnAc] and ammonium fluoride (NH4F) as the source of fluorine with deposition duration of only 120 s for each sample. The effects of different amounts of fluorine as the dopant on the structural, electrical and optical properties of FZO thin films were investigated. The results show a polycrystalline structure at higher temperatures compared to amorphous structure at lower temperatures. The x-ray diffraction patterns of the polycrystalline films were identified as a hexagonal wurtzite structure of zinc oxide (ZnO) with the (002) preferred orientation. Also, the sheet resistance decreased from 17.8 MΩ/□ to 28.9 KΩ/□ for temperatures 325°C to 450°C, respectively. In order to further decrease the sheet resistance of the undoped ZnO thin films, fluorine was added using NH4F as the precursor, and again a drastic change in sheet resistance of only 17.7 Ω/□ was obtained. Based on the field emission scanning electron microscopy images, the fluorine concentration in CVD source is an important factor affecting the grain size and modifies electrical parameters. Ultraviolet-visible measurements revealed reduction of transparency of the layers with increasing fluorine as the dopant.

  20. A Rapid Deposition of Fluorine Doped Zinc Oxide Using the Atmospheric Pressure Chemical Vapour Deposition Method

    Science.gov (United States)

    Najafi, Navid; Rozati, S. M.

    2017-12-01

    Fluorine-doped zinc oxide (FZO) (ZnO:F) thin films were manufactured by atmospheric pressure chemical vapor deposition (APCVD) on glass substrates using zinc acetate dihydrate [C4H6O4Zn·2H2O, ZnAc] and ammonium fluoride (NH4F) as the source of fluorine with deposition duration of only 120 s for each sample. The effects of different amounts of fluorine as the dopant on the structural, electrical and optical properties of FZO thin films were investigated. The results show a polycrystalline structure at higher temperatures compared to amorphous structure at lower temperatures. The x-ray diffraction patterns of the polycrystalline films were identified as a hexagonal wurtzite structure of zinc oxide (ZnO) with the (002) preferred orientation. Also, the sheet resistance decreased from 17.8 MΩ/□ to 28.9 KΩ/□ for temperatures 325°C to 450°C, respectively. In order to further decrease the sheet resistance of the undoped ZnO thin films, fluorine was added using NH4F as the precursor, and again a drastic change in sheet resistance of only 17.7 Ω/□ was obtained. Based on the field emission scanning electron microscopy images, the fluorine concentration in CVD source is an important factor affecting the grain size and modifies electrical parameters. Ultraviolet-visible measurements revealed reduction of transparency of the layers with increasing fluorine as the dopant.

  1. Rapid Analysis of Cefazolin in Serum by High-Pressure Liquid Chromatography

    Science.gov (United States)

    Wold, John S.

    1977-01-01

    A high-pressure liquid chromatography (HPLC) method has been developed for the analysis of cefazolin in serum. Serum was deproteinized by the addition of 6% trichloroacetic acid and injected onto a reverse-phase column with a mobile phase of 10 to 15% methanol in 1% aqueous acetic acid. Cefazolin chromatographed without interference from ultraviolet-absorbing components of serum, with a retention time of 3.1 min. Standard curves comparing peak area with concentration prepared from dog or human sera were linear over a range of 1.6 to 200 μg/ml. Results from the HPLC assay were compared with microbiological assays (cylinder plate method) on both standard serum samples and sera from dogs and human subjects receiving intramuscular cefazolin. The HPLC method was somewhat more accurate in comparison with the microbiological assay performed on serum samples of known concentration. The comparison of results from an analysis of serum levels of dogs or human subjects receiving cefazolin indicated that the two methods would lead to identical conclusions concerning pharmacokinetics or the achievement of therapeutic serum levels. The HPLC assay method presents an alternative to conventional microbiological assays, with marked improvement in speed (30 min) and considerable potential for future development. PMID:836007

  2. Pressure drop, heat transfer, critical heat flux, and flow stability of two-phase flow boiling of water and ethylene glycol/water mixtures - final report for project "Efficent cooling in engines with nucleate boiling."

    Energy Technology Data Exchange (ETDEWEB)

    Yu, W.; France, D. M.; Routbort, J. L. (Energy Systems)

    2011-01-19

    Because of its order-of-magnitude higher heat transfer rates, there is interest in using controllable two-phase nucleate boiling instead of conventional single-phase forced convection in vehicular cooling systems to remove ever increasing heat loads and to eliminate potential hot spots in engines. However, the fundamental understanding of flow boiling mechanisms of a 50/50 ethylene glycol/water mixture under engineering application conditions is still limited. In addition, it is impractical to precisely maintain the volume concentration ratio of the ethylene glycol/water mixture coolant at 50/50. Therefore, any investigation into engine coolant characteristics should include a range of volume concentration ratios around the nominal 50/50 mark. In this study, the forced convective boiling heat transfer of distilled water and ethylene glycol/water mixtures with volume concentration ratios of 40/60, 50/50, and 60/40 in a 2.98-mm-inner-diameter circular tube has been investigated in both the horizontal flow and the vertical flow. The two-phase pressure drop, the forced convective boiling heat transfer coefficient, and the critical heat flux of the test fluids were determined experimentally over a range of the mass flux, the vapor mass quality, and the inlet subcooling through a new boiling data reduction procedure that allowed the analytical calculation of the fluid boiling temperatures along the experimental test section by applying the ideal mixture assumption and the equilibrium assumption along with Raoult's law. Based on the experimental data, predictive methods for the two-phase pressure drop, the forced convective boiling heat transfer coefficient, and the critical heat flux under engine application conditions were developed. The results summarized in this final project report provide the necessary information for designing and implementing nucleate-boiling vehicular cooling systems.

  3. Caída de presión de un flujo turbulento en un espacio anular con hélices insertadas//The pressure drop of turbulent flow in an annular space with wire coil inserts

    Directory of Open Access Journals (Sweden)

    Josué Imbert González

    2015-05-01

    Full Text Available El trabajo presentado evaluó el comportamiento experimental de la caída de presión en un espacio anular con alambres enrollados insertados para números de Reynolds entre 1500 y 5000. La zona de prueba se seleccionó alejada de la influencia de los efectos de entrada. Anteriormente se realizaron pruebas de visualización del flujo para verificar la presencia de un flujo turbulento en esta gama del número de Reynolds. A partir de los datos experimentales se obtuvieron ecuaciones de correlación del factor de fricción para el flujo turbulento. Las ecuaciones obtenidas se compararon con los datos experimentales. Los resultados indican hasta qué punto las hélices inducen la aparición de turbulencias en un espacio anularPalabras claves: caída de presión, flujo anular, análisis hidrodinámico, visualización de flujo, hélices insertadas.______________________________________________________________________________AbstractThe work presented evaluates the experimental behavior of the pressure drop in an annular space with coiled wires inserted forReynolds numbers between 1500 and 5000. The test zone was selected away from the influence of entrance effects. Previously flow visualization tests were performed to verify the presence of a turbulent flow in this range of Reynolds number. From the experimental data were obtained correlation equations of the friction factor for turbulent flow. The equations obtained were compared with experimental data. The results indicate to what extent the helices induce the occurrence of turbulence in an annular space.Key words: drop pressure, annular flow, hydrodynamic analysis, visualization flow, wire coil inserts.

  4. Electrowetting-enhanced microfluidic device for drop generation

    NARCIS (Netherlands)

    Gu, H.; Malloggi, F.G.J.; Vanapalli, Srinivas; Vanapalli Veera, V.S.A.R.; Mugele, Friedrich Gunther

    2008-01-01

    We integrated electrowetting into a microfluidic flow focusing device to study drop generation under the influence of electric fields. Using both the dispersed phase inlet pressure and the applied voltage as control parameters, we find that the range of drop sizes and the drop generation rate can be

  5. How microstructures affect air film dynamics prior to drop impact

    NARCIS (Netherlands)

    van der Veen, Roeland; Hendrix, M.H.W.; Tran, Tuan; Sun, Chao; Tsai, Peichun Amy; Lohse, Detlef

    2014-01-01

    When a drop impacts a surface, a dimple can be formed due to the increased air pressure beneath the drop before it wets the surface. We employ a high-speed color interferometry technique to measure the evolution of the air layer profiles under millimeter-sized drops impacting hydrophobic

  6. Micro-explosion of compound drops

    Science.gov (United States)

    Chen, Chun-Kuei; Lin, Ta-Hui

    2014-08-01

    Introducing water into spray combustion systems, by either water-in-oil emulsification or supplementary water injection, is one of the major techniques for combustion improvement and NOx reduction. Plentiful researches are available on combustion of water-in-oil emulsion fuel drops. The emulsified liquid is a heterogeneous mixture of immiscible liquids. One component forms the continuous phase and the other component forms the discrete phase. The discrete phase consists of globules of the one fluid that are suspended in the continuous phase fluid. Water-in-oil emulsions are commonly considered for combustion applications because emulsions can result in micro-explosion, thereby reducing the average drop diameter to enhance liquid vaporization, and suppressing the formation of soot and NOx. However, the water addition generally does not exceed about 20% for smooth engine operations[!, 21. The combustion characteristics and micro-explosion of emulsion drop were studied by many researchers. The micro-explosion of water in fuel emulsion drops was caused by very fast growth of superheated water vapor bubbles, its superheat limits must be lower than the boiling point temperature of the fuel. These bubbles were primarily governed by the pressure difference between the superheated vapor and the liquid, and by the inertia imparted to the liquid by the motion of the bubble surface[3 6 In this study, we used a coaxial nozzle to generation the multi-component drop. The different type of water-in-oil fuel drops called the compound drops. Unlike an emulsion drop, a compound drop consists of a water core and a fuel shell, which can originate from the phase separation of emulsion[7, 81 or a water drop colliding with a fuel drop[9, 101 Burning and micro-explosion of compound drops have been found to be distinct from those of emulsion drops[9-111 Wang et al.[9 , 101 studied the combustion characteristics of collision merged alkane-water drops. The merged drops appeared in adhesive

  7. Scanning drop sensor

    Science.gov (United States)

    Jin, Jian; Xiang, Chengxiang; Gregoire, John M.; Shinde, Aniketa A.; Guevarra, Dan W.; Jones, Ryan J.; Marcin, Martin R.; Mitrovic, Slobodan

    2017-05-09

    Electrochemical or electrochemical and photochemical experiments are performed on a collection of samples by suspending a drop of electrolyte solution between an electrochemical experiment probe and one of the samples that serves as a test sample. During the electrochemical experiment, the electrolyte solution is added to the drop and an output solution is removed from the drop. The probe and collection of samples can be moved relative to one another so the probe can be scanned across the samples.

  8. Assessing the impact of electrolyte conductivity and viscosity on the reactor cost and pressure drop of redox-active polymer flow batteries

    Science.gov (United States)

    Iyer, Vinay A.; Schuh, Jonathon K.; Montoto, Elena C.; Pavan Nemani, V.; Qian, Shaoyi; Nagarjuna, Gavvalapalli; Rodríguez-López, Joaquín; Ewoldt, Randy H.; Smith, Kyle C.

    2017-09-01

    Redox-active small molecules, used traditionally in redox flow batteries (RFBs), are susceptible to crossover and require expensive ion exchange membranes (IEMs) to achieve long lifetimes. Redox-active polymer (RAP) solutions show promise as candidate electrolytes to mitigate crossover through size-exclusion, enabling the use of porous separators instead of IEMs. Here, poly(vinylbenzyl ethyl viologen) is studied as a surrogate RAP for RFBs. For oxidized RAPs, ionic conductivity varies weakly between 1.6 and 2.1 S m-1 for RAP concentrations of 0.13-1.27 mol kg-1 (monomeric repeat unit per kg solvent) and 0.32 mol kg-1 LiBF4 with a minor increase upon reduction. In contrast, viscosity varies between 1.8 and 184.0 mPa s over the same concentration range with weakly shear-thinning rheology independent of oxidation state. Techno-economic analysis is used to quantify reactor cost as a function of electrolyte transport properties for RAP concentrations of 0.13-1.27 mol kg-1, assuming a hypothetical 3V cell and facile kinetics. Among these concentrations, reactor cost is minimized over a current density range of 600-1000 A m-2 with minimum reactor cost between 11-17 per kWh, and pumping pressures below 10 kPa. The predicted low reactor cost of RAP RFBs is enabled by sustained ionic mobility in spite of the high viscosity of concentrated RAP solutions.

  9. Effect of Aspect Ratio, Channel Orientation, Rib Pitch-to-Height Ratio, and Number of Ribbed Walls on Pressure Drop Characteristics in a Rotating Channel with Detached Ribs

    Directory of Open Access Journals (Sweden)

    K. Arun

    2007-01-01

    Full Text Available The present work involves experimental investigation of the effects of aspect ratio, channel orientation angle, rib pitch-to-height ratio (P/e, and number of ribbed walls on friction factor in orthogonally rotating channel with detached ribs. The ribs are separated from the base wall to provide a small region of flow between the base wall and the ribs. Experiments have been conducted at Reynolds number ranging from 10000–17000 with rotation numbers varying from 0–0.38. Pitch-to-rib height ratios (P/e of 5 and 10 at constant rib height-to-hydraulic diameter ratio (e/D of 0.1 and a clearance ratio (C/e of 0.38 are considered. The rib angle of attack with respect to mainstream flow is 90∘. The channel orientation at which the ribbed wall becomes trailing surface (pressure side on which the Coriolis force acts is considered as the 0∘ orientation angle. For one-wall ribbed case, channel is oriented from 0∘ to 180∘ about its axis in steps of 30∘ to change the orientation angle. For two-wall ribbed case, the orientation angle is changed from 0∘ to 90∘ in steps of 30∘. Friction factors for the detached ribbed channels are compared with the corresponding attached ribbed channel. It is found that in one-wall detached ribbed channel, increase in the friction factor ratio with the orientation angle is lower for rectangular channel compared to that of square channel for both the pitch-to-rib height ratios of 5 and 10 at a given Reynolds number and rotation number. Friction factor ratios of two-wall detached ribbed rectangular channel are comparable with corresponding two-wall detached ribbed square channel both under stationary and rotating conditions.

  10. Dynamics of deforming drops

    NARCIS (Netherlands)

    Bouwhuis, W.

    2015-01-01

    Liquid drops play a dominant role in numerous industrial applications, such as spray coating, spray painting, inkjet printing, lithography processes, and spraying/sprinkling in agriculture or gardening. In all of these examples, the generation, flight, impact, and spreading of drops are separate

  11. Lambda-dropping

    DEFF Research Database (Denmark)

    Danvy, Olivier; Schultz, Ulrik Pagh

    1997-01-01

    Lambda-lifting a functional program transforms it into a set of recursive equations. We present the symmetric transformation: lambda-dropping. Lambda-dropping a set of recursive equations restores block structure and lexical scope.For lack of scope, recursive equations must carry around all...... to float (for lambda-lifting) or to sink (for lambda-dropping) along the vertices of the scope tree.We believe lambda-lifting and lambda-dropping are interesting per se, both in principle and in practice, but our prime application is partial evaluation: except for Malmkjær and Ø...... with dozens of parameters, which most compilers do not handle efficiently. Lambda-dropping in a post-processing phase restores their block structure and lexical scope thereby significantly reducing both the compile time and the run time of residual programs....

  12. The impact of rapid sediment accumulation on pore pressure development and dehydration reactions during shallow subduction in the Gulf of Alaska

    Science.gov (United States)

    Meridth, Lanie N.; Screaton, Elizabeth J.; Jaeger, John M.; James, Stephanie R.; Villaseñor, Tania

    2017-01-01

    In the Gulf of Alaska region, sediment has rapidly accumulated (>1 km/my) in the trench sourced from intensified glaciation in the past ˜1.2 million years. This rapid sediment accumulation increases overburden and should accelerate dehydration of hydrous minerals by insulating the underlying sediment column. These processes have the potential to generate fluid overpressures in the low permeability sediments entering the subduction zone. A 1-D model was developed to simulate dehydration reaction progress and investigate excess pore pressures as sediments approach the trench and are subducted. At the deformation front, simulated temperatures increase by ˜30°C due to the insulating effect of trench sediments. As a result, opal-A begins to react to form quartz while smectite remains mostly unreacted. Loading due to the trench sediments elevates excess pore pressures to ˜30% of lithostatic pressure at the deformation front; however, deformation front excess pore pressures are sensitive to assumptions about the permeability of outer wedge sediments. If the outer wedge sediments are coarse-grained and high-permeability rather than mud-dominated, excess pore pressures are lower but still have an insulating effect. During early subduction, simulated pore pressures continue to rise and reach ˜70% of lithostatic by 60 km landward. The 1-D modeling results suggest that the elevated pore pressures are primarily due to loading and that dehydration reactions are not a significant component of excess pore pressure generation at this margin.

  13. Dancing drops over vibrating substrates

    Science.gov (United States)

    Borcia, Rodica; Borcia, Ion Dan; Helbig, Markus; Meier, Martin; Egbers, Christoph; Bestehorn, Michael

    2017-04-01

    We study the motion of a liquid drop on a solid plate simultaneously submitted to horizontal and vertical harmonic vibrations. The investigation is done via a phase field model earlier developed for describing static and dynamic contact angles. The density field is nearly constant in every bulk region (ρ = 1 in the liquid phase, ρ ≈ 0 in the vapor phase) and varies continuously from one phase to the other with a rapid but smooth variation across the interfaces. Complicated explicit boundary conditions along the interface are avoided and captured implicitly by gradient terms of ρ in the hydrodynamic basic equations. The contact angle θ is controlled through the density at the solid substrate ρ S , a free parameter varying between 0 and 1 [R. Borcia, I.D. Borcia, M. Bestehorn, Phys. Rev. E 78, 066307 (2008)]. We emphasize the swaying and the spreading modes, earlier theoretically identified by Benilov and Billingham via a shallow-water model for drops climbing uphill along an inclined plane oscillating vertically [E.S. Benilov, J. Billingham, J. Fluid Mech. 674, 93 (2011)]. The numerical phase field simulations will be completed by experiments. Some ways to prevent the release of the dancing drops along a hydrophobic surface into the gas atmosphere are also discussed in this paper.

  14. Center of Pressure Displacement of Standing Posture during Rapid Movements Is Reorganised Due to Experimental Lower Extremity Muscle Pain.

    Directory of Open Access Journals (Sweden)

    Shinichiro Shiozawa

    Full Text Available Postural control during rapid movements may be impaired due to musculoskeletal pain. The purpose of this study was to investigate the effect of experimental knee-related muscle pain on the center of pressure (CoP displacement in a reaction time task condition.Nine healthy males performed two reaction time tasks (dominant side shoulder flexion and bilateral heel lift before, during, and after experimental pain induced in the dominant side vastus medialis or the tibialis anterior muscles by hypertonic saline injections. The CoP displacement was extracted from the ipsilateral and contralateral side by two force plates and the net CoP displacement was calculated.Compared with non-painful sessions, tibialis anterior muscle pain during the peak and peak-to-peak displacement for the CoP during anticipatory postural adjustments (APAs of the shoulder task reduced the peak-to-peak displacement of the net CoP in the medial-lateral direction (P<0.05. Tibialis anterior and vastus medialis muscle pain during shoulder flexion task reduced the anterior-posterior peak-to-peak displacement in the ipsilateral side (P<0.05.The central nervous system in healthy individuals was sufficiently robust in maintaining the APA characteristics during pain, although the displacement of net and ipsilateral CoP in the medial-lateral and anterior-posterior directions during unilateral fast shoulder movement was altered.

  15. Rapid atmospheric pressure plasma jet processed reduced graphene oxide counter electrodes for dye-sensitized solar cells.

    Science.gov (United States)

    Liu, Hsiao-Wei; Liang, Sheng-Ping; Wu, Ting-Jui; Chang, Haoming; Kao, Peng-Kai; Hsu, Cheng-Che; Chen, Jian-Zhang; Chou, Pi-Tai; Cheng, I-Chun

    2014-09-10

    In this work, we present the use of reduced graphene oxide (rGO) as the counter electrode materials in dye-sensitized solar cells (DSSCs). rGO was first deposited on a fluorine-doped tin oxide glass substrate by screen-printing, followed by post-treatment to remove excessive organic additives. We investigated the effect of atmospheric pressure plasma jet (APPJ) treatment on the DSSC performance. A power conversion efficiency of 5.19% was reached when DSSCs with an rGO counter electrode were treated by APPJs in the ambient air for a few seconds. For comparison, it requires a conventional calcination process at 400 °C for 15 min to obtain comparable efficiency. Scanning electron micrographs show that the APPJ treatment modifies the rGO structure, which may reduce its conductivity in part but simultaneously greatly enhances its catalytic activity. Combined with the rapid removal of organic additives by the highly reactive APPJ, DSSCs with APPJ-treated rGO counter electrode show comparable efficiencies to furnace-calcined rGO counter electrodes with greatly reduced process time. This ultrashort process time renders an estimated energy consumption per unit area of 1.1 kJ/cm(2), which is only one-third of that consumed in a conventional furnace calcination process. This new methodology thus saves energy, cost, and time, which is greatly beneficial to future mass production.

  16. Estimation of pressure drop in the mixing zone of beds in operation filters as drinking water treatment by a mathematical model; Estimacion de la perdida de carga en la zona de mezcla mediante una ecuacion matematica en filtros pilotos para el tratamiento del agua potable

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez Miranda, J. P.

    2010-07-01

    This paper describes the correlation of a mathematical model that considers the pressure drop (energy) in the mixing zone of beds in operation filters as drinking water treatment, filters applied in conventional pilot operated and mounted on a water treatment plant of a municipally in Colombia. (Author) 20 refs.

  17. Micro-splashing by drop impacts

    KAUST Repository

    Thoroddsen, Sigurdur T.

    2012-07-18

    We use ultra-high-speed video imaging to observe directly the earliest onset of prompt splashing when a drop impacts onto a smooth solid surface. We capture the start of the ejecta sheet travelling along the solid substrate and show how it breaks up immediately upon emergence from the underneath the drop. The resulting micro-droplets are much smaller and faster than previously reported and may have gone unobserved owing to their very small size and rapid ejection velocities, which approach 100 m s-1, for typical impact conditions of large rain drops. We propose a phenomenological mechanism which predicts the velocity and size distribution of the resulting microdroplets. We also observe azimuthal undulations which may help promote the earliest breakup of the ejecta. This instability occurs in the cusp in the free surface where the drop surface meets the radially ejected liquid sheet. © 2012 Cambridge University Press.

  18. Rapid and variable-volume sample loading in sieving electrophoresis microchips using negative pressure combined with electrokinetic force.

    Science.gov (United States)

    Qi, Li-Ya; Yin, Xue-Feng; Zhang, Lei; Wang, Min

    2008-07-01

    A rapid and variable-volume sample loading scheme for chip-based sieving electrophoresis was developed by negative pressure combined with electrokinetic force. This was achieved by using a low-cost microvacuum pump and a single potential supply at a constant voltage. Both 12% linear polyacrylamide (LPA) with a high viscosity of 15000 cP and 2% hydroxyethylcellulose (HEC) with a low viscosity of 102 cP were chosen as the sieving materials to study the behavior and the versatility of the proposed method. To reduce the hydrodynamic resistance in the sampling channel, sieving material was only filled in the separation channel between the buffer waste reservoir (BW) to the edge of the crossed intersection. By applying a subambient pressure to the headspace of sample waste reservoir (SW), sample and buffer solution were drawn immediately from sample reservoir (S) and buffer reservoir (B) across the intersection to SW. At the same time, the charged sample in the sample flow was driven across the interface between the sample flow and the sieving matrix into the sieving material filled separation channel by the applied electric field. The injected sample plug length is in proportion with the loading time. Once the vacuum in SW reservoir was released to activate electrophoretic separation, flows from S and B to SW were immediately terminated by the back flow induced by the difference of the liquid levels in the reservoirs to prevent sample leakage during the separation stage. The sample consumption was about 1.7 x 10(2) nL at a loading time of 1 s for each cycle. Only 0.024 s was required to transport bias-free analyte to the injection point. It is easy to freely choose the sample plug volume in this method by simply changing the loading time and to inject high quality sample plug with non-distorted shape into the separation channel. The system has been proved to possess an exciting potential for improving throughput, repeatability, sensitivity and separation performance of

  19. Stability analysis applied to the early stages of viscous drop breakup by a high-speed gas stream

    Science.gov (United States)

    Padrino, Juan C.; Longmire, Ellen K.

    2013-11-01

    The instability of a liquid drop suddenly exposed to a high-speed gas stream behind a shock wave is studied by considering the gas-liquid motion at the drop interface. The discontinuous velocity profile given by the uniform, parallel flow of an inviscid, compressible gas over a viscous liquid is considered, and drop acceleration is included. Our analysis considers compressibility effects not only in the base flow, but also in the equations of motion for the perturbations. Recently published high-resolution images of the process of drop breakup by a passing shock have provided experimental evidence supporting the idea that a critical gas dynamic pressure can be found above which drop piercing by the growth of acceleration-driven instabilities gives way to drop breakup by liquid entrainment resulting from the gas shearing action. For a set of experimental runs from the literature, results show that, for shock Mach numbers >= 2, a band of rapidly growing waves forms in the region well upstream of the drop's equator at the location where the base flow passes from subsonic to supersonic, in agreement with experimental images. Also, the maximum growth rate can be used to predict the transition of the breakup mode from Rayleigh-Taylor piercing to shear-induced entrainment. The authors acknowledge support of the NSF (DMS-0908561).

  20. Rapid sample classification using an open port sampling interface coupled with liquid introduction atmospheric pressure ionization mass spectrometry.

    Science.gov (United States)

    Van Berkel, Gary J; Kertesz, Vilmos

    2017-02-15

    An "Open Access"-like mass spectrometric platform to fully utilize the simplicity of the manual open port sampling interface for rapid characterization of unprocessed samples by liquid introduction atmospheric pressure ionization mass spectrometry has been lacking. The in-house developed integrated software with a simple, small and relatively low-cost mass spectrometry system introduced here fills this void. Software was developed to operate the mass spectrometer, to collect and process mass spectrometric data files, to build a database and to classify samples using such a database. These tasks were accomplished via the vendor-provided software libraries. Sample classification based on spectral comparison utilized the spectral contrast angle method. Using the developed software platform near real-time sample classification is exemplified using a series of commercially available blue ink rollerball pens and vegetable oils. In the case of the inks, full scan positive and negative ion ESI mass spectra were both used for database generation and sample classification. For the vegetable oils, full scan positive ion mode APCI mass spectra were recorded. The overall accuracy of the employed spectral contrast angle statistical model was 95.3% and 98% in case of the inks and oils, respectively, using leave-one-out cross-validation. This work illustrates that an open port sampling interface/mass spectrometer combination, with appropriate instrument control and data processing software, is a viable direct liquid extraction sampling and analysis system suitable for the non-expert user and near real-time sample classification via database matching. Published in 2016. This article is a U.S. Government work and is in the public domain in the USA. Published in 2016. This article is a U.S. Government work and is in the public domain in the USA.

  1. Probing the nanoscale: the first contact of an impacting drop

    KAUST Repository

    Li, Erqiang

    2015-11-16

    When a drop impacts onto a solid surface, the lubrication pressure in the air deforms its bottom into a dimple. This makes the initial contact with the substrate occur not at a point but along a ring, thereby entrapping a central disc of air. We use ultra-high-speed imaging, with 200 ns time resolution, to observe the structure of this first contact between the liquid and a smooth solid surface. For a water drop impacting onto regular glass we observe a ring of microbubbles, due to multiple initial contacts just before the formation of the fully wetted outer section. These contacts are spaced by a few microns and quickly grow in size until they meet, thereby leaving behind a ring of microbubbles marking the original air-disc diameter. On the other hand, no microbubbles are left behind when the drop impacts onto molecularly smooth mica sheets. We thereby conclude that the localized contacts are due to nanometric roughness of the glass surface, and the presence of the microbubbles can therefore distinguish between glass with 10 nm roughness and perfectly smooth glass. We contrast this entrapment topology with the initial contact of a drop impacting onto a film of extremely viscous immiscible liquid, where the initial contact appears to be continuous along the ring. Here, an azimuthal instability occurs during the rapid contraction at the triple line, also leaving behind microbubbles. For low impact velocities the nature of the initial contact changes to one initiated by ruptures of a thin lubricating air film.

  2. Leuna methods of rapid emptying and pressure release of operating equipment filled with combustible liquids and gases, as means of prevention of spreading fires

    Energy Technology Data Exchange (ETDEWEB)

    1944-12-14

    At times, the considerable amounts of combustible liquids in the equipment during distillation, gas separation, scrubbing, etc. required special precautionary measures even under normal conditions. Obviously, such amounts of combustibles carried the danger of spreading fires from any disturbance, such as breaks in the piping, of the slides, explosions, and small fires. The past precautions taken in this matter had been fire extinguishers, construction of localizing compartments, spray systems, reduction of the amount of liquids, and other similar measures. However, such measures were of little use in case of an attack. Leuna decided to provide a means of rapid emptying with a simultaneous rapid exhausting of all equipment under danger. Releasing the pressure would prevent the formation of sharp-pointed flames with their devastating consequences. The installation consisted essentially of groups of valves (easily accessible), long pipe lines, storage farms for liquids, and a discharge into the air. Provisions were made for returning the materials under atmospheric pressure to prevent losses. The figures showed rapid emptying of scrubbers for circulating gas under high pressure, gasoline catchpot still, and pressure release of gas separation unit. These installations proved worthy and became a necessary part of operations. Four diagrams are given showing this installation. 4 diagrams

  3. Impact of granular drops

    KAUST Repository

    Marston, J. O.

    2013-07-15

    We investigate the spreading and splashing of granular drops during impact with a solid target. The granular drops are formed from roughly spherical balls of sand mixed with water, which is used as a binder to hold the ball together during free-fall. We measure the instantaneous spread diameter for different impact speeds and find that the normalized spread diameter d/D grows as (tV/D)1/2. The speeds of the grains ejected during the “splash” are measured and they rarely exceed twice that of the impact speed.

  4. Drop Tower Facility at Queensland University of Technology

    Science.gov (United States)

    Plagens, Owen; Castillo, Martin; Steinberg, Theodore; Ong, Teng-Cheong

    The Queensland University of Technology (QUT) Drop Tower Facility is a {raise.17exscriptstyle˜}2.1 second, 21.3 m fall, dual capsule drop tower system. The dual capsule comprises of an uncoupled exterior hollow drag shield that experiences drag by the ambient atmosphere with the experimental capsule falling within the drag shield. The dual capsule system is lifted to the top of the drop tower via a mechanical crane and the dropping process is initiated by the cutting of a wire coupling the experimental package and suspending the drag shield. The internal experimental capsule reaches the bottom of the drag shield floor just prior to the deceleration stage at the air bag and during this time experience gravity levels of {raise.17exscriptstyle˜}10textsuperscript{-6} g. The deceleration system utilizes an inflatable airbag where experimental packages can be designed to experience a maximum deceleration of {raise.17exscriptstyle˜}10textsuperscript{18} g for {raise.17exscriptstyle˜}0.1 seconds. The drag shield can house experimental packages with a maximum diameter of 0.8 m and height of 0.9 m. The drag shield can also be used in foam mode, where the walls are lined with foam and small experiments can be dropped completely untethered. This mode is generally used for the study of microsatellite manipulation. Payloads can be powered by on-board power systems with power delivered to the experiment until free fall occurs. Experimental data that can be collected includes but is not limited to video, temperature, pressure, voltage/current from the power supply, and triggering mechanisms outputs which are simultaneously collected via data logging systems and high speed video recording systems. Academic and commercial projects are currently under investigation at the QUT Drop Tower Facility and collaboration is openly welcome at this facility. Current research includes the study of heterogeneously burning metals in oxygen which is aimed at fire safety applications and

  5. Microvolume turbidimetry for rapid and sensitive determination of the acid labile sulfide fraction in waters after headspace single-drop microextraction with in situ generation of volatile hydrogen sulfide.

    Science.gov (United States)

    Lavilla, I; Pena-Pereira, F; Gil, S; Costas, M; Bendicho, C

    2009-08-04

    In this work, we demonstrate the feasibility of applying headspace single-drop microextraction with in-drop precipitation for the quantitative determination of the acid labile sulfide fraction (H2S, HS-, and S2- (free sulfide), amorphous FeS and some metal sulfide complexes-clusters as ZnS) in aqueous samples by microvolume turbidimetry. The methodology lies in the in situ hydrogen sulfide generation and subsequent sequestration into an alkaline microdrop containing ZnO(2)(2-) and exposed to the headspace above the stirred aqueous sample. The ZnS formed in the drop was then determined by microvolume turbidimetry. The optimum experimental conditions of the proposed method were: 2 microL of a microdrop containing 750 mg L(-1) Zn(II) in 1 mol L(-1) NaOH exposed to the headspace of a 20-mL aqueous sample stirred at 1600 rpm during 80 s after derivatization with 1 mL of 6 mol L(-1) HCl. An enrichment factor of 1710 was achieved in only 80 s. The calibration graph was linear in the range of 5-100 microg L(-1) with a detection limit of 0.5 microg L(-1). The repeatability, expressed as relative standard deviation, was 5.8% (N = 9). Finally, the proposed methodology was successfully applied to the determination of the acid labile sulfide fraction in different natural water samples.

  6. Rapid analysis of formic acid, acetic acid, and furfural in pretreated wheat straw hydrolysates and ethanol in a bioethanol fermentation using atmospheric pressure chemical ionisation mass spectrometry

    Science.gov (United States)

    2011-01-01

    Atmospheric pressure chemical ionisation mass spectrometry (APCI-MS) offers advantages as a rapid analytical technique for the quantification of three biomass degradation products (acetic acid, formic acid and furfural) within pretreated wheat straw hydrolysates and the analysis of ethanol during fermentation. The data we obtained using APCI-MS correlated significantly with high-performance liquid chromatography analysis whilst offering the analyst minimal sample preparation and faster sample throughput. PMID:21896164

  7. Drop tube technical tasks

    Science.gov (United States)

    Workman, G. L.

    1986-01-01

    Criteria, using fundamental thermochemical dynamics, were developed to assist a scientist using the Drop Tube Facility in designing a good experiment. The types of parameters involved in designing the experiments include the type of furnace, the type of atmosphere, and in general which materials are better behaved than others as determined by past experience in the facility. One of the major advantages of the facility lies in its ability to provide large undercoolings in the cooling curve during the drops. A beginning was to consider the effect of oxygen and other gases upon the amount of undercooling observed. The starting point of the thermochemistry was given by Ellingham and later transformed into what is known as the Richardson Chart. The effect of surface oxidations upon the nucleation phenomena can be observed in each specimen.

  8. Dropped object protection analyses

    OpenAIRE

    Nilsen, Ingve

    2014-01-01

    Master's thesis in Offshore structural engineering Impact from dropped object is a typical accident action (NOKSOK N-004, 2013). Hence, the DOP structure is to be analyzed in an accidental limit state (ALS) design practice, which means that a non-linear finite element analysis can be applied. The DOP structure will be based on a typical DOP structure. Several FEM analyses are performed for the DOP structure. Different shapes size and weights and various impact positions are used for si...

  9. Electrowetting-enhanced microfluidic device for drop generation

    Science.gov (United States)

    Gu, Hao; Malloggi, Florent; Vanapalli, Siva A.; Mugele, Frieder

    2008-11-01

    We integrated electrowetting into a microfluidic flow focusing device to study drop generation under the influence of electric fields. Using both the dispersed phase inlet pressure and the applied voltage as control parameters, we find that the range of drop sizes and the drop generation rate can be controlled in a much finer way than with hydrodynamics alone. In particular a "conical spray" regime occurring at a voltage of O(50 V) allows for continuous tuning of the (highly monodisperse) drop diameter from ≈5 to 50 μm at a fixed continuous flow rate.

  10. Drop Testing Representative Multi-Canister Overpacks

    Energy Technology Data Exchange (ETDEWEB)

    Snow, Spencer D. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Morton, Dana K. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-06-01

    The objective of the work reported herein was to determine the ability of the Multi- Canister Overpack (MCO) canister design to maintain its containment boundary after an accidental drop event. Two test MCO canisters were assembled at Hanford, prepared for testing at the Idaho National Engineering and Environmental Laboratory (INEEL), drop tested at Sandia National Laboratories, and evaluated back at the INEEL. In addition to the actual testing efforts, finite element plastic analysis techniques were used to make both pre-test and post-test predictions of the test MCOs structural deformations. The completed effort has demonstrated that the canister design is capable of maintaining a 50 psig pressure boundary after drop testing. Based on helium leak testing methods, one test MCO was determined to have a leakage rate not greater than 1x10-5 std cc/sec (prior internal helium presence prevented a more rigorous test) and the remaining test MCO had a measured leakage rate less than 1x10-7 std cc/sec (i.e., a leaktight containment) after the drop test. The effort has also demonstrated the capability of finite element methods using plastic analysis techniques to accurately predict the structural deformations of canisters subjected to an accidental drop event.

  11. STUDY ON SOFTENING AND DROPPING PROPERTIES OF METALIZED BURDEN INSIDE BLAST FURNACE

    Directory of Open Access Journals (Sweden)

    Bi-yang Tuo

    2014-12-01

    Full Text Available The inferences of burden metallization rate on softening-melting dropping properties were investigated through softening-melting dropping test of three kinds of metalized burden pressure drop. The results indicated that the softeningmelting temperature interval of pre-reduction mixed burden is bigger than primeval mixed burden, the melting interval narrow with the rise of metallization rate of ferric burden as well as dropping temperature interval. The average pressure drop, maximum pressure drop and softening-melting dropping properties eigenvalue decrease with the rise of metallization rate of ferric burden. Besides, the dropping temperature of burden reduces with the rise of carbon content of molten iron. The combination high metalized burden and higher carbon content of molten iron is benefit to decreasing thickness of cohesive zone and improve permeability of cohesive zone.

  12. Rapid Analysis of Apolar Low Molecular Weight Constituents in Wood Using High Pressure Liquid Chromatography with Evaporative Light Scattering Detection

    NARCIS (Netherlands)

    Claassen, F.W.; Haar, van de C.; Beek, van T.A.; Dorado, J.; Martinez-Inigo, M.; Sierra-Alvarez, R.

    2000-01-01

    A new high pressure liquid chromatographic method with evaporative light scattering detection was developed for the qualitative and quantitative analysis of apolar, low molecular weight constituents in wood. The wood extractives were obtained by means of a 6 h Soxhlet extraction with acetone. The

  13. Drop Pinch-Off for Discrete Flows from a Capillary

    Directory of Open Access Journals (Sweden)

    Wilson M.C.T.

    2013-07-01

    Full Text Available The problem of drop formation and pinch-off from a capillary tube under the influence of gravity has been extensively studied when the internal capillary pressure gradient is constant. This ensures a continuous time independent flow field inside the capillary tube typically of the Poiseuille flow type. Characteristic drop ejection behaviour includes: periodic drop ejection, drop ejection with associated satellite production, complex dripping, chaotic behaviour and jetting. It is well known that this characteristic behaviour is governed by the Weber (We and Ohnesorge (Oh numbers (for a given Bond number and may be delineated in a We verses Oh operability diagram. An in-depth physical understanding of drop ejection is also of great importance to industry where the tight control of drop size and ejection velocity are of critical importance in industrial processes such as sealants used in electronics assembly and inkjet printing. However, the use of such a continuous flow approach for drop ejection in industry is often impractical since such flows cannot be operator controlled. For this reason it is important to investigate so-called discrete pipe flows where the flow can be turned on and off at will. This means the flow inside the pipe is now time-dependent being controlled in a step-wise fashion. As a first stage in the investigation of drop pinch-off behaviour in discrete pipe flows this paper will study the critical pinch-off time required for drop ejection starting from a pendant drop. This is the discrete amount of time the pipe flow is turned on for in order for a drop to be ejected from the capillary. A Newtonian incompressible free-surface CFD flow code developed at the University of Leeds is used to investigate the critical pinch-off time for a range of internal pipe velocities (the central flow maximum in Poiseuille flow. It is found that the time required for drop ejection to occur decreases exponentially with internal pipe velocity

  14. Time-resolved imaging of a compressible air disc under a drop impacting on a solid surface

    KAUST Repository

    Li, Erqiang

    2015-09-07

    When a drop impacts on a solid surface, its rapid deceleration is cushioned by a thin layer of air, which leads to the entrapment of a bubble under its centre. For large impact velocities the lubrication pressure in this air layer becomes large enough to compress the air. Herein we use high-speed interferometry, with 200 ns time-resolution, to directly observe the thickness evolution of the air layer during the entire bubble entrapment process. The initial disc radius and thickness shows excellent agreement with available theoretical models, based on adiabatic compression. For the largest impact velocities the air is compressed by as much as a factor of 14. Immediately following the contact, the air disc shows rapid vertical expansion. The radial speed of the surface minima just before contact, can reach 50 times the impact velocity of the drop.

  15. Drop jumping. II. The influence of dropping height on the biomechanics of drop jumping

    NARCIS (Netherlands)

    Bobbert, M F; Huijing, P A; van Ingen Schenau, G J

    In the literature, athletes preparing for explosive activities are recommended to include drop jumping in their training programs. For the execution of drop jumps, different techniques and different dropping heights can be used. This study was designed to investigate for the performance of bounce

  16. Simultaneous measurements of velocity, temperature, and pressure using rapid CW wavelength-modulation laser-induced fluorescence of OH

    Science.gov (United States)

    Chang, A. Y.; Battles, B. E.; Hanson, R. K.

    1990-01-01

    In high speed flows, laser induced fluorescence (LIF) on Doppler shifted transitions is an attractive technique for velocity measurement. LIF velocimetry was applied to combined single-point measurements of velocity, temperature, and pressure and 2-D imaging of velocity and pressure. Prior to recent research using NO, LIF velocimetry in combustion related flows relied largely on the use of seed molecules. Simultaneous, single-point LIF measurements is reported of velocity, temperature, and pressure using the naturally occurring combustion species OH. This experiment is an extension of earlier research in which a modified ring dye laser was used to make time resolved temperature measurements behind reflected shock waves by using OH absorption an in postflame gases by using OH LIF. A pair of fused-silica rhombs mounted on a single galvanonmeter in an intracavity-doubled Spectra-Physics 380 ring laser permit the UV output to be swept continuously over a few wave numbers at an effective frequency of 3kHz.

  17. Pressure Effect on Entrance Flow

    DEFF Research Database (Denmark)

    Christensen, Jens Horslund; Couch, Mark

    1997-01-01

    The paper reports on experimentally determined pressure drops associated with orifice and capillary dies, where the exit pressure is elevated. The effect of hydrostatic pressure up to 70 MPa is reported for PS, LDPE and PP melts.......The paper reports on experimentally determined pressure drops associated with orifice and capillary dies, where the exit pressure is elevated. The effect of hydrostatic pressure up to 70 MPa is reported for PS, LDPE and PP melts....

  18. High-Speed Interferometry Under Impacting Drops

    KAUST Repository

    Langley, Kenneth R.

    2017-08-31

    Over the last decade the rapid advances in high-speed video technology, have opened up to study many multi-phase fluid phenomena, which tend to occur most rapidly on the smallest length-scales. One of these is the entrapment of a small bubble under a drop impacting onto a solid surface. Here we have gone from simply observing the presence of the bubble to detailed imaging of the formation of a lubricating air-disc under the drop center and its subsequent contraction into the bubble. Imaging the full shape-evolution of the air-disc has required μm and sub-μs space and time resolutions. Time-resolved 200 ns interferometry with monochromatic light, has allowed us to follow individual fringes to obtain absolute air-layer thicknesses, based on the eventual contact with the solid. We can follow the evolution of the dimple shape as well as the compression of the gas. The improved imaging has also revealed new levels of detail, like the nature of the first contact which produces a ring of micro-bubbles, highlighting the influence of nanometric surface roughness. Finally, for impacts of ultra-viscous drops we see gliding on ~100 nm thick rarified gas layers, followed by extreme wetting at numerous random spots.

  19. Multicomponent mixed dopant optimization for rapid screening of polycyclic aromatic hydrocarbons using ultra high performance liquid chromatography coupled to atmospheric pressure photoionization high-resolution mass spectrometry

    KAUST Repository

    Sioud, Salim

    2012-05-04

    RATIONALE To enhance the ionization efficiencies in atmospheric pressure photoionization mass spectrometry a dopant with favorable ionization energy such as chlorobenzene is typically used. These dopants are typically toxic and difficult to mix with water-soluble organic solvents. In order to achieve a more efficient and less toxic dopant, a multicomponent mixed dopant was explored. METHODS A multicomponent mixed dopant for non-targeted rapid screening of polycyclic aromatic hydrocarbons (PAHs) was developed and optimized using ultra high performance liquid chromatography (UPLC) coupled to atmospheric pressure photoionization high-resolution mass spectrometry. Various single and multicomponent mixed dopants consisting of ethanol, chlorobenzene, bromobenzene, anisole and toluene were evaluated. RESULTS Fourteen out of eighteen PAHs were successfully separated and detected at low pg/μL levels within 5 min with high mass accuracy ≤4 ppm. The optimal mixed multicomponent dopant consisted of ethanol/chlorobenzene/bromobenzene/anisole (98.975:0.1:0.9:0.025, v/v %) and it improved the limit of detection (LOD) by 2- to 10-fold for the tested PAHs compared to those obtained with pure chlorobenzene. CONCLUSIONS A novel multicomponent dopant that contains 99% ethanol and 1% mixture of chlorobenzene, bromobenzene and anisole was found to be an effective dopant mixture to ionize PAHs. The developed UPLC multicomponent dopant assisted atmospheric pressure photoionization high-resolution mass spectrometry offered a rapid non targeted screening method for detecting the PAHs at low pg/;μL levels within a 5 min run time with high mass accuracy a;circ4 ppm. Copyright © 2012 John Wiley & Sons, Ltd.

  20. Multicomponent mixed dopant optimization for rapid screening of polycyclic aromatic hydrocarbons using ultra high performance liquid chromatography coupled to atmospheric pressure photoionization high-resolution mass spectrometry.

    Science.gov (United States)

    Sioud, Salim; Amad, Ma'an; Al-Talla, Zeyad A

    2012-06-30

    To enhance the ionization efficiencies in atmospheric pressure photoionization mass spectrometry a dopant with favorable ionization energy such as chlorobenzene is typically used. These dopants are typically toxic and difficult to mix with water-soluble organic solvents. In order to achieve a more efficient and less toxic dopant, a multicomponent mixed dopant was explored. A multicomponent mixed dopant for non-targeted rapid screening of polycyclic aromatic hydrocarbons (PAHs) was developed and optimized using ultra high performance liquid chromatography (UPLC) coupled to atmospheric pressure photoionization high-resolution mass spectrometry. Various single and multicomponent mixed dopants consisting of ethanol, chlorobenzene, bromobenzene, anisole and toluene were evaluated. Fourteen out of eighteen PAHs were successfully separated and detected at low pg/μL levels within 5 min with high mass accuracy ≤4 ppm. The optimal mixed multicomponent dopant consisted of ethanol/chlorobenzene/bromobenzene/anisole (98.975:0.1:0.9:0.025, v/v %) and it improved the limit of detection (LOD) by 2- to 10-fold for the tested PAHs compared to those obtained with pure chlorobenzene. A novel multicomponent dopant that contains 99% ethanol and 1% mixture of chlorobenzene, bromobenzene and anisole was found to be an effective dopant mixture to ionize PAHs. The developed UPLC multicomponent dopant assisted atmospheric pressure photoionization high-resolution mass spectrometry offered a rapid non targeted screening method for detecting the PAHs at low pg/μL levels within a 5 min run time with high mass accuracy ≤4 ppm. Copyright © 2012 John Wiley & Sons, Ltd.

  1. Development and validation of a rapid ultra high pressure liquid chromatographic method for the determination of methylxanthines in herbal infusions.

    Science.gov (United States)

    Zacharis, Constantinos K; Kika, Fotini S; Tzanavaras, Paraskevas D; Fytianos, Konstantinos

    2013-05-15

    An ultra high pressure liquid chromatographic method coupled with diode array detector (UHPLC-DAD) has been developed and validated for the fast separation and determination of three major methylxanthines, i.e., caffeine, theophylline and theobromine, in various herbal beverages. Isocratic elution using 0.1vol% formic acid/CH3OH (92.5:7.5, v/v) enabled the completion of the separation cycle in less than 3min using a flow rate of 0.7mL/min and a column temperature of 50°C. Validation of the method included linearity (0.5-50mg/L), limits of detection (12-35μg/L) and quantification (40-120μg/L), precision, matrix effect and accuracy. The percent recoveries ranged between 90 and 108%. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Non-Invasive Method for the Rapid Assessment of Central Venous Pressure: Description and Validation by a Single Examiner

    Directory of Open Access Journals (Sweden)

    Zidulka, Arnold

    2008-11-01

    Full Text Available Objectives: This study describes a means of assessing the external jugular venous pressure (JVP as an indicator of normal or elevated central venous pressure (CVP.Methods: Intensive care unit patients having CVP monitoring were examined. With patients in bed, the external jugular vein (EJV was occluded at the base of the neck and observed to distend. The occlusion was then removed and the vein observed for collapse. Complete collapse was hypothesized to indicate a non-elevated CVP (≤8cm of water. In those patients whose EJV collapsed incompletely, the vein was then occluded with the finger near the angle of the jaw. With the occlusion maintained, the vein was milked downwards with the other hand to cause its emptying and was then observed for filling from below. Filling from below was hypothesized to indicate an elevated CVP (>8cm of water.Results: In 12 of the 40 patients examined, the EJV could not be assessed (EJV not seen at all: 5, and difficult to visualize: 7. For the remaining 28 patients, 11 had a CVP > 8 cm, while 17 had a CVP of < 8. EJV assessment was 100% accurate (95% Confidence Interval 88-100 in predicting whether or not a patient’s CVP was greater or less than 8 cm of water.Conclusion: EJV assessment, when visible, is accurate to clinically assess a patient’s CVP in the hands of the author. Further studies are needed to see if they are reproducible by other observer.[WestJEM. 2008;9:201-205.

  3. Chaos in a Water Drop.

    Science.gov (United States)

    Schneider, Scott Dudley

    Nature is chaotic. It appears to be more disorderly and random than orderly and regular. The path of a leaf in a rocky stream can appear as complex as the smoke from a cigarette or the outline of a cloud. In trying to model the path of a leaf in a rocky stream, the dynamical equations become rapidly complicated. A branch of scientific analysis know as Chaos has sprung up in the last few decades with techniques that can be applied to most of the physical sciences in an attempt to describe or categorize the various non-linear phenomena found in Nature. The aim of this paper is to provide an introduction to the study of chaotic behavior, with an emphasis on the potential teaching possibilities contained in some of the analysis. An appropriate beginning would be motion that is regular and "easy" to understand--stable motion. Along the way, various graphical representations will be developed that enable a clear viewing of the motion of the system under study. Next, the Logistic model will be used to gain an understanding of the nature of chaos; it is very comprehensive in representing the characteristics of chaos that will be studied in other systems. Another system studied is the three-dimensional Rossler model. In the study of the "dripping faucet", a time series of the periods between drips of water is recorded. Various techniques (collected from the introductory systems) are applied in an attempt to model the mechanism behind the water drops, or at least to characterize the graphical "animals" that we find. The water drop "attractor" is found to be chaotic, exhibiting many of the chaotic characteristics seen in other models. It is hoped that this work can be used as a primer for those students beginning a journey into Chaos, or as a reference tool for those already familiar with the topics enclosed. Many areas in this work were touched lightly; there is a rich un-tapped complexity still waiting future study. The waters here have only begun to be charted.

  4. Analysis of an Electrostatic MEMS Squeeze-film Drop Ejector

    Directory of Open Access Journals (Sweden)

    Edward P. Furlani

    2009-10-01

    Full Text Available We present an analysis of an electrostatic drop-on-demand MEMS fluid ejector. The ejector consists of a microfluidic chamber with a piston that is suspended a few microns beneath a nozzle plate. A drop is ejected when a voltage is applied between the orifice plate and the piston. This produces an electrostatic force that moves the piston towards the nozzle. The moving piston generates a squeeze-film pressure distribution that causes drop ejection. We discuss the operating physics of the ejector and present a lumped-element model for predicting its performance. We calibrate the model using coupled structural-fluidic CFD analysis.

  5. Laser impact on a drop

    CERN Document Server

    Klein, Alexander L; Bouwhuis, Wilco; Lhuissier, Henri; Sun, Chao; Snoeijer, Jacco H; Villermaux, Emmanuel; Lohse, Detlef; Gelderblom, Hanneke

    2016-01-01

    The impact of a laser pulse on a highly absorbing liquid drop can lead to a violent response: the drop is accelerated, strongly deforms, and eventually fragments. Shock waves, the ejection of matter, and even plasma formation can accompany this process ...

  6. Experimental studies on the evaporative heat transfer and pressure drop of CO{sub 2} and CO{sub 2}/propane mixtures flowing upward in smooth and micro-fin tubes with outer diameter of 5 mm for an inclination angle of 45

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jin Min; Kim, Min Soo [School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-744 (Korea); Kim, Yong Jin [School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

    2010-08-15

    Heat transfer characteristics show different tendency according to the tube orientations such as horizontal, vertical, and inclined positions. In this study, evaporative heat transfer characteristics and pressure drop of CO{sub 2} and CO{sub 2}/propane mixtures flowing upward are investigated in inclined smooth and micro-fin tubes. Smooth and micro-fin tubes with outer diameter of 5 mm and length of 1.44 m with inclination angle of 45 were chosen as test tubes. Average inner diameters of test tubes are 4.0 mm (smooth tube) and 4.13 mm (micro-fin tube). The tests were conducted at mass fluxes from 212 to 656 kg/m{sup 2} s, saturation temperatures from -10 to 30 C and heat fluxes from 15 to 60 kW/m{sup 2} for CO{sub 2}. In addition, for CO{sub 2}/propane mixtures, the test was carried out at inlet temperatures from -10 to 30 C for several compositions (75/25, 50/50, 25/75 wt%) with the same mass fluxes, heat fluxes applied for CO{sub 2}. Heat transfer coefficients in inclined tube are approximately 1.8-3 times higher than those in horizontal tube and the average pressure drop of inclined tube exists between that of horizontal and vertical tubes. (author)

  7. Diseño en cosmosfloworks del conducto experimental para la medición de la caída de presión del aire al paso de bandejas metálicas Cosmosfloworks design of an experimental duct for measurement of the drop in air pressure after its passage through metal trays

    Directory of Open Access Journals (Sweden)

    Alejandro Escalante

    2009-07-01

    Full Text Available En el siguiente artículo se presenta el proceso de desarrollo de diseño del conducto experimental que facilita la medición de la caída de presión del aire tras su paso por bandejas metálicas. El diseño se fundamenta en los resultados arrojados por las simulaciones realizadas a diferentes disposiciones en la etapa inicial del conducto, y la validación de los datos de la simulación más representativa con un prototipo del conducto real con esta misma distribución. Para este estudio se usó software Cosmosfloworks [1], con el cual se analizaron las líneas de corriente y la caída de presión del fluido en el conducto.The following article presents the development’s process of designing an experimental duct which facilitates the measurement of the drop in air pressure after its going through metal trays. The design is based on the results of simulations conducted at various provisions of the duct, and validation of data from the most representative simulation through actual prototype with the same distribution. For this study, we used [1], with which curves of fluid and pressure drop of the fluid were analyzed.

  8. In vivo biosynthesis of L-(/sup 35/S)Cys-arginine vasopressin, -oxytocin, and -somatostatin: rapid estimation using reversed phase high pressure liquid chromatography. [Rats

    Energy Technology Data Exchange (ETDEWEB)

    Franco-Bourland, R.E.; Fernstrom, J.D.

    1981-01-01

    L(/sup 35/S)Cys-arginine vasopressin, -oxytocin, and -somatostatin were purified from hypothalami and neurohypophyses 4 h after rats received L(/sup 35/S)Cys via the third ventricle. After acetic acid extraction, Sephadex G-25 filtration, and chemoadsorption to C18-silica (Sep-Pak cartridges), the labeled peptides were rapidly separated by gradient elution, reversed phase, high pressure liquid chromatography (HPLC). The identity and isotopic purity of the labeled peptides were determined by several reversed phase HPLC procedures in conjunction with chemical modification. The labeled peptide fractions were at least 50% radiochemically pure. Using this HPLC isolation procedure, incorporation of L-(/sup 35/S)Cys into each peptide was determined in hydrated and dehydrated rats. Label incorporation into arginine vasopressin and oxytocin in the hypothalamus and the neurohypophysis of dehydrated rats was 2-3 times greater than that in hydrated rats. Incorporation of label into hypothalamic and neurohypophyseal somatostatin was unaffected by the hydration state of the animal. This procedure thus provides a very rapid, but sensitive, set of techniques for studying the control of small peptide biosynthesis in the brain.

  9. Coalescence and noncoalescence of sessile drops: impact of surface forces.

    Science.gov (United States)

    Karpitschka, Stefan; Hanske, Christoph; Fery, Andreas; Riegler, Hans

    2014-06-17

    Due to capillarity, sessile droplets of identical liquids will instantaneously fuse when they come in contact at their three-phase lines. However, with drops of different, completely miscible liquids, instantaneous coalescence can be suppressed. Instead, the drops remain in a state of noncoalescence for some time, with the two drop bodies connected only by a thin neck. The reason for this noncoalescence is the surface tension difference, Δγ, between the liquids. If Δγ is sufficiently large, then it induces a sufficiently strong Marangoni flow, which keeps the main drop bodies temporarily separated. Studies with spreading drops have revealed that the boundary between instantaneous coalescence and noncoalescence is sharp (Karpitschka, S.; Riegler, H. J. Fluid. Mech. 2014, 743, R1). The boundary is a function of two parameters only: Δγ and Θ(a), the arithmetic mean of the contact angles in the moment of drop-drop contact. It appears plausible that surface forces (the disjoining pressure) could also influence the coalescence behavior. However, in experiments with spreading drops, surface forces always promote coalescence and their influence might be obscured. Therefore, we present here coalescence experiments with partially wetting liquids and compare the results to the spreading case. We adjust different equilibrium contact angles (i.e., different surface forces) with different substrate surface coatings. As for spreading drops, we observe a sharp boundary between regimes of coalescence and noncoalescence. The boundary follows the same power law relation for both partially and completely wetting cases. Therefore, we conclude that surface forces have no significant, explicit influence on the coalescence behavior of sessile drops from different miscible liquids.

  10. Drop spreading with random viscosity

    CERN Document Server

    Xu, Feng

    2016-01-01

    We examine theoretically the spreading of a viscous liquid drop over a thin film of uniform thickness, assuming the liquid's viscosity is regulated by the concentration of a solute that is carried passively by the spreading flow. The solute is assumed to be initially heterogeneous, having a spatial distribution with prescribed statistical features. To examine how this variability influences the drop's motion, we investigate spreading in a planar geometry using lubrication theory, combining numerical simulations with asymptotic analysis. We assume diffusion is sufficient to suppress solute concentration gradients across but not along the film. The solute field beneath the bulk of the drop is stretched by the spreading flow, such that the initial solute concentration immediately behind the drop's effective contact lines has a long-lived influence on the spreading rate. Over long periods, solute swept up from the precursor film accumulates in a short region behind the contact line, allowing patches of elevated v...

  11. 45-FOOT HIGH DROP TOWER

    Data.gov (United States)

    Federal Laboratory Consortium — The Drop Tower is used to simulate and measure the impact shocks that are exerted on parachute loads when they hit the ground. It is also used for HSL static lift to...

  12. Volcanoes drive climate variability by emitting ozone weeks before eruptions, by forming lower stratospheric aerosols, by causing sustained ozone depletion, and by causing rapid changes in regional ozone concentrations affecting temperature and pressure differences driving atmospheric oscillations

    Science.gov (United States)

    Ward, P. L.

    2016-12-01

    Total column ozone observed by satellite on February 19, 2010, increased 75% in a plume from Eyjafjallajökull volcano in southern Iceland eastward past Novaya Zemlya, extending laterally from northern Greenland to southern Norway (http://youtu.be/wJFZcPEfoR4). Contemporaneous ground deformation and rapidly increasing numbers of earthquakes imply magma began rising from a sill 4-6 km below the volcano, erupting a month later. Whether the ozone formed from the magma or from very hot gases rising through cracks in the ground is unclear. On February 20-22, 1991, similar increases in ozone were observed north of Pinatubo volcano before its initial eruption on April 2 (http://youtu.be/5y1PU2Qu3ag). Annual average total column ozone during the year of most moderate to large explosive volcanic eruptions since routine observations of ozone began in 1927 has been substantially higher than normal. Increased total column ozone absorbs more solar ultraviolet-B radiation, warming the ozone layer and cooling Earth. Most major volcanic eruptions form sulfuric-acid aerosols in the lower part of the ozone layer providing aqueous surfaces on which heterogeneous chemical reactions enhance ozone depletion. Within a year, aerosol droplets grew large enough to reflect and scatter high-frequency solar radiation, cooling Earth 0.5oC for 2-3 years. Temperature anomalies in the northern hemisphere rose 0.7oC in 28 years from 1970 to 1998 (HadCRUT4), while annual average ozone at Arosa dropped 27 DU because of manufactured CFC gases. Beginning in August 2014, temperature anomalies in the northern hemisphere rose another 0.6oC in less than two years apparently because of the 6-month eruption of Bárðarbunga volcano in central Iceland, the highest rate of basaltic lava extrusion since 1783. Large extrusions of basaltic lava are typically contemporaneous with the greatest periods of warming throughout Earth history. Ozone concentrations at Arosa change by season typically from 370 DU during

  13. Fast H-DROP: A thirty times accelerated version of H-DROP for interactive SVM-based prediction of helical domain linkers

    Science.gov (United States)

    Richa, Tambi; Ide, Soichiro; Suzuki, Ryosuke; Ebina, Teppei; Kuroda, Yutaka

    2017-02-01

    Efficient and rapid prediction of domain regions from amino acid sequence information alone is often required for swift structural and functional characterization of large multi-domain proteins. Here we introduce Fast H-DROP, a thirty times accelerated version of our previously reported H-DROP (Helical Domain linker pRediction using OPtimal features), which is unique in specifically predicting helical domain linkers (boundaries). Fast H-DROP, analogously to H-DROP, uses optimum features selected from a set of 3000 ones by combining a random forest and a stepwise feature selection protocol. We reduced the computational time from 8.5 min per sequence in H-DROP to 14 s per sequence in Fast H-DROP on an 8 Xeon processor Linux server by using SWISS-PROT instead of Genbank non-redundant (nr) database for generating the PSSMs. The sensitivity and precision of Fast H-DROP assessed by cross-validation were 33.7 and 36.2%, which were merely 2% lower than that of H-DROP. The reduced computational time of Fast H-DROP, without affecting prediction performances, makes it more interactive and user-friendly. Fast H-DROP and H-DROP are freely available from http://domserv.lab.tuat.ac.jp/.

  14. Drop coalescence through a liquid/liquid interface

    Science.gov (United States)

    Mohamed-Kassim, Zulfaa; Longmire, Ellen K.

    2004-07-01

    Particle image velocimetry (PIV) experiments were conducted to study the coalescence of single drops through planar liquid/liquid interfaces. Sequences of velocity vector fields were obtained with a high-speed video camera and subsequent PIV analysis. Two ambient liquids with different viscosity but similar density were examined resulting in Reynolds numbers based on a surface tension velocity of 10 and 26. Prior to rupture, the drops rested on a thin film of ambient liquid above an underlying interface. After rupture, which was typically off-axis, the free edge of the thin film receded rapidly allowing the drop fluid to sink into the bulk liquid below. Vorticity generated in the collapsing fluid developed into a vortex ring straddling the upper drop surface. The ring core traveled radially inward with a ring-shaped capillary wave effectively pinching the upper drop surface and increasing the drop collapse speed. The inertia of the collapse deflected the interface downward before it rebounded upward. During this time, the vortex core split so that part of its initial vorticity moved inside the drop fluid while part remained in the ambient fluid above it. A second ring-shaped capillary wave formed along the interface outside of the drop and propagated radially outward during the collapse. Changing the ambient fluid viscosity resulted in several effects. First, the velocity of the receding free edge was smaller for higher ambient viscosity. Second, the pinching of the upper drop surface caused by the shrinking capillary ring wave was stronger when the ambient viscosity was lower, and this resulted in a higher maximum collapse speed and higher vorticity values in the dominant vortex ring.

  15. VTrans Small Culvert Inventory - Drop Inlets

    Data.gov (United States)

    Vermont Center for Geographic Information — Vermont Agency of Transportation Small Culvert Inventory: Drop Inlets. This data contains drop inlets locations along VTrans maintained roadways. The data was...

  16. Optimization of pressurized liquid extraction (PLE) for rapid determination of mineral oil saturated (MOSH) and aromatic hydrocarbons (MOAH) in cardboard and paper intended for food contact.

    Science.gov (United States)

    Moret, Sabrina; Sander, Maren; Purcaro, Giorgia; Scolaro, Marianna; Barp, Laura; Conte, Lanfranco S

    2013-10-15

    Packaging can represent a primary source of food contamination with mineral oil saturated hydrocarbons (MOSH) and aromatic hydrocarbons (MOAH), especially when recycled cardboard or mineral oil based printing inks are used. A pressurized liquid extraction (PLE) method, followed by on-line LC-GC analysis, has been optimized for rapid mineral oil determination in cardboard and paper samples. The proposed method involves extraction with hexane (2 cycles) at 60°C for 5 min, and allows for the processing of up to 6 samples in parallel with minimal sample manipulation and solvent consumption. It gave good repeatability (coefficient of variation lower than 5%) and practically quantitative extraction yield (less than 2% of the total contamination found in a third separate cycle). The method was applied to different cardboards and paper materials intended for food contact. Results obtained were similar to those obtained by applying classical solvent extraction with hexane/ethanol 1:1 (v/v) as described by Lorenzini et al. [20]. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Drop Spreading with Random Viscosity

    Science.gov (United States)

    Xu, Feng; Jensen, Oliver

    2016-11-01

    Airway mucus acts as a barrier to protect the lung. However as a biological material, its physical properties are known imperfectly and can be spatially heterogeneous. In this study we assess the impact of these uncertainties on the rate of spreading of a drop (representing an inhaled aerosol) over a mucus film. We model the film as Newtonian, having a viscosity that depends linearly on the concentration of a passive solute (a crude proxy for mucin proteins). Given an initial random solute (and hence viscosity) distribution, described as a Gaussian random field with a given correlation structure, we seek to quantify the uncertainties in outcomes as the drop spreads. Using lubrication theory, we describe the spreading of the drop in terms of a system of coupled nonlinear PDEs governing the evolution of film height and the vertically-averaged solute concentration. We perform Monte Carlo simulations to predict the variability in the drop centre location and width (1D) or area (2D). We show how simulation results are well described (at much lower computational cost) by a low-order model using a weak disorder expansion. Our results show for example how variability in the drop location is a non-monotonic function of the solute correlation length increases. Engineering and Physical Sciences Research Council.

  18. Detection of bubble nucleation event in superheated drop detector ...

    Indian Academy of Sciences (India)

    The present work demonstrates the detection of bubble nucleation events by using the pressure sensor. The associated circuits for the measurement are described in this article. The detection of events is verified by measuring the events with the acoustic sensor. The measurement was done using drops of various sizes to ...

  19. Matrix-assisted laser desorption/ionization mass spectrometry for quantitative determination of β-blocker drugs in one-drop of human serum sample.

    Science.gov (United States)

    Shrivas, Kamlesh; Patel, Devesh Kumar

    2011-01-01

    Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) has been applied for the quantitative determination of β-blocker drugs in one-drop of human serum samples using drop-to-drop solvent microextraction (DDSME) as a preconcentrating probe. The optimum experimental conditions for β-blocker drugs were investigated and 1.8 μL volume of toluene for 10 min extraction time with the 5% addition of NaCl under pH 11.0 was found to be the best conditions for the separation and preconcentration of drugs from 30 μL of serum sample from a patient with high blood pressure. The optimized methodologies for DDSME/MALDI-MS analyses exhibited a good linearity with intra- and inter day precision value of 8.5-10.5% and 9.4-12.6%, respectively. The proposed DDSME/MALDI-MS offers a very simple, rapid and low-cost technique for the determination of β-blocker drugs in one drop of serum sample. The reported method has been successfully applied for the determination of propranolol and nadolol in small volume of serum sample from patient suffering from high blood pressure. In future, this technique could be applied for pharmacokinetic and clinical studies. Copyright © 2010 Elsevier B.V. All rights reserved.

  20. Queda de pressão estática por meio de uma coluna de noz macadâmia Static pressure drop through a column of macadamia nut

    Directory of Open Access Journals (Sweden)

    Marco A. M. Biaggioni

    2005-08-01

    Full Text Available As unidades de beneficiamento de macadâmia adotam silos secadores distintos, para cada etapa de secagem, a fim de garantir a manutenção da qualidade do produto pela redução da umidade a níveis desejáveis. Diante da necessidade de quantificar a resistência apresentada pelas nozes, submetidas a diferentes fluxos de ar durante a secagem, bem como avaliar a possibilidade de utilização de modelos empíricos, que estimem o gradiente de pressão a partir da vazão de ar, conduziram-se vários testes em laboratório para obtenção de dados experimentais e ajuste de modelos. Frutos de macadâmia (M. integrifolia, com umidade de 0,11 b.s., após limpeza e classificação, foram colocados no interior de um protótipo constituído por uma coluna de chapa galvanizada (com tomadas para medição da pressão estática, plenum e ventilador, sendo submetidos a diferentes fluxos de ar. Os testes consistiram de três medidas por profundidade, para cada um dos três lotes de nozes, perfazendo um total de nove medidas de pressão estática por profundidade na coluna. Os resultados obtidos permitiram concluir que os fluxos de ar testados apresentaram efeito significativo sobre a queda de pressão estática na coluna de macadâmia, a qual aumentou linearmente com a profundidade. Os dados experimentais ajustaram-se muito bem aos modelos de Shedd e Hunter, sugerindo sua boa aplicabilidade para a macadâmia.The macadamia processing units use different drying silos, for each drying stage, in order to reduce nuts-in-shell moisture content. Due to the need to quantify the resistance presented by the nuts submitted to different drying airflows, as well as, to evaluate the use of empiric models that predicted pressure losses from airflow, it was carried out several tests in laboratory to obtain experimental data and adjustment of models. Macadamia nuts (M. integrifolia with 0.11 b.s. moisture content after cleaning and classification were placed into an apparatus

  1. Combining spray nozzle simulators with meshes: characterization of rainfall intensity and drop properties

    Science.gov (United States)

    Carvalho, Sílvia C. P.; de Lima, João L. M. P.; de Lima, M. Isabel P.

    2013-04-01

    Rainfall simulators can be a powerful tool to increase our understanding of hydrological and geomorphological processes. Nevertheless, rainfall simulators' design and operation might be rather demanding, for achieving specific rainfall intensity distributions and drop characteristics. The pressurized simulators have some advantages over the non-pressurized simulators: drops do not rely on gravity to reach terminal velocity, but are sprayed out under pressure; pressurized simulators also yield a broad range of drop sizes in comparison with drop-formers simulators. The main purpose of this study was to explore in the laboratory the potential of combining spray nozzle simulators with meshes in order to change rainfall characteristics (rainfall intensity and diameters and fall speed of drops). Different types of spray nozzles were tested, such as single full-cone and multiple full-cone nozzles. The impact of the meshes on the simulated rain was studied by testing different materials (i.e. plastic and steel meshes), square apertures and wire thicknesses, and different vertical distances between the nozzle and the meshes underneath. The diameter and fall speed of the rain drops were measured using a Laser Precipitation Monitor (Thies Clima). The rainfall intensity range and coefficients of uniformity of the sprays and the drop size distribution, fall speed and kinetic energy were analysed. Results show that when meshes intercept drop trajectories the spatial distribution of rainfall intensity and the drop size distribution are affected. As the spray nozzles generate typically small drop sizes and narrow drop size distributions, meshes can be used to promote the formation of bigger drops and random their landing positions.

  2. Accurate Mass Fragment Library for Rapid Analysis of Pesticides on Produce Using Ambient Pressure Desorption Ionization with High-Resolution Mass Spectrometry

    Science.gov (United States)

    Kern, Sara E.; Lin, Lora A.; Fricke, Frederick L.

    2014-08-01

    U.S. food imports have been increasing steadily for decades, intensifying the need for a rapid and sensitive screening technique. A method has been developed that uses foam disks to sample the surface of incoming produce. This work provides complimentary information to the extensive amount of published pesticide fragmentation data collected using LCMS systems (Sack et al. Journal of Agricultural and Food Chemistry, 59, 6383-6411, 2011; Mol et al. Analytical and Bioanalytical Chemistry, 403, 2891-2908, 2012). The disks are directly analyzed using transmission-mode direct analysis in real time (DART) ambient pressure desorption ionization coupled to a high resolution accurate mass-mass spectrometer (HRAM-MS). In order to provide more certainty in the identification of the pesticides detected, a library of accurate mass fragments and isotopes of the protonated parent molecular ion (the [M+H]+) has been developed. The HRAM-MS is equipped with a quadrupole mass filter, providing the capability of "data-dependent" fragmentation, as opposed to "all -ion" fragmentation (where all of the ions enter a collision chamber and are fragmented at once). A temperature gradient for the DART helium stream and multiple collision energies were employed to detect and fragment 164 pesticides of varying chemical classes, sizes, and polarities. The accurate mass information of precursor ([M+H]+ ion) and fragment ions is essential in correctly identifying chemical contaminants on the surface of imported produce. Additionally, the inclusion of isotopes of the [M+H]+ in the database adds another metric to the confirmation process. The fragmentation data were collected using a Q-Exactive mass spectrometer and were added to a database used to process data collected with an Exactive mass spectrometer, an instrument that is more readily available for this screening application. The commodities investigated range from smooth-skinned produce such as apples to rougher surfaces like broccoli. The

  3. Drops, contact lines, and electrowetting

    NARCIS (Netherlands)

    't Mannetje, Dieter

    2013-01-01

    In this work, we study the behaviour of drops and contact lines under the influence of electric fields, and how these can answer fundamental and industrial questions. Our focus is on studying the varying balance of the electric field, hysteresis forces and inertia as the speed of a contact line

  4. Astrocyte Structural and Molecular Response to Elevated Intraocular Pressure Occurs Rapidly and Precedes Axonal Tubulin Rearrangement within the Optic Nerve Head in a Rat Model.

    Directory of Open Access Journals (Sweden)

    Shandiz Tehrani

    Full Text Available Glaucomatous axon injury occurs at the level of the optic nerve head (ONH in response to uncontrolled intraocular pressure (IOP. The temporal response of ONH astrocytes (glial cells responsible for axonal support to elevated IOP remains unknown. Here, we evaluate the response of actin-based astrocyte extensions and integrin-based signaling within the ONH to 8 hours of IOP elevation in a rat model. IOP elevation of 60 mm Hg was achieved under isoflurane anesthesia using anterior chamber cannulation connected to a saline reservoir. ONH astrocytic extension orientation was significantly and regionally rearranged immediately after IOP elevation (inferior ONH, 43.2° ± 13.3° with respect to the anterior-posterior axis versus 84.1° ± 1.3° in controls, p<0.05, and re-orientated back to baseline orientation 1 day post IOP normalization. ONH axonal microtubule filament label intensity was significantly reduced 1 and 3 days post IOP normalization, and returned to control levels on day 5. Phosphorylated focal adhesion kinase (FAK levels steadily decreased after IOP normalization, while levels of phosphorylated paxillin (a downstream target of FAK involved in focal adhesion dynamics were significantly elevated 5 days post IOP normalization. The levels of phosphorylated cortactin (a downstream target of Src kinase involved in actin polymerization were significantly elevated 1 and 3 days post IOP normalization and returned to control levels by day 5. No significant axon degeneration was noted by morphologic assessment up to 5 days post IOP normalization. Actin-based astrocyte structure and signaling within the ONH are significantly altered within hours after IOP elevation and prior to axonal cytoskeletal rearrangement, producing some responses that recover rapidly and others that persist for days despite IOP normalization.

  5. Experimental investigation of a rapidly rotating turbulent duct flow

    Energy Technology Data Exchange (ETDEWEB)

    Maartensson, G.E.; Johansson, A.V. [Department of Mechanics, KTH, 10044 Stockholm (Sweden); Gunnarsson, J. [Bombardier Transportation, Vaesteraas (Sweden); Moberg, H. [Alfa Laval, 14780 Tumba (Sweden)

    2002-09-01

    Rapidly rotating duct flow is studied experimentally with Rotation numbers in the interval. To achieve this, in combination with relatively high Reynolds numbers (5,000-30,000 based on the hydraulic radius), water was used as the working medium. Square and rectangular duct cross-sections were used and the angle between the rotation vector and the main axis of the duct was varied. The influence of the rotation on the pressure drop in the duct was investigated and suitable scalings of this quantity were studied. (orig.)

  6. Experimental investigation of picoliter liquid drops evaporation on a heated solid surface

    Science.gov (United States)

    Kirichenko, D. P.; Zaitsev, D. V.; Kabov, O. A.

    2017-11-01

    This paper presents a study of the evaporation of sessile picoliter liquid drops on a heated solid surface. It has been shown that during evaporation diameter of the drop is almost constant (the contact line is pinned) and starts to decrease only at the final moment of drop life. It has been shown that the specific evaporation rate of a droplet (droplet weight loss per unit time per unit droplet surface area) is not constant over time: it gradually grows with time up to a maximum, but at the final stage, when the height of the drop becomes on the order of 1 μm, it decreases rapidly.

  7. Plants survive rapid decompression: Implications for bioregenerative life support

    Science.gov (United States)

    Wheeler, R. M.; Wehkamp, C. A.; Stasiak, M. A.; Dixon, M. A.; Rygalov, V. Y.

    2011-05-01

    Radish (Raphanus sativus), lettuce (Latuca sativa), and wheat (Triticum aestivum) plants were grown at either 98 kPa (ambient) or 33 kPa atmospheric pressure with constant 21 kPa oxygen and 0.12 kPa carbon dioxide in atmospherically closed pressure chambers. All plants were grown rockwool using recirculating hydroponics with a complete nutrient solution. At 20 days after planting, chamber pressures were pumped down as rapidly as possible, reaching 5 kPa after about 5 min and ˜1.5 kPa after about 10 min. The plants were held at 1.5 kPa for 30 min and then pressures were restored to their original settings. Temperature (22 °C) and humidity (65% RH) controls were engaged throughout the depressurization, although temperatures dropped to near 16 °C for a brief period. CO2 and O2 were not detectable at the low pressure, suggesting that most of the 1.5 kPa atmosphere consisted of water vapor. Following re-pressurization, plants were grown for another 7 days at the original pressures and then harvested. The lettuce, radish, and wheat plants showed no visible effects from the rapid decompression, and there were no differences in fresh or dry mass when compared to control plants maintained continuously at 33 or 98 kPa. But radish storage root fresh mass and lettuce head fresh and dry masses were less at 33 kPa compared to 98 kPa for both the controls and decompression treatment. The results suggest that plants are extremely resilient to rapid decompression, provided they do not freeze (from evaporative cooling) or desiccate. The water of the hydroponic system was below the boiling pressure during these tests and this may have protected the plants by preventing pressures from dropping below 1.5 kPa and maintaining humidity near 1.5 kPa. Further testing is needed to determine how long plants can withstand such low pressure, but the results suggest there are at least 30 min to respond to catastrophic pressure losses in a plant production chamber that might be used for life

  8. Vaporization response of evaporating drops with finite thermal conductivity

    Science.gov (United States)

    Agosta, V. D.; Hammer, S. S.

    1975-01-01

    A numerical computing procedure was developed for calculating vaporization histories of evaporating drops in a combustor in which travelling transverse oscillations occurred. The liquid drop was assumed to have a finite thermal conductivity. The system of equations was solved by using a finite difference method programmed for solution on a high speed digital computer. Oscillations in the ratio of vaporization of an array of repetitivity injected drops in the combustor were obtained from summation of individual drop histories. A nonlinear in-phase frequency response factor for the entire vaporization process to oscillations in pressure was evaluated. A nonlinear out-of-phase response factor, in-phase and out-of-phase harmonic response factors, and a Princeton type 'n' and 'tau' were determined. The resulting data was correlated and is presented in graphical format. Qualitative agreement with the open literature is obtained in the behavior of the in-phase response factor. Quantitatively the results of the present finite conductivity spray analysis do not correlate with the results of a single drop model.

  9. Mapping coalescence of micron-sized drops and bubbles.

    Science.gov (United States)

    Berry, Joseph D; Dagastine, Raymond R

    2017-02-01

    Emulsion formulation, solvent extraction and multiphase microfluidics are all examples of processes that require precise control of drop or bubble collision stability. We use a previously validated numerical model to map the exact conditions under which micron-sized drops or bubbles undergo coalescence in the presence of colloidal forces and hydrodynamic effects relevant to Brownian motion and low Reynolds number flows. We demonstrate that detailed understanding of how the equilibrium surface forces vary with film thickness can be applied to make accurate predictions of the outcome of a drop or bubble collision when hydrodynamic effects are negligible. In addition, we illuminate the parameter space (i.e. interaction velocity, drop deformation, interfacial tension, etc.) at which hydrodynamic effects can stabilise collisions that are unstable at equilibrium. Further, we determine conditions for which drop or bubble collisions become unstable upon separation, caused by negative hydrodynamic pressure in the film. Lastly, we show that scaling analyses are not applicable for constant force collisions where the approach timescale is comparable to the coalescence timescale, and demonstrate that initial conditions under these circumstances cannot be ignored. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Influence of droplet geometry on the coalescence of low viscosity drops.

    Science.gov (United States)

    Eddi, A; Winkels, K G; Snoeijer, J H

    2013-10-04

    The coalescence of water drops on a substrate is studied experimentally. We focus on the rapid growth of the bridge connecting the two drops, which very quickly after contact ensues from a balance of surface tension and liquid inertia. For drops with contact angles below 90°, we find that the bridge grows with a self-similar dynamics that is characterized by a height h~t(2/3). By contrast, the geometry of coalescence changes dramatically for contact angles at 90°, for which we observe h~t(1/2), just as for freely suspended spherical drops in the inertial regime. We present a geometric model that quantitatively captures the transition from 2/3 to 1/2 exponent, and unifies the inertial coalescence of sessile drops and freely suspended drops.

  11. Acoustically levitated dancing drops: Self-excited oscillation to chaotic shedding

    Science.gov (United States)

    Lin, Po-Cheng; I, Lin

    2016-02-01

    We experimentally demonstrate self-excited oscillation and shedding of millimeter-sized water drops, acoustically levitated in a single-node standing waves cavity, by decreasing the steady acoustic wave intensity below a threshold. The perturbation of the acoustic field by drop motion is a possible source for providing an effective negative damping for sustaining the growing amplitude of the self-excited motion. Its further interplay with surface tension, drop inertia, gravity and acoustic intensities, select various self-excited modes for different size of drops and acoustic intensity. The large drop exhibits quasiperiodic motion from a vertical mode and a zonal mode with growing coupling, as oscillation amplitudes grow, until falling on the floor. For small drops, chaotic oscillations constituted by several broadened sectorial modes and corresponding zonal modes are self-excited. The growing oscillation amplitude leads to droplet shedding from the edges of highly stretched lobes, where surface tension no longer holds the rapid expanding flow.

  12. Increased medial foot loading during drop jump in subjects with patellofemoral pain

    DEFF Research Database (Denmark)

    Rathleff, Michael S; Richter, Camilla; Brushøj, Christoffer

    2014-01-01

    PURPOSE: To compare medial-to-lateral plantar forces during drop jump and single leg squat in individuals with and without patellofemoral pain. METHODS: This cross-sectional study compared 23 young adults with patellofemoral pain to 20 age- and sex-matched controls without knee pain. The plantar...... pressure distribution was collected during drop jump and single leg squat using pressure-sensitive Pedar insoles, inserted into a standard flat shoe. The primary outcome was the medial-to-lateral force, quantified as the peak force under the medial forefoot as the percentage of force under the total...... forefoot during drop jump. Secondary outcomes included peak medial-to-lateral force during single leg squat and mean forces during drop jump and single leg squat. RESULTS: The primary outcome showed that individuals with patellofemoral pain had a 22 % higher medial-to-lateral peak force during drop jump...

  13. Microfluidic Wheatstone bridge for rapid sample analysis.

    Science.gov (United States)

    Tanyeri, Melikhan; Ranka, Mikhil; Sittipolkul, Natawan; Schroeder, Charles M

    2011-12-21

    We developed a microfluidic analogue of the classic Wheatstone bridge circuit for automated, real-time sampling of solutions in a flow-through device format. We demonstrate precise control of flow rate and flow direction in the "bridge" microchannel using an on-chip membrane valve, which functions as an integrated "variable resistor". We implement an automated feedback control mechanism in order to dynamically adjust valve opening, thereby manipulating the pressure drop across the bridge and precisely controlling fluid flow in the bridge channel. At a critical valve opening, the flow in the bridge channel can be completely stopped by balancing the flow resistances in the Wheatstone bridge device, which facilitates rapid, on-demand fluid sampling in the bridge channel. In this article, we present the underlying mechanism for device operation and report key design parameters that determine device performance. Overall, the microfluidic Wheatstone bridge represents a new and versatile method for on-chip flow control and sample manipulation.

  14. Drag and drop display & builder

    Energy Technology Data Exchange (ETDEWEB)

    Bolshakov, Timofei B.; Petrov, Andrey D.; /Fermilab

    2007-12-01

    The Drag and Drop (DnD) Display & Builder is a component-oriented system that allows users to create visual representations of data received from data acquisition systems. It is an upgrade of a Synoptic Display mechanism used at Fermilab since 2002. Components can be graphically arranged and logically interconnected in the web-startable Project Builder. Projects can be either lightweight AJAX- and SVG-based web pages, or they can be started as Java applications. The new version was initiated as a response to discussions between the LHC Controls Group and Fermilab.

  15. Studies on micro-structures at vapor-liquid interfaces of film boiling on hot liquid surface at arriving of a shock pressure

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Akira; Lee, S. [Tokyo Inst. of Tech. (Japan)

    1998-01-01

    In vapor explosions, a pressure wave (shock wave) plays a fundamental role in the generation, propagation and escalation of the explosion. Transient volume change by rapid heat flow from a high temperature liquid to a low temperature volatile one and phase change generate micro-scale flow and the pressure wave. One of key issues for the vapor explosion is to make clear the mechanism to support the explosive energy release from hot drop to cold liquid. According to our observations by an Image Converter Camera, growth rate of vapor film around a hot tin drop became several times higher than that around a hot Platinum tube at the same conditions when a pressure pulse collapsed the film. The thermally induced fragmentation was followed by the explosive growth rate of the hot drop. In the previous report, we have proposed that the interface instability and fragmentation model in which the fine Taylor instability of vapor-liquid interface at the collapsing and re-growth phase of vapor film and the instability induced by the high pressure spots at the drop surface were assumed. In this study, the behavior of the vapor-liquid interface region at arrival of a pressure pulse was investigated by the CIPRIS code which is able to simulate dynamics of transient multi-phase interface regions. It is compared with the observation results. Through detailed investigations of these results, the mechanisms of the thermal fragmentation of single drop are discussed. (J.P.N.)

  16. Heat transfer and pressure drop in microchannels with random roughness

    NARCIS (Netherlands)

    Pelevic, N.; van der Meer, Theodorus H.

    2016-01-01

    The effect of surface roughness on heat transfer and fluid flow phenomena within a microchannel has been investigated by using the lattice Boltzmann method. The surface roughness has been generated by using Gaussian function. Gaussian function is an efficient and convenient method to create surface

  17. Complex cooling water systems optimization with pressure drop consideration

    CSIR Research Space (South Africa)

    Gololo, KV

    2012-12-01

    Full Text Available -integer nonlinear programming (MINLP) structure. The cooling tower model is used to predict the exit conditions of the cooling towers, given the inlet conditions from the cooling water network model. The case studies showed that the circulating cooling water flow...

  18. Sludge pipe flow pressure drop prediction using composite power ...

    African Journals Online (AJOL)

    ... pipes, the rheology of the fluid plays an important role, especially with increasing concentration of the suspended matter in the sludge. The f-Re relationship is often applied when designing pipelines, but it depends on the rheological parameters of the fluid and what definition of non-Newtonian Reynolds number is used.

  19. Modeling of Pressure Drop During Refrigerant Condensation in Pipe Minichannels

    Science.gov (United States)

    Sikora, Małgorzata; Bohdal, Tadeusz

    2017-12-01

    Investigations of refrigerant condensation in pipe minichannels are very challenging and complicated issue. Due to the multitude of influences very important is mathematical and computer modeling. Its allows for performing calculations for many different refrigerants under different flow conditions. A large number of experimental results published in the literature allows for experimental verification of correctness of the models. In this work is presented a mathematical model for calculation of flow resistance during condensation of refrigerants in the pipe minichannel. The model was developed in environment based on conservation equations. The results of calculations were verified by authors own experimental investigations results.

  20. A simple low pressure drop suspension-based microfluidic mixer

    NARCIS (Netherlands)

    Workamp, M.J.; Saggiomo, V.; Dijksman, J.A.

    2015-01-01

    We present a novel microfluidic mixer that is easy to fabricate and simple to use. The mixer features a single mixing chamber in which particles are driven by a moving magnet. We show that the mixing efficiency is markedly increased by addition of particles to the chip, as a result of the diffusive

  1. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... Search Form Search the NHLBI, use the drop down list to select: the entire site, the Health ... flow more freely, causing blood pressure to go down. Alpha-Beta Blockers: Reduce nerve impulses the same ...

  2. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... Font Size Accessible Search Form Search the NHLBI, use the drop down list to select: the entire ... primary high blood pressure. Health care providers can use this information to develop your treatment plan. Some ...

  3. Drop shaping by laser-pulse impact

    CERN Document Server

    Klein, Alexander L; Visser, Claas Willem; Lhuissier, Henri; Sun, Chao; Snoeijer, Jacco H; Villermaux, Emmanuel; Lohse, Detlef; Gelderblom, Hanneke

    2015-01-01

    We study the hydrodynamic response of a falling drop hit by a laser pulse. Combining high-speed with stroboscopic imaging we report that a millimeter-sized dyed water drop hit by a milli-Joule nanosecond laser-pulse deforms and propels forward at several meters per second, until it eventually fragments. We show that the drop motion results from the recoil momentum imparted at the drop surface by water vaporization. We measure the propulsion speed and the time-deformation law of the drop, complemented by boundary integral simulations. We explain the drop propulsion and shaping in terms of the laser pulse energy and drop surface tension. These findings are crucial for the generation of extreme ultraviolet (EUV) light in lithography machines.

  4. Viscous drops bounce faster: prompt tumbling-rebound from a sublimating slope

    Science.gov (United States)

    Antonini, Carlo; Jung, Stefan; Wetzel, Andreas; Heer, Emmanuel; Schoch, Philippe; Mazloomi, M. Ali; Chikatamarla, Shyam S.; Karlin, Ilya; Marengo, Marco; Poulikakos, Dimos

    2015-11-01

    We discovered a new drop rebound regime, characteristic of highly viscous liquids impacting onto tilted sublimating surfaces. By focusing on non-axisymmetric impact conditions at increasing viscosity, we demonstrate that low viscous drops show a ``slide, spread, recoil and rebound'' behavior, whereas viscous drops exhibit a ``prompt tumbling-rebound'' behavior. As such, viscous glycerol drops surprisingly rebound faster than three orders of magnitude less viscous water drops. This is made possible by a small conversion of translational to rotational kinetic energy, at non-axisymmetric impact conditions, as also confirmed by additional Lattice Boltzmann simulations: a rapid transition of the internal angular velocity prior to rebound to a constant value, as in a tumbling solid body, promotes a rapid rebound of more viscous drops, which are capable to rebound without recoiling. By studying drop impact dynamics, we explore the drop behavior in contactless and frictionless conditions, and identify the Ohnesorge number as the primary parameter to predict the transition between different impact regimes on tilted sublimating slopes, with tumbling observed for Ohnesorge numbers higher than unity.

  5. Inhibition of Condensation Frosting by Arrays of Hygroscopic Antifreeze Drops.

    Science.gov (United States)

    Sun, Xiaoda; Damle, Viraj G; Uppal, Aastha; Linder, Rubin; Chandrashekar, Sriram; Mohan, Ajay R; Rykaczewski, Konrad

    2015-12-29

    The formation of frost and ice can have negative impacts on travel and a variety of industrial processes and is typically addressed by dispensing antifreeze substances such as salts and glycols. Despite the popularity of this anti-icing approach, some of the intricate underlying physical mechanisms are just being unraveled. For example, recent studies have shown that in addition to suppressing ice formation within its own volume, an individual salt saturated water microdroplet forms a region of inhibited condensation and condensation frosting (RIC) in its surrounding area. This occurs because salt saturated water, like most antifreeze substances, is hygroscopic and has water vapor pressure at its surface lower than water saturation pressure at the substrate. Here, we demonstrate that for macroscopic drops of propylene glycol and salt saturated water, the absolute RIC size can remain essentially unchanged for several hours. Utilizing this observation, we demonstrate that frost formation can be completely inhibited in-between microscopic and macroscopic arrays of propylene glycol and salt saturated water drops with spacing (S) smaller than twice the radius of the RIC (δ). Furthermore, by characterizing condensation frosting dynamics around various hygroscopic drop arrays, we demonstrate that they can delay complete frosting over of the samples 1.6 to 10 times longer than films of the liquids with equivalent volume. The significant delay in onset of ice nucleation achieved by dispensing propylene glycol in drops rather than in films is likely due to uniform dilution of the drops driven by thermocapillary flow. This transport mode is absent in the films, leading to faster dilution, and with that facilitated homogeneous nucleation, near the liquid-air interface.

  6. Planar Microfluidic Drop Splitting and Merging

    Science.gov (United States)

    Collignon, Sean; Friend, James; Yeo, Leslie; MAD-LAB Team

    2015-11-01

    Open drop microfluidic platforms offer attractive alternatives to closed microchannel devices, however, to be effective they require efficient schemes for planar drop transport and manipulation. While there are many methods that have been reported for drop transport, it is far more difficult to carry out drop operations of dispensing, merging and splitting. In this work, we introduce a novel alternative to merge and split drops using laterally-offset modulated surface acoustic waves (SAWs). To do so, the energy delivery into the drop is modulated to induce drop stretching. Upon removal of the SAW energy, capillary forces at the center of the elongated drop drain the capillary bridge region towards both ends, resulting in its collapse and consequential splitting of the drop. This occurs only below a critical Ohnesorge number, a balance between the viscous forces that retard the drainage and the sufficiently large capillary forces that cause the liquid bridge to pinch. By this scheme we show the possibility of both reliable symettric splitting of a drop with an average deviation in droplet volumes of only around 4%, and no greater than 10%, as well as asymmetric splitting, by tuning the input energy to the device--thus presenting a comparable alternative to electrowetting.

  7. Characteristics of Unequal Size Drop Collisions

    Science.gov (United States)

    Kim, Jungyong; Longmire, Ellen; Kim, Man Sik

    2009-11-01

    Pairs of water/glycerin drops were injected into silicone oil and traveled on downward trajectories before colliding. Unequal size drop collisions with drop size ratios (Ds/DL) of 0.7 and 0.5 were investigated. Simultaneous dual-field PIV measurements were obtained to characterize coalescence and rebounding behavior. The initial injection angle and tube height were adjusted to access appropriate impact parameters. In the current study, the collision angle of the large drop was, in general, shallower than that of the small drop, and a range of velocity ratios and impact parameters was examined. Coalescence occurs above We* = 11 similar to collision outcomes for equal size drops. As drop size ratio decreases, the intervening film deforms more. If the velocity ratio uL/us 1, the interface flattens before coalescence. The rupture location varies due to the asymmetry of the drops. As collision offset increases (B > 0), the film rupture time is shortened and mixing of the fluid within the drops is enhanced after coalescence. These results will be compared with the behavior observed previously for equal size drop collisions.

  8. The dynamics of drops coating the underside of a flexible wall

    Science.gov (United States)

    Richard, Craster; Wray, Alex; Papageorgiou, Demetrios; Matar, Omar

    2012-11-01

    Lister et al., 2009, showed that a thin fluid coating the underside of a ceiling (a model which extends in particular the works of Hammond, 1983, and Lister et al., 2005) can give rise to pendent drops. If these are fixed in place by boundary conditions, they drain to give drops of constant pressure surrounded by annular trenches. These authors also showed that, on larger domains starting from an initial perturbation, these drops will undergo a self-induced quasi-steady translation. This is driven by the release of gravitational potential energy as the fluid in the film falls into the drop. The speed and growth of these drops is accessible to analytical computation by the self-similar study of the thin trenches surrounding them, and matching to far external conditions. The subsequent dynamics are intricate, allowing for coalescence (not seen in 1 dimension) as well as complex drop-drop interactions. We extend this model to allow for the ceiling to be a flexible substrate, and also to account for inertial effects in the drops. We then investigate the effect this has on the dynamics of the drops. EPSRC DTA.

  9. Electrowetting-induced drop generation and control in a microfluidic flow-focusing device

    Science.gov (United States)

    Malloggi, Florent; Vanapalli, Siva A.; Gu, Hao; van den Ende, Dirk; Mugele, Frieder

    2007-11-01

    Recent upsurge in droplet-based microfluidic research is fueled by the potential application of drops as well-controlled environments for biochemical reactions, single cell analysis and fluid logical devices. Commonly pressure driven flows are used to create droplets continuously either in a flow-focusing or in T-junction geometry. While this approach provides high throughput capability, it is neither amenable to detailed on-demand generation of individual drops nor to dynamic control of surface wettability, which can dramatically affect the dynamics of two-phase microflows. Alternatively, electrowetting (EW)-on-dielectric is used to digitally manipulate drops. The EW provides exquisite control over individual drops and surface wettability. However, current implementations have low throughput and cannot readily be integrated with existing channel-based technologies. Here, we adopt a unified approach to create a soft microfluidic platform that harvests the power of both methods and offers the capability to address their limitations. We achieve this integration by incorporating EW into a flow-focusing device and demonstrate EW-controlled drop formation. We identify experimentally the range of voltages and driving pressures that yields EW-induced droplet generation. A theoretical description based on the balance of external pressures and voltage-controlled capillary pressures quantitatively accounts for the observations. Moreover we show that the smaller the geometric scales the more efficient the electrowetting control of drop generation.

  10. Design, manufacture, and testing of the Armstrong Hall drop tower decelerator

    Science.gov (United States)

    Ocampo, Jaime Andres

    A decelerator was needed for the Armstrong Hall Microgravity tower. Three designs were considered as concepts and the one chosen was an airbag. The airbag is 5 feet tall and 4.5 feet in diameter due to floor constraints. The deceleration was controlled by designing the vent system to provide the needed vent area as a function of time. This dynamics vent area controls the rate at which volume is expelled from the airbag. The volume expelled depends on the pressure inside the airbag, thus, a direct relation between the vent area and the deceleration profile was determined. The airbag and associated infrastructure was designed, manufactured, and tested. This system includes an airbag with a cushion on top to prevent wear, cart and rails, a drop package, and a latch and release system. More than forty tests were done with different drop height and drop weight combinations culminating in three drops of 200 lbs from the third floor. The drop weight was varied by adjusting the water level in a plastic barrel in the drop package. Pressure measurements inside the bag and vent were taken using two pressure transducers. The pressure transducers sampled the pressure at one of the exit vents and at the center of the bottom of the airbag. The signals were low-pass filtered for noise and scaled for pressure. The pressure traces were processed to find the mean deceleration. The deceleration was found to be independent of drop weight, only depending on drop height. The traces were also integrated to find a momentum per unit area. This value was then compared to the momentum of the drop package. From these two results an effective impact area can be found. It was found that the cushion not only reduced wear but also increased the effective impact area substantially. This increase in area reduced the value of the mean deceleration by reducing the pressure inside the airbag. The airbag proved to work well for the drops, decelerating the package and preventing a direct hit with the

  11. Analysis of random drop for gateway congestion control. M.S. Thesis

    Science.gov (United States)

    Hashem, Emam Salaheddin

    1989-01-01

    Lately, the growing demand on the Internet has prompted the need for more effective congestion control policies. Currently No Gateway Policy is used to relieve and signal congestion, which leads to unfair service to the individual users and a degradation of overall network performance. Network simulation was used to illustrate the character of Internet congestion and its causes. A newly proposed gateway congestion control policy, called Random Drop, was considered as a promising solution to the pressing problem. Random Drop relieves resource congestion upon buffer overflow by choosing a random packet from the service queue to be dropped. The random choice should result in a drop distribution proportional to the bandwidth distribution among all contending TCP connections, thus applying the necessary fairness. Nonetheless, the simulation experiments demonstrate several shortcomings with this policy. Because Random Drop is a congestion control policy, which is not applied until congestion has already occurred, it usually results in a high drop rate that hurts too many connections including well-behaved ones. Even though the number of packets dropped is different from one connection to another depending on the buffer utilization upon overflow, the TCP recovery overhead is high enough to neutralize these differences, causing unfair congestion penalties. Besides, the drop distribution itself is an inaccurate representation of the average bandwidth distribution, missing much important information about the bandwidth utilization between buffer overflow events. A modification of Random Drop to do congestion avoidance by applying the policy early was also proposed. Early Random Drop has the advantage of avoiding the high drop rate of buffer overflow. The early application of the policy removes the pressure of congestion relief and allows more accurate signaling of congestion. To be used effectively, algorithms for the dynamic adjustment of the parameters of Early Random Drop

  12. Footprint Geometry and Sessile Drop Resonance

    Science.gov (United States)

    Chang, Chun-Ti; Daniel, Susan; Steen, Paul H.

    2016-11-01

    How does a sessile drop resonate if its footprint is square (square drop)? In this talk, we discuss the two distinct families of observed modes in our experiments. One family (spherical modes) is identified with the natural modes of capillary spherical caps, and the other (grid modes) with Faraday waves on a square bath (square Faraday waves). A square drop exhibits grid or spherical modes depending on its volume, and the two families of modes arise depending on how wavenumber selection of footprint geometry and capillarity compete. For square drops, a dominant effect of footprint constraint leads to grid modes which are constrained response; otherwise the drops exhibit spherical modes, the characteristic of sessile drops on flat plates. Chun-Ti Chang takes his new position at National Taiwan University on Aug. 15th, 2016. Until then, Chun-Ti Chang is affiliated with Technical University Dortmund, Germany.

  13. Large bubble entrainment in drop impact

    Science.gov (United States)

    Thoraval, Marie-Jean; Li, Yangfan; Thoroddsen, Sigurdur T.

    2015-11-01

    A drop impacting on a pool of the same liquid can entrap air bubbles in many different ways. A peculiar entrapment was observed by Pumphrey and Elmore (1990) and remained unexplained until now. For a small range of parameters, the cavity produced by the impacting drop spreads radially in a dish-shape and then closes to entrap a bubble larger than the drop. We demonstrate that the large bubble is caused by a vortex ring produced in the liquid during the impact of the drop. We combine experiments and numerical simulations to show that the vortex ring pulls on the interface on the side of the cavity to stretch it radially, explaining the shape of the cavity. Only prolate drops are able to generate large bubbles. This is due to the self-destruction of the vortex earlier during the impact for flatter drops.

  14. Dynamics of sessile and pendant drop excited by surface acoustic waves: gravity effects and correlation between oscillatory and translational motions

    CERN Document Server

    Bussonière, Adrien; Brunet, Philippe; Matar, Olivier Bou

    2016-01-01

    When sessile droplets are excited by ultrasonic traveling surface acoustic waves (SAWs), they undergo complex dynamics with both oscillations and translational motion. While the nature of the Rayleigh-Lamb quadrupolar drop oscillations has been identified, their origin and their influence on the drop mobility remains unexplained. Indeed the physics behind this peculiar dynamics is complex with nonlinearities involved both at the excitation level (acoustic streaming and radiation pressure) and in the droplet response (nonlinear oscillations and contact line dynamics). In this paper, we investigate the dynamics of sessile and pendant drops excited by SAWs. For pendant drops, so-far unreported dynamics are observed close to the drop detachment threshold with the suppression of the translational motion. Away from this threshold, the comparison between pendant and sessile drop dynamics allows us to identify the role played by gravity or more generally by an initial or dynamically induced stretching of the drop. In...

  15. Investigation of drop coalescence using tomographic PIV

    Science.gov (United States)

    Ortiz-Duenas, Cecilia; Kim, Jungyong; Longmire, Ellen

    2008-11-01

    High-speed tomographic PIV was used to obtain evolving volumetric velocity fields of the coalescence of single drops and two side-by-side drops through liquid/liquid interfaces. Reynolds numbers (Re=ρsUσD/μs) based on surface tension velocity (Uσ=D/tσ) and surrounding ambient fluid were 8-10, and the viscosity ratio between the fluid drop and surrounding fluid was 0.14. The coalescence process investigated is driven by gravity and thus the initial drops are non-spherical and the interface is deformed by the drops. Previously, Mohamed-Kassim & Longmire (2004) showed that under these conditions, the film rupture typically occurs off-axis, and therefore the flow is three-dimensional. For a single drop, volumetric velocity vector fields are used to characterize the asymmetric film rupture occurring for 0drop into a vortex ring are relatively axisymmetric. For two side-by-side drops, the first drop to coalesce ruptures off-axis on the side closest to the second drop. The volumetric velocity and vorticity fields indicate an asymmetric collapse of the drop for 0.1drop while the capillary waves are axisymmetric.

  16. Therapeutic Effect of 0.1% Tacrolimus Eye Drops in the Tarsal Form of Vernal Keratoconjunctivitis.

    Science.gov (United States)

    Wan, Qi; Tang, Jing; Han, Yu; Wang, Dan; Ye, Hongquan

    2017-08-12

    The purpose of this study was to evaluate the efficacy and safety of 0.1% tacrolimus eye drops in the tarsal form of vernal keratoconjunctivitis (VKC) and to survey the changes of dendritic cells at the palpebral conjunctiva in patients with VKC by in vivo confocal microscopy. A total of 17 patients (34 eyes) with the tarsal form of VKC were enrolled in this prospective, nonrandomized case series. They were treated with 0.1% tacrolimus eye drops twice daily after discontinuation of all other topical medications. Subjective ocular symptoms and objective ocular signs were scored on a 4-point scale by one ophthalmologist and the characteristics of the dendritic cells in each right eye at the palpebral conjunctiva were evaluated by in vivo confocal microscopy before treatment and at the 1st, 2th, 4th, and 8th weeks after treatment. After 1 week of treatment with 0.1% tacrolimus eye drops, the score for each symptom in all patients showed a significant (p < 0.001) improvement, and 13 patients (76%) experienced dramatic relief of symptoms. In addition, there was a significantly (p < 0.001) decreased clinical sign score (except for giant papillae) after 4 weeks, and a significant (p < 0.001) improvement in the score of giant papillae after 8 weeks of treatment. The characteristics of dendritic cells (including cell count, total area, average size, perimeter, and diameter) showed a significant (p < 0.05) decrease after 2 weeks of treatment. During the follow-up, no other topical medications were required and no significant changes in visual acuity were documented. No cataracts or elevation of intraocular pressures were detected. Only 5 patients (29%) had a tingling or burning sensation or discomfort. Tacrolimus 0.1% eye drops are an effective and safe treatment for the tarsal form of VKC, and can rapidly inhibit the activity of dendritic cells, improve symptoms, reduce papillary hyperplasia, and reverse damage at the palpebral conjunctiva. The side effects could affect the

  17. Neutral fragment filtering for rapid identification of new diester-diterpenoid alkaloids in roots of Aconitum carmichaeli by ultra-high-pressure liquid chromatography coupled with linear ion trap-orbitrap mass spectrometry.

    Directory of Open Access Journals (Sweden)

    Jing Zhang

    Full Text Available A rapid and effective method was developed for separation and identification of diester-diterpenoid alkaloids (DDA in the roots of Aconitum carmichaeli by ultra-high-pressure liquid chromatography coupled with high resolution LTQ-Orbitrap tandem mass spectrometry (UHPLC-LTQ-Orbitrap-MS(n. According to accurate mass measurement and the characteristic neutral loss filtering strategy, a total of 42 diester-diterpenoid alkaloids (DDA were rapidly detected and characterized or tentatively identified. Meanwhile, the proposed fragmentation pathways and the major diagnostic fragment ions of aconitine, mesaconitine and hypaconitine were investigated to trace DDA derivatives in crude plant extracts. 23 potential new compounds were successfully screened and characterized in Aconitum carmichaeli, including 16 short chain fatty acyls DDA, 4 N-dealkyl DDA and several isomers of aconitine, mesaconitine and hypaconitine.

  18. Drops moving along and across a filament

    Science.gov (United States)

    Sahu, Rakesh P.; Sinha-Ray, Suman; Yarin, Alexander; Pourdeyhimi, Behnam

    2013-11-01

    The present work is devoted to the experimental study of oil drop motion both along and across a filament due to the air jet blowing. In case of drop moving along the filament, phenomena such as drop stick-slip motion, shape oscillations, shedding of a tail along the filament, the tail capillary instability and drop recoil motion were observed which were rationalized in the framework of simplified models. Experiments with cross-flow of the surrounding gas relative to the filament with an oil drop on it were conducted, with air velocity in the range of 7.23 to 22.7 m s-1. The Weber number varied from 2 to 40 and the Ohnesorge number varied from 0.07 to 0.8. The lower and upper critical Weber numbers were introduced to distinguish between the beginning of the drop blowing off the filament and the onset of the bag-stamen breakup. The range of the Weber number between these two critical values is filled with three types of vibrational breakup: V1 (a balloon-like drop being blown off), V2 (a drop on a single stamen being blown off), and V3 (a drop on a double stamen being blown off). The Weber number/Ohnesorge number plane was delineated into domains of different breakup regimes. The work is supported by the Nonwovens Cooperative Research Center (NCRC).

  19. Assessment of evaporation equilibrium and stability concerning an acoustically excited drop in combustion products

    Science.gov (United States)

    Mauriot, Yves; Prud'homme, Roger

    2014-04-01

    The evaporation of drops in a sound field has been the subject of numerous studies aimed at determining its role in combustion instability. The models generally assume local equilibrium evaporation at the interface. We determine here the conditions of validity of this assumption, without calling into question other a priori assumptions of the classical model, in particular spherically symmetric quasi-steady evolution in the gas phase and liquid phase thermal unsteadiness with pure heat conduction. Another possible phenomenon concerns the differential recoil of the vapor. In the case of rapid evaporation, a pressure difference appears between both sides of the interface, even if the latter is plane. This pressure difference, usually neglected, is proportional to the square of speed and the resulting force is oriented toward the denser fluid, i.e. the liquid. A very fast evaporation may even cause local deformation, i.e. Hickman instability. The stability condition concerning this phenomenon has also been determined. This study was co-funded by CNES (French Space Agency) and ONERA and was performed in the framework of CNES-ONERA French Research &  Technology activities on the high-frequency combustion stability of liquid-propellant rocket engines.

  20. Creep- and fatigue-resistant, rapid piezoresistive responses of elastomeric graphene-coated carbon nanotube aerogels over a wide pressure range.

    Science.gov (United States)

    Tsui, Michelle N; Islam, Mohammad F

    2017-01-19

    Lightweight, flexible piezoresistive materials with wide operational pressure ranges are in demand for applications such as human physical activity and health monitoring, robotics, and for functional interfacing between living systems and wearable electronics. Piezoresistivity of many elastomeric foams of polymers and carbon allotropes satisfies much of the required characteristics for these applications except creep and fatigue resistance due to their viscoelasticity, critically limiting the reliability and lifetime of integrated devices. We report the piezoresistive responses from aerogels of graphene-coated single-walled carbon nanotubes (SWCNTs), made using a facile and versatile sol-gel method. Graphene crosslinks the junctions of the underlying random network of SWCNTs, generating lightweight elastomeric aerogels with a mass density of ≈11 mg mL-1 (volume fraction ≈7.7 × 10-3) and a Young's modulus of ≈0.4 MPa. The piezoresistivity of these aerogels spans wide compressive pressures up to at least 120 kPa with sensitivity that exhibit ultrafast temporal responses of <27 ms and <3% delay ratio over 104 compressive loading-unloading cycles at rates between 0.1-10 Hz. Most importantly, the piezoresistive responses do not show any creep at least for 1 hour and 80 kPa of compressive static loading. We suggest that the fatigue- and creep-resistant, ultrafast piezoresistive responses of these elastomeric aerogels are highly attractive for use in dynamic and static lightweight, pressure sensing applications such as human activity monitoring and soft robotics.

  1. Relations between a novel, reliable, and rapid index of arterial compliance (PP-HDI) and well-established inidices of arterial blood pressure (ABP) in a sample of hypertensive elderly subjects.

    Science.gov (United States)

    Bergamini, L; Finelli, M E; Bendini, C; Ferrari, E; Veschi, M; Neviani, F; Manni, B; Pelosi, A; Rioli, G; Neri, M

    2009-01-01

    Hypertension is a risk factor for a long-lasting arterial wall-remodelling leading to stiffness. The rapid method measuring the pulse pressure (PP) by means of the tool of Hypertension Diagnostic Instruments (HDI) called PP-HDI, overcomes some of the problems arising with more-time consuming methods, like ambulatory blood pressure monitoring (ABPM), and give information about the elasticity of the arterial walls. We studied the relationship between the PP-HDI, the large artery compliance (LA-C) and small artery compliance (SA-C) and few well-established indices of arterial blood pressure (ABP) in a sample of 75 hypertensive subjects, aged 65 years and over. Significant correlations between LA-C and heart rate (HR), PP-ABPM and PP-HDI were found. SA-C relates with HR and systolic blood pressure (SBP) measured in lying and standing positions. Applying a stepwise regression analysis, we found that LA-C variance stems from PP-HDI and HR, while SA-C variance stems from SBP in lying position. Receiver operator characteristic (ROC) curves for thresholds of PP showed that PP-HDI reached levels of sensitivity/specificity similar to PP-ABPM. In conclusion, surveillance of ABP through hemo-dynamic indices, in particular of SBP, is essential, nevertheless the advantage of this control is not known in an elderly population where the organ damage is already evident. PP needs necessarily an instrumental measurement. The PP-HDI result is similar in reliability with respect to PPABPM, but is more rapid and well applicable in an elderly population.

  2. Cooperative breakups induced by drop-to-drop interactions in one-dimensional flows of drops against micro-obstacles.

    Science.gov (United States)

    Schmit, Alexandre; Salkin, Louis; Courbin, Laurent; Panizza, Pascal

    2015-03-28

    Depending on the capillary number at play and the parameters of the flow geometry, a drop may or may not break when colliding with an obstacle in a microdevice. Modeling the flow of one-dimensional trains of monodisperse drops impacting a micro-obstacle, we show numerically that complex dynamics may arise through drop-to-drop hydrodynamic interactions: we observe sequences of breakup events in which the size of the daughter drops created upon breaking mother ones becomes a periodic function of time. We demonstrate the existence of numerous bifurcations between periodic breakup regimes and we establish diagrams mapping the possible breakup dynamics as a function of the governing (physicochemical, hydrodynamic, and geometric) parameters. Microfluidic experiments validate our model as they concur very well with predictions.

  3. Dynamics of sessile drops. Part 3. Theory of forced oscillations

    CERN Document Server

    Bostwick, Joshua B

    2016-01-01

    A partially-wetting sessile drop is driven by a sinusoidal pressure field that produces capillary waves on the liquid/gas interface. The analysis presented in Part 1 of this series (Bostwick & Steen 2014) is extended by computing response diagrams and phase shifts for the viscous droplet, whose three phase contact-line moves with contact-angle that is a smooth function of the contact line speed. Viscous dissipation is incorporated through the viscous potential flow approximation and the critical Ohnesorge number bounding regions beyond which a given mode becomes over-damped is computed. Davis dissipation originating from the contact-line speed condition leads to damped oscillations for drops with finite contact-line mobility, even for inviscid fluids. The critical mobility and associated driving frequency to generate the largest Davis dissipation is computed. Lastly, regions of modal coexistence where two modes can be simultaneously excited by a single forcing frequency are identified. Predictions compare...

  4. Rapid on-site detection of explosives on surfaces by ambient pressure laser desorption and direct inlet single photon ionization or chemical ionization mass spectrometry.

    Science.gov (United States)

    Ehlert, S; Hölzer, J; Rittgen, J; Pütz, M; Schulte-Ladbeck, R; Zimmermann, R

    2013-09-01

    Considering current security issues, powerful tools for detection of security-relevant substances such as traces of explosives and drugs/drug precursors related to clandestine laboratories are required. Especially in the field of detection of explosives and improvised explosive devices, several relevant compounds exhibit a very low vapor pressure. Ambient pressure laser desorption is proposed to make these substances available in the gas phase for the detection by adapted mass spectrometers or in the future with ion-mobility spectrometry as well. In contrast to the state-of-the-art thermal desorption approach, by which the sample surface is probed for explosive traces by a wipe pad being transferred to a thermal desorber unit, by the ambient pressure laser desorption approach presented here, the sample is directly shockwave ablated from the surface. The laser-dispersed molecules are sampled by a heated sniffing capillary located in the vicinity of the ablation spot into the mass analyzer. This approach has the advantage that the target molecules are dispersed more gently than in a thermal desorber unit where the analyte molecules may be decomposed by the thermal intake. In the technical realization, the sampling capillary as well as the laser desorption optics are integrated in the tip of an endoscopic probe or a handheld sampling module. Laboratory as well as field test scenarios were performed, partially in cooperation with the Federal Criminal Police Office (Bundeskriminalamt, BKA, Wiesbaden, Germany), in order to demonstrate the applicability for various explosives, drugs, and drug precursors. In this work, we concentrate on the detection of explosives. A wide range of samples and matrices have been investigated successfully.

  5. Many Drops Make a Lake

    Directory of Open Access Journals (Sweden)

    Chaitanya S. Mudgal

    2014-03-01

    greater knowledge, better skills and disseminate this knowledge through this journal to influence as many physicians and their patients as possible. They have taken the knowledge of their teachers, recognized their giants and are now poised to see further than ever before. My grandmother often used to quote to me a proverb from India, which when translated literally means “Many drops make a lake”. I cannot help but be amazed by the striking similarities between the words of Newton and this Indian saying. Therefore, while it may seem intuitive, I think it must be stated that it is vital for the betterment of all our patients that we recognize our own personal lakes to put our drops of knowledge into. More important is that we recognize that it is incumbent upon each and every one of us to contribute to our collective lakes of knowledge such as ABJS. And finally and perhaps most importantly we need to be utterly cognizant of never letting such lakes of knowledge run dry.... ever.

  6. Sound Wave Energy Resulting from the Impact of Water Drops on the Soil Surface.

    Directory of Open Access Journals (Sweden)

    Magdalena Ryżak

    Full Text Available The splashing of water drops on a soil surface is the first step of water erosion. There have been many investigations into splashing-most are based on recording and analysing images taken with high-speed cameras, or measuring the mass of the soil moved by splashing. Here, we present a new aspect of the splash phenomenon's characterization the measurement of the sound pressure level and the sound energy of the wave that propagates in the air. The measurements were carried out for 10 consecutive water drop impacts on the soil surface. Three soils were tested (Endogleyic Umbrisol, Fluvic Endogleyic Cambisol and Haplic Chernozem with four initial moisture levels (pressure heads: 0.1 kPa, 1 kPa, 3.16 kPa and 16 kPa. We found that the values of the sound pressure and sound wave energy were dependent on the particle size distribution of the soil, less dependent on the initial pressure head, and practically the same for subsequent water drops (from the first to the tenth drop. The highest sound pressure level (and the greatest variability was for Endogleyic Umbrisol, which had the highest sand fraction content. The sound pressure for this soil increased from 29 dB to 42 dB with the next incidence of drops falling on the sample The smallest (and the lowest variability was for Fluvic Endogleyic Cambisol which had the highest clay fraction. For all experiments the sound pressure level ranged from ~27 to ~42 dB and the energy emitted in the form of sound waves was within the range of 0.14 μJ to 5.26 μJ. This was from 0.03 to 1.07% of the energy of the incident drops.

  7. Sound Wave Energy Resulting from the Impact of Water Drops on the Soil Surface.

    Science.gov (United States)

    Ryżak, Magdalena; Bieganowski, Andrzej; Korbiel, Tomasz

    2016-01-01

    The splashing of water drops on a soil surface is the first step of water erosion. There have been many investigations into splashing-most are based on recording and analysing images taken with high-speed cameras, or measuring the mass of the soil moved by splashing. Here, we present a new aspect of the splash phenomenon's characterization the measurement of the sound pressure level and the sound energy of the wave that propagates in the air. The measurements were carried out for 10 consecutive water drop impacts on the soil surface. Three soils were tested (Endogleyic Umbrisol, Fluvic Endogleyic Cambisol and Haplic Chernozem) with four initial moisture levels (pressure heads: 0.1 kPa, 1 kPa, 3.16 kPa and 16 kPa). We found that the values of the sound pressure and sound wave energy were dependent on the particle size distribution of the soil, less dependent on the initial pressure head, and practically the same for subsequent water drops (from the first to the tenth drop). The highest sound pressure level (and the greatest variability) was for Endogleyic Umbrisol, which had the highest sand fraction content. The sound pressure for this soil increased from 29 dB to 42 dB with the next incidence of drops falling on the sample The smallest (and the lowest variability) was for Fluvic Endogleyic Cambisol which had the highest clay fraction. For all experiments the sound pressure level ranged from ~27 to ~42 dB and the energy emitted in the form of sound waves was within the range of 0.14 μJ to 5.26 μJ. This was from 0.03 to 1.07% of the energy of the incident drops.

  8. Head-dropping mechanism in traffic control

    Science.gov (United States)

    Liu, Xintong; Yang, Oliver W.

    2004-09-01

    In this paper, we investigate the application of the head dropping policy as a partial solution to the problem of queue oscillation encountered by RED and its variants. With this method, instead of the tail dropping, which is currently used by RED and many other AQM schemes, the TCP source can be informed of the congestion occurring in the bottleneck router a time period earlier. Specifically, that is a time period of the queuing delay. We have compared DH-RED (drop head RED) and DH-BLUE (drop head BLUE) with the current RED and BLUE in a variety of situations and found that the performances such as the queue size stability as well as packet drop rate can be greatly improved.

  9. Ferrofluid drops in rotating magnetic fields

    CERN Document Server

    Lebedev, A V; Morozov, K I; Bauke, H

    2003-01-01

    Drops of a ferrofluid floating in a non-magnetic liquid of the same density and spun by a rotating magnetic field are investigated experimentally and theoretically. The parameters for the experiment are chosen such that different stationary drop shapes including non-axis-symmetric configurations could be observed. Within an approximate theoretical analysis the character of the occurring shape bifurcations, the different stationary drop forms, as well as the slow rotational motion of the drop is investigated. The results are in qualitative, and often quantitative agreement, with the experimental findings. It is also shown that a small eccentricity of the rotating field may have a substantial impact on the rotational motion of the drop.

  10. Axisymmetric Drop Shape Analysis (ADSA): An Outline.

    Science.gov (United States)

    Saad, Sameh M I; Neumann, A Wilhelm

    2016-12-01

    Drop shape techniques for the measurement of interfacial tension are powerful, versatile and flexible. The shape of the drop/bubble depends on the balance between surface tension and external forces, e.g. gravity. This balance is reflected mathematically in the Laplace equation of capillarity. Axisymmetric Drop Shape Analysis (ADSA) is a commonly used drop shape technique. A streamlined version of the development of ADSA over the past several decades is presented to illustrate its validity and range of utility. Several configurations of interest will be considered and presented systematically. Shape and surface tension will be linked to a shape parameter based on proper concepts of differential geometry. The resulting shape parameter will be shown to allow determination of the range of applicability of such a drop shape method. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Rapid determination of vial heat transfer parameters using tunable diode laser absorption spectroscopy (TDLAS) in response to step-changes in pressure set-point during freeze-drying.

    Science.gov (United States)

    Kuu, Wei Y; Nail, Steven L; Sacha, Gregory

    2009-03-01

    The purpose of this study was to perform a rapid determination of vial heat transfer parameters, that is, the contact parameter K(cs) and the separation distance l(v), using the sublimation rate profiles measured by tunable diode laser absorption spectroscopy (TDLAS). In this study, each size of vial was filled with pure water followed by a freeze-drying cycle using a LyoStar II dryer (FTS Systems) with step-changes of the chamber pressure set-point at to 25, 50, 100, 200, 300, and 400 mTorr. K(cs) was independently determined by nonlinear parameter estimation using the sublimation rates measured at the pressure set-point of 25 mTorr. After obtaining K(cs), the l(v) value for each vial size was determined by nonlinear parameter estimation using the pooled sublimation rate profiles obtained at 25 to 400 mTorr. The vial heat transfer coefficient K(v), as a function of the chamber pressure, was readily calculated, using the obtained K(cs) and l(v) values. It is interesting to note the significant difference in K(v) of two similar types of 10 mL Schott tubing vials, primary due to the geometry of the vial-bottom, as demonstrated by the images of the contact areas of the vial-bottom. (c) 2008 Wiley-Liss, Inc. and the American Pharmacists Association

  12. The Drop Tower Bremen -An Overview

    Science.gov (United States)

    von Kampen, Peter; Könemann, Thorben; Rath, Hans J.

    The Center of Applied Space Technology and Microgravity (ZARM) was founded in 1985 as an institute of the University of Bremen, which focuses on research on gravitational and space-related phenomena. In 1988, the construction of ZARM`s drop tower began. Since its inau-guration in September 1990, the eye-catching Drop Tower Bremen with a height of 146m and its characteristic glass roof has become twice a landmark on the campus of the University of Bremen and the emblem of the technology park Bremen. As such an outstanding symbol of space science in Bremen the drop tower provides an european unique facility for experiments under conditions of high-quality weightlessness with residual gravitational accelerations in the microgravity regime. The period of maximum 4.74s of each freely falling experiment at the Drop Tower Bremen is only limited by the height of the drop tower vacuum tube, which was fully manufactured of steal and enclosed by an outer concrete shell. Thus, the pure free fall height of each microgravity drop experiment is approximately 110m. By using the later in-stalled catapult system established in 2004 ZARM`s short-term microgravity laboratory is able to nearly double the time of free fall. This world-wide inimitable capsule catapult system meets scientists` demand of extending the period of weightlessness. During the catapult operation the experiment capsule performs a vertical parabolic flight within the drop tower vacuum tube. In this way the time of microgravity can be extended to slightly over 9s. Either in the drop or in the catapult operation routine the repetition rates of microgravity experiments at ZARM`s drop tower facility are the same, generally up to 3 times per day. In comparison to orbital platforms the ground-based laboratory Drop Tower Bremen represents an economic alternative with a permanent access to weightlessness on earth. Moreover, the exceptional high quality of weightlessness in order of 1e-6 g (in the frequency range below 100

  13. Investigation of drop motion through circular orifices

    Science.gov (United States)

    Bordoloi, Ankur; Longmire, Ellen; Kong, Xiangzhao; Saar, Martin

    2011-11-01

    The motion of drops though porous media occurs in numerous science and engineering fields including multiphase fluid flow in the subsurface during groundwater flow, geothermal energy recovery, and geologic carbon dioxide sequestration. Here, we simplify the porous medium to a thin plate with an orifice to study the interactions between the drop and the solid medium. Drops of water/glycerin with diameter, D, are released in a tank of silicone oil with matched refractive index and allowed to fall downward by gravity. After reaching terminal speed, the drops encounter a thin plate with orifice diameter, d, placed horizontally within the surrounding tank. Drop deformation, contact with the orifice, and breakage are investigated using high-speed imaging, and velocity fields are determined by particle image velocimetry (PIV). Effects of diameter ratio d/D, drop Reynolds number, and drop offset with respect to the orifice center are examined. The experimental results are compared to results from numerical simulations using an immiscible, two-color BGK lattice-Boltzmann method performed under similar test conditions. Supported by DOE (DOE EERE-PMC-10EE0002764).

  14. Drop impact splashing and air entrapment

    KAUST Repository

    Thoraval, Marie-Jean

    2013-03-01

    Drop impact is a canonical problem in fluid mechanics, with numerous applications in industrial as well as natural phenomena. The extremely simple initial configuration of the experiment can produce a very large variety of fast and complex dynamics. Scientific progress was made in parallel with major improvements in imaging and computational technologies. Most recently, high-speed imaging video cameras have opened the exploration of new phenomena occurring at the micro-second scale, and parallel computing allowed realistic direct numerical simulations of drop impacts. We combine these tools to bring a new understanding of two fundamental aspects of drop impacts: splashing and air entrapment. The early dynamics of a drop impacting on a liquid pool at high velocity produces an ejecta sheet, emerging horizontally in the neck between the drop and the pool. We show how the interaction of this thin liquid sheet with the air, the drop or the pool, can produce micro-droplets and bubble rings. Then we detail how the breakup of the air film stretched between the drop and the pool for lower impact velocities can produce a myriad of micro-bubbles.

  15. Staffing Up and Dropping Out

    Directory of Open Access Journals (Sweden)

    Mark Fetler

    1997-07-01

    Full Text Available Growing public school enrollment and the need to maintain or improve service to students has increased the demand for teachers, perhaps more rapidly than existing sources can accommodate. While some schools recruit well qualified teachers by offering higher salaries or better working conditions, others may satisfy their need for staff by relaxing hiring standards or assigning novice teachers to difficult classrooms. Schools' hiring policies have consequences for student success. Dropout rates tend to be higher where faculties include a greater percentage of minimally educated teachers or teachers with little experience. The relationship between dropout rate and teacher qualifications is independent of student poverty, school size, and location. A proposed strategy to reduce dropout rates is to encourage higher preparation and employment standards, and to provide appropriate classroom assignments, mentoring, and support for new teachers.

  16. "Self-Shaping" of Multicomponent Drops.

    Science.gov (United States)

    Cholakova, Diana; Valkova, Zhulieta; Tcholakova, Slavka; Denkov, Nikolai; Smoukov, Stoyan K

    2017-06-13

    In our recent study we showed that single-component emulsion drops, stabilized by proper surfactants, can spontaneously break symmetry and transform into various polygonal shapes during cooling [ Denkov Nature 2015 , 528 , 392 - 395 ]. This process involves the formation of a plastic rotator phase of self-assembled oil molecules beneath the drop surface. The plastic phase spontaneously forms a frame of plastic rods at the oil drop perimeter which supports the polygonal shapes. However, most of the common substances used in industry appear as mixtures of molecules rather than pure substances. Here we present a systematic study of the ability of multicomponent emulsion drops to deform upon cooling. The observed trends can be summarized as follows: (1) The general drop-shape evolution for multicomponent drops during cooling is the same as with single-component drops; however, some additional shapes are observed. (2) Preservation of the particle shape upon freezing is possible for alkane mixtures with chain length difference Δn ≤ 4; for greater Δn, phase separation within the droplet is observed. (3) Multicomponent particles prepared from alkanes with Δn ≤ 4 plastify upon cooling due to the formation of a bulk rotator phase within the particles. (4) If a compound, which cannot induce self-shaping when pure, is mixed with a certain amount of a compound which induces self-shaping, then drops prepared from this mixture can also self-shape upon cooling. (5) Self-emulsification phenomena are also observed for multicomponent drops. In addition to the three recently reported mechanisms of self-emulsification [ Tcholakova Nat. Commun. 2017 , ( 8 ), 15012 ], a new (fourth) mechanism is observed upon freezing for alkane mixtures with Δn > 4. It involves disintegration of the particles due to a phase separation of alkanes upon freezing.

  17. A rapid, sensitive and validated method for the determination of ondansetron in human plasma by reversed-phase high-pressure liquid chromatography.

    Science.gov (United States)

    Chandrasekar, Durairaj; Ramakrishna, Sistla; Diwan, Prakash V

    2004-01-01

    A simple and sensitive method for the determination of ondansetron (CAS 116002-70-1) in human plasma was developed using high-pressure liquid chromatography (HPLC). The procedure involves extraction of human plasma with tertiary butyl methyl ether containing 2 mol/l sodium hydroxide, followed by reversed-phase HPLC using a LiChrospher 100 RP-18e 5 microm column and UV detection at 305 nm. The retention times of ondansetron and internal standard (propranolol hydrochloride, CAS 318-98-9) were 9.38 and 13.40 min, respectively. The calibration curves were linear over the range of 10 ng/ml (lower limit of quantitation, LOQ) and 380 ng/ml for ondansetron. The intra- and inter-assay coefficients of variation for all the criteria of validation were less than 15% over the linearity range. Ondansetron was stable upon storage in human plasma. The sensitivity and precision of the method were within the accepted limits (< 15 %) throughout the validation period. The present method is useful for determination of plasma concentrations of ondansetron during human pharmacokinetic studies.

  18. Rapidly changing subglacial hydrological pathways at a tidewater glacier revealed through simultaneous observations of water pressure, supraglacial lakes, meltwater plumes and surface velocities

    Science.gov (United States)

    How, Penelope; Benn, Douglas I.; Hulton, Nicholas R. J.; Hubbard, Bryn; Luckman, Adrian; Sevestre, Heïdi; van Pelt, Ward J. J.; Lindbäck, Katrin; Kohler, Jack; Boot, Wim

    2017-11-01

    Subglacial hydrological processes at tidewater glaciers remain poorly understood due to the difficulty in obtaining direct measurements and lack of empirical verification for modelling approaches. Here, we investigate the subglacial hydrology of Kronebreen, a fast-flowing tidewater glacier in Svalbard during the 2014 melt season. We combine observations of borehole water pressure, supraglacial lake drainage, surface velocities and plume activity with modelled run-off and water routing to develop a conceptual model that thoroughly encapsulates subglacial drainage at a tidewater glacier. Simultaneous measurements suggest that an early-season episode of subglacial flushing took place during our observation period, and a stable efficient drainage system effectively transported subglacial water through the northern region of the glacier tongue. Drainage pathways through the central and southern regions of the glacier tongue were disrupted throughout the following melt season. Periodic plume activity at the terminus appears to be a signal for modulated subglacial pulsing, i.e. an internally driven storage and release of subglacial meltwater that operates independently of marine influences. This storage is a key control on ice flow in the 2014 melt season. Evidence from this work and previous studies strongly suggests that long-term changes in ice flow at Kronebreen are controlled by the location of efficient/inefficient drainage and the position of regions where water is stored and released.

  19. Rapidly changing subglacial hydrological pathways at a tidewater glacier revealed through simultaneous observations of water pressure, supraglacial lakes, meltwater plumes and surface velocities

    Directory of Open Access Journals (Sweden)

    P. How

    2017-11-01

    Full Text Available Subglacial hydrological processes at tidewater glaciers remain poorly understood due to the difficulty in obtaining direct measurements and lack of empirical verification for modelling approaches. Here, we investigate the subglacial hydrology of Kronebreen, a fast-flowing tidewater glacier in Svalbard during the 2014 melt season. We combine observations of borehole water pressure, supraglacial lake drainage, surface velocities and plume activity with modelled run-off and water routing to develop a conceptual model that thoroughly encapsulates subglacial drainage at a tidewater glacier. Simultaneous measurements suggest that an early-season episode of subglacial flushing took place during our observation period, and a stable efficient drainage system effectively transported subglacial water through the northern region of the glacier tongue. Drainage pathways through the central and southern regions of the glacier tongue were disrupted throughout the following melt season. Periodic plume activity at the terminus appears to be a signal for modulated subglacial pulsing, i.e. an internally driven storage and release of subglacial meltwater that operates independently of marine influences. This storage is a key control on ice flow in the 2014 melt season. Evidence from this work and previous studies strongly suggests that long-term changes in ice flow at Kronebreen are controlled by the location of efficient/inefficient drainage and the position of regions where water is stored and released.

  20. Probing the nanoscale with high-speed interferometry of an impacting drop

    KAUST Repository

    Thoroddsen, Sigurdur T.

    2017-02-28

    The simple phenomenon of a water drop falling onto a glass plate may seem like a trivial fluid mechanics problem. However, detailed imaging has shown that this process is highly complex and a small air-bubble is always entrapped under the drop when it makes contact with the solid. This bubble can interfere with the uniformity of spray coatings and degrade inkjet fabrication of displays etc. We will describe how we use high-speed interferometry at 5 million frames per second to understand the details of this process. As the impacting drop approaches the solid, the dynamics are characterized by a balance between the lubrication pressure in the thin air layer and the inertia of the bot-tom of the drop. This deforms the drop, forming a dimple at its bottom and making the drop touch the surface along a ring, thereby entrapping the air-layer, which is typically 1-3 mu m thick. This air-layer can be highly compressed and the deceleration of the bottom of the drop can be as large as 300,000 g. We describe how the thicknessevolution of the lubricating air-layer is extracted from following the interference fringes between frames. Two-color interferometry is also used to extract absolute layer thicknesses. Finally, we identify the effects of nanometric surface roughness on the first contact of the drop with the substrate. Here we need to resolve the 100 nm thickness changes occurring during 200 ns intervals, requiring these state of the art high-speed cameras. Surprisingly, we see a ring of micro-bubbles marking the first contact of the drop with the glass, only for microscope slides, which have a typical roughness of 20 nm, while such rings are absent for drop impacts onto molecularly smooth mica surfaces.

  1. A Double Blind Clinical Trial on the Efficacy of Honey Drop in Vernal Keratoconjunctivitis

    Directory of Open Access Journals (Sweden)

    Ali Salehi

    2014-01-01

    Full Text Available Purpose. This trial was designed to evaluate the efficacy and safety of topical honey eye drops in patients with diagnosed VKC. Methods. This clinical trial was conducted on 60 patients with diagnosed VKC. The patients were selected and randomly allocated between two groups of 30. Patients in two groups received honey eye drop (60% in artificial tear or placebo, other than cromolyn and fluorometholone 1% eye drops, to be used topically in each eye, four times per day. The patients were examined with slit lamp and torch at baseline and the follow-up visits on the 1st, 3rd, and 6th months of the study for redness, limbal papillae, and intraocular pressure. Results. Out of 60 patients who completed the study, 19 patients (31.7% were female. There was significant increase in eye pressure and reduction in redness as well as limbal papillae, following the consumption of the honey drop in honey group compared to placebo control group (P<0.05. At the end of trial, one patient in honey group and 7 ones in placebo group had limbal papillae (P<0.05. Conclusion. Topical honey eye drops, when used along with Cromolyn and Fluorometholone eye drops, might be beneficial for the treatment of VKC.

  2. A double blind clinical trial on the efficacy of honey drop in vernal keratoconjunctivitis.

    Science.gov (United States)

    Salehi, Ali; Jabarzare, Solmaz; Neurmohamadi, Mohammadreza; Kheiri, Soleiman; Rafieian-Kopaei, Mahmoud

    2014-01-01

    Purpose. This trial was designed to evaluate the efficacy and safety of topical honey eye drops in patients with diagnosed VKC. Methods. This clinical trial was conducted on 60 patients with diagnosed VKC. The patients were selected and randomly allocated between two groups of 30. Patients in two groups received honey eye drop (60% in artificial tear) or placebo, other than cromolyn and fluorometholone 1% eye drops, to be used topically in each eye, four times per day. The patients were examined with slit lamp and torch at baseline and the follow-up visits on the 1st, 3rd, and 6th months of the study for redness, limbal papillae, and intraocular pressure. Results. Out of 60 patients who completed the study, 19 patients (31.7%) were female. There was significant increase in eye pressure and reduction in redness as well as limbal papillae, following the consumption of the honey drop in honey group compared to placebo control group (P < 0.05). At the end of trial, one patient in honey group and 7 ones in placebo group had limbal papillae (P < 0.05). Conclusion. Topical honey eye drops, when used along with Cromolyn and Fluorometholone eye drops, might be beneficial for the treatment of VKC.

  3. Blood drop patterns: Formation and applications.

    Science.gov (United States)

    Chen, Ruoyang; Zhang, Liyuan; Zang, Duyang; Shen, Wei

    2016-05-01

    The drying of a drop of blood or plasma on a solid substrate leads to the formation of interesting and complex patterns. Inter- and intra-cellular and macromolecular interactions in the drying plasma or blood drop are responsible for the final morphologies of the dried patterns. Changes in these cellular and macromolecular components in blood caused by diseases have been suspected to cause changes in the dried drop patterns of plasma and whole blood, which could be used as simple diagnostic tools to identify the health of humans and livestock. However, complex physicochemical driving forces involved in the pattern formation are not fully understood. This review focuses on the scientific development in microscopic observations and pattern interpretation of dried plasma and whole blood samples, as well as the diagnostic applications of pattern analysis. Dried drop patterns of plasma consist of intricate visible cracks in the outer region and fine structures in the central region, which are mainly influenced by the presence and concentration of inorganic salts and proteins during drying. The shrinkage of macromolecular gel and its adhesion to the substrate surface have been thought to be responsible for the formation of the cracks. Dried drop patterns of whole blood have three characteristic zones; their formation as functions of drying time has been reported in the literature. Some research works have applied engineering treatment to the evaporation process of whole blood samples. The sensitivities of the resultant patterns to the relative humidity of the environment, the wettability of the substrates, and the size of the drop have been reported. These research works shed light on the mechanisms of spreading, evaporation, gelation, and crack formation of the blood drops on solid substrates, as well as on the potential applications of dried drop patterns of plasma and whole blood in diagnosis. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

  4. Integrity Evaluation of Control Rod Assembly for Sodium-Cooled Fast Reactor due to Drop Impact

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyun Seung; Yoon, Kyung Ho; Kim, Hyung Kyu; Cheon, Jin Sik; Lee, Chan Bock [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2017-03-15

    The CA (Control Assembly) of an SFR has a CRA(Control Rod Assembly) with an inner duct and control rod. During an emergency situation, the CRA falls into the duct of the CA for a rapid shut-down. The drop time and impact velocity of the CRA are important parameters with respect to the reactivity insertion time and the structural integrity of the CRA. The objective of this study was to investigate the dynamic behavior and integrity of the CRA owing to a drop impact. The impact analysis of the CRA under normal/abnormal drop conditions was carried out using the commercial FEM code LS-DYNA. Results of the drop impact analysis demonstrated that the CRA maintained structural integrity, and could be safely inserted into the flow hole of the damper under abnormal conditions.

  5. Drop Performance Test of CRDMs for JRTR

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Myoung-Hwan; Cho, Yeong-Garp; Chung, Jong-Ha [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Jung-Hyun [POSCO Plandtec Co. Ltd, Ulsan (Korea, Republic of); Lee, Kwan-Hee [RIST, Pohang (Korea, Republic of)

    2015-10-15

    The drop test results of CRDMs with AC-type electromagnet show that the initial delay times are not satisfied with the requirement, 0.15 seconds. After the replacement of the electromagnet from AC-type to DCtype, the drop times of CARs and accelerations due to the impact of moving parts are satisfied with all requirements. As a result, it is found that four CRDMs to be installed at site have a good drop performance, and meet all performance requirements. A control rod drive mechanism (CRDM) is a device to control the position of a control absorber rod (CAR) in the core by using a stepping motor which is commanded by the reactor regulating system (RRS) to control the reactivity during the normal operation of the reactor. The top-mounted CRDM driven by the stepping motor for Jordan Research and Training Reactor (JRTR) has been developed in KAERI. The CRDM for JRTR has been optimized by the design improvement based on that of the HANARO. It is necessary to verify the performances such as the stepping, drop, endurance, vibration, seismic and structural integrity for active components. Especially, the CAR drop curves are important data for the safety analysis. This paper describes the test results to demonstrate the drop performances of a prototype and 4 CRDMs to be installed at site. The tests are carried out at a test rig simulating the actual reactor's conditions.

  6. Instability of protein drops via applied electric field: mathematical and experimental aspects.

    Science.gov (United States)

    Penkova, Anita; Mladenov, Ivaïlo M

    2009-04-01

    Drops (5-15 microL) consisting of a protein solution readily crystallize and could provide an opportunity for a simultaneous examination of their thermodynamic and kinetic properties at various sizes. These drops experienced different pressures and therefore different surface tensions. Starting from the expression for the interface traction between protein fluid and silicon medium (with different dielectric constants), we have derived an equation accounting the influence of the electric field strength on the geometry of a protein drop. If the field strength increases, the lysozyme drop between two electrodes elongates and some crystals nucleate on the cathode side. In this situation numerous factors besides the intensity of the electric field--such as the solution composition, the charge and size of the protein molecule, the purity of the protein substance, and the consistency of bubbles of water--can have a significant effect on the crystallization rate and location.

  7. Pressures Detector Calibration and Measurement

    CERN Document Server

    AUTHOR|(CDS)2156315

    2016-01-01

    This is report of my first and second projects (of 3) in NA61. I did data taking and analysis in order to do calibration of pressure detectors and verified it. I analyzed the data by ROOT software using the C ++ programming language. The first part of my project was determination of calibration factor of pressure sensors. Based on that result, I examined the relation between pressure drop, gas flow rate of in paper filter and its diameter.

  8. Efficacy of atropine and anisodamine eye drops for adolescent pseudomyopia

    Directory of Open Access Journals (Sweden)

    Hui-Jie Wang

    2017-03-01

    Full Text Available AIM:To investigate the effect and local influence of atropine and anisodamine eye drops on adolescent pseudomyopia. METHODS:Totally 110 cases of juvenile pseudomyopia were randomly divided into two groups, the control group was given 10g/L atropine sulfate eye gel, and the observation group was treated with 5g/L raceanisodamine eye drops. The efficacy of two methods, the changes of axial length and intraocular pressure before and after treatment, and the incidence of adverse reactions were compared. RESULTS: There was no significant difference in cure rate between the two groups(χ2=0.533, P=0.465, but the effective rate of observation group was significantly better than the control group(χ2=3.907, P=0.048. Compared with the same group before treatment, the length of the axial length of the two groups increased in different degrees,and the increase value of the observation group was significantly higher than that of the control group, the difference was statistically significant(PP>0.05. The intraocular pressure of the two groups was significantly lower than that of the same group before treatment, and the difference between the two groups after treatments was not statistically significant(P >0.05. The incidence of adverse reactions in the observation group was significantly lower than that in the control group(χ2=18.939, PCONCLUSION: Anisodamine eye drops in the treatment of juvenile pseudomyopia has obvious curative effect, its efficacy and safety are better than atropine eye gel.

  9. The Drop Tower Bremen -Experiment Operation

    Science.gov (United States)

    Könemann, Thorben; von Kampen, Peter; Rath, Hans J.

    The idea behind the drop tower facility of the Center of Applied Space Technology and Micro-gravity (ZARM) in Bremen is to provide an inimitable technical opportunity of a daily access to short-term weightlessness on earth. In this way ZARM`s european unique ground-based microgravity laboratory displays an excellent economic alternative for research in space-related conditions at low costs comparable to orbital platforms. Many national and international ex-perimentalists motivated by these prospects decide to benefit from the high-quality and easy accessible microgravity environment only provided by the Drop Tower Bremen. Corresponding experiments in reduced gravity could open new perspectives of investigation methods and give scientists an impressive potential for a future technology and multidisciplinary applications on different research fields like Fundamental Physics, Astrophysics, Fluid Dynamics, Combus-tion, Material Science, Chemistry and Biology. Generally, realizing microgravity experiments at ZARM`s drop tower facility meet new requirements of the experimental hardware and may lead to some technical constraints in the setups. In any case the ZARM Drop Tower Operation and Service Company (ZARM FAB mbH) maintaining the drop tower facility is prepared to as-sist experimentalists by offering own air-conditioned laboratories, clean rooms, workshops and consulting engineers, as well as scientific personal. Furthermore, ZARM`s on-site apartment can be used for accommodations during the experiment campaigns. In terms of approaching drop tower experimenting, consulting of experimentalists is mandatory to successfully accomplish the pursued drop or catapult capsule experiment. For this purpose there will be a lot of expertise and help given by ZARM FAB mbH in strong cooperation to-gether with the experimentalists. However, in comparison to standard laboratory setups the drop or catapult capsule setup seems to be completely different at first view. While defining a

  10. [Optimize dropping process of Ginkgo biloba dropping pills by using design space approach].

    Science.gov (United States)

    Shen, Ji-Chen; Wang, Qing-Qing; Chen, An; Pan, Fang-Lai; Gong, Xing-Chu; Qu, Hai-Bin

    2017-07-01

    In this paper, a design space approach was applied to optimize the dropping process of Ginkgo biloba dropping pills. Firstly, potential critical process parameters and potential process critical quality attributes were determined through literature research and pre-experiments. Secondly, experiments were carried out according to Box-Behnken design. Then the critical process parameters and critical quality attributes were determined based on the experimental results. Thirdly, second-order polynomial models were used to describe the quantitative relationships between critical process parameters and critical quality attributes. Finally, a probability-based design space was calculated and verified. The verification results showed that efficient production of Ginkgo biloba dropping pills can be guaranteed by operating within the design space parameters. The recommended operation ranges for the critical dropping process parameters of Ginkgo biloba dropping pills were as follows: dropping distance of 5.5-6.7 cm, and dropping speed of 59-60 drops per minute, providing a reference for industrial production of Ginkgo biloba dropping pills. Copyright© by the Chinese Pharmaceutical Association.

  11. Mutual adaptation of a Faraday instability pattern with its flexible boundaries in floating fluid drops

    CERN Document Server

    Pucci, Giuseppe; Amar, Martine Ben; Couder, Yves; 10.1103/PhysRevLett.106.024503

    2013-01-01

    Hydrodynamic instabilities are usually investigated in confined geometries where the resulting spatiotemporal pattern is constrained by the boundary conditions. Here we study the Faraday instability in domains with flexible boundaries. This is implemented by triggering this instability in floating fluid drops. An interaction of Faraday waves with the shape of the drop is observed, the radiation pressure of the waves exerting a force on the surface tension held boundaries. Two regimes are observed. In the first one there is a coadaptation of the wave pattern with the shape of the domain so that a steady configuration is reached. In the second one the radiation pressure dominates and no steady regime is reached. The drop stretches and ultimately breaks into smaller domains that have a complex dynamics including spontaneous propagation.

  12. Dropping out of School among ELL Students: Implications to Schools and Teacher Education

    Science.gov (United States)

    Sheng, Zhaohui; Sheng, Yanyan; Anderson, Christine J.

    2011-01-01

    English language learners (ELLs) are the most rapidly growing student population in U.S. elementary and secondary schools, and this growth rate will continue throughout the next few decades. Indirect evidence has suggested that the youth population that grows the fastest has the highest risk of dropping out of school. This article reviews the…

  13. Cavity optomechanics in a levitated helium drop

    Science.gov (United States)

    Childress, L.; Schmidt, M. P.; Kashkanova, A. D.; Brown, C. D.; Harris, G. I.; Aiello, A.; Marquardt, F.; Harris, J. G. E.

    2017-12-01

    We describe a proposal for a type of optomechanical system based on a drop of liquid helium that is magnetically levitated in vacuum. In the proposed device, the drop would serve three roles: its optical whispering-gallery modes would provide the optical cavity, its surface vibrations would constitute the mechanical element, and evaporation of He atoms from its surface would provide continuous refrigeration. We analyze the feasibility of such a system in light of previous experimental demonstrations of its essential components: magnetic levitation of mm-scale and cm-scale drops of liquid He , evaporative cooling of He droplets in vacuum, and coupling to high-quality optical whispering-gallery modes in a wide range of liquids. We find that the combination of these features could result in a device that approaches the single-photon strong-coupling regime, due to the high optical quality factors attainable at low temperatures. Moreover, the system offers a unique opportunity to use optical techniques to study the motion of a superfluid that is freely levitating in vacuum (in the case of 4He). Alternatively, for a normal fluid drop of 3He, we propose to exploit the coupling between the drop's rotations and vibrations to perform quantum nondemolition measurements of angular momentum.

  14. Drop impact entrapment of bubble rings

    KAUST Repository

    Thoraval, M.-J.

    2013-04-29

    We use ultra-high-speed video imaging to look at the initial contact of a drop impacting on a liquid layer. We observe experimentally the vortex street and the bubble-ring entrapments predicted numerically, for high impact velocities, by Thoraval et al. (Phys. Rev. Lett., vol. 108, 2012, article 264506). These dynamics mainly occur within 50 -s after the first contact, requiring imaging at 1 million f.p.s. For a water drop impacting on a thin layer of water, the entrapment of isolated bubbles starts through azimuthal instability, which forms at low impact velocities, in the neck connecting the drop and pool. For Reynolds number Re above -12 000, up to 10 partial bubble rings have been observed at the base of the ejecta, starting when the contact is -20% of the drop size. More regular bubble rings are observed for a pool of ethanol or methanol. The video imaging shows rotation around some of these air cylinders, which can temporarily delay their breakup into micro-bubbles. The different refractive index in the pool liquid reveals the destabilization of the vortices and the formation of streamwise vortices and intricate vortex tangles. Fine-scale axisymmetry is thereby destroyed. We show also that the shape of the drop has a strong influence on these dynamics. 2013 Cambridge University Press.

  15. Drop splash on a smooth, dry surface

    Science.gov (United States)

    Riboux, Guillaume; Gordillo, Jose Manuel; Korobkin, Alexander

    2013-11-01

    It is our purpose here to determine the conditions under which a drop of a given liquid with a known radius R impacting against a smooth impermeable surface at a velocity V, will either spread axisymmetrically onto the substrate or will create a splash, giving rise to usually undesired star-shaped patterns. In our experimental setup, drops are generated injecting low viscosity liquids falling under the action of gravity from a stainless steel hypodermic needle. The experimental observations using two high speed cameras operating simultaneously and placed perpendicularly to each other reveal that, initially, the drop deforms axisymmetrically, with A (T) the radius of the wetted area. For high enough values of the drop impact velocity, a thin sheet of liquid starts to be ejected from A (T) at a velocity Vjet > V for instants of time such that T >=Tc . If Vjet is above a certain threshold, which depends on the solid wetting properties as well as on the material properties of both the liquid and the atmospheric gas, the rim of the lamella dewets the solid to finally break into drops. Using Wagner's theory we demonstrate that A (T) =√{ 3 RVT } and our results also reveal that Tc We - 1 / 2 =(ρV2 R / σ) - 1 / 2 and Vjet We 1 / 4 .

  16. Drop impact on inclined superhydrophobic surfaces

    Science.gov (United States)

    Choi, Wonjae; Leclear, Sani; Leclear, Johnathon; Abhijeet, .; Park, Kyoo-Chul

    We report an empirical study and dimensional analysis on the impact patterns of water drops on inclined superhydrophobic surfaces. While the classic Weber number determines the spreading and recoiling dynamics of a water drop on a horizontal / smooth surface, for a superhydrophobic surface, the dynamics depends on two distinct Weber numbers, each calculated using the length scale of the drop or of the pores on the surface. Impact on an inclined superhydrophobic surface is even more complicated, as the velocity that determines the Weber number is not necessarily the absolute speed of the drop but the velocity components normal and tangential to the surface. We define six different Weber numbers, using three different velocities (absolute, normal and tangential velocities) and two different length scales (size of the drop and of the texture). We investigate the impact patterns on inclined superhydrophobic surfaces with three different types of surface texture: (i) posts, (ii) ridges aligned with and (iii) ridges perpendicular to the impact direction. Results suggest that all six Weber numbers matter, but affect different parts of the impact dynamics, ranging from the Cassie-Wenzel transition, maximum spreading, to anisotropic deformation. We acknowledge financial support from the Office of Naval Research (ONR) through Contract 3002453812.

  17. Drop impact on spherical soft surfaces

    Science.gov (United States)

    Chen, Simeng; Bertola, Volfango

    2017-08-01

    The impact of water drops on spherical soft surfaces is investigated experimentally through high-speed imaging. The effect of a convex compliant surface on the dynamics of impacting drops is relevant to various applications, such as 3D ink-jet printing, where drops of fresh material impact on partially cured soft substrates with arbitrary shape. Several quantities which characterize the morphology of impacting drops are measured through image-processing, including the maximum and minimum spreading angles, length of the wetted curve, and dynamic contact angle. In particular, the dynamic contact angle is measured using a novel digital image-processing scheme based on a goniometric mask, which does not require edge fitting. It is shown that the surface with a higher curvature enhances the retraction of the spreading drop; this effect may be due to the difference of energy dissipation induced by the curvature of the surface. In addition, the impact parameters (elastic modulus, diameter ratio, and Weber number) are observed to significantly affect the dynamic contact angle during impact. A quantitative estimation of the deformation energy shows that it is significantly smaller than viscous dissipation.

  18. A New Mechanism for Pore Pressure Changes Induced by Distant Earthquakes

    Science.gov (United States)

    Brodsky, E. E.; Roeloffs, E.; Woodcock, D.; Gall, I.; Manga, M.

    2001-12-01

    Observations during the Mw=7.3 1992 Landers earthquake, Mw=7.4 Izmit earthquake and Mw=7.2 Hector Mine earthquake suggest that seismicity is triggered hundreds of kilometers from a mainshock epicenter. This puzzling phenomenon is not explained by traditional elastic models of seismic stresses. The fact that the triggered sites are often geothermal or magmatic suggests that fluids may be an important part of the triggering process. Rapid changes in pore pressure either reduce the effective stress on faults locally or prompt hydrofracturing to initiate local earthquakes. The challenge is to discover how the seismic waves generate a change in pore fluid pressure. We constrain a mechanism for seismically-induced pore pressure changes by studying coseismic water level drops at a well in Grants Pass, Oregon. Water level drops at the site have been associated with earthquakes for nearly 20 years. High-sample rate (up to 1 Hz) digital water level data is available for the two coseismic drops that have occurred since 1994. The approach of this study is to use the amplification of the seismic waves in the well to constrain variations of the aquifer properties during the water level drops. We find that the amplification of the seismic waves in the well is consistent with standard theory for 7 digitally recorded events without drops, but during an earthquake with a drop a dramatic change in amplification occurs during the passage of the Rayleigh waves. The change in amplification indicates that the transmissivity increases by a factor of 50 during the 11 cm coseismic water level drop accompanying the 1999 Mw=7.5 1999 Oaxaca, Mexico earthquake. Based on these observations, we propose a new model for coseismic pore pressure changes. Drops occur if an earthquake occurs when the well has become temporarily clogged by a solid precipitate or sediment. The seismic shaking induces a flow which removes the obstruction. Once a barrier is removed, water flows rapidly to generate dramatic

  19. Impact of mydriatic eye drops on neonatal cerebral blood flow

    Directory of Open Access Journals (Sweden)

    Atef Alshafei

    2017-11-01

    Full Text Available Retinopathy of prematurity (ROP screening is a common routine procedure carried out on preterm infants in neonatal intensive care units (NICUs. Mydriatic eye drops containing phenylephrine hydrochloride 2.5% (a sympathomimetic agent and tropicamide 0.5% (a cycloplegic medication are readily absorbed from the conjunctiva and produce systemic responses in various organs. To our knowledge, no studies have investigated the direct effects of these medications on cerebral blood flow velocities (CBFVs in preterm infants. To evaluate the systemic effects of locally instilled mydriatic eye drops (phenylephrine hydrochloride 2.5% and tropicamide 0.5% used for ROP screening, on cerebral blood flow velocity in preterm infants, a prospective observational study was conducted among preterm infants with gestational age (GA < 31 weeks admitted to the NICU at Dubai Hospital between February 20, 2017 and June 20, 2017. The infants (at a post-menstrual age of 31-34 weeks underwent duplex ultrasound evaluation of CBFV before and after mydriatic eye drops administration.Pulsed-wave Doppler ultrasound studies were performed 1 h before and 1 h after eye mydriasis. We measured peak systolic velocity (PSV and end diastolic velocity (EDV for both the anterior cerebral artery (ACA and middle cerebral artery (MCA and calculated the resistive index (RI, defined as PSV – EDV/PSV. Mean arterial blood pressure (MAP, heart rate, oxygen saturation and pain score were assessed before and 1 h after ROP examination.A paired t-test and McNemar’s test were used to assess the statistical significance of the difference between pairs of means and the qualitative variables measured twice for the same study group.Among the 42 eligible preterm infants, the mean (SD GA was 27 (2.68 weeks (range, 24-31 weeks. The mean (SD RI of ACA before and 1 h after eye drops administration was 0.84 (0.06 and 0.83 (0.07 respectively (p = 0.453. The mean (SD RIs of MCA before and then 1 h after

  20. Nonreciprocal photonic crystal add-drop filter

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Keyu [THz Technical Research Center of Shenzhen University, Shenzhen 518067 (China); Shenzhen Key Laboratory of Micro-Nano Photonic Information Technology, Shenzhen 518067 (China); College of Electronic Science and Technology, Shenzhen University, Shenzhen 518067 (China); Department of Mechanical Engineering, University of Colorado Boulder, Boulder, Colorado 80309 (United States); Xiao, Jun-Jun [College of Electronic and Information Engineering, Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Yin, Xiaobo, E-mail: Xiaobo.Yin@Colorado.Edu [Department of Mechanical Engineering, University of Colorado Boulder, Boulder, Colorado 80309 (United States); Materials Science and Engineering Program, University of Colorado Boulder, Boulder, Colorado 80309 (United States)

    2014-11-24

    We present a versatile add-drop integrated photonic filter (ADF) consisting of nonreciprocal waveguides in which the propagation of light is restricted in one predetermined direction. With the bus and add/drop waveguides symmetrically coupled through a cavity, the four-port device allows each individual port to add and/or drop a signal of the same frequency. The scheme is general and we demonstrate the nonreciprocal ADF with magneto-optical photonic crystals. The filter is immune to waveguide defects, allowing straightforward implementation of multi-channel ADFs by cascading the four-port designs. The results should find applications in wavelength-division multiplexing and related integrated photonic techniques.

  1. Drop impact on porous superhydrophobic polymer surfaces.

    Science.gov (United States)

    Rioboo, R; Voué, M; Vaillant, A; De Coninck, J

    2008-12-16

    Water drop impacts are performed on porous-like superhydrophobic surfaces. We investigate the influence of the drop size and of the impact velocity on the event. The Cassie-Baxter/Wenzel transition is observed to be a function of the drop size, as well as the outcomes of the impact or deposition process, which can be deposition, rebound, sticking, or fragmentation. A quantitative analysis on the experimental conditions required to observe rebound is provided. Our analysis shows that the wettability hysteresis controls the limit between deposition and rebound events. This limit corresponds to a constant Weber number. A survey of literature results on impact over patterned superhydrophobic surfaces is provided as a comparison.

  2. Liquid toroidal drop under uniform electric field

    Science.gov (United States)

    Zabarankin, Michael

    2017-06-01

    The problem of a stationary liquid toroidal drop freely suspended in another fluid and subjected to an electric field uniform at infinity is addressed analytically. Taylor's discriminating function implies that, when the phases have equal viscosities and are assumed to be slightly conducting (leaky dielectrics), a spherical drop is stationary when Q=(2R2+3R+2)/(7R2), where R and Q are ratios of the phases' electric conductivities and dielectric constants, respectively. This condition holds for any electric capillary number, CaE, that defines the ratio of electric stress to surface tension. Pairam and Fernández-Nieves showed experimentally that, in the absence of external forces (CaE=0), a toroidal drop shrinks towards its centre, and, consequently, the drop can be stationary only for some CaE>0. This work finds Q and CaE such that, under the presence of an electric field and with equal viscosities of the phases, a toroidal drop having major radius ρ and volume 4π/3 is qualitatively stationary-the normal velocity of the drop's interface is minute and the interface coincides visually with a streamline. The found Q and CaE depend on R and ρ, and for large ρ, e.g. ρ≥3, they have simple approximations: Q˜(R2+R+1)/(3R2) and CaE∼3 √{3 π ρ / 2 } (6 ln ⁡ρ +2 ln ⁡[96 π ]-9 )/ (12 ln ⁡ρ +4 ln ⁡[96 π ]-17 ) (R+1 ) 2/ (R-1 ) 2.

  3. Water Drops Dancing on Ice: How Sublimation Leads to Drop Rebound

    Science.gov (United States)

    Antonini, C.; Bernagozzi, I.; Jung, S.; Poulikakos, D.; Marengo, M.

    2013-07-01

    Drop rebound is a spectacular event that appears after impact on hydrophobic or superhydrophobic surfaces but can also be induced through the so-called Leidenfrost effect. Here we demonstrate that drop rebound can also originate from another physical phenomenon, the solid substrate sublimation. Through drop impact experiments on a superhydrophobic surfaces, a hot plate, and solid carbon dioxide (commonly known as dry ice), we compare drop rebound based on three different physical mechanisms, which apparently share nothing in common (superhydrophobicity, evaporation, and sublimation), but lead to the same rebound phenomenon in an extremely wide temperature range, from 300°C down to even below -79°C. The formation and unprecedented visualization of an air vortex ring around an impacting drop are also reported.

  4. Transformation of the bridge during drop separation

    Science.gov (United States)

    Chashechkin, Yu. D.; Prokhorov, V. E.

    2016-05-01

    The geometry of flows during separation of pendant drops of liquids with significantly different physical properties (alcohol, water, glycerin, oil) has been studied by high-speed video recording. The dynamics of the processes involving the formation of bridges of two characteristic shapes—slightly nonuniform in thickness and with thinning of the upper and lower ends—has been investigated. It has been shown that the shape change of the separated bridge has a number of stages determined by the properties of the liquid. As a result, the bridge is transformed into a small drop—a satellite drop.

  5. Shuttlecock Velocity of a Badminton Drop Shot

    Directory of Open Access Journals (Sweden)

    Ampharin Ongvises

    2013-01-01

    Full Text Available In a badminton ‘drop shot’, the shuttlecock is struck by a non-rotating racquet at low speed. In this investigation, a shuttlecock was hit by a badminton racquet in a linear collision, simulating a drop shot. The collision was recorded with high-speed video and the velocities of the racquet and shuttlecock determined. The relationship between the impact velocity of the racquet and the velocity of the shuttlecock as it leaves the badminton racquet after collision was found to be proportional over the range tested.

  6. Shuttlecock Velocity of a Badminton Drop Shot

    Directory of Open Access Journals (Sweden)

    Ampharin Ongvises

    2013-12-01

    Full Text Available In a badminton ‘drop shot’, the shuttlecock is struck by a non-rotating racquet at low speed. In this investigation, a shuttlecock was hit by a badminton racquet in a linear collision, simulating a drop shot. The collision was recorded with high-speed video and the velocities of the racquet and shuttlecock determined. The relationship between the impact velocity of the racquet and the velocity of the shuttlecock as it leaves the badminton racquet after collision was found to be proportional over the range tested.

  7. Skating on a Film of Air: Drops Impacting on a Surface

    CERN Document Server

    Kolinski, John M; Mandre, Shreyas; Brenner, Michael P; Weitz, David A; Mahadevan, L

    2011-01-01

    Drops impacting on a surface are ubiquitous in our everyday experience. This impact is understood within a commonly accepted hydrodynamic picture: it is initiated by a rapid shock and a subsequent ejection of a sheet leading to beautiful splashing patterns. However, this picture ignores the essential role of the air that is trapped between the impacting drop and the surface. Here we describe a new imaging modality that is sensitive to the behavior right at the surface. We show that a very thin film of air, only a few tens of nanometers thick, remains trapped between the falling drop and the surface as the drop spreads. The thin film of air serves to lubricate the drop enabling the fluid to skate on the air film laterally outward at surprisingly high velocities, consistent with theoretical predictions. Eventually this thin film of air must break down as the fluid wets the surface. We suggest that this occurs in a spinodal-like fashion, and causes a very rapid spreading of a wetting front outwards; simultaneous...

  8. Drop Impact on Oblique Superhydrophobic Surfaces with Two-Tier Roughness.

    Science.gov (United States)

    Zhang, Rui; Hao, Pengfei; He, Feng

    2017-04-11

    This paper investigates the complex physical phenomenon of oblique drop impact on superhydrophobic substrates with two-tier roughness (patterned with varied submillimeter-scale posts and coated with nanoparticles). Experimental results show that the impact Weber number of drops and the solid fraction of the submillimeter-scale post structures are crucial for the outcomes of oblique drop collisions. Water droplets with 10 surface solid fraction decreases, four possible bouncing patterns occur in sequence: sliding rebound, stretched rebound, penetration rebound, and breakup rebound. We demonstrate that the stretched rebound, in which the drops bounce off the surface rapidly in an elongated shape without tangential retraction, allows a 10%∼30% reduction of contact time compared with conventional sliding rebound on oblique surfaces. Three types of stretched rebound are observed on substrates with moderate solid fraction (0.1 patterns. These findings are believed to provide valuable guidance to the design of self-cleaning and anti-icing surfaces under oblique liquid impacts where rapid drop shedding is profitable.

  9. Reduction in drop size of ophthalmic topical drop preparations and the impact of treatment

    Directory of Open Access Journals (Sweden)

    Shiva Kumar

    2011-01-01

    Full Text Available In this work we devised a method to create smaller eye drops of the glaucoma medication timolol maleate by altering the dropper tip design and changing the physical properties of the formulation. Most ocular diseases are treated with topical application of eye drops. After instillation of an eye drop, typically, less than 5% of the applied drug penetrates the cornea and reaches the intraocular tissues; the major fraction of the instilled drug is absorbed and enters the systemic circulation. Ophthalmic solutions are available in multidose or single-dose glass/plastic dropper bottles that deliver drops with a volume that ranges from 25 μL to 70 μL (average 40 μL. Because of the low capacity of the precorneal area, the optimal drop volume is about 20 μL; with larger volumes there is the risk of adverse systemic effects due to absorption of the drug via the nasal mucosa. Thus, both from the biopharmaceutical and economic point of view, drops of only 5-15 mL volume should be instilled into the eye. In this present work we devised a method to reduce the size of the drop by inserting a glass capillary tube into the dropper tip and by changing the physical properties of the formulation (by altering the concentration of Tween 80™, i.e., 0.05% and 0.1% of Tween 80™. We measured the drop sizes of the different timolol eye drop formulations available in the market and estimated the yearly cost of the medications. Our timolol maleate formulation with 0.1% concentration of Tween 80™ delivered through the dropper tip with the inserted glass capillary was shown to be better than the other formulations available in the market in terms of ability to deliver smaller drops, meaning that each bottle would last longer and that the yearly cost of treatment would be lower.

  10. Resistance properties of a bend in dense-phase pneumatic conveying of pulverized coal under high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Y.; Chen, X.P.; Liang, C.; Xu, P. [Southeast University, School of Energy and Environment, Nanjing (China)

    2011-01-15

    Experiments of high-pressure dense-phase pneumatic conveying of pulverized coal with different mean particle sizes using nitrogen were carried out in an experimental test facility with a conveying pressure of up to 4 MPa. The effects of three representative operating parameters (solids-to-gas mass flow ratio, conveying pressure, mean particle size) on the total pressure drop were examined. The pressure drops across the horizontal and vertical bends were analyzed by experimental and analytical calculation. The results show that the pressure drop due to gas friction is of much less significance, while the pressure drop due to the solids friction component of the total pressure drop dominates. There exists a relationship between the pressure drop due to solids kinetic energy loss and mass flux of solids. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Dropped head congenital muscular dystrophy caused by de novo mutations in LMNA.

    Science.gov (United States)

    Karaoglu, Pakize; Quizon, Nicolas; Pergande, Matthias; Wang, Haicui; Polat, Ayşe Ipek; Ersen, Ayca; Özer, Erdener; Willkomm, Lena; Hiz Kurul, Semra; Heredia, Raúl; Yis, Uluç; Selcen, Duygu; Çirak, Sebahattin

    2017-04-01

    Dropped head syndrome is an easily recognizable clinical presentation of Lamin A/C-related congenital muscular dystrophy. Patients usually present in the first year of life with profound neck muscle weakness, dropped head, and elevated serum creatine kinase. Two patients exhibited head drop during infancy although they were able to sit independently. Later they developed progressive axial and limb-girdle weakness. Creatine kinase levels were elevated and muscle biopsies of both patients showed severe dystrophic changes. The distinctive clinical hallmark of the dropped head led us to the diagnosis of Lamin A/C-related congenital muscular dystrophy, with a pathogenic de novo mutation p.Glu31del in the head domain of the Lamin A/C gene in both patients. Remarkably, one patient also had a central involvement with white matter changes on brain magnetic resonance imaging. Lamin A/C-related dropped-head syndrome is a rapidly progressive congenital muscular dystrophy and may lead to loss of ambulation, respiratory insufficiency, and cardiac complications. Thus, the genetic diagnosis of dropped-head syndrome as L-CMD and the implicated clinical care protocols are of vital importance for these patients. This disease may be underdiagnosed, as only a few genetically confirmed cases have been reported. Copyright © 2016 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

  12. Evolution of under-pressure in Bravo Dome and its implications for geological carbon storage

    Science.gov (United States)

    Akhbari, D.; Hesse, M. A.

    2016-12-01

    Geological carbon storage has the potential to reduce anthropogenic CO2 emissions, if large volumes can be injected. Storage capacity is generally thought to be limited by regional pressure build-up in the subsurface, although natural CO2 reservoirs are commonly under-pressured. To understand the processes that lead to the development of under-pressure we have studied the Bravo Dome natural CO2 reservoir. Pre-production pressures show that Bravo Dome is divided into compartments (Figure a, b, and c) that appear not communicate with each other and the ambient aquifer. While this allows the preservation of under-pressures, it raises question about the emplacement of the reservoir. Noble gas signatures suggest that the reservoir filled from west to east rather than each reservoir being charged individually. Such uni-directional filling is consistent with an eastward decline in pre-production pressure (Figure d). However, this requires that the currently isolated compartments must have been connected during the emplacement. To preserve the overall pressure gradients this connectivity must have been lost relatively quickly after emplacement ended. We suggest that hydraulic fracturing connected the compartments during emplacement and that a pressure drop due to CO2 dissolution helped seal the compartments afterwards. To explore the dynamics, we have developed a numerical model of this fill-fracture-spill-seal process. Initial results suggest that a pressure drop after CO2 emplacement due to continued CO2 dissolution only occurs if the emplacement was very rapid. Understanding the pressure evolution at Bravo Dome is important as Bravo Dome has stored a very large amount of CO2 on millennial time scales, but it does not correspond to the current conception of an ideal storage formation such as Sleipner site in the North Sea, which is laterally open and has high permeability. This demonstrates that successful CO2 storage is possible in a broader range of formations that

  13. Clinical observation of diclofenac sodium eye drops for postoperative recurrence of pterygium

    Directory of Open Access Journals (Sweden)

    Zhi-Rong Xu

    2014-09-01

    Full Text Available AIM: To observe the clinical efficacy of diclofenac sodium eye drops for postoperative recurrence of pterygium, and to provide safer drug regimens to prevent the recurrence of pterygium. METHODS: From November 2011 to September 2013, 124 patients 134 eyes who underwent surgery because of pterygium in our hospital were randomly divided into trial group( diclofenac sodium eye drops and sodium hyaluronate eye dropsand control group(tobramycin dexamethasone eye drops and sodium hyaluronate eye drops, all patients were followed up for 3mo(once a weekand the cornea, intraocular pressure and recurrence of pterygium were observed and compared between the two groups.RESULTS: Followed up for 3mo, 43 cases(45 eyesin the trial group and 38 cases(39 eyesin the control group had done the follow up as planned, in which 14 cases(15 eyesshowed the signs of recurrence, 2 cases(3 eyesrecurred eventually in the trial group, and in the meantime there were 12 cases(13 eyeswith signs of recurrence and 2 cases(2 eyeswith a recurrence eventually in the control group, but no statistical difference was found between the two groups(P>0.05; there were 6 cases(9 eyesdropped out of the study with a higher intraocular pressure in the control group, compared to trial group(0 cases of 0 eye, the difference was statistically significant(PP>0.05. CONCLUSION:Diclofenac sodium eye drops is effective and safe in preventing the recurrence of pterygium.

  14. An experimental study on the drop/interface partial coalescence with surfactants

    Science.gov (United States)

    Dong, Teng; Weheliye, Weheliye Hashi; Chausset, Pierre; Angeli, Panagiota

    2017-10-01

    This paper presents investigations on the partial coalescence of an aqueous drop with an organic-aqueous interface with and without surfactants. The organic phase was different silicone oils and the aqueous phase was a glycerol-water solution at different concentrations. It is found that when the surfactant Span 80 is introduced into the organic phase, the partial coalescence region is reduced in the Oh-Bo coalescence map. The range of the inertio-capillary regime reduces when surfactants are present, while the drop size ratio decreases with increasing surfactant concentration. The velocity fields inside the aqueous drop were studied with high speed particle image velocimetry for the first time. In the surfactant-free system, it was found that the inward motion of the fluids at the upper part of the drop favours the generation of a liquid cylinder at the early stages of coalescence. The pressure gradient created by the downward stream at the bottom of the liquid cylinder drives the pinch-off of the secondary drop. When surfactants are present, the rupture of the film between the drop and the interface occurs at an off-axis location. The liquid cylinder formed in this case is not symmetric and does not lead to pinch-off. It is also found that the vortices inside the droplet have little impact on the partial coalescence.

  15. [Contemporary possibilities of intraocular pressure measurement].

    Science.gov (United States)

    Hornová, J; Baxant, A

    2013-10-01

    Authors introduced current possibilities of measuring intraocular pressure (IOP). A list of available methods of monitoring IOP is published; contact measurement method IOP directly on the cornea, but also over upper lid, methodology of minimal contact and non-contact measurement. Following contact methods are described; former measurements of IOP by impression Schiotz tonometer and the current methodology applanation. So far as the gold standard measurement Goldmann applanation tonometer (GAT) is considered, another methodology with applanation measurements are compared: Pascal dynamic contoured tonometer (DCT ), BioResonator - resonant applanation tonometer (ART ), digital applanation tonometer Tonopen and last hit: continuous measurement of IOP by Sensimed Triggerfish. Orientation and rapid assessment is palpation pressure control over the lid and measuring by tonometer Diaton. Rebound tonometer (RBT) iCare belongs to measurements with minimal contact, no need anesthetic drops and fluorescein, therefore a self - home version of IOP measurements (Icare ONE) is developed. Non-contact measurement of IOP by different pneumotonometers is popular for screening assessment of IOP. Reichert Ocular Response Analyzer (ORA) is a non-contact applanation IOP measurement and reveals additional properties of the cornea. In the discussion of a range methodology is evaluated, the experience of other authors and their own experience is compared. For monitoring of patients is necessary to select the most suitable methodology, measure repeatedly and accurately to allow long-term monitoring of intraocular pressure.

  16. Rapid wide-scope screening of drugs of abuse, prescription drugs with potential for abuse and their metabolites in influent and effluent urban wastewater by ultrahigh pressure liquid chromatography-quadrupole-time-of-flight-mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, Felix, E-mail: felix.hernandez@qfa.uji.es [Research Institute for Pesticides and Water, University Jaume I, Avda. Sos Baynat s/n, E-12071 Castellon (Spain); Bijlsma, Lubertus, E-mail: bijlsma@guest.uji.es [Research Institute for Pesticides and Water, University Jaume I, Avda. Sos Baynat s/n, E-12071 Castellon (Spain); Sancho, Juan V.; Diaz, Ramon; Ibanez, Maria [Research Institute for Pesticides and Water, University Jaume I, Avda. Sos Baynat s/n, E-12071 Castellon (Spain)

    2011-01-17

    This work illustrates the potential of hybrid quadrupole-time-of-flight mass spectrometry (QTOF MS) coupled to ultrahigh pressure liquid chromatography (UHPLC) to investigate the presence of drugs of abuse in wastewater. After solid-phase extraction with Oasis MCX cartridges, seventy-six illicit drugs, prescription drugs with potential for abuse, and metabolites were investigated in the samples by TOF MS using electrospray interface under positive ionization mode, with MS data acquired over an m/z range of 50-1000 Da. For 11 compounds, reference standards were available, and experimental data (e.g., retention time and fragmentation data) could be obtained, facilitating a more confident identification. The use of a QTOF instrument enabled the simultaneous application of two acquisition functions with different collision energies: a low energy (LE) function, where none or poor fragmentation took place, and a high energy (HE) function, where fragmentation in the collision cell was promoted. This approach, known as MS{sup E}, enabled the simultaneous acquisition of full-spectrum accurate mass data of both protonated molecules and fragment ions in a single injection, providing relevant information that facilitates the rapid detection and reliable identification of these emerging contaminants in the sample matrices analyzed. In addition, isomeric compounds, like the opiates, morphine and norcodeine, could be discriminated by their specific fragments observed in HE TOF MS spectra, without the need of reference standards. UHPLC-QTOF MS was proven to be a powerful and efficient technique for rapid wide-scope screening and identification of many relevant drugs in complex matrices, such as influent and effluent urban wastewater.

  17. Drop Tower Experiments concerning Fluid Management under Microgravity

    Science.gov (United States)

    Gaulke, Diana; Dreyer, Michael

    2012-07-01

    Transport and positioning of liquid under microgravity is done utilizing capillary forces. Therefore, capillary transport processes have to be understood for a wide variety of space applications, ranging from propellant management in tanks of space transportation systems to eating and drinking devices for astronauts. There are two types of liquid transportation in microgravity using capillary forces. First, the driven liquid flow in open channels where the capillary forces at free surfaces ensure a gas and vapor free flow. Here it is important to know the limiting flow rate through such an open channel before the free surface collapses and gas is sucked into the channel. A number of different experiments at the drop tower Bremen, on sounding rockets and at the ISS have been conducted to analyse this phenomenon within different geometries. As result a geometry dependent theory for calculating the maximum flow rate has been found. On the other hand liquid positioning and transportation requires the capillary pressure of curved surfaces to achieve a liquid flow to a desired area. Especially for space applications the weight of structure has to be taken into account for development. For example liquid positioning in tanks can be achieved via a complicated set of structure filling the whole tank resulting in heavy devices not reasonable in space applications. Astrium developed in cooperation with ZARM a propellant management device much smaller than the tank volume and ensuring a gas and vapour free supply of propellant to the propulsion system. In the drop tower Bremen a model of this device was tested concerning different microgravity scenarios. To further decrease weight and ensure functionality within different scenarios structure elements are designed as perforated geometries. Capillary transport between perforated plates has been analyzed concerning the influence of geometrical pattern of perforations. The conducted experiments at the drop tower Bremen show the

  18. Modeling merging behavior at lane drops.

    Science.gov (United States)

    2015-02-01

    In work-zone configurations where lane drops are present, merging of traffic at the taper presents an operational concern. In : addition, as flow through the work zone is reduced, the relative traffic safety of the work zone is also reduced. Improvin...

  19. 49 CFR 178.603 - Drop test.

    Science.gov (United States)

    2010-10-01

    ... of anti-freeze. Water/anti-freeze solutions with a minimum specific gravity of 0.95 for testing at... than flat drops, the center of gravity of the test packaging must be vertically over the point of... is performed with water: (i) Where the materials to be carried have a specific gravity not exceeding...

  20. Goose droppings as food for reindeer

    NARCIS (Netherlands)

    van der Wal, R; Loonen, MJJE

    Feeding conditions for Svalbard reindeer, Rangifer tarandus platyrhynchus, on Spitsbergen are generally poor, owing to low availability of forage. We report on coprophagy: the use of goose faeces as an alternative food source for reindeer. Fresh droppings from Barnacle Geese, Branta leucopsis,

  1. DROP AMALGAM VOLTAMMETRIC STUDY OF LEAD ...

    African Journals Online (AJOL)

    a

    ABSTRACT. A study of inorganic complexation of lead using drop amalgam voltammetry is described. The study has been carried out in simulated salt lake water and at ionic strength of. 7.35 M, the predetermined ionic strength of Lake Katwe. The complexation of lead with the simple ligands (Cl-, CO3. 2-) created anodic ...

  2. Spontaneous evaporation of the acetone drop

    Science.gov (United States)

    Dunin, S. Z.; Nagornov, O. V.

    2017-12-01

    The exact solution of the problem on evaporation of the acetone sessile drop at solid substrate is derived. The solution allows us to analyze the temperature field behavior at various thermodynamic parameters. The Marangoni forces are calculated in explicit form. The solution can be used to check numerical approaches for similar problems.

  3. An evaporation model of multicomponent solution drops

    Science.gov (United States)

    Sartori, Silvana; Liñán, Amable; Lasheras, Juan C.

    2010-11-01

    Solutions of polymers are widely used in the pharmaceutical industry as tablets coatings. These allow controlling the rate at which the drug is delivered, taste or appearance. The coating is performed by spraying and drying the tablets at moderate temperatures. The wetting of the coating solution on the pill's surface depends on the droplet Webber and Re numbers, angle of impact and on the rheological properties of the droplet. We present a model for the evaporation of multicomponent solutions droplets in a hot air environment with temperatures substantially lower than the boiling temperature of the solvent. As the liquid vaporizes from the surface the fluid in the drop increases in concentration, until reaching its saturation point. After saturation, precipitation occurs uniformly within the drop. As the surface regresses, a compacting front formed by the precipitate at its maximum packing density advances into the drop, while the solute continues precipitating uniformly. This porous shell grows fast due to the double effect of surface regression and precipitation. The evaporation rate is determined by the rates at which heat is transported to the droplet surface and at which liquid vapor diffuses away from it. When the drop is fully compacted, the evaporation is drastically reduced.

  4. Utah Drop-Out Drug Use Questionnaire.

    Science.gov (United States)

    Governor's Citizen Advisory Committee on Drugs, Salt Lake City, UT.

    This questionnaire assesses drug use practices in high school drop-outs. The 79 items (multiple choice or apply/not apply) are concerned with demographic data and use, use history, reasons for use/nonuse, attitudes toward drugs, availability of drugs, and drug information with respect to narcotics, amphetamines, LSD, Marijuana, and barbiturates.…

  5. 49 CFR 178.965 - Drop test.

    Science.gov (United States)

    2010-10-01

    ... Large Packaging design types and performed periodically as specified in § 178.955(e) of this subpart. (b...) Conditioning. Rigid plastic Large Packagings and Large Packagings with plastic inner receptacles must be... § 178.960(d). (d) Test method. (1) Samples of all Large Packaging design types must be dropped onto a...

  6. 49 CFR 178.810 - Drop test.

    Science.gov (United States)

    2010-10-01

    ..., DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS REGULATIONS SPECIFICATIONS FOR PACKAGINGS Testing of IBCs... design types and performed periodically as specified in § 178.801(e) of this subpart. (b) Special preparation for the drop test. (1) Metal, rigid plastic, and composite IBCs intended to contain solids must be...

  7. Check valves with drop-shaped disk

    Energy Technology Data Exchange (ETDEWEB)

    1943-03-19

    This report discusses improvements possible with drop check valves. Up to the time of the report, the most important improvements had been: (1) lightening of the drop by hollowing it out, (2) reducing lift to reduce impact, (3) increasing clearance in the guide to minimize the danger of it getting stuck, (4) drilling of a safety hole which would indicate excessive wear of the housing by a leak. Other possibilities for the above improvements had produced the following conclusions: (1) a further lightening of the drop was found possible by milling out the halves with a milling cutter, by welding them together and thus eliminating the threaded portion, or by having the drop open on the bottom; (2) further reduction in lift was not found possible in most sizes, but for reduction of the impact effect by a cushion of oil or paste, the seating surface was widened as much as possible; (3) sticking of certain check valves caused by ferrous sulfide deposits could be solved by use of a certain bushing in the housing; (4) some plants favored and some disfavored the safety hole, but in general, plants were to service check valves and change them at such regular intervals as experience dictated; (5) the seat plate was no longer solid steel, but a welded piece.

  8. Lightweight, Economical Device Alleviates Drop Foot

    Science.gov (United States)

    Deis, B. C.

    1983-01-01

    Corrective apparatus alleviates difficulties in walking for victims of drop foot. Elastic line attached to legband provides flexible support to toe of shoe. Device used with flat (heelless) shoes, sneakers, crepe-soled shoes, canvas shoes, and many other types of shoes not usable with short leg brace.

  9. Biomechanical analysis of drop and countermovement jumps

    NARCIS (Netherlands)

    Bobbert, M. F.; Mackay, M.T.; Schinkelshoek, D.; Huijing, P. A.; van Ingen Schenau, G. J.

    For 13 subjects the performance of drop jumps from a height of 40 cm (DJ) and of countermovement jumps (CMJ) was analysed and compared. From force plate and cine data biomechanical variables including forces, moments, power output and amount of work done were calculated for hip, knee and ankle

  10. A bilateral foot drop due to neuroschistosomiasis.

    NARCIS (Netherlands)

    Wilbers, J.; Idema, A.J.S.; Gijtenbeek, A.

    2010-01-01

    Schistosomiasis is a parasitic disease, uncommon in Europe and the USA. We present an unusual case of intracerebral schistosomiasis, presenting with a bilateral foot drop. We describe unique magnetic resonance spectroscopy characteristics that can contribute to diagnosis and follow up of a

  11. Alternative method for determining the original drop volume of bloodstains on knit fabrics.

    Science.gov (United States)

    Li, Jingyao; Li, Xingyu; Michielsen, Stephen

    2016-06-01

    Bloodstains are often observed at violent crime scenes and on the skin and clothing of persons involved. The diameters of the blood drops that created these stains are related to the force or energy that caused these drops to become airborne. This has resulted in several attempts to determine the diameter of the original drops, beginning with the methods reported in the pioneering work of Henry Lee [6]. However, his methods destroyed the bloodstain during the measurement. Other methods described in the literature cannot be applied to bloodstains on textiles. A new, rapid, reliable, non-destructive method for determining the diameter of the original drop of blood that results in a stain has been developed for bloodstains on cotton single jersey knit (tee-shirt) fabrics, which is one of the most common fabrics analyzed for BPA both at crime scenes and in forensic laboratories. In this method, a drop of known volume of an appropriate artificial blood substitute is applied to a region similar to the stained region but in an area away from any stains/areas of interest. The areas of the original stain and the artificial blood substitute stain are determined, from which the original drop diameter can be calculated. Errors in the drop diameters, the Reynolds numbers and the Weber numbers resulting from this procedure are less than approximately 6%. This procedure has only been verified on cotton single jersey knit fabrics with 30μL≤drop volume≤80μL. It should not be applied to other materials. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  12. Custom-Made Foot Orthoses Decrease Medial Foot Loading During Drop Jump in Individuals With Patellofemoral Pain

    DEFF Research Database (Denmark)

    Rathleff, Michael S; Richter, Camilla; Brushøj, Christoffer

    2016-01-01

    OBJECTIVE: To investigate the effect of foot orthoses on medial-to-lateral plantar forces during drop jump and single leg squat, and second, to explore the self-reported change in symptoms after 12 weeks of wearing the orthoses in individuals with patellofemoral pain (PFP). DESIGN: Cohort study...... with 12 weeks of follow-up. SETTING: Hospital setting. PARTICIPANTS: 23 adults with PFP. INTERVENTIONS: Custom-made foot orthoses. MAIN OUTCOME MEASURES: Foot loading (plantar pressure) was collected from the most painful side during drop jump and single leg squat using pressure sensitive Pedar insoles...... in peak medial-to-lateral force during drop jump. Individuals with a self-reported improvement after 12 weeks had a significant 4.2%-point larger reduction in medial-to-lateral foot loading during drop jump. CONCLUSIONS: This preliminary study showed that foot orthoses were associated with a decrease...

  13. Differential pressure gauge has fast response

    Science.gov (United States)

    Weber, H. S.

    1965-01-01

    Differential pressure gage with semiconductor type strain gage elements measures rapidly changing pressure. Output of the strain gage elements is a dc voltage that is directly proportional to the pressure difference being measured.

  14. Artificial tektites: an experimental technique for capturing the shapes of spinning drops

    Science.gov (United States)

    Baldwin, K. A.

    2014-12-01

    Tektites are small stones formed from rapidly cooling drops of molten rock ejected from high velocity asteroid impacts with the Earth, that freeze into a myriad of shapes during flight. Many splash-form tektites have an elongated or dumb-bell shape owing to their rotation prior to solidification[1]. Here we present a novel method for creating 'artificial tektites' from spinning drops of molten wax, using diamagnetic levitation to suspend the drops[2]. We find that the solid wax models produced this way are the stable equilibrium shapes of a spinning liquid droplet held together by surface tension. In addition to the geophysical interest in tektite formation, the stable equilibrium shapes of liquid drops have implications for many physical phenomena, covering a wide range of length scales, from nuclear physics (e.g. in studies of rapidly rotating atomic nuclei), to astrophysics (e.g. in studies of the shapes of astronomical bodies such as asteroids, rapidly rotating stars and event horizons of rotating black holes). For liquid drops bound by surface tension, analytical and numerical methods predict a series of stable equilibrium shapes with increasing angular momentum. Slowly spinning drops have an oblate-like shape. With increasing angular momentum these shapes become secularly unstable to a series of triaxial pseudo-ellipsoids that then evolve into a family of two-lobed 'dumb-bell' shapes as the angular momentum is increased still further. Our experimental method allows accurate measurements of the drops to be taken, which are useful to validate numerical models. This method has provided a means for observing tektite formation, and has additionally confirmed experimentally the stable equilibrium shapes of liquid drops, distinct from the equivalent shapes of rotating astronomical bodies. Potentially, this technique could be applied to observe the non-equilibrium dynamic processes that are also important in real tektite formation, involving, e.g. viscoelastic

  15. Effect of drop volume and surface statistics on the superhydrophobicity of randomly rough substrates

    Science.gov (United States)

    Afferrante, L.; Carbone, G.

    2018-01-01

    In this paper, a simple theoretical approach is developed with the aim of evaluating shape, interfacial pressure, apparent contact angle and contact area of liquid drops gently deposed on randomly rough surfaces. This method can be useful to characterize the superhydrophobic properties of rough substrates, and to investigate the contact behavior of impacting drops. We assume that (i) the size of the apparent liquid–solid contact area is much larger than the micromorphology of the substrate, and (ii) a composite interface is always formed at the microscale. Results show apparent contact angle and liquid–solid area fraction are slightly influenced by the drop volume only at relatively high values of the root mean square roughness h rms, whereas the effect of volume is practically negligible at small h rms. The main statistical quantity affecting the superhydrophobic properties is found to be the Wenzel roughness parameter r W, which depends on the average slope of the surface heights. Moreover, transition from the Cassie–Baxter state to the Wenzel one is observed when r W reduces below a certain critical value, and theoretical predictions are found to be in good agreement with experimental data. Finally, the present method can be conveniently exploited to evaluate the occurrence of pinning phenomena in the case of impacting drops, as the Wenzel critical pressure for liquid penetration gives an estimation of the maximum impact pressure tolerated by the surface without pinning occurring.

  16. Drop impact upon micro- and nanostructured superhydrophobic surfaces.

    Science.gov (United States)

    Tsai, Peichun; Pacheco, Sergio; Pirat, Christophe; Lefferts, Leon; Lohse, Detlef

    2009-10-20

    We experimentally investigate drop impact dynamics onto different superhydrophobic surfaces, consisting of regular polymeric micropatterns and rough carbon nanofibers, with similar static contact angles. The main control parameters are the Weber number We and the roughness of the surface. At small We, i.e., small impact velocity, the impact evolutions are similar for both types of substrates, exhibiting Fakir state, complete bouncing, partial rebouncing, trapping of an air bubble, jetting, and sticky vibrating water balls. At large We, splashing impacts emerge forming several satellite droplets, which are more pronounced for the multiscale rough carbon nanofiber jungles. The results imply that the multiscale surface roughness at nanoscale plays a minor role in the impact events for small We less than or approximately equal 120 but an important one for large We greater than or approximately equal 120. Finally, we find the effect of ambient air pressure to be negligible in the explored parameter regime We less than or approximately equal 150.

  17. Coalescence collision of liquid drops II: Off-center collisions of unequal-size drops

    Directory of Open Access Journals (Sweden)

    Alejandro Acevedo-Malavé

    2011-09-01

    Full Text Available We applied the Smoothed Particle Hydrodynamics method to simulate for first time in the three-dimensional space the hydrodynamic off-center collisions of unequal-size liquid drops in a vacuum environment. The Weber number for several conditions of the droplets dynamics is determined. Also the velocity vector fields inside the drops are shown in the collision process. The evolution of the kinetic and internal energy is shown for the permanent coalescence case. The resulting drops tend to deform, and depending of the Weber number two possible outcomes for the collision of droplets arise: either permanent coalescence or flocculation. In the permanent coalescence of the drops a fragmentation case is modeled, yielding the formation of little satellite droplets.

  18. Coalescence collision of liquid drops I: Off-center collisions of equal-size drops

    Directory of Open Access Journals (Sweden)

    Alejandro Acevedo-Malavé

    2011-09-01

    Full Text Available The Smoothed Particle Hydrodynamics method (SPH is used here to model off-center collisions of equal-size liquid drops in a three-dimensional space. In this study the Weber number is calculated for several conditions of the droplets dynamics and the velocity vector fields formed inside the drops during the collision process are shown. For the permanent coalescence the evolution of the kinetic and internal energy is shown and also the approaching to equilibrium of the resulting drop. Depending of the Weber number three possible outcomes for the collision of droplets is obtained: permanent coalescence, flocculation and fragmentation. The fragmentation phenomena are modeled and the formation of small satellite drops can be seen. The ligament that is formed follows the “end pinching” mechanism and it is transformed into a flat structure.

  19. Micro Coriolis mass flow sensor with integrated resistive pressure sensors

    NARCIS (Netherlands)

    Groenesteijn, Jarno; Alveringh, Dennis; Schut, Thomas; Wiegerink, Remco J.; Sparreboom, Wouter; Lötters, Joost Conrad

    2017-01-01

    We report on novel resistive pressure sensors, integrated on-chip at the inlet- and outlet-channels of a micro Coriolis mass flow sensor. The pressure sensors can be used to measure the pressure drop over the Coriolis sensor which can be used to compensate pressure-dependent behaviour that might

  20. PATTERN OF INTRAOCULAR PRESSURE IN

    African Journals Online (AJOL)

    manoeuver, forced blinking, intraocular inflammation, ocular trauma, ocular surgery, retinal or choroidal detachment, restriction, arid systemic diseases such as diabetes mellitus and thyroid disorders.“ Procedures such as retrobulbar anaesthesia, general anaesthesia, external pressure on the eyeball, topical eye drops ...

  1. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... Accessible Search Form Search the NHLBI, use the drop down list to select: the entire site, the Health Topics section only, or the News and Resources section. NHLBI ... for Health Professionals What Is High blood pressure is a common disease in which blood flows through blood vessels (arteries) ...

  2. Head-on collision of drops: A numerical investigation

    Science.gov (United States)

    Nobari, M. R.; Jan, Y.-J.; Tryggvason, G.

    1993-01-01

    The head-on collision of equal sized drops is studied by full numerical simulations. The Navier-Stokes equations are solved for fluid motion both inside and outside the drops using a front tracking/finite difference technique. The drops are accelerated toward each other by a body force that is turned off before the drops collide. When the drops collide, the fluid between them is pushed outward leaving a thin later bounded by the drop surface. This layer gets progressively thinner as the drops continue to deform and in several of the calculations this double layer is artificially removed once it is thin enough, thus modeling rupture. If no rupture takes place, the drops always rebound, but if the film is ruptured the drops may coalesce permanently or coalesce temporarily and then split again.

  3. Max Launch Abort System (MLAS) Landing Parachute Demonstrator (LPD) Drop Test

    Science.gov (United States)

    Shreves, Christopher M.

    2011-01-01

    The Landing Parachute Demonstrator (LPD) was conceived as a low-cost, rapidly-developed means of providing soft landing for the Max Launch Abort System (MLAS) crew module (CM). Its experimental main parachute cluster deployment technique and off-the-shelf hardware necessitated a full-scale drop test prior to the MLAS mission in order to reduce overall mission risk. This test was successfully conducted at Wallops Flight Facility on March 6, 2009, with all vehicle and parachute systems functioning as planned. The results of the drop test successfully qualified the LPD system for the MLAS flight test. This document captures the design, concept of operations and results of the drop test.

  4. D.R.O.P. The Durable Reconnaissance and Observation Platform

    Science.gov (United States)

    McKenzie, Clifford; Parness, Aaron

    2012-01-01

    The Durable Reconnaissance and Observation Platform (DROP) is a prototype robotic platform with the ability to climb concrete surfaces up to 85deg at a rate of 25cm/s, make rapid horizontal to vertical transitions, carry an audio/visual reconnaissance payload, and survive impacts from 3 meters. DROP is manufactured using a combination of selective laser sintering (SLS) and shape deposition manufacturing (SDM) techniques. The platform uses a two-wheel, two-motor design that delivers high mobility with low complexity. DROP extends microspine climbing technology from linear to rotary applications, providing improved transition ability, increased speeds, and simpler body mechanics while maintaining microspines ability to opportunistically grip rough surfaces. Various aspects of prototype design and performance are discussed, including the climbing mechanism, body design, and impact survival.

  5. Dynamic response characteristics analysis of the doubly-fed wind power system under grid voltage drop

    Science.gov (United States)

    Chen, Y.; Wang, J.; Wang, H. H.; Yang, L.; Chen, W.; Xu, Y. T.

    2016-08-01

    Double-fed induction generator (DFIG) is sensitive to the disturbances of grid, so the security and stability of the grid and the DFIG itself are under threat with the rapid increase of DFIG. Therefore, it is important to study dynamic response of the DFIG when voltage drop failure is happened in power system. In this paper, firstly, mathematical models and the control strategy about mechanical and electrical response processes is respectively introduced. Then through the analysis of response process, it is concluded that the dynamic response characteristics are related to voltage drop level, operating status of DFIG and control strategy adapted to rotor side. Last, the correctness of conclusion is validated by the simulation about mechanical and electrical response processes in different voltage levels drop and different DFIG output levels under DIgSILENT/PowerFactory software platform.

  6. Electrical stimulation to increase lower esophageal sphincter pressure after POEM.

    Science.gov (United States)

    Ciotola, Franco; Ditaranto, Andres; Bilder, Claudio; Badaloni, Adolfo; Lowenstein, Daniel; Riganti, Juan Martin; Hoppo, Toshitaka; Jobe, Blair; Nachman, Fabio; Nieponice, Alejandro

    2015-01-01

    Postoperative reflux remains to be a challenge for patients with achalasia undergoing Heller myotomy. Similarly, per-oral endoscopic myotomy (POEM) is gaining rapid acceptance but the impossibility of adding a fundoplication is questioned as the main pitfall to control reflux. Electrical stimulation of the lower esophageal sphincter (LES) has emerged as a new alternative for the treatment of reflux disease. The objective of this study was to evaluate the potential benefits of combining electrical stimulation with endoscopic esophageal myotomy to prevent post procedural reflux. Five pigs were subjected to POEM. After myotomy was completed, two electrical leads were implanted at the LES level and electrical stimulation was applied with the Endostim system with a regimen of 215 μs (5 mA amplitude), at 20 Hz for 25 min. LES pressures were recorded with manometry at pre and post-myotomy and after LES stimulation. Myotomy was completed successfully in all cases. Mean pre-myotomy LES pressure was 35.99 ± 8.08 mmHg. After myotomy, the LES pressure significantly dropped to 10.60 ± 3.24 mmHg (p = 0.03). Subsequent to LES-EST, LES pressure significantly increased to 21.74 ± 4.65 mmHg (p = 0.01). The findings of this study show that LES-EST in healthy animals increases LES pressure after POEM procedure, and could be useful tool to minimize gastroesophageal reflux.

  7. Cracks formation during blood drop evaporation

    Science.gov (United States)

    Sobac, Benjamin; Brutin, David; Université de Provence Team

    2011-03-01

    We firstly presented the pattern formation occurring when drops of whole blood desiccate in a recent publication. The phenomena presented evidence to involve lots of physical field such as surface chemistry, haematolology, fluid mechanics, heat transfer, colloids science... All these mechanisms are acting together and produce an axisymetric and reproducible pattern. Dried cellular components are segregated and deposited by a capillary flow. During the evaporation, the system is slowly drying and cracks when stresses are too important leading to the final pattern observed. In this presentation, we will present the mechanisms involved in the formation of crack patterns. The phenomenon presented here with red blood cells as the main colloids involved is very similar to the drying of drop of nanoparticules. We will explain the common point and the differences encountered.

  8. DROP: Durable Reconnaissance and Observation Platform

    Science.gov (United States)

    Parness, Aaron; McKenzie, Clifford F.

    2012-01-01

    Robots have been a valuable tool for providing a remote presence in areas that are either inaccessible or too dangerous for humans. Having a robot with a high degree of adaptability becomes crucial during such events. The adaptability that comes from high mobility and high durability greatly increases the potential uses of a robot in these situations, and therefore greatly increases its usefulness to humans. DROP is a lightweight robot that addresses these challenges with the capability to survive large impacts, carry a usable payload, and traverse a variety of surfaces, including climbing vertical surfaces like wood, stone, and concrete. The platform is crash-proof, allowing it to be deployed in ways including being dropped from an unmanned aerial vehicle or thrown from a large MSL-class (Mars Science Laboratory) rover.

  9. Drop interactions on a viscous film

    Science.gov (United States)

    Costalonga, Maxime; Hack, Michiel; Snoeijer, Jacco

    2017-11-01

    Every morning at their breakfast, cereal eaters can see that floating objects on a liquid bath attracts to form clusters: this is the so-called Cheerios effect. It has been shown recently that droplets on elastic substrates also interact, either attracting or repelling each other depending on the local slope of the substrate where they lie. Here we present an experiment extending these results to the interaction of droplets deposited on a thin viscous film. By measuring independently the velocity of the droplets and the surface topography of the film, we identify non-monotonic interactions that are due to waves appearing on the film. The drag force exerted onto the droplets is also investigated. We show that the thickness of the film below the drop is intrinsically selected by the velocity of the drop, by a mechanism similar to Bretherton's bubble rising in a confining tube.

  10. Semisupervised Community Detection by Voltage Drops

    Directory of Open Access Journals (Sweden)

    Min Ji

    2016-01-01

    Full Text Available Many applications show that semisupervised community detection is one of the important topics and has attracted considerable attention in the study of complex network. In this paper, based on notion of voltage drops and discrete potential theory, a simple and fast semisupervised community detection algorithm is proposed. The label propagation through discrete potential transmission is accomplished by using voltage drops. The complexity of the proposal is OV+E for the sparse network with V vertices and E edges. The obtained voltage value of a vertex can be reflected clearly in the relationship between the vertex and community. The experimental results on four real networks and three benchmarks indicate that the proposed algorithm is effective and flexible. Furthermore, this algorithm is easily applied to graph-based machine learning methods.

  11. Impact of water drops on small targets

    Science.gov (United States)

    Rozhkov, A.; Prunet-Foch, B.; Vignes-Adler, M.

    2002-10-01

    The collision of water drops against small targets was studied experimentally by means of a high-speed photography technique. The drop impact velocity was about 3.5 m/s. Drop diameters were in the range of 2.8-4.0 mm. The target was a stainless steel disk of 3.9 mm diameter. The drop spread beyond the target like a central cap surrounded by a thin, slightly conical lamella bounded by a thicker rim. By mounting a small obstacle near the target, surface-tension driven Mach waves in the flowing lamella were generated, which are formally equivalent to the familiar compressibility driven Mach waves in gas dynamics. From the measurement of the Mach angle, the values of some flow parameters could be obtained as functions of time, which provided insight into the flow structure. The liquid flowed from the central cap to the liquid rim through the thin lamella at constant momentum flux. At a certain stage of the process, most of the liquid accumulated in the rim and the internal part of the lamella became metastable. In this situation, a rupture wave propagating through the metastable internal part of the lamella caused the rim to retract while forming outwardly directed secondary jets. The jets disintegrated into secondary droplets due to the Savart-Plateau-Rayleigh instability. Prior to the end of the retraction, an internal circular wave of rupture was formed. It originated at the target and then it propagated to meet the retracting rim. Their meeting resulted in a crown of tiny droplets. A theoretical analysis of the ejection process is proposed.

  12. Drag and Drop API v HTML5

    OpenAIRE

    BARABÁŠ, Vít

    2013-01-01

    The work (the bachelor´s thesis) deals with a new way of web application management via the "drag and drop" technique in the HTML5 programming language. The work is divided into two parts. The first part consists of DND API description in HTML5. The support analysis within common web browsers is included as a part of this description. The second, practical part of the thesis focuses on a concept and the following realisation of a photogallery using DND API.

  13. Rotor drop and following thermal growth simulations using detailed auxiliary bearing and damper models

    Science.gov (United States)

    Sun, Guangyoung

    2006-01-01

    Catcher bearings (CBs) or auxiliary bearings provide mechanical backup protection in the events of magnetic bearing failure. This paper presents numerical analysis for a rotor drop on CBs and following thermal growths due to their mechanical rub using detailed CB and damper models. The detailed CB model is determined based on its material, geometry, speed and preload using the nonlinear Hertzian load-deflection formula, and the thermal growths of bearing components during the rotor drop are estimated using a 1D thermal model. A finite-element squeeze film damper provides the pressure profile of an annular oil film and the resulting viscous damping force. Numerical simulations of an energy storage flywheel with magnetic suspensions failed reveal that an optimal CB design using the detailed simulation models stabilizes the rotor drop dynamics and lowers the thermal growths while preventing the high-speed backward whirl. Furthermore, CB design guides based on the simulation results are presented.

  14. A Water-Drop Method of Hardening of the Welded Joints of Drill Pipes

    Science.gov (United States)

    Maisuradze, M. V.; Yudin, Yu. V.; Eismondt, Yu. G.

    2015-09-01

    A combined computational and experimental technique is developed for implementing a scientifically based approach to the selection of a technology of heat hardening of welded joints of drill pipes made of steel 25KhGM with the use of water-drop quenching. The basic service characteristics of the water-drop cooling device are presented. An analytic model that relates the parameters of the water-drop quenching device (standard size and number of jets in device, pressure of fed water, distance from the jet nozzle to the cooled surface) to the properties of the welded joint is proposed. With the new technique the construction of a quenching device may be developed and the technology of heat treatment of the welded joints of drill pipes optimized in order to increase the level of mechanical properties.

  15. Drop impacts on electrospun nanofiber membranes

    Science.gov (United States)

    Sahu, Rakesh P.; Sinha-Ray, Suman; Yarin, Alexander; Pourdeyhimi, Behnam

    2013-11-01

    This work reports a study of drop impacts of polar and non-polar liquids onto electrospun nanofiber membranes (of 8-10 mm thickness and pore sizes of 3-6 nm) with an increasing degree of hydrophobicity. The nanofibers used were electrospun from polyacrylonitrile (PAN), nylon 6/6, polycaprolactone (PCL) and Teflon. It was found that for any liquid/fiber pair there exists a threshold impact velocity (1.5 to 3 m/s) above which water penetrates membranes irrespective of their wettability. The low surface tension liquid left the rear side of sufficiently thin membranes as a millipede-like system of tiny jets protruding through a number of pores. For such a high surface tension liquid as water, jets immediately merged into a single bigger jet, which formed secondary drops due to capillary instability. An especially non-trivial result is that superhydrophobicity of the porous nano-textured Teflon skeleton with the interconnected pores is incapable of preventing water penetration due to drop impact, even at relatively low impact velocities close to 3.46 m/s. A theoretical estimate of the critical membrane thickness sufficient for complete viscous dissipation of the kinetic energy of penetrating liquid corroborates with the experimental data. The current work is supported by the Nonwovens Cooperative Research Center (NCRC).

  16. Laplacian drop shapes and effect of random perturbations on accuracy of surface tension measurement for different drop constellations.

    Science.gov (United States)

    Saad, Sameh M I; Neumann, A Wilhelm

    2015-08-01

    Theoretical drop shapes are calculated for three drop constellations: pendant drops, constrained sessile drops, and unconstrained sessile drops. Based on total Gaussian curvature, shape parameter and critical shape parameter are discussed as a function of different drop sizes and surface tensions. The shape parameter is linked to physical parameters for every drop constellation. The as yet unavailable detailed dimensional analysis for the unconstrained sessile drop is presented. Results show that the unconstrained sessile drop shape depends on a dimensionless volume term and the contact angle. Random perturbations are introduced and the accuracy of surface tension measurement is assessed for precise and perturbed profiles of the three drop constellations. It is concluded that pendant drops are the best method for accurate surface tension measurement, followed by constrained sessile drops. The unconstrained sessile drops come last because they tend to be more spherical at low and moderate contact angles. Of course, unconstrained sessile drops are the only option if contact angles are to be measured. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Sound wave energy emitted by water drop during the splash on the soil surface

    Science.gov (United States)

    Bieganowski, Andrzej; Ryżak, Magdalena; Korbiel, Tomasz

    2017-04-01

    A drop of rain falling on the surface of bare soil not only moisturizes but also can cause splash or compaction, depending on the energy of incident drops and the condition of the surface on which it falls. The splash phenomenon can be characterized by the weight of detached soil material (using splash cups) as well as the number and trajectory of splashed particles (using high-speed cameras). The study presents a new aspect of the analysis of the splash phenomenon by measurement of the sound pressure level and the sound energy of the wave that propagates in the air. The measurements were carried out in an anechoic chamber. Three soils (Endogleyic Umbrisol, Fluvic Endogleyic Cambisol, and Haplic Chernozem) with four initial moisture levels (pressure heads: 0.1 kPa, 1 kPa, 3.16 kPa, and 16 kPa) were tested. Drops of 4.2 mm diameter were falling from a height of 1.5m. The sound pressure level was recorded after 10 consecutive water drop impacts using a special set of microphones. In all measuring conditions with 1m distance, the sound pressure level ranged from 27 to 42dB. The impact of water drops on the ground created sound pulses, which were recalculated to the energy emitted in the form of sound waves. For all soil samples, the sound wave energy was within the range of 0.14 μJ to 5.26 μJ, which corresponds to 0.03-1.07% of the energy of the incident drops (Ryżak et al., 2016). This work was partly financed from the National Science Centre, Poland; project no. 2014/14/E/ST10/00851. References Ryżak M., Bieganowski A., Korbiel T.: Sound wave Energy resulting from the impact of water drops on the soil surface. PLoS One 11(7):e0158472. doi:10.1371/journal.pone.0158472, 2016

  18. Drop by drop scattering properties of a radar bin : a numerical experiment

    Science.gov (United States)

    Gires, Auguste; Tchiguirinskaia, Ioulia; Schertzer, Daniel

    2016-04-01

    This paper presents the development and initial results of a numerical simulation of pseudo-radar observations computed as the sum of the electric field backscattered by each drop. Simulations are carried out for three successive radar bins with a gate length of 30 m and beam width of 1°. The first step is the simulation of a 100 m x 100 m x 100 m volume with all its drops. The 3D raindrop generator relies on the findings on the rainfall field very small scales (mm to few tens of m) spatio-temporal structure, of the HYDROP experiment and a recent analysis of 2D video disdrometer data in a Multifractal framework. More precisely: (i) The Liquid Water Content (LWC) distribution is represented with the help a multiplicative cascade down to 0.5 m, below which it is considered as homogeneous. (ii) Within each 0.5 x 0.5 x 0.5 m3 patch, liquid water is distributed into drops according to a pre-defined Drop Size Distribution (DSD) and located randomly uniformly. (iii) Such configuration is compared with the one consisting of the same drops uniformly distributed over the 50 x 50 x 50 m3 volume. Then the backscattered field by the drops located within a radar bin are computed as the sum a individual contribution. Antenna beam weighing is taken into account Due to the fact that the radar wave length is much smaller than the "patches" size for rainfall, it appears that as theoretically expected we retrieved an exponential distribution for potential measure horizontal reflectivity. A much lower dispersion is noticed for differential reflectivity. We show that a simple ballistic assumption for drop velocities does not enable to reproduce radar observations, and turbulence must be taken into account. Finally the sensitivity of these outputs to the various model parameters is quantified.

  19. Reconstruction of brachial pressure from finger arterial pressure during orthostasis

    DEFF Research Database (Denmark)

    Bogert, Lysander W J; Harms, Mark P M; Pott, Frank

    2004-01-01

    In patients with recurrent syncope, monitoring of intra-arterial pressure during orthostatic stress testing is recommended because of the potentially sudden and rapid development of hypotension. Replacing brachial arterial pressure (BAP) by the non-invasively obtained finger arterial pressure (Fin...

  20. Investigating the Effects of Knee Flexion during the Eccentric Heel-Drop Exercise

    Directory of Open Access Journals (Sweden)

    Robert A. Weinert-Aplin, Anthony M.J. Bull, Alison H. McGregor

    2015-06-01

    Full Text Available This study aimed to characterise the biomechanics of the widely practiced eccentric heel-drop exercises used in the management of Achilles tendinosis. Specifically, the aim was to quantify changes in lower limb kinematics, muscle lengths and Achilles tendon force, when performing the exercise with a flexed knee instead of an extended knee. A musculoskeletal modelling approach was used to quantify any differences between these versions of the eccentric heel drop exercises used to treat Achilles tendinosis. 19 healthy volunteers provided a group from which optical motion, forceplate and plantar pressure data were recorded while performing both the extended and flexed knee eccentric heel-drop exercises over a wooden step when barefoot or wearing running shoes. This data was used as inputs into a scaled musculoskeletal model of the lower limb. Range of ankle motion was unaffected by knee flexion. However, knee flexion was found to significantly affect lower limb kinematics, inter-segmental loads and triceps muscle lengths. Peak Achilles load was not influenced despite significantly reduced peak ankle plantarflexion moments (p < 0.001. The combination of reduced triceps lengths and greater ankle dorsiflexion, coupled with reduced ankle plantarflexion moments were used to provide a basis for previously unexplained observations regarding the effect of knee flexion on the relative loading of the triceps muscles during the eccentric heel drop exercises. This finding questions the role of the flexed knee heel drop exercise when specifically treating Achilles tendinosis.

  1. Numerical Studies of the Aspiration of Small Drops Using a Micropipette

    Science.gov (United States)

    Leal, Gary; Ramchandran, Arun

    2008-11-01

    Aspiration of small drops, vesicles, or biological cells using a micropipette has been used as a means of characterizing the properties of the interface or membrane. The basic idea is that the shape of the deformable particle can be imaged, and this data can be translated into information about the interface or membrane properties by comparison with theoretical predictions. For the simple case of a drop, there is a critical condition of flow rate or pressure drop that depends on the interfacial tension (among other parameters) beyond which the drop is aspirated completely into the pipette. With a proper theory, this critical condition can then be used to determine the interfacial tension. Experiments to date when interpreted using a static force balance (neglecting all viscous forces) yield literature values for the interfacial tension. In this study, we use axisymmetric boundary integral methods for drops of different sizes relative to the pipette and different viscosities relative to the suspending fluid, in order to establish the range of validity of this simple method of data interpretation.

  2. Simplified procedure for determining of drop and stilling basin

    Directory of Open Access Journals (Sweden)

    Ali R. Vatankhah

    2014-03-01

    Full Text Available Drops are used to effectively dissipate the surplus energy of the water flow. A closed conduit drop conveys water and stills it at its downstream. I-type pipe drop is one kind of the closed conduit drops which is used in irrigation networks as a typical hydraulic structure. Sump elevation is an important design parameter for I-type pipe drop. Similarly, in supercritical flow structures, such as open channel chutes, determination of stilling basin invert elevation is very important. At present, these key design parameters are determined by the momentum and energy equations using tedious trial-and-error procedure. In this study, square conduit drop, pipe drop, and rectangular stilling basin are considered, and three explicit equations have been developed by (multiple nonlinear regression technique to determine the sump and stilling basin invert elevations. Being very simple and accurate, these equations can be easily used to design the closed conduit drops and stilling basins by hydraulic engineers.

  3. Cerebral infarction presenting with unilateral isolated foot drop.

    Science.gov (United States)

    Kim, Ki-Wan; Park, Jung-Soo; Koh, Eun-Jeong; Lee, Jong-Myong

    2014-09-01

    Weakness of the dorsiflexor muscles of the ankle or toe, referred to as foot drop, is a relatively common presentation. In most cases, foot drop is caused by a lower motor neuron disease such as peroneal peripheral neuropathy, L4-5 radiculopathic sciatic neuropathy, or polyneuropathy. Although upper motor neuron lesions can present as foot drop, the incidence is very rare. Here, we report an extremely rare case in which foot drop was the only presenting symptom of cerebral infarction.

  4. Cerebral Infarction Presenting with Unilateral Isolated Foot Drop

    OpenAIRE

    Kim, Ki-Wan; Park, Jung-Soo; Koh, Eun-Jeong; Lee, Jong-Myong

    2014-01-01

    Weakness of the dorsiflexor muscles of the ankle or toe, referred to as foot drop, is a relatively common presentation. In most cases, foot drop is caused by a lower motor neuron disease such as peroneal peripheral neuropathy, L4-5 radiculopathic sciatic neuropathy, or polyneuropathy. Although upper motor neuron lesions can present as foot drop, the incidence is very rare. Here, we report an extremely rare case in which foot drop was the only presenting symptom of cerebral infarction.

  5. Martian Atmospheric Pressure Static Charge Elimination Tool

    Science.gov (United States)

    Johansen, Michael R.

    2014-01-01

    A Martian pressure static charge elimination tool is currently in development in the Electrostatics and Surface Physics Laboratory (ESPL) at NASA's Kennedy Space Center. In standard Earth atmosphere conditions, static charge can be neutralized from an insulating surface using air ionizers. These air ionizers generate ions through corona breakdown. The Martian atmosphere is 7 Torr of mostly carbon dioxide, which makes it inherently difficult to use similar methods as those used for standard atmosphere static elimination tools. An initial prototype has been developed to show feasibility of static charge elimination at low pressure, using corona discharge. A needle point and thin wire loop are used as the corona generating electrodes. A photo of the test apparatus is shown below. Positive and negative high voltage pulses are sent to the needle point. This creates positive and negative ions that can be used for static charge neutralization. In a preliminary test, a floating metal plate was charged to approximately 600 volts under Martian atmospheric conditions. The static elimination tool was enabled and the voltage on the metal plate dropped rapidly to -100 volts. This test data is displayed below. Optimization is necessary to improve the electrostatic balance of the static elimination tool.

  6. [The observation of tacrolimus eye drops preventing the early immunological rejection after penetrating keratoplasty for fungal keratitis].

    Science.gov (United States)

    Xiang, D M; Wang, Y X; Jia, Y N; Li, S X; Zhai, H L; Shi, W Y; Gao, H

    2017-04-11

    Objective: To observe the early immunological rejection prevention effect of tacrolimus eye drops combined with glucocorticoids on fungal keratitis patients who received penetrating keratoplasty (PKP). Methods: In a retrospective case series study, medical records of fungal keratitis patients who received PKP in Shandong Eye Institute from March 2013 to December 2015 were reviewed. Twenty-six patients (26 eyes) were given tacrolimus eye drops, and 24 patients (24 eyes) were given 1% cyclosporine A eye drops immediately after PKP. Two weeks after PKP, these patients were given low concentration of glucocorticoids if no fungal recurrence was found. Immune rejection, fungal recurrence, intraocular pressure, and drug irritation symptoms were monitored. Data were analyzed by chi-square test and independent t-test. Results: The average follow-up was 7 months (range, 3 to 12 months) postoperatively. The rejection rate was 15.3% in the tacrolimus group and 47.8% in the cyclosporine A group (χ(2)=5.510, Ptacrolimus group and two patients in the cyclosporine A group suffered fungal recurrence. Two patients in the tacrolimus group and four patients in the cyclosporine A group had secondary glaucoma. The intraocular pressure was controlled. Three patients receiving tacrolimus eye drops and 13 patients receiving cyclosporine A eye drops had mild irritation symptoms. Conclusions: Tacrolimus eye drops combined with low concentration of glucocorticoids can prevent the early immunological rejection after PKP for fungalkeratitis effectively and safely. (Chin J Ophthalmol, 2017, 53:305-310).

  7. Preparation and Stability of Voriconazole Eye Drop Solution▿

    OpenAIRE

    Dupuis, Antoine; Tournier, Nicolas; Le Moal, Gwenaël; Venisse, Nicolas

    2008-01-01

    The combined systemic and topical administration of voriconazole has successfully been used to treat keratomycosis. Because no voriconazole eye drop product is commercially available, we prepared a sterile eye drop solution (10 mg/ml). Voriconazole remains stable over 30 days, providing an eye drop solution suitable for use for the topical treatment of fungal keratitis.

  8. Coalescence, evaporation and particle deposition of consecutively printed colloidal drops

    Science.gov (United States)

    Chhasatia, Viral; Yang, Xin; Shah, Jaymeen; Sun, Ying

    2012-11-01

    In applications such as inkjet printing and spray deposition, colloid drops are often used as building blocks for line and pattern printing where their interactions play important roles in determining the deposition morphology and properties. In this study, the particle deposition dynamics of two consecutively printed evaporating colloidal drops is examined using a fluorescence microscope and a synchronized side-view camera. The results show that the relaxation time of the water-air interface of the merged drop is shorter than that of a single drop impacting on a dry surface. It is also found that both morphology and particle distribution uniformity of the deposit change significantly with varying jetting delay and spatial spacing between two drops. As the drop spacing increases while keeping jetting delay constant, the circularity of the coalesced drop reduces. For the regime where the time scale for drop evaporation is comparable with the relaxation time scale for two drops to completely coalesce, the capillary flow induced by the local curvature variation of the air-water interface redistributes particles inside a merged drop, causing suppression of the coffee-ring effect for the case of a high jetting frequency while resulting in a region of particle accumulation in the middle of the merged drop at a low jetting frequency. By tuning the interplay of wetting, evaporation, capillary relaxation, and particle assembly, the deposition morphology of consecutively printed colloidal drops can be controlled.

  9. Drops on hydrophobic surfaces & vibrated fluid surfaces

    DEFF Research Database (Denmark)

    Wind-Willassen, Øistein

    in the literature. Furthermore, we quantify the energy associated with center of mass translation and internal fluid motion. The model predicts trajectories for tracer particles deposited inside the drop, and satisfactorily describes the sliding motion of steadily accelerating droplets. The model can be used...... numerically, and the results are compared to experiments. We provide, again, the most detailed regime diagram of the possible orbits depending on the forcing and the rotation rate of the fluid bath. We highlight each class of orbit, and analyze in depth the wobbling state, precessing orbits, wobble......-leap dynamics, exotic trajectories and the emergence of statistical behavior when the forcing is near the Faraday threshold....

  10. Spontaneous self-coating of a water drop by flaky copper powders: critical role of the particle shape.

    Science.gov (United States)

    Chang, Cheng-Chung; Wu, Cyuan-Jhang; Sheng, Yu-Jane; Tsao, Heng-Kwong

    2015-06-14

    The self-coating process of solid particles over a liquid drop is important for the formation of a liquid marble. Generally, some external forces such as rolling or flipping are used to cover a drop by small particles. In this work, it is observed that flaky copper powders can spontaneously spread over the planar water surface and form a dense flat cluster with a fractal dimension of 2. Moreover, flaky copper powders can cover the water pendant and sessile drops spontaneously and rapidly. This powder-coated drop can roll on an inclined plane at a relatively high speed. However, spontaneous self-coating disappears for spheroidal copper powders. To explain our observations, the shape factors of particles are introduced into the spreading coefficient S for powders on the liquid surface. The flaky powders have the lowest shape factors and therefore spontaneous self-coating formation, with S > 0.

  11. Experimental study of drop breakup in a turbulent flow; Etude experimentale de la rupture de gouttes dans un ecoulement turbulent

    Energy Technology Data Exchange (ETDEWEB)

    Galinat, S.

    2005-04-15

    This work presents the drop breakup phenomenon in a turbulent flow induced by a cross-section restriction in a pipe. A global analysis of single-drop breakup, in a finite volume downstream of the orifice, has allowed deriving statistical quantities such as the break-up probability and the daughter-drop distribution. These parameters are function of a global Weber number based on the maximal pressure drop through the orifice. At a local scale, the locations of breakup events are distributed heterogeneously and depend on the flow Reynolds number. The local hydrodynamic study in downstream of the orifice, which has been done by using Particle Image Velocimetry, reveals the specific breakup zones. Otherwise, this analysis has proved that the turbulence is the predominant external stress at the drop scale. The relation between drop deformation and the external stress along the trajectory has been simulated numerically by the response of a damped oscillator to the locally measured instantaneous turbulence forcing. The results of statistical analysis have allowed to introduce a breakup criterion, based on a unique deformation threshold value for all experiments. This multi-scale approach has been conducted to study drop breakup mechanisms in a concentrated dispersion. The breakup probability decrease with the increase of dispersed phase concentration, which influences the turbulent Weber number distribution in downstream of the orifice. (author)

  12. Rapid Prototyping

    Science.gov (United States)

    1999-01-01

    Javelin, a Lone Peak Engineering Inc. Company has introduced the SteamRoller(TM) System as a commercial product. The system was designed by Javelin during a Phase II NASA funded small commercial product. The purpose of the invention was to allow automated-feed of flexible ceramic tapes to the Laminated Object Manufacturing rapid prototyping equipment. The ceramic material that Javelin was working with during the Phase II project is silicon nitride. This engineered ceramic material is of interest for space-based component.

  13. Equilibrium drop surface profiles in electric fields

    Science.gov (United States)

    Mugele, F.; Buehrle, J.

    2007-09-01

    Electrowetting is becoming a more and more frequently used tool to manipulate liquids in various microfluidic applications. On the scale of the entire drop, the effect of electrowetting is to reduce the apparent contact angle of partially wetting conductive liquids upon application of an external voltage. Microscopically, however, strong electric fields in the vicinity of the three phase contact line give rise to local deformations of the drop surface. We determined the equilibrium surface profile using a combined numerical, analytical, and experimental approach. We find that the local contact angle in electrowetting is equal to Young's angle independent of the applied voltage. Only on the scale of the thickness of the insulator and beyond does the surface slope assume a value consistent with the voltage-dependent apparent contact angle. This behaviour is verified experimentally by determining equilibrium surface profiles for insulators of various thicknesses between 10 and 250 µm. Numerically and analytically, we find that the local surface curvature diverges algebraically upon approaching the contact line with an exponent -1<μ<0. We discuss the relevance of the local surface properties for dynamic aspects of the contact line motion.

  14. Impact Dynamics of Oxidized Liquid Metal Drops

    CERN Document Server

    Xu, Qin; Jaeger, Heinrich M

    2013-01-01

    With exposure to air, many liquid metals spontaneously generate an oxide layer on their surface. In oscillatory rheological tests, this skin is found to introduce a yield stress that typically dominates the elastic response but can be tuned by exposing the metal to hydrochloric acid solutions of different concentration. We systematically studied the normal impact of eutectic gallium-indium (eGaIn) drops under different oxidation conditions and show how this leads to two different dynamical regimes. At low impact velocity (or low Weber number), eGaIn droplets display strong recoil and rebound from the impacted surface when the oxide layer is removed. In addition, the degree of drop deformation or spreading during the impact is controlled by the oxide skin. We show that the scaling law known from ordinary liquids for the maximum spreading radius as a function of impact velocity can still be applied to the case of oxidized eGaIn if an effective Weber number $We^{\\star}$ is employed that uses an effective surface...

  15. Deformed liquid marbles: Freezing drop oscillations with powders

    KAUST Repository

    Marston, Jeremy

    2012-09-01

    In this work we show that when a liquid drop impacts onto a fine-grained hydrophobic powder, the final form of the drop can be very different from the spherical form with which it impacts. In all cases, the drop rebounds due to the hydrophobic nature of the powder. However, we find that above a critical impact speed, the drop undergoes a permanent deformation to a highly non-spherical shape with a near-complete coverage of powder, which then freezes the drop oscillations during rebound. © 2012 Elsevier B.V.

  16. Investigation of liquid-liquid drop coalescence using tomographic PIV

    Science.gov (United States)

    Ortiz-Dueñas, Cecilia; Kim, Jungyong; Longmire, Ellen K.

    2010-07-01

    High-speed tomographic PIV was used to investigate the coalescence of drops placed on a liquid/liquid interface; the coalescence of a single drop and of a drop in the presence of an adjacent drop (side-by-side drops) was investigated. The viscosity ratio between the drop and surrounding fluids was 0.14, the Ohnesorge number (Oh = μd/(ρdσD)1/2) was 0.011, and Bond numbers (Bo = ( ρ d - ρ s ) gD 2/ σ) were 3.1-7.5. Evolving volumetric velocity fields of the full coalescence process allowed for quantification of the velocity scales occurring over different time scales. For both single and side-by-side drops, the coalescence initiates with an off-axis film rupture and film retraction speeds an order of magnitude larger than the collapse speed of the drop fluid. This is followed by the formation and propagation of an outward surface wave along the coalescing interface with wavelength of approximately 2D. For side-by-side drops, the collapse of the first drop is asymmetric due to the presence of the second drop and associated interface deformation. Overall, tomographic PIV provides insight into the flow physics and inherent three-dimensionalities in the coalescence process that would not be achievable with flow visualization or planar PIV only.

  17. Effect of neighboring particles on drop coalescence at an interface

    Science.gov (United States)

    Bordoloi, Ankur; Adhikari, Deepak; Longmire, Ellen

    2010-11-01

    The coalescence of a liquid drop in the presence of an adjacent solid particle or liquid drop is studied using high-speed visualization and Tomographic PIV. A drop of water/glycerin (W/G), surrounded by silicone oil of matched refractive index, is released onto an underlying W/G interface. A nylon sphere, neutrally buoyant with respect to the drop liquid, is placed adjacent to the drop. Three initial conditions are considered: the particle is wetted in W/G so that the interface maintains an angle of contact with the particle, the particle is wetted in oil so that it rests above the interface, and the particle is placed so that it maintains an angle of contact with the drop already resting above the interface. These cases are compared with that of two neighboring W/G drops. Off-axis rupture near the solid particle was found to be dominant in cases where the particle was wetted with W/G. However, when the particle was wetted with oil, the point of rupture occurred closer to the drop-axis. The film rupture in the drop is followed by retraction of the film and finally collapse of the drop. Both visualization and PIV results show that the trajectory of the collapsing drop depends on the initial contact condition as well as the rupture location.

  18. Dropping macadamia nuts-in-shell reduces kernel roasting quality.

    Science.gov (United States)

    Walton, David A; Wallace, Helen M

    2010-10-01

    Macadamia nuts ('nuts-in-shell') are subjected to many impacts from dropping during postharvest handling, resulting in damage to the raw kernel. The effect of dropping on roasted kernel quality is unknown. Macadamia nuts-in-shell were dropped in various combinations of moisture content, number of drops and receiving surface in three experiments. After dropping, samples from each treatment and undropped controls were dry oven-roasted for 20 min at 130 °C, and kernels were assessed for colour, mottled colour and surface damage. Dropping nuts-in-shell onto a bed of nuts-in-shell at 3% moisture content or 20% moisture content increased the percentage of dark roasted kernels. Kernels from nuts dropped first at 20%, then 10% moisture content, onto a metal plate had increased mottled colour. Dropping nuts-in-shell at 3% moisture content onto nuts-in-shell significantly increased surface damage. Similarly, surface damage increased for kernels dropped onto a metal plate at 20%, then at 10% moisture content. Postharvest dropping of macadamia nuts-in-shell causes concealed cellular damage to kernels, the effects not evident until roasting. This damage provides the reagents needed for non-enzymatic browning reactions. Improvements in handling, such as reducing the number of drops and improving handling equipment, will reduce cellular damage and after-roast darkening. Copyright © 2010 Society of Chemical Industry.

  19. Emulsion Design. Analysis of Drop Deformations in Mixed Flows

    DEFF Research Database (Denmark)

    Egholm, Runi Ditlev

    2008-01-01

    does not rely on numerical flow field calculations. The results from this analysis indicate that there is a relationship between the average drop deformation and the apparent shear rate. In the second method the experimentally obtained particle track is used together with numerical calculations...... the drop deformation and drop position a twin camera system is applied. In the subsequent data analysis the recorded movies are analysed using an automated image analysis procedure which leads to the deformation history of the drop and the drop trajectory in the device. However, due to the geometric...... by the drop in the rotor-stator device is emulated in the computational box used for carrying out drop shape simulations. Comparison of simulated and experimentally obtained deformations show that in general the agreement is acceptable on a qualitative level. However, the simulations predict deformations...

  20. Electrowetting-driven spreading and jumping of drops in oil

    Science.gov (United States)

    Hong, Jiwoo; Lee, Sang Joon

    2013-11-01

    Electrowetting-based practical applications include digital microfluidics, liquid lenses, and reflective displays. Most of them are performed in water/oil system, because oil medium reduces the contact-angle hysteresis and prevents drop evaporation. In this study, the effects of drop volume, oil viscosity, and applied voltage on the dynamic behaviors of spreading drops, such as transition of spreading pattern and response time, are investigated. Interestingly, jumping phenomena of drops are observed in oil when the applied voltage is turned off after reaching the electrowetted equilibrium radius of drops. A numerical model to predict the transient behavior of jumping drops is formulated based on the phase-field method. The numerical results for the transient deformation of jumping drops show quantitative agreement with the experimental results.