WorldWideScience

Sample records for two-phase water air

  1. NUMERICAL SIMULATION ON 2-D WATER-AIR TWO-PHASE FLOW OVER TOP OUTLET

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Flood discharge over top outlet of dam is simu-lated by 2-dimension water-air two-phase mathematical model.Distribution of dynamic pressure, turbulent kinetic energy (k), turbulent dissipation rate (ε) , free water surface and veloci-ty field have been obtained. The simulated results were testedby physical model, which shows that the computed results areidentical with that of the physical model.

  2. Numerical simulation of air-water two-phase flow over stepped spillways

    Institute of Scientific and Technical Information of China (English)

    CHENG; Xiangju; CHEN; Yongcan

    2006-01-01

    Stepped spillways for significant energy dissipation along the chute have gained interest and popularity among researchers and dam engineers. Due to the complexity of air-water two-phase flow over stepped spillways, the finite volume computational fluid dynamics module of the FLUENT software was used to simulate the main characteristics of the flow. Adopting the RNG k-ε turbulence model, the mixture flow model for air-water two-phase flow was used to simulate the flow field over stepped spillway with the PISO arithmetic technique. The numerical result successfully reproduced the complex flow over a stepped spillway of an experiment case, including the interaction between entrained air bubbles and cavity recirculation in the skimming flow regime, velocity distribution and the pressure profiles on the step surface as well. The result is helpful for understanding the detailed information about energy dissipation over stepped spillways.

  3. Interfacial structures of confined air-water two-phase bubbly flow

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S.; Ishii, M.; Wu, Q.; McCreary, D.; Beus, S.G.

    2000-08-01

    The interfacial structure of the two-phase flows is of great importance in view of theoretical modeling and practical applications. In the present study, the focus is made on obtaining detailed local two-phase parameters in the air-water bubbly flow in a rectangular vertical duct using the double-sensor conductivity probe. The characteristic wall-peak is observed in the profiles of the interracial area concentration and the void fraction. The development of the interfacial area concentration along the axial direction of the flow is studied in view of the interfacial area transport and bubble interactions. The experimental data is compared with the drift flux model with C{sub 0} = 1.35.

  4. Time-resolved Fast Neutron Radiography of Air-water Two-phase Flows

    Science.gov (United States)

    Zboray, Robert; Dangendorf, Volker; Mor, Ilan; Tittelmeier, Kai; Bromberger, Benjamin; Prasser, Horst-Michael

    Neutron imaging, in general, is a useful technique for visualizing low-Z materials (such as water or plastics) obscured by high-Z materials. However, when significant amounts of both materials are present and full-bodied samples have to be examined, cold and thermal neutrons rapidly reach their applicability limit as the samples become opaque. In such cases one can benefit from the high penetrating power of fast neutrons. In this work we demonstrate the feasibility of time-resolved, fast neutron radiography of generic air-water two-phase flows in a 1.5 cm thick flow channel with Aluminum walls and rectangular cross section. The experiments have been carried out at the high-intensity, white-beam facility of the Physikalisch-Technische Bundesanstalt, Germany. Exposure times down to 3.33 ms have been achieved at reasonable image quality and acceptable motion artifacts. Different two-phase flow regimes such as bubbly slug and churn flows have been examined. Two-phase flow parameters like the volumetric gas fraction, bubble size and bubble velocities have been measured.

  5. Two-phase air-water flows:Scale effects in physical modeling

    Institute of Scientific and Technical Information of China (English)

    PFISTER Michael; CHANSON Hubert

    2014-01-01

    Physical modeling represents probably the oldest design tool in hydraulic engineering together with analytical approaches. In free surface flows, the similitude based upon a Froude similarity allows for a correct representation of the dominant forces, namely gravity and inertia. As a result fluid flow properties such as the capillary forces and the viscous forces might be incorrectly reproduced, affecting the air entrainment and transport capacity of a high-speed model flow. Small physical models operating under a Froude similitude systematically underestimate the air entrainment rate and air-water interfacial properties. To limit scale effects, minimal values of Reynolds or Weber number have to be respected. The present article summarizes the physical background of such limitations and their combination in terms of the Morton number. Based upon a literature review, the existing limits are presented and discussed, resulting in a series of more conservative recommendations in terms of air concentration scaling. For other air-water flow parameters, the selection of the criteria to assess scale effects is critical because some parameters (e.g., bubble sizes, turbulent scales) can be affected by scale effects, even in relatively large laboratory models.

  6. Structure of two-phase adiabatic flow in air sparging regime in vertical cylindrical channel with water

    Directory of Open Access Journals (Sweden)

    V. I. Solonin

    2014-01-01

    Full Text Available The article presents a research of two-phase adiabatic flow in air sparging regime in vertical cylindrical channel filled with water. A purpose of the work is to obtain experimental data for further analysis of a character of the moving phases. Research activities used the optic methods PIV (Particle Image Visualization because of their noninvasiveness to obtain data without disturbing effect on the flow. A laser sheet illuminated the fluorescence particles, which were admixed in water along the channel length. A digital camera recorded their motion for a certain time interval that allowed building the velocity vector fields. As a result, gas phase velocity components typical for a steady area of the channel and their relations for various intensity of volume air rate were obtained. A character of motion both for an air bubble and for its surrounding liquid has been conducted. The most probable direction of phases moving in the channel under sparging regime is obtained by building the statistic scalar fields. The use of image processing enabled an analysis of the initial area of the air inlet into liquid. A characteristic curve of the bubbles offset from the axis for various intensity of volume gas rate and channel diameter is defined. A character of moving phases is obtained by building the statistic scalar fields. The values of vertical components of liquid velocity in the inlet part of channel are calculated. Using the obtained data of the gas phase velocities a true void fraction was calculated. It was compared with the values of void fraction, calculated according to the liquid level change in the channel. Obtained velocities were compared with those of the other researchers, and a small difference in their values was explained by experimental conditions. The article is one of the works to research the two-phase flows with no disturbing effect on them. Obtained data allow us to understand a character of moving the two-phase flows in

  7. 3D NUMERICAL SIMULATION ON WATER AND AIR TWO-PHASE FLOWS OF THE STEPS AND FLARING GATE PIER

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ting; WU Chao; LIAO Hua-sheng; HU Yao-hua

    2005-01-01

    A new-style flood discharging dam, which consolidates the flaring gate pier and the stepped spillway for discharging the flood through the dam surface, had been applied in China. The theoretical study on it is in a beginning stage at present. The three-dimensional numerical simulation has not been reported. In this paper, the 3D numerical calculation on the two-phase flow of water and air with discharge per unit width 195m3/s* m is presented . The results indicate that there is negative pressure on the juncture of the spillway surface and the first step. There forms obvious longitudinal and transverse eddies on the steps and the velocity decreases obviously compared with the smooth spillway. The figures of the velocity distributions and the water-air two-phase flows are plotted. The results calculated on the pressure are in agreement with the experimental data. Based on the position of the negative pressure obtained from calculation, measurement points of pressure are arranged in physical model. The experimental results validate the existence of the negative pressure. Being an applied and trial study, the results obtained are of theoretical and practical significance.

  8. Slug flow transitions in horizontal gas/liquid two-phase flows. Dependence on channel height and system pressure for air/water and steam/water two-phase flows

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Hideo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1996-05-01

    The slug flow transitions and related phenomena for horizontal two-phase flows were studied for a better prediction of two-phase flows that typically appear during the reactor loss-of-coolant accidents (LOCAs). For better representation of the flow conditions experimentally, two large-scaled facility: TPTF for high-pressure steam/water two-phase flows and large duct test facility for air/water two-phase flows, were used. The visual observation of the flow using a video-probe was performed in the TPTF experiments for good understanding of the phenomena. The currently-used models and correlations based mostly on the small-scale low-pressure experiments were reviewed and improved based on these experimental results. The modified Taitel-Dukler model for prediction of transition into slug flow from wavy flow and the modified Steen-Wallis correlation for prediction of onset of liquid entrainment from the interfacial waves were obtained. An empirical correlation for the gas-liquid interfacial friction factor was obtained further for prediction of liquid levels at wavy flow. The region of slug flow regime that is generally under influences of the channel height and system pressure was predicted well when these models and correlations were applied together. (author). 90 refs.

  9. Liquid-phase turbulence measurements in air-water two-phase flows over a wide range of void fractions

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xinquan [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, 201 W. 19th Ave., Columbus, OH 43210 (United States); Sun, Xiaodong, E-mail: sun.200@osu.edu [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, 201 W. 19th Ave., Columbus, OH 43210 (United States); Liu, Yang [Nuclear Engineering Program, Department of Mechanical Engineering, Virginia Tech, 635 Prices Fork Road, Blacksburg, VA 24061 (United States)

    2016-12-15

    This paper focuses on liquid-phase turbulence measurements in air-water two-phase flows over a wide range of void fractions and flow regimes, spanning from bubbly, cap-bubbly, slug, to churn-turbulent flows. The measurements have been conducted in two test facilities, the first one with a circular test section and the second one with a rectangular test section. A particle image velocimetry-planar laser-induced fluorescence (PIV-PLIF) system was used to acquire local liquid-phase turbulence information, including the time-averaged velocity and velocity fluctuations in the streamwise and spanwise directions, and Reynolds stress. An optical phase separation method using fluorescent particles and optical filtration technique was adopted to extract the liquid-phase velocity information. An image pre-processing scheme was imposed on the raw PIV images acquired to remove noise due to the presence of bubble residuals and optically distorted particles in the raw PIV images. Four-sensor conductivity probes and high-speed images were also used to acquire the gas-phase information, which was aimed to understand the flow interfacial structure. The highest area-averaged void fraction covered in the measurements for the circular and rectangular test sections was about 40%.

  10. Voidage Measurement of Air-Water Two-phase Flow Based on ERT Sensor and Data Mining Technology

    Institute of Scientific and Technical Information of China (English)

    王保良; 孟振振; 黄志尧; 冀海峰; 李海青

    2012-01-01

    Based on an electrical resistance tomography(ERT) sensor and the data mining technology,a new voidage measurement method is proposed for air-water two-phase flow.The data mining technology used in this work is a least squares support vector machine(LS-SVM) algorithm together with the feature extraction method,and three feature extraction methods are tested:principal component analysis(PCA),partial least squares(PLS) and independent component analysis(ICA).In the practical voidage measurement process,the flow pattern is firstly identified directly from the conductance values obtained by the ERT sensor.Then,the appropriate voidage measurement model is selected according to the flow pattern identification result.Finally,the voidage is calculated.Experimental results show that the proposed method can measure the voidage effectively,and the measurement accuracy and speed are satisfactory.Compared with the conventional voidage measurement methods based on ERT,the proposed method doesn't need any image reconstruction process,so it has the advantage of good real-time performance.Due to the introduction of flow pattern identification,the influence of flow pattern on the voidage measurement is overcome.Besides,it is demonstrated that the LS-SVM method with PLS feature extraction presents the best measurement performance among the tested methods.

  11. Flow pattern, void fraction and pressure drop of two-phase air-water flow in a horizontal circular micro-channel

    Energy Technology Data Exchange (ETDEWEB)

    Saisorn, Sira [Energy Division, The Joint Graduate School of Energy and Environment (JGSEE), King Mongkut' s University of Technology Thonburi, Bangmod, Bangkok 10140 (Thailand); Wongwises, Somchai [Fluid Mechanics, Thermal Engineering and Multiphase Flow Research Laboratory (FUTURE), Department of Mechanical Engineering, King Mongkut' s University of Technology Thonburi, Bangmod, Bangkok 10140 (Thailand)

    2008-01-15

    Adiabatic two-phase air-water flow characteristics, including the two-phase flow pattern as well as the void fraction and two-phase frictional pressure drop, in a circular micro-channel are experimentally studied. A fused silica channel, 320 mm long, with an inside diameter of 0.53 mm is used as the test section. The test runs are done at superficial velocity of gas and liquid ranging between 0.37-16 and 0.005-3.04 m/s, respectively. The flow pattern map is developed from the observed flow patterns i.e. slug flow, throat-annular flow, churn flow and annular-rivulet flow. The flow pattern map is compared with those of other researchers obtained from different working fluids. The present single-phase experiments also show that there are no significant differences in the data from the use of air or nitrogen gas, and water or de-ionized water. The void fraction data obtained by image analysis tends to correspond with the homogeneous flow model. The two-phase pressure drops are also used to calculate the frictional multiplier. The multiplier data show a dependence on flow pattern as well as mass flux. A new correlation of two-phase frictional multiplier is also proposed for practical application. (author)

  12. Experimental study on two-phase flow natural circulation in a core catcher cooling channel for EU-APR1400 using air-water system

    Energy Technology Data Exchange (ETDEWEB)

    Song, Ki Won [Division of Advanced Nuclear Engineering, POSTECH, Pohang 790-784 (Korea, Republic of); Korea Atomic Energy Research Institute, Daejeon 34057 (Korea, Republic of); Nguyen, Thanh Hung [School of Nuclear Engineering, Purdue University, West Lafayette, IN 47906 (United States); Ha, Kwang Soon; Kim, Hwan Yeol; Song, Jinho [Korea Atomic Energy Research Institute, Daejeon 34057 (Korea, Republic of); Park, Hyun Sun [Division of Advanced Nuclear Engineering, POSTECH, Pohang 790-784 (Korea, Republic of); Revankar, Shripad T., E-mail: shripad@postech.ac.kr [Division of Advanced Nuclear Engineering, POSTECH, Pohang 790-784 (Korea, Republic of); School of Nuclear Engineering, Purdue University, West Lafayette, IN 47906 (United States); Kim, Moo Hwan [Division of Advanced Nuclear Engineering, POSTECH, Pohang 790-784 (Korea, Republic of); Korea Institute of Nuclear Safety, Daejeon 305-338 (Korea, Republic of)

    2017-05-15

    Highlights: • Two-phase flow regimes and transition behavior were observed in the coolant channel. • Test were conducted for natural circulation with air-water. • Data were obtained on flow regime, void fraction, flow rates and re-wetting time. • The data were related to a cooling capability of core catcher system. - Abstract: Ex-vessel core catcher cooling system driven by natural circulation is designed using a full scaled air-water system. A transparent half symmetric section of a core catcher coolant channel of a pressurized water reactor was designed with instrumentations for local void fraction measurement and flow visualization. Two designs of air-water top separator water tanks are studied including one with modified ‘super-step’ design which prevents gas entrainment into down-comer. In the experiment air flow rates are set corresponding to steam generation rate for given corium decay power. Measurements of natural circulation flow rate, spatial local void fraction distribution and re-wetting time near the top wall are carried out for various air flow rates which simulate boiling-induced vapor generation. Since heat transfer and critical heat flux are strongly dependent on the water mass flow rate and development of two-phase flow on the heated wall, knowledge of two-phase flow characteristics in the coolant channel is essential. Results on flow visualization showing two phase flow structure specifically near the high void accumulation regions, local void profiles, rewetting time, and natural circulation flow rate are presented for various air flow rates that simulate corium power levels. The data are useful in assessing the cooling capability of and safety of the core catcher system.

  13. Caracterización hidrodinámica de una columna de burbujeo agua aire // Hydrodynamic characterization of a two phase water air column

    Directory of Open Access Journals (Sweden)

    M. Piedra-Díaz

    2009-01-01

    Full Text Available Lograr determinar y evaluar los mecanismos que gobiernan los procesos de transporte entre lasfases permite predecir el comportamiento de los sistemas multifásicos y establecer estrategias dediseño y de operación para obtener mayores rendimientos y mejoras tecnológicas en los equiposdonde tienen lugar estos flujos. Para el estudio de los procesos de transporte es necesario lograr lacombinación de metodologías de carácter teórico - experimental con la incorporación de lastécnicas novedosas de análisis numérico. En este trabajo se plantea como objetivo desarrollar yconstruir una instalación experimental para el estudio de las características del flujo multifásicoagua - aire. Se presentan resultados sobre la influencia de la fracción de gas y el No de Re en laforma de la columna bifásica.Palabras claves: flujo Multifásico, hidrodinámica, mecánica de los fluidos._____________________________________________________________________________AbstractWith the determination and evaluation of the governing mechanisms of transport processesbetween two phases, is possible to predict multiphase system behavior and to establish strategiesto design and operate the equipment with the highest performance. To study transport processes isnecessary to get the combination of theoretical and experimental methodologies with thenecessary numerical analysis. The main objective of this study is to build an experimentalinstallation in order to study the characteristics of water air multiphase flows. Results about theinfluence of gas fraction and Reynolds number in the shape of the biphasic column are presented.Key words: two phase flow, multiphase flows, hydrodynamic, fluid mechanic

  14. The effects of channel diameter on flow pattern, void fraction and pressure drop of two-phase air-water flow in circular micro-channels

    Energy Technology Data Exchange (ETDEWEB)

    Saisorn, Sira [Energy Division, The Joint Graduate School of Energy and Environment (JGSEE), King Mongkut' s University of Technology Thonburi, Bangmod, Bangkok 10140 (Thailand); Wongwises, Somchai [Fluid Mechanics, Thermal Engineering and Multiphase Flow Research Lab. (FUTURE), Department of Mechanical Engineering, King Mongkut' s University of Technology Thonburi, Bangmod, Bangkok 10140 (Thailand)

    2010-05-15

    Two-phase air-water flow characteristics are experimentally investigated in horizontal circular micro-channels. Test sections are made of fused silica. The experiments are conducted based on three different inner diameters of 0.53, 0.22 and 0.15 mm with the corresponding lengths of 320, 120 and 104 mm, respectively. The test runs are done at superficial velocities of gas and liquid ranging between 0.37-42.36 and 0.005-3.04 m/s, respectively. The flow visualisation is facilitated by systems mainly including stereozoom microscope and high-speed camera. The flow regime maps developed from the observed flow patterns are presented. The void fractions are determined based on image analysis. New correlation for two-phase frictional multiplier is also proposed for practical applications. (author)

  15. Two-phase Lattice Boltzmann modelling of streaming potentials: influence of the air-water interface on the electrokinetic coupling

    Science.gov (United States)

    Fiorentino, Eve-Agnès; Toussaint, Renaud; Jouniaux, Laurence

    2017-02-01

    The streaming potential phenomenon is an electrokinetic effect that occurs in porous media. It is characterized by an electrokinetic (EK) coefficient. The aim of this paper is to simulate the EK coefficient in unsaturated conditions using the Lattice Boltzmann method in a 2-D capillary channel. The multiphase flow is simulated with the model of Shan & Chen. The Poisson-Boltzmann equation is solved by implementing the model of Chai & Shi. The streaming potential response shows a non-monotonous behaviour due to the combination of the increase of charge density and decrease of flow velocity with decreasing water saturation. Using a ζ potential of -20 mV at the air-water interface, an enhancement of a factor 5-30 of the EK coefficient, compared to the saturated state, can be observed due to the positive charge excess at this interface which is magnified by the fluid velocity away from the rock surface. This enhancement is correlated to the fractioning of the bubbles, and to the dynamic state of these bubbles, moving or entrapped in the crevices of the channel.

  16. Time-resolved fast-neutron radiography of air-water two-phase flows in a rectangular channel by an improved detection system

    CERN Document Server

    Zboray, Robert; Mor, Ilan; Bromberger, Benjamin; Tittelmeier, Kai

    2015-01-01

    In a previous work we have demonstrated the feasibility of high-frame-rate, fast-neutron radiography of generic air-water two-phase flows in a 1.5 cm thick, rectangular flow channel. The experiments have been carried out at the high-intensity, white-beam facility of the Physikalisch-Technische Bundesanstalt, Germany, using an multi-frame, time-resolved detector developed for fast neutron resonance radiography. The results were however not fully optimal and therefore we have decided to modify the detector and optimize it for the given application, which is described in the present work. Furthermore, we managed to improve the image post-processing methodology and the noise suppression. Using the tailored detector and the improved post-processing significant increase in the image quality and an order of magnitude lower exposure times, down to 3.33 ms, have been achieved with minimized motion artifacts. Similar to the previous study, different two-phase flow regimes such as bubbly slug and churn flows have been e...

  17. Measurement of Gas and Liquid Velocities in an Air-Water Two-Phase Flow using Cross-Correlation of Signals from a Double Senor Hot-Film Probe

    Energy Technology Data Exchange (ETDEWEB)

    B. Gurau; P. Vassalo; K. Keller

    2002-02-19

    Local gas and liquid velocities are measured by cross-correlating signals from a double sensor hot-film anemometer probe in pure water flow and air water two-phase flow. The gas phase velocity measured in two-phase flow agrees with velocity data obtained using high-speed video to within +/-5%. A turbulent structure, present in the liquid phase, allows a correlation to be taken, which is consistent with the expected velocity profiles in pure liquid flow. This turbulent structure is also present in the liquid phase of a two-phase flow system. Therefore, a similar technique can be applied to measure the local liquid velocity in a two-phase system, when conditions permit.

  18. Measurement of the local void fraction in two-phase air-water flow with a hot-film anemometer; Mesure du taux de vide local en ecoulement diphasique eau-air par un anemometre a film chaud

    Energy Technology Data Exchange (ETDEWEB)

    Delhaye, J. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1968-07-01

    The experimental knowledge of the local void-fraction is basic for the derivation of the constitutive equations of two-phase flows. This report deals with measurements of the local void-fraction based on the use of a constant temperature hot-film anemometer associated with a multichannel analyser. After determining the void-fraction profile along a diameter of a vertical pipe (40 mm I.D.), in which air and water flow upwards, we compare the void-fraction averaged over the diameter with the average value measured directly by a {gamma}-ray method. Two runs were made in bubble flow and a third in slug flow. The two methods give results in a good agreement especially for bubble flow. The void-fraction averaged over the cross-section was also calculated from the different profiles and compared in a good manner with the experimental results of R. ROUMY. For bubble flow we verified the theory of S.G. BANKOFF about the shape of the void-fraction profiles. (author) [French] Nous proposons une methode de mesure du taux de vide local a en ecoulement diphasique, basee sur l'emploi d'un anemometre a film chaud a temperature constante dont on etudie la repartition du signal en amplitude dans un analyseur multicanaux. Ayant trace un profil de taux de vide local suivant un diametre d'une conduite verticale de section circulaire parcourue par un ecoulement ascendant d'eau et d'air, nous avons compare la moyenne de {alpha} sur ce diametre a la valeur obtenue par une methode d'absorption de rayons {gamma}. Les essais ont ete faits en ecoulements a bulles et a bouchons. Les deux methodes donnent des resultats concordants en particulier pour les ecoulements a bulles. Le taux de vide moyenne dans la section, calcule a partir des differents profils, a egalement ete compare avec succes aux resultats experimentaux de R. ROUMY. Dans l'etude de la structure radiale des ecoulements a bulles, nous avons verifie l'hypothese de S.G. BAJMKOFF. (auteur)

  19. Characterization of horizontal air–water two-phase flow

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Ran; Kim, Seungjin, E-mail: skim@psu.edu

    2017-02-15

    Highlights: • A visualization study is performed to develop flow regime map in horizontal flow. • Database in horizontal bubbly flow is extended using a local conductivity probe. • Frictional pressure drop analysis is performed in horizontal bubbly flow. • Drift flux analysis is performed in horizontal bubbly flow. - Abstract: This paper presents experimental studies performed to characterize horizontal air–water two-phase flow in a round pipe with an inner diameter of 3.81 cm. A detailed flow visualization study is performed using a high-speed video camera in a wide range of two-phase flow conditions to verify previous flow regime maps. Two-phase flows are classified into bubbly, plug, slug, stratified, stratified-wavy, and annular flow regimes. While the transition boundaries identified in the present study compare well with the existing ones (Mandhane et al., 1974) in general, some discrepancies are observed for bubbly-to-plug/slug, and plug-to-slug transition boundaries. Based on the new transition boundaries, three additional test conditions are determined in horizontal bubbly flow to extend the database by Talley et al. (2015a). Various local two-phase flow parameters including void fraction, interfacial area concentration, bubble velocity, and bubble Sauter mean diameter are obtained. The effects of increasing gas flow rate on void fraction, bubble Sauter mean diameter, and bubble velocity are discussed. Bubbles begin to coalesce near the gas–liquid layer instead of in the highly packed region when gas flow rate increases. Using all the current experimental data, two-phase frictional pressure loss analysis is performed using the Lockhart–Martinelli method. It is found that the coefficient C = 24 yields the best agreement with the data with the minimum average difference. Moreover, drift flux analysis is performed to predict void-weighted area-averaged bubble velocity and area-averaged void fraction. Based on the current database, functional

  20. Microporous silica gels from alkylsilicate-water two phase hydrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Chu, L.; Tejedor-Tejedor, M.I.; Anderson, M.A. [Univ. of Wisconsin, Madison, WI (United States). Water Chemistry Program

    1994-12-31

    Microporous silica gels have been synthesized through a nano-particulate sol-gel route. These gels have uniformly distributed and extremely small pores(< 15 {angstrom} in diameter). Hydrolysis and condensation reactions leading to these gels were carried out in an alkyl silicate-water (ammonia) two phase system. These reactions took place at the alkyl silicate droplet-water interfacial boundary. No alcohol was added. A clear, stable and uniformly distributed colloidal silica suspension having an average particle size less than 6 nm was prepared by this method. Fast hydrolysis, slow condensation and low solubility all contribute to a high supersaturation level and result in the formation of small particles. This process is consistent with classic nucleation theory. When the particles are produced under acidic rather than under basic reaction conditions, smaller particles are formed due to the slower condensation rate and lower solubility of these silica particles in acidic conditions. At the same pH, alkylsilicates having smaller alkyl groups react faster with water leading to smaller primary particles. Homogeneous nucleation conditions are achieved when the water/alkylsilicate ratio is high.

  1. A phenomenological model of two-phase (air/fuel droplet developing and breakup

    Directory of Open Access Journals (Sweden)

    Pavlović Radomir R.

    2013-01-01

    Full Text Available Effervescent atomization namely the air-filled liquid atomization comprehends certain complex two-phase phenomenon that are difficult to be modeled. Just a few researchers have found the mathematical expressions for description of the complex atomization model of the two-phase mixture air/diesel fuel. In the following review, developing model of twophase (air/fuel droplet of Cummins spray pump-injector is shown. The assumption of the same diameters of the droplet and the opening of the atomizer is made, while the air/fuel mass ratio inside the droplet varies.

  2. Effects of a two-phase oil-water mouthwash on halitosis.

    Science.gov (United States)

    Yaegaki, K; Sanada, K

    1992-01-01

    Many oral microorganisms possess hydrophobic outer surfaces. A two-phase, oil-water mouthwash has, therefore, recently been developed to remove such oral microorganisms. The oil phase consists of olive oil and other essential oils. The aqueous phase includes cetylpyridinium chloride, which is a disinfectant that promotes the adhesion of microorganisms to oil droplets. This study determined the effects of this mouthwash on the production of volatile sulfide in vivo and in vitro. Neither rinsing with water nor brushing teeth decreased the concentration of sulfide in mouth air at 3.5 h after treatment. A reduction of only 30% of sulfide was observed when a commercial mouthwash was used. However, this study demonstrated that use of the two-phase mouthwash led to approximately 80% reduction of sulfide. Furthermore, volatile sulfide and 2-ketobutyrate productions from methionine in a saliva putrefaction system were completely inhibited by the two-phase mouthwash; and consumption of methionine was decreased by 65 percent. It is concluded that the two-phase mouthwash strongly inhibits the production of volatile sulfide.

  3. A MODEL FOR PREDICTING PHASE INVERSION IN OIL-WATER TWO-PHASE PIPE FLOW

    Institute of Scientific and Technical Information of China (English)

    GONG Jing; LI Qing-ping; YAO Hai-yuan; YU Da

    2006-01-01

    Experiments of phase inversion characteristics for horizontal oil-water two-phase flow in a stainless steel pipe loop (25.7 mm inner diameter,52 m long) are conducted. A new viewpoint is brought forward about the process of phase inversion in oil-water two-phase pipe flow. Using the relations between the total free energies of the pre-inversion and post-inversion dispersions, a model for predicting phase inversion in oil-water two-phase pipe flow has been developed that considers the characteristics of pipe flow. This model is compared against other models with relevant data of phase inversion in oil-water two-phase pipe flow. Results indicate that this model is better than other models in terms of calculation precision and applicability. The model is useful for guiding the design for optimal performance and safety in the operation of oil-water two-phase pipe flow in oil fields.

  4. Heat transfer studies in a spiral plate heat exchanger for water: palm oil two phase system

    Directory of Open Access Journals (Sweden)

    S. Ramachandran

    2008-09-01

    Full Text Available Experimental studies were conducted in a spiral plate heat exchanger with hot water as the service fluid and the two-phase system of water – palm oil in different mass fractions and flow rates as the cold process fluid. The two phase heat transfer coefficients were correlated with Reynolds numbers (Re in the form h = a Re m, adopting an approach available in literature for two phase fluid flow. The heat transfer coefficients were also related to the mass fraction of palm oil for identical Reynolds numbers. The two-phase multiplier (ratio of the heat transfer coefficient of the two phase fluid and that of the single phase fluid was correlated with the Lockhart Martinelli parameter in a polynomial form. This enables prediction of the two-phase coefficients using single-phase data. The predicted coefficients showed a spread of ± 10 % in the laminar range.

  5. Nonlinear analysis of gas-water/oil-water two-phase flow in complex networks

    CERN Document Server

    Gao, Zhong-Ke; Wang, Wen-Xu

    2014-01-01

    Understanding the dynamics of multi-phase flows has been a challenge in the fields of nonlinear dynamics and fluid mechanics. This chapter reviews our work on two-phase flow dynamics in combination with complex network theory. We systematically carried out gas-water/oil-water two-phase flow experiments for measuring the time series of flow signals which is studied in terms of the mapping from time series to complex networks. Three network mapping methods were proposed for the analysis and identification of flow patterns, i.e. Flow Pattern Complex Network (FPCN), Fluid Dynamic Complex Network (FDCN) and Fluid Structure Complex Network (FSCN). Through detecting the community structure of FPCN based on K-means clustering, distinct flow patterns can be successfully distinguished and identified. A number of FDCN’s under different flow conditions were constructed in order to reveal the dynamical characteristics of two-phase flows. The FDCNs exhibit universal power-law degree distributions. The power-law exponent ...

  6. Study on law of negative corona discharge in microparticle-air two-phase flow media

    Directory of Open Access Journals (Sweden)

    Bo He

    2016-03-01

    Full Text Available To study the basic law of negative corona discharge in solid particle-air two-phase flow, corona discharge experiments in a needle-plate electrode system at different voltage levels and different wind speed were carried out in the wind tunnel. In this paper, the change law of average current and current waveform were analyzed, and the observed phenomena were systematically explained from the perspectives of airflow, particle charging, and particle motion with the help of PIV (particle image velocity measurements and ultraviolet observations.

  7. The Effect of Sudden Change in Pipe Diameter on Flow Patterns of Air-Water Two-Phase Flow in Vertical Pipe (Ⅱ) Sudden-Expansion Cross-Section

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In this companion paper, flow patterns in the upstream and downstream tubes of a sudden-expansion cross-section (SECS) in a vertical straight pipe were presented. The effect of SECS on flow patterns upstream and downstream was analyzed by comparing with flow patterns in uniform cross-section vertical tubes. It is found the effect is great. There exist great instabilities of two-phase flow in the neighboring areas of the SECS both downstream and upstream.

  8. Neutron imaging of diabatic two-phase flows relevant to air conditioning

    Energy Technology Data Exchange (ETDEWEB)

    Geoghegan, Patrick J [ORNL; Sharma, Vishaldeep [ORNL

    2017-01-01

    The design of the evaporator of an air conditioning system relies heavily on heat transfer coefficients and pressure drop correlations that predominantly involve an estimate of the changing void fraction and the underlying two-phase flow regime. These correlations dictate whether the resulting heat exchanger is oversized or not and the amount of refrigerant charge necessary to operate. The latter is particularly important when dealing with flammable or high GWP refrigerants. Traditional techniques to measure the void fraction and visualize the flow are either invasive to the flow or occur downstream of the evaporator, where some of the flow distribution will have changed. Neutron imaging has the potential to visualize two-phase flow in-situ where an aluminium heat exchanger structure becomes essentially transparent to the penetrating neutrons. The subatomic particles are attenuated by the passing refrigerant flow. The resulting image may be directly related to the void fraction and the overall picture provides a clear insight into the flow regime present. This work presents neutron images of the refrigerant Isopentane as it passes through the flow channels of an aluminium evaporator at flowrates relevant to air conditioning. The flow in a 4mm square macro channel is compared to that in a 250 m by 750 m rectangular microchannel in terms of void fraction and regime. All neutron imaging experiments were conducted at the High Flux Isotope Reactor, an Oak Ridge National Laboratory facility

  9. Gastric stromal tumor: two-phase dynamic CT findings with water as oral contrast agents

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Se Hyo; Cho, June Sik; Shin, Kyung Sook; Jeong, Ki Ho; Park, Jin Yong; Yu, Ho Jun; Kim, Young Min; Jeon, Kwang Jin [College of Medicine, Chungnam National University, Taejon (Korea, Republic of)

    2000-01-01

    To evaluate two-phase dynamic CT with water as oral contrast agents in the CT diagnosis of gastric stromal tumors. We retrospectively reviewed the CT findings in 21 patients with pathologically proven gastric stromal tumors. Six were found to be benign, twelve were malignant, and there were three cases of STUMP (stromal tumor uncertain malignant potential). Two-phase dynamic CT scans with water as oral contrast agents were obtained 60-70 secs (portal phase) and 3 mins (equilibrium phase) after the start of IV contrast administration. We determined the size, growth pattern, and enhancement pattern of the tumors and overlying mucosa, the presence or absence of ulceration and necrosis, tumor extent, and lymph nod and distant metastasis. The CT and pathologic findings were correlated. All six benign tumors and three STUMP were less than 5.5 cm in size, and during the portal phase showed round endogastric masses with highly enhanced, intact overlying mucosa. Twelve malignant tumors were 4.5-15.5 cm in size (mean, 11.5 cm); an endogastric mass was seen in three cases, an exogastric mass in one, and a mixed pattern in eight. On portal phase images the tumors were not significantly enhanced, but highly enhanced feeding vessels were noted in five larger tumors (greater than 10 cm). All 12 malignant tumors showed ulceration and necrosis, and interruption of overlying mucosa was clearly seen during the portal phase. We were readily able to evaluate tumor extent during this phase, and in ten malignant tumors there was no invasion of adjacent organs. Seven malignant tumors showed air density within their necrotic portion (p less than 0.05). On equilibrium phase images, all malignant tumors showed heterogeneous enhancement due to necrosis, and poorly enhanced overlying mucosa. Dynamic CT during the portal phase with water as oral contrast agents was useful for depicting the submucosal origin of gastric stromal tumors and for evaluating the extent of malignant stromal tumors. Our

  10. Well logging interpretation of production profile in horizontal oil-water two phase flow pipes

    Science.gov (United States)

    Zhai, Lu-Sheng; Jin, Ning-De; Gao, Zhong-Ke; Zheng, Xi-Ke

    2012-03-01

    Due to the complicated distribution of local velocity and local phase hold up along the radial direction of pipe in horizontal oil-water two phase flow, it is difficult to measure the total flow rate and phase volume fraction. In this study, we carried out dynamic experiment in horizontal oil-water two phases flow simulation well by using combination measurement system including turbine flowmeter with petal type concentrating diverter, conductance sensor and flowpassing capacitance sensor. According to the response resolution ability of the conductance and capacitance sensor in different range of total flow rate and water-cut, we use drift flux model and statistical model to predict the partial phase flow rate, respectively. The results indicate that the variable coefficient drift flux model can self-adaptively tone the model parameter according to the oil-water two phase flow characteristic, and the prediction result of partial phase flow rate of oil-water two phase flow is of high accuracy.

  11. Performance characteristics of two-phase-flow turbo-expanders used in water-cooled chillers

    Energy Technology Data Exchange (ETDEWEB)

    Brasz, J.J. [United Technologies Carrier, New York, NY (United States)

    1999-07-01

    Use of two-phase-flow throttle loss recovery devices in water-cooled chillers requires satisfactory part-load operation. This paper describes the results of two-phase-flow impulse turbine testing and the data reduction of the test results into a two-phase-flow turbine off-design performance model. It was found that the main parameter controlling the efficiency of two-phase-flow turbine is the ratio of the nozzle spouting velocity to the rotor speed. The turbine mass flow rate is mainly controlled by inlet subcooling of the entering liquid. The strong sensitivity of turbine mass flow rate on inlet subcooling allows the use of a conventional float valve upstream of the turbine as an effective means of controlling the turbine during part-load operation. For a well-designed two-phase-flow turbine, nozzle spouting velocity and therefore turbine efficiency is hardly affected by the amount of inlet subcooling. Also, capacity can be substantially reduced by a reduction in the amount of inlet subcooling entering the turbine nozzles. Hence, turbine part-load efficiency equals its full-load efficiency over a wide range of flow rates using this control concept. (Author)

  12. Design and evaluation of a two-phase turbine for low quality steam--water mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Comfort, W.J. III

    1977-05-16

    A new two-phase turbine was designed and built for testing in the laboratory, using a low quality steam-water mixture as a working fluid. The measured performance compares well with performance predictions of a numerical model of the expander. Details of the selection of the type of expander are given. The design of an experimental expander for use in a clean two-phase flow laboratory experiment and the development of a numerical model for performance analysis and extrapolations are described. Experiments including static cascade performance with two-phase fluid, disk friction and windage measurements, and two-phase performance measurements of the experimental expander are reported. Comparisons of the numerical model and experimental results, and the prediction of the performance of an advanced design, indicating how performance improvements can be achieved, are also included. An engine efficiency of 23 percent for a single-nozzle test was measured. Full admission performance, based upon the numerical model and achievable nozzle thrust coefficients indicate that an engine efficiency of between 38 and 48 percent can be realized with present technology. If maximum liquid removal loss is assumed, this performance range is predicted to be 38 to 41 percent. Droplet size reduction and the development and implementation of enhanced two-phase flow analysis techniques should make it possible to achieve the research goal of 70 percent engine efficiency.

  13. Experimental study on steam-water two-phase flow frictional pressure drops in helical coils

    Institute of Scientific and Technical Information of China (English)

    1997-01-01

    Experiments of steam-water two-phase flow frictional pressure drop in a vertical helical coil were carried out in the high-pressure water test loop of Xi'an jiaotong University,The coil is made of stainless steel tube with an inner diameter of 16mm,the helix diameter measured from tube axis to tube axis is 1.3m,and helix angle of the coil is 3.65°,The experimental conditions are:pressurep=4-18MPa,mass velocity G=400-1400kg/(m2.s),inner wall heat flux q=100-700kW/m2,Based on these data,a correlation for predicting the steam-water two-phase flow frictional pressure drop was derived,it can be used for the design of steam generator of HTGR.

  14. Negative DC corona discharge current characteristics in a flowing two-phase (air + suspended smoke particles) fluid

    Science.gov (United States)

    Berendt, Artur; Domaszka, Magdalena; Mizeraczyk, Jerzy

    2017-04-01

    The electrical characteristics of a steady-state negative DC corona discharge in a two-phase fluid (air with suspended cigarette smoke particles) flowing along a chamber with a needle-to-plate electrode arrangement were experimentally investigated. The two-phase flow was transverse in respect to the needle-to-plate axis. The velocity of the transverse two-phase flow was limited to 0.8 m/s, typical of the electrostatic precipitators. We found that three discharge current modes of the negative corona exist in the two-phase (air + smoke particles) fluid: the Trichel pulses mode, the "Trichel pulses superimposed on DC component" mode and the DC component mode, similarly as in the corona discharge in air (a single-phase fluid). The shape of Trichel pulses in the air + suspended particles fluid is similar to that in air. However, the Trichel pulse amplitudes are higher than those in "pure" air while their repetition frequency is lower. As a net consequence of that the averaged corona discharge current in the two-phase fluid is lower than in "pure" air. It was also found that the average discharge current decreases with increasing suspended particle concentration. The calculations showed that the dependence of the average negative corona current (which is a macroscopic corona discharge parameter) on the particle concentration can be explained by the particle-concentration dependencies of the electric charge of Trichel pulse and the repetition frequency of Trichel pulses, both giving a microscopic insight into the electrical phenomena in the negative corona discharge. Our investigations showed also that the average corona discharge current in the two-phase fluid is almost unaffected by the transverse fluid flow up to a velocity of 0.8 m/s. Contribution to the topical issue "The 15th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XV)", edited by Nicolas Gherardi and Tomáš Hoder

  15. Heat transfer performance of two-phase closed thermosyphon with oxidized CNT/water nanofluids

    Science.gov (United States)

    Zeinali Heris, Saeed; Fallahi, Marjan; Shanbedi, Mehdi; Amiri, Ahmad

    2016-01-01

    In this paper, the effects of different acids on the thermal performance of oxidized carbon nanotubes (CNT)/water nanofluids in a two-phase closed thermosyphon were studied. The structures morphology and functionalization degree were studied concurrently. The results indicated that strong oxidants increased dispersivity of CNT in the nanofluids. In other words, as the number of COOH groups increased in the nanofluids, an upward trend was also observed in the thermal efficiency of the thermosyphon.

  16. EFFECT OF SURFACTANT ON TWO-PHASE FLOW PATTERNS OF WATER-GAS IN CAPILLARY TUBES

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Flow patterns of liquid-gas two-phase flow were experimentally investigated. The experiments were carried out in both vertical and horizontal capillary tubes having inner diameters of 1.60 mm. The working liquid was the mixture of water and Sodium Dodecyl Benzoyl Sulfate (SDBS). The working gas was Nitrogen. For the water/SDBS mixture-gas flow in the vertical capillary tube, flow-pattern transitions occurred at lower flow velocities than those for the water-gas flow in the same tube. For the water/SDBS mixture-gas flow in the horizontal capillary tube, surface tension had little effect on the bubbly-intermittent transition and had only slight effect on the plug-slug and slug-annular transitions. However, surface tension had significant effect on the wavy stratified flow regime. The wavy stratified flow regime of water/SDBS mixture-gas flow expanded compared with that of water-gas.

  17. Two-phase Flow Ejector as Water Refrigerant by Using Waste Heat

    Science.gov (United States)

    Yamanaka, H.; Nakagawa, M.

    2013-04-01

    Energy saving and the use of clean energy sources have recently become significant issues. It is expected that clean energy sources such as solar panels and fuel cells will be installed in many private dwellings. However, when electrical power is generated, exhaust heat is simultaneously produced. Especially for the summer season, the development of refrigeration systems that can use this waste heat is highly desirable. One approach is an ejector that can reduce the mechanical compression work required in a normal refrigeration cycle. We focus on the use of water as a refrigerant, since this can be safely implemented in private dwellings. Although the energy conversion efficiency is low, it is promising because it can use heat that would otherwise be discarded. However, a steam ejector refrigeration cycle requires a large amount of energy to change saturated water into vapour. Thus, we propose a more efficient two-phase flow ejector cycle. Experiments were carried out in which the quality of the two-phase flow from a tank was varied, and the efficiency of the ejector and nozzle was determined. The results show that a vacuum state can be achieved and suction exerted with a two-phase flow state at the ejector nozzle inlet.

  18. OIL-WATER TWO-PHASE FLOW INSIDE T-JUNCTION

    Institute of Scientific and Technical Information of China (English)

    WANG Li-yang; WU Ying-xiang; ZHENG Zhi-chu; GUO Jun; ZHANG Jun; TANG Chi

    2008-01-01

    The oil / water two-phase flow inside T-junctions was numerically simulated with a 3-D two-fluid model, and the turbulence was described using the mixture model. Some experiments of oil / water flow inside a single T-junction were conducted in the laboratory. The results show that the separating performance of T-junction largely depends on the inlet volumetric fraction and flow patterns. A reasonable agreement is reached between the numerical simulation and the experiments for both the oil fraction distribution and the separation efficiency.

  19. Numerical simulation of oil-water two-phase flow in horizontal pipes

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Michelly Martuchele; Ramirez, Ramiro Gustavo [Federal University of Itajuba (UNIFEI), MG (Brazil)], E-mail: ramirez@unifei.edu.br

    2010-07-01

    The numerical simulation of two phase flow through the CFD techniques have become of great interest due to the complexity of this type of flow. The present work aims to simulate the oil-water two-phase flow in horizontal pipes for stratification analysis of the mixture. In numerical simulations, incompressible flow, isothermal, steady state and laminar flow were considered. Numerical analysis of flow stratification was carried out for horizontal straight and curved pipe. FLUENT was the commercial software employed in the simulation. Three-dimensional mesh generated by ICEM-CFD program was used for numerical simulation. The numerical analysis flow pattern was carried out employing the Eulerian model, considering the drag and lift interphase forces. The simulation results for the horizontal straight pipe were qualitatively validated with experimental data obtained in the Laboratory of Phase Separation of UNIFEI. (author)

  20. Experimental study of two-phase water flow in vertical thin rectangular channels

    Science.gov (United States)

    Wright, Christopher T.; O'Brien, James E.; Anderson, Elgin A.

    2001-11-01

    An experimental heat transfer study of two-phase water flow in vertical thin rectangular channels with side vents is conducted. A multiple, heated channel configuration with up- and down-flow conditions is investigated. Parallel heated and unheated flow channels test the effects of cross flow on the onset of nucleate boiling (ONB) and critical heat flux (CHF). The test apparatus provides pressure and substrate temperature data and visual data of the boiling regimes and side-vent flow patterns. The objectives are to determine the two-phase, heat and mass transfer characteristics between adjacent channels as permitted by side-vent cross flow. These data will help develop ONB and CHF correlations for flow geometries typical of plate-type nuclear reactors and heat exchangers. Fundamentally, the data shows how the geometry, flow conditions, and channel configurations affect the heat transfer characteristics of interior channel flows, essential in understanding the ONB and CHF phenomena.

  1. CFD Analysis of a Supersonic Air Ejector. Part I: Experimental Validation of Single-Phase and Two-Phase Operation

    OpenAIRE

    Hemidi, Amel; Henry, François; Leclaire, Sébastien; Seynhaeve, Jean-Marie; Bartosiewicz, Yann

    2009-01-01

    CFD Analysis of a Supersonic Air Ejector. Part I: Experimental Validation of Single-Phase and Two-Phase Operation correspondance: Corresponding author. (Bartosiewicz, Yann) (Bartosiewicz, Yann) Universite catholique de Louvain UCL--> , Faculty of Applied Sciences--> , Mechanical Engineering Department--> , TERM Division--> , Place du Levant 2--> , B-1348--> , L...

  2. Oil-water two-phase flow measurement with combined ultrasonic transducer and electrical sensors

    Science.gov (United States)

    Tan, Chao; Yuan, Ye; Dong, Xiaoxiao; Dong, Feng

    2016-12-01

    A combination of ultrasonic transducers operated in continuous mode and a conductance/capacitance sensor (UTCC) is proposed to estimate the individual flow velocities in oil-water two-phase flows. Based on the Doppler effect, the transducers measure the flow velocity and the conductance/capacitance sensor estimates the phase fraction. A set of theoretical correlations based on the boundary layer models of the oil-water two-phase flow was proposed to describe the velocity profile. The models were separately established for the dispersion flow and the separate flow. The superficial flow velocity of each phase is calculated with the velocity measured in the sampling volume of the ultrasonic transducer with the phase fraction through the velocity profile models. The measuring system of the UTCC was designed and experimentally verified on a multiphase flow loop. The results indicate that the proposed system and correlations estimate the overall flow velocity at an uncertainty of U J   =  0.038 m s-1, and the water superficial velocity at U Jw   =  0.026 m s-1, and oil superficial velocity at U Jo   =  0.034 m s-1. The influencing factors of uncertainty were analyzed.

  3. A modified Rusanov scheme for shallow water equations with topography and two phase flows

    Science.gov (United States)

    Mohamed, Kamel; Benkhaldoun, F.

    2016-06-01

    In this work, we introduce a finite volume method for numerical simulation of shallow water equations with source terms in one and two space dimensions, and one-pressure model of two-phase flows in one space dimension. The proposed method is composed of two steps. The first, called predictor step, depends on a local parameter allowing to control the numerical diffusion. A strategy based on limiters theory enables to control this parameter. The second step recovers the conservation equation. The scheme can thus be turned to order 1 in the regions where the flow has a strong variation, and order 2 in the regions where the flow is regular. The numerical scheme is applied to several test cases in one and two space dimensions. This scheme demonstrates its well-balanced property, and that it is an efficient and accurate approach for solving shallow water equations with and without source terms, and water faucet problem.

  4. Calibration of Mineralization Degree for Dynamic Pure-water Measurement in Horizontal Oil-water Two-phase Flow

    Science.gov (United States)

    Kong, Weihang; Li, Lei; Kong, Lingfu; Liu, Xingbin

    2016-08-01

    In order to solve the problem of dynamic pure-water electrical conductivity measurement in the process of calculating water content of oil-water two-phase flow of production profile logging in horizontal wells, a six-group local-conductance probe (SGLCP) is proposed to measure dynamic pure-water electrical conductivity in horizontal oil-water two-phase flow. The structures of conductance sensors which include the SGLCP and ring-shaped conductance probe (RSCP) are analyzed by using the finite-element method (FEM). In the process of simulation, the electric field distribution generated by the SGLCP and RSCP are investigated, and the responses of the measuring electrodes are calculated under the different values of the water resistivity. The static experiments of the SGLCP and RSCP under different mineralization degrees in horizontal oil-water two-phase flow are carried out. Results of simulation and experiments demonstrate a nice linearity between the SGLCP and RSCP under different mineralization degrees. The SGLCP has also a good adaptability to stratified flow, stratified flow with mixing at the interface and dispersion of oil in water and water flow. The validity and feasibility of pure-water electrical conductivity measurement with the designed SGLCP under different mineralization degrees are verified by experimental results.

  5. Enzymatic hydrolysis of penicillin in mixed ionic liquids/water two-phase system.

    Science.gov (United States)

    Jiang, Yangyang; Xia, Hansong; Guo, Chen; Mahmood, Iram; Liu, Huizhou

    2007-01-01

    In this paper, an integrated process involving the mixed ionic liquids/water two-phase system (MILWS) is proposed to improve the efficiency for enzymatic hydrolysis of penicillin G. First, hydrophilic [C4mim]BF4 (1-butyl-3-methylimidazolium tetrafluoraborate) and NaH2PO4 salt form an ionic liquids aqueous two-phase system (ILATPS), which could extract penicillin from its fermentation broth efficiently. Second, a hydrophobic [C4mim]PF6 (1-butyl-3-methylimidazolium hexafluoraphosphate) is introduced into the ionic liquids-rich phase of ILATPS containing penicillin and converses it into MILWS. Penicillin is hydrolyzed by penicillin acylase in the water phase of MILWS at pH 5. The byproduct phenylacetic acid (PAA) is partitioned into the ionic liquids mixture phase, while the intended product 6-aminopenicillanic acid (6-APA) is precipitated at this pH. In comparison with a similar butyl acetate/water system (BAWS) at pH 4, MILWS exhibits two advantages. (1) The selectivity between PAA and penicillin is greatly optimized at pH 5 by varying the mole ratio of [C4mim]PF6/[C4mim]BF4 in MILWS, whereas in BAWS the unalterable nature of the organic solvent restricts the optimized pH for maximum selectivity between PAA and penicillin at pH 4. (2) The pH for 6-APA precipitation in BAWS is 4, whereas it shifts to pH 5 in MILWS due to the complexation between negatively charged 6-APA and the cationic surface of the ionic liquids micelle. As a result, the removal of the two products from the enzyme sphere at relatively high pH is permitted in MILWS, which is beneficial for enzymatic activity and stability in comparison with the acidic pH 4 environment in BAWS.

  6. Two-phase flow experiments in a model of the hot leg of a pressurised water reactor. Technical report

    Energy Technology Data Exchange (ETDEWEB)

    Seidel, Tobias; Vallee, Christophe; Lucas, Dirk; Beyer, Matthias; Deendarlianto

    2011-09-15

    In order to investigate the two-phase flow behaviour in a complex reactor-typical geometry and to supply suitable data for CFD code validation, a model of the hot leg of a pressurised water reactor was built at FZD. The hot leg model is operated in the pressure chamber of the TOPFLOW test facility, which is used to perform high-pressure experiments under pressure equilibrium with the inside atmosphere of the chamber. This technique makes it possible to visualise the two-phase flow through large windows, also at reactor-typical pressure levels. In order to optimise the optical observation possibilities, the test section was designed with a rectangular cross-section. Experiments were performed with air and water at 1.5 and 3.0 bar at room temperature as well as with steam and water at 15, 30 and 50 bar and the corresponding saturation temperature (i.e. up to 264 C). The total of 194 runs are divided into 4 types of experiments covering stationary co-current flow, counter-current flow, flow without water circulation and transient counter-current flow limitation (CCFL) experiments. This report provides a detailed documentation of the experiments including information on the experimental setup, experimental procedure, test matrix and on the calibration of the measuring devices. The available data is described and data sheets were arranged for each experiment in order to give an overview of the most important parameters. For the cocurrent flow experiments, water level histograms were arranged and used to characterise the flow in the hot leg. In fact, the form of the probability distribution was found to be sensitive to the boundary conditions and, therefore, is useful for the CFD comparison. Furthermore, the flooding characteristics of the hot leg model plotted in terms of the classical Wallis parameter or Kutateladze number were found to fail to properly correlate the data of the air/water and steam/water series. Therefore, a modified Wallis parameter is proposed, which

  7. The Effect of Water Compressibility on a Rigid Body Movement in Two Phase Flow

    Science.gov (United States)

    Park, Chan Wook; Kim, Hak Sun; Lee, Sungsu

    2008-11-01

    The motion of a rigid body in a tube full of water-filled, initiated by a sudden release of highly pressurized air is simulated presuming the flow field as a two dimensional one. The effects of water compressibility on the body movement are investigated, comparing results based on the Fluent VOF model where water is treated as an incompressible medium with those from the presently developed VOF scheme. The present model considers compressibility of both air and water. The Fluent results show that the body moves farther and at higher speeds than the present ones. As time proceeds, the relative difference of speed and displacement between the two results drops substantially, after acoustic waves in water traverse and return the full length of the tube several times. To estimate instantaneous accelerations, however, requires implementation of the water compressibility effect as discrepancies between them do not decrease even after several pressure wave cycles. This work was supported by a research fund granted from Agency for Defense Development, South Korea.

  8. Heat transfer characteristics of titanium/water two-phase closed thermosyphon

    Energy Technology Data Exchange (ETDEWEB)

    Qi Baojin [State-Key Laboratory of Chemical Engineering, School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237 (China); Zhang Li [State-Key Laboratory of Chemical Engineering, School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237 (China)], E-mail: lzhang@ecust.edu.cn; Xu Hong; Sun Yan [State-Key Laboratory of Chemical Engineering, School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237 (China)

    2009-09-15

    Experimental investigations were carried out to study heat transfer characteristics of titanium (commercially pure titanium, TA2)/water two-phase closed thermosyphon (Ti/H{sub 2}O TPCT). Experiments of copper/water (Cu/H{sub 2}O) TPCT with same dimension and manufacturing process had also been performed for contrast. Experimental results show that there are no remarkable differences of heat transfer coefficients in evaporator (h{sub e}) between the two kinds of TPCTs, whereas surprisingly the experimental results of heat transfer coefficient in condenser (h{sub c}) of Ti/H{sub 2}O TPCTs are about 2-3 times more than that of Cu/H{sub 2}O TPCTs, moreover the Nusselt's theoretical correlation based on laminar filmwise condensation is not suitable for simulating the h{sub c} of Ti/H{sub 2}O TPCTs. Experimental results and theoretical analysis of surface free energy difference between condensate and solid surface indicate that the mixed condensation mode with dropwise and filmwise condensation coexisting on titanium surface result in the higher h{sub c} for Ti/H{sub 2}O TPCTs. Experiments on condensation mechanism of titanium surface are ongoing to further validate the point.

  9. Heat transfer characteristics of titanium/water two-phase closed thermosyphon

    Energy Technology Data Exchange (ETDEWEB)

    Baojin, Qi; Li, Zhang; Hong, Xu; Yan, Sun [State-Key Laboratory of Chemical Engineering, School of Mechanical and Power Engineering, East China Univ. of Science and Technology, Shanghai 200237 (China)

    2009-09-15

    Experimental investigations were carried out to study heat transfer characteristics of titanium (commercially pure titanium, TA2)/water two-phase closed thermosyphon (Ti/H{sub 2}O TPCT). Experiments of copper/water (Cu/H{sub 2}O) TPCT with same dimension and manufacturing process had also been performed for contrast. Experimental results show that there are no remarkable differences of heat transfer coefficients in evaporator (h{sub e}) between the two kinds of TPCTs, whereas surprisingly the experimental results of heat transfer coefficient in condenser (h{sub c}) of Ti/H{sub 2}O TPCTs are about 2-3 times more than that of Cu/H{sub 2}O TPCTs, moreover the Nusselt's theoretical correlation based on laminar filmwise condensation is not suitable for simulating the h{sub c} of Ti/H{sub 2}O TPCTs. Experimental results and theoretical analysis of surface free energy difference between condensate and solid surface indicate that the mixed condensation mode with dropwise and filmwise condensation coexisting on titanium surface result in the higher h{sub c} for Ti/H{sub 2}O TPCTs. Experiments on condensation mechanism of titanium surface are ongoing to further validate the point. (author)

  10. AQUEOUS TWO-PHASE GAS FLOATATION SPECTROPHOTOMETRIC DETERMINATION OF TRACE TETRACYCLINE IN ENVIRONMENTAL WATER SAMPLE

    Institute of Scientific and Technical Information of China (English)

    HOU Yanmin; YAN Yongsheng; LI Chunxiang; ZHAO Xiaojun; WANG Liang

    2008-01-01

    A green method for separating and enriching trace tetracycline (TC) in environment water by Aqueous Two-phase Gas Fioatation Spectrophotometry has been proposed, the principium was discussed.In this paper, the hydrophobic complex composed of Mg(Ⅱ) and TC was floated into organic phase under the optimal conditions: pH=10, the floatatlon equipment is home-made, n-propyl alcohol as the organic solvent, sodium chloride as the separating phase reagent.The data were obtained by spectrophotometry after floatatlon; The linear regression ,equation is A=2.33×105 C(mol/L)+0.2179, linear range is from 3.77×107mol/L to 6.32×105mol/L, respectively, with the correlation coefficient (r) better than 0.9997, relative recoveries is 99.7% to 100.3%, limit of detection was 4.29×10-8mol/L, The method can be applied to analyse the trace TC in water sample, the result is better.

  11. AQUEOUS TWO-PHASE GAS FLOATATION SPECTROPHOTOMETRIC DETERMINATION OF TRACE TETRACYCLINE IN ENVIRONMENTAL WATER SAMPLE

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A green method for separating and enriching trace tetracycline (TC) in environment water by Aqueous Two-phase Gas Floatation Spectrophotometry has been proposed, the principium was discussed. In this paper, the hydrophobic complex composed of Mg(II) and TC was floated into organic phase under the optimal conditions: pH=10, the floatation equipment is home-made, n-propyl alcohol as the organic solvent, sodium chloride as the separating phase reagent. The data were obtained by spectrophotometry after floatation; The linear regression equation is A=2.33×105C(mol/L)+0.2179, linear range is from 3.77×10-7mol/L to 6.32×10-5mol/L, respectively, with the correlation coefficient (r) better than 0.9997, relative recoveries is 99.7% to 100.3%, limit of detection was 4.29×10-8mol/L, The method can be applied to analyse the trace TC in water sample, the result is better.

  12. Numerical simulation of gas-liquid two-phase jet flow in air-bubble generator

    Institute of Scientific and Technical Information of China (English)

    陈文义; 王静波; 姜楠; 赵斌; 王振东

    2008-01-01

    Air-bubble generator is the key part of the self-inspiration type swirl flotation machines,whose flow field structure has a great effect on flotation.The multiphase volume of fluid(VOF),standard k-ε turbulent model and the SIMPLE method were chosen to simulate the present model;the first order upwind difference scheme was utilized to perform a discrete solution for momentum equation.The distributing law of the velocity,pressure,turbulent kinetic energy of every section along the flow direction of air-bubble generator was analyzed.The results indicate that the bubbles are heavily broken up in the middle cross section of throat sect and the entrance of diffuser sect along the flow direction,and the turbulent kinetic energy of diffuser sect is larger than the entrance of throat sect and mixing chamber.

  13. Study of organic compounds-water interactions by partition in aqueous two-phase systems.

    Science.gov (United States)

    Madeira, Pedro P; Bessa, Ana; Teixeira, Miguel A; Álvares-Ribeiro, Luís; Aires-Barros, M Raquel; Rodrigues, Alírio E; Zaslavsky, Boris Y

    2013-12-27

    Partition coefficients of fourteen organic compounds were determined in 10 or 20 different polymer/polymer aqueous two-phase systems (ATPS) all at physiological pH (0.15M NaCl in 0.01M phosphate buffer, pH 7.4). Solute-specific coefficients characterizing different types of solute-water interactions for the compounds examined were determined by the multiple linear regression analysis. It is shown that (i) the partition behavior for the polar organic compounds is affected not only by dipole-dipole and hydrogen-bond interactions with aqueous environment but, notably, in most cases also by dipole-ion interactions; (ii) it is possible to predict partition behavior for compounds with pre-determined solute-specific coefficients in ATPS with characterized solvent features; and (iii) linear combinations of the solute-specific coefficients for the organic compounds might be useful in the development of quantitative structure-activity relationship (QSAR) analysis to describe their odor detection threshold.

  14. A Fast Algorithm to Simulate Droplet Motions in Oil/Water Two Phase Flow

    KAUST Repository

    Zhang, Tao

    2017-06-09

    To improve the research methods in petroleum industry, we develop a fast algorithm to simulate droplet motions in oil and water two phase flow, using phase field model to describe the phase distribution in the flow process. An efficient partial difference equation solver—Shift-Matrix method is applied here, to speed up the calculation coding in high-level language, i.e. Matlab and R. An analytical solution of order parameter is derived, to define the initial condition of phase distribution. The upwind scheme is applied in our algorithm, to make it energy decay stable, which results in the fast speed of calculation. To make it more clear and understandable, we provide the specific code for forming the coefficient matrix used in Shift-Matrix Method. Our algorithm is compared with other methods in different scales, including Front Tracking and VOSET method in macroscopic and LBM method using RK model in mesoscopic scale. In addition, we compare the result of droplet motion under gravity using our algorithm with the empirical formula common used in industry. The result proves the high efficiency and robustness of our algorithm and it’s then used to simulate the motions of multiple droplets under gravity and cross-direction forces, which is more practical in industry and can be extended to wider application.

  15. Two-phase experimental heat transfer studies on a water-diesel system in a shell and tube heat exchanger

    Directory of Open Access Journals (Sweden)

    V. Alagesan

    2012-06-01

    Full Text Available Two-phase heat transfer involving two immiscible systems is gaining importance in petrochemical and allied industries. Varying compositions of diesel and water were experimentally studied in a 1:2 shell and tube heat exchanger. The data on pure water and diesel were fitted to an equation of the form. h1φ = a NmRe.The two-phase multiplier, Φ L, was related to the Lockhart Martinelli (L-M parameter, χtt², using the two-phase data and a correlation Φ L = b+c(χtt²+d/(χtt²² was established. The two-phase heat transfer coefficient was calculated based on the coefficients 'a' and 'm' for pure diesel and pure water along with ФL and the L-M parameter. The calculated values of the two-phase heat transfer coefficient h2φ based on pure diesel and pure water suggest that diesel is a better reference fluid since the average error is much smaller compared to pure water as reference.

  16. The Finite Element Analysis for a Mini-Conductance Probe in Horizontal Oil-Water Two-Phase Flow

    Directory of Open Access Journals (Sweden)

    Weihang Kong

    2016-08-01

    Full Text Available Oil-water two-phase flow is widespread in petroleum industry processes. The study of oil-water two-phase flow in horizontal pipes and the liquid holdup measurement of oil-water two-phase flow are of great importance for the optimization of the oil production process. This paper presents a novel sensor, i.e., a mini-conductance probe (MCP for measuring pure-water phase conductivity of oil-water segregated flow in horizontal pipes. The MCP solves the difficult problem of obtaining the pure-water correction for water holdup measurements by using a ring-shaped conductivity water-cut meter (RSCWCM. Firstly, using the finite element method (FEM, the spatial sensitivity field of the MCP is investigated and the optimized MCP geometry structure is determined in terms of the characteristic parameters. Then, the responses of the MCP for the oil-water segregated flow are calculated, and it is found that the MCP has better stability and sensitivity to the variation of water-layer thickness in the condition of high water holdup and low flow velocity. Finally, the static experiments for the oil-water segregated flow were carried out and a novel calibration method for pure-water phase conductivity measurements was presented. The validity of the pure-water phase conductivity measurement with segregated flow in horizontal pipes was verified by experimental results.

  17. The Finite Element Analysis for a Mini-Conductance Probe in Horizontal Oil-Water Two-Phase Flow.

    Science.gov (United States)

    Kong, Weihang; Kong, Lingfu; Li, Lei; Liu, Xingbin; Xie, Ronghua; Li, Jun; Tang, Haitao

    2016-08-24

    Oil-water two-phase flow is widespread in petroleum industry processes. The study of oil-water two-phase flow in horizontal pipes and the liquid holdup measurement of oil-water two-phase flow are of great importance for the optimization of the oil production process. This paper presents a novel sensor, i.e., a mini-conductance probe (MCP) for measuring pure-water phase conductivity of oil-water segregated flow in horizontal pipes. The MCP solves the difficult problem of obtaining the pure-water correction for water holdup measurements by using a ring-shaped conductivity water-cut meter (RSCWCM). Firstly, using the finite element method (FEM), the spatial sensitivity field of the MCP is investigated and the optimized MCP geometry structure is determined in terms of the characteristic parameters. Then, the responses of the MCP for the oil-water segregated flow are calculated, and it is found that the MCP has better stability and sensitivity to the variation of water-layer thickness in the condition of high water holdup and low flow velocity. Finally, the static experiments for the oil-water segregated flow were carried out and a novel calibration method for pure-water phase conductivity measurements was presented. The validity of the pure-water phase conductivity measurement with segregated flow in horizontal pipes was verified by experimental results.

  18. Measurement and Correlation of Equilibrium Data for Aqueous Two-phase System Ethanol+Water+K2HPO4

    Institute of Scientific and Technical Information of China (English)

    LIN Jin-qing; TAN Ping-hua; JIN Chun-ying; LI Ming-chun

    2004-01-01

    The isothermal solubility data of aqueous two-phase system ethanol+water+K2HPO4 were determined with the turbidity titration method at 303.2 K. The binodal curves were described by using the Mistry equation very well. An experimental procedure for measuring the liquid-liquid equilibrium data of the aqueous two-phase system was proposed, in which the concentrations of the coexisting phases were determined with the corresponding densities of the solution. The tie lines were satisfactorily described by using the Othmer Tobias and Bancroft equations.

  19. Individual extraction constants of some univalent anions in the two-phase water-phenyltrifluoromethyl sulfone system.

    Science.gov (United States)

    Makrlík, Emanuel; Selucký, Pavel; Vaňura, Petr

    2011-12-01

    From extraction experiments and g-activity measurements, the extraction constants corresponding to the general equilibrium Cs+(aq) + A- (aq) Cs+(org) + A- (org) taking place in the two-phase water-phenyltrifluoromethyl sulfone (FS 13) system (A-= I-, ClO4-, MnO4-, Br-3, I-3, picrate, tetraphenylborate (BPh-4); aq = aqueous phase, org = FS 13 phase) were evaluated. Furthermore, the individual extraction constants of these 7 anions in the mentioned two-phase system were calculated; they were found to increase in the series of I-< ClO4- < Br-3 < MnO4-, picrate < I-3 < BPh-4.

  20. Two-Phase Flow Instability in Water-side Tube of SG under Axially Uniform Heat Flux Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eui Kwang; Kim, Dehee; Jung, Yoon; Lee, Tae-Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    The SG of PGSFR is of once through integrated type, and is a vertical counter flow shell and tube heat exchanger with sodium on shell side and water-steam in tubes. The phenomenon of two-phase flow instability has been observed in many industrial domains like boiling systems, steam generators. In this paper the numerical methods were studied, and a computer code was developed for two-phase flow instability in steam generator, and representative results of the model calculations are presented. A computer code is developed for investigating two-phase flow stability under constant heat flux conditions. Solution algorithm for the sodium flow field and tube conduction will be developed for the application to sodium-heated SG.

  1. Stable response of axisymmetric two-phase water-saturated soil

    Institute of Scientific and Technical Information of China (English)

    蔡袁强; 孟楷; 徐长节

    2004-01-01

    Biot's dynamic consolidation equations and Hankel transform were used to derive the integral solutions of stress and displacement for axisymmetric harmonic excitations in the two-phase saturated soil with subjacent rock-stratum. The influence of the coefficient of permeability and loading frequency on the soil displacement at the ground surface were studied. The results showed that higher loading frequency led to more dynamic characteristics; and that the effect of the soil permeability was more obvious at higher frequencies.

  2. An Experimental Study of Air-Solid Two-Phase Flow in a 90° Bend Using LDV System

    Institute of Scientific and Technical Information of China (English)

    1992-01-01

    The measurements of he mean streamwise and radial velocities,the associated turbulence and the relative particle densities were made in an air-solid two-phase flow in square sectioned(30mm×30mm) 90° vertical to horizontal bend using laser Doppler velocimetry.The radius ratio of the bedn was 2.0.Glass beads of 100um in diameter were employed to form the solid phase.The measurements of air and solid phases were performed separately at the same bulk velocity 19.34m/s,correaponding to a Reynolds number of 3.87×104.The mass ratio of solid to air was 1.6%,The results indicate that the particle trajectories are very close to straight lines.The streamwise velocity profiles for the gas and the solids cross over near the outer wall with the solids having the higher speed.At θ=30° and 45°,particle-wall collisions happen mostly in the region fromθ=30°to θ=75°,and cause a sudden change in solid velocity,The particles tned to move towards the outer wall in 90°bend,The particle concentration near the outer wall is umch higher than that near the inner wall in the bend,and there are few particles in the inside of the bend.The bend leads to apparent phase separation.atθ=45°,the solids concentrate in the half of the duct near the outer wall,After θ=60° the second peak concentration appears,and goes gradually towards the inner wall.

  3. In Situ Measurement, Characterization, and Modeling of Two-Phase Pressure Drop Incorporating Local Water Saturation in PEMFC Gas Channels

    Science.gov (United States)

    See, Evan J.

    Proton Exchange Membrane Fuel Cells (PEMFCs) have been an area of focus as an alternative for internal combustion engines in the transportation sector. Water and thermal management techniques remain as one of the key roadblocks in PEMFC development. The ability to model two-phase flow and pressure drop in PEMFCs is of significant importance to the performance and optimization of PEMFCs. This work provides a perspective on the numerous factors that affect the two-phase flow in the gas channels and presents a comprehensive pressure drop model through an extensive in situ fuel cell investigation. The study focused on low current density and low temperature operation of the cell, as these conditions present the most challenging scenario for water transport in the PEMFC reactant channels. Tests were conducted using two PEMFCs that were representative of the actual full scale commercial automotive geometry. The design of the flow fields allowed visual access to both cathode and anode sides for correlating the visual observations to the two-phase flow patterns and pressure drop. A total of 198 tests were conducted varying gas diffusion layer (GDL), inlet humidity, current density, and stoichiometry; this generated over 1500 average pressure drop measurements to develop and validate two-phase models. A two-phase 1+1 D modeling scheme is proposed that incorporates an elemental approach and control volume analysis to provide a comprehensive methodology and correlation for predicting two-phase pressure drop in PEMFC conditions. Key considerations, such as condensation within the channel, consumption of reactant gases, water transport across the membrane, and thermal gradients within the fuel cell, are reviewed and their relative importance illustrated. The modeling scheme is shown to predict channel pressure drop with a mean error of 10% over the full range of conditions and with a mean error of 5% for the primary conditions of interest. The model provides a unique and

  4. Ultrasonic method for measuring water holdup of low velocity and high-water-cut oil-water two-phase flow

    Science.gov (United States)

    Zhao, An; Han, Yun-Feng; Ren, Ying-Yu; Zhai, Lu-Sheng; in, Ning-De

    2016-03-01

    Oil reservoirs with low permeability and porosity that are in the middle and late exploitation periods in China's onshore oil fields are mostly in the high-water-cut production stage. This stage is associated with severely non-uniform local-velocity flow profiles and dispersed-phase concentration (of oil droplets) in oil-water two-phase flow, which makes it difficult to measure water holdup in oil wells. In this study, we use an ultrasonic method based on a transmission-type sensor in oil-water two-phase flow to measure water holdup in low-velocity and high water-cut conditions. First, we optimize the excitation frequency of the ultrasonic sensor by calculating the sensitivity of the ultrasonic field using the finite element method for multiphysics coupling. Then we calculate the change trend of sound pressure level attenuation ratio with the increase in oil holdup to verify the feasibility of the employed diameter for the ultrasonic sensor. Based on the results, we then investigate the effects of oil-droplet diameter and distribution on the ultrasonic field. To further understand the measurement characteristics of the ultrasonic sensor, we perform a flow loop test on vertical upward oil-water two-phase flow and measure the responses of the optimized ultrasonic sensor. The results show that the ultrasonic sensor yields poor resolution for a dispersed oil slug in water flow (D OS/W flow), but the resolution is favorable for dispersed oil in water flow (D O/W flow) and very fine dispersed oil in water flow (VFD O/W flow). This research demonstrates the potential application of a pulsed-transmission ultrasonic method for measuring the fraction of individual components in oil-water two-phase flow with a low mixture velocity and high water cut.

  5. Liquid holdup measurement with double helix capacitance sensor in horizontal oil-water two-phase flow pipes

    Institute of Scientific and Technical Information of China (English)

    Lusheng Zhai; Ningde Jin; Zhongke Gao; Zhenya Wang

    2015-01-01

    This paper presents the characteristics of a double helix capacitance sensor for measurement of the liquid holdup in horizontal oil–water two-phase flow. The finite element method is used to calculate the sensitivity field of the sensor in a pipe with 20 mm inner diameter and the effect of sensor geometry on the distribution of sensitivity field is presented. Then, a horizontal oil–water two-phase flow experiment is carried out to measure the response of the double helix capacitance sensor, in which a novel method is proposed to calibrate the liquid holdup based on three pairs of paral el-wire capacitance probes. The performance of the sensor is analyzed in terms of the flow structures detected by mini-conductance array probes.

  6. Experimental measurement of oil-water two-phase flow by data fusion of electrical tomography sensors and venturi tube

    Science.gov (United States)

    Liu, Yinyan; Deng, Yuchi; Zhang, Maomao; Yu, Peining; Li, Yi

    2017-09-01

    Oil-water two-phase flows are commonly found in the production processes of the petroleum industry. Accurate online measurement of flow rates is crucial to ensure the safety and efficiency of oil exploration and production. A research team from Tsinghua University has developed an experimental apparatus for multiphase flow measurement based on an electrical capacitance tomography (ECT) sensor, an electrical resistance tomography (ERT) sensor, and a venturi tube. This work presents the phase fraction and flow rate measurements of oil-water two-phase flows based on the developed apparatus. Full-range phase fraction can be obtained by the combination of the ECT sensor and the ERT sensor. By data fusion of differential pressures measured by venturi tube and the phase fraction, the total flow rate and single-phase flow rate can be calculated. Dynamic experiments were conducted on the multiphase flow loop in horizontal and vertical pipelines and at various flow rates.

  7. Investigation of oil-air two-phase mass flow rate measurement using Venturi and void fraction sensor

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hong-jian; YUE Wei-ting; HUANG Zhi-yao

    2005-01-01

    Oil-air two-phase flow measurement was investigated with a Venturi and void fraction meters in this work. This paper proposes a new flow rate measurement correlation in which the effect of the velocity ratio between gas and liquid was considered.With the pressure drop across the Venturi and the void fraction that was measured by electrical capacitance tomography apparatus,both mixture flow rate and oil flow rate could be obtained by the correlation. Experiments included bubble-, slug-, wave and annular flow with the void fraction ranging from 15% to 83%, the oil flow rate ranging from 0.97 kg/s to 1.78 kg/s, the gas flow rate ranging up to 0.018 kg/s and quality ranging nearly up to 2.0%. The root-mean-square errors of mixture mass flow rate and that ofoil mass flow rate were less than 5%. Furthermore, coefficients of the correlation were modified based on flow regimes, with the results showing reduced root-mean-square errors.

  8. Availability of MCNP & MATLAB for reconstructing the water-vapor two-phase flow pattern in neutron radiography

    Institute of Scientific and Technical Information of China (English)

    FENG Qixi; FENG Quanke; TAKESHI Kawai

    2008-01-01

    The China Advanced Research Reactor (CARR) is scheduled to be operated in the autumn of 2008. In this paper, we report preparations for installing the neutron radiography instrument (NRI) and for utilizing it efficiently. The 2-D relative neutron intensity profiles for the water-vapor two-phase flow inside the tube were obtained using the MCNP code without influence of γ-ray and electronic-noise. The MCNP simulation of the 2-D neutron intensity profile for the water-vapor two-phase flow was demonstrated. The simulated 2-D neutron intensity profiles could be used as the benchmark data base by calibrating part of the data measured by the CARR-NRI. The 3-D objective images allow us to understand the flow pattern more clearly and it is reconstructed using the MATLAB through the threshold transformation techniques. And thus it is concluded that the MCNP code and the MATLAB are very useful for constructing the benchmark data base for the investigation of the water-vapor two-phase flow using the CARR-NRI.

  9. FLOW PATTERN AND PRESSURE LOSS OF OIL-WATER TWO-PHASE FLOW IN HORIZONTAL STEEL PIPE

    Institute of Scientific and Technical Information of China (English)

    CHEN Jie; YAN Da-fan; ZHAO Jing-mei; AN Wei-jie; YAN Da-chun

    2005-01-01

    Experimental Study on oil-water two-phase flow patterns and pressure loss was conducted on a horizontal steel pipe loop with 26.1mm inner diameter and 30m total length.The working fluids are white oil, diesel oil and tap water.Several instruments, including a new type of liquid-probe are successfully integrated to identify 7 different flow patterns.The characteristics of the flow patterns and the transition process were observed and depicted in this paper.Investigation revealed that the pressure loss was mainly depended on the flow patterns.

  10. Mechanism modeling for phase fraction measurement with ultrasound attenuation in oil–water two-phase flow

    Science.gov (United States)

    Su, Qian; Tan, Chao; Dong, Feng

    2017-03-01

    When measuring the phase fraction of oil–water two-phase flow with the ultrasound attenuation, the phase distribution and fraction have direct influence on the attenuation coefficient. Therefore, the ultrasound propagation at various phase fractions and distributions were investigated. Mechanism models describing phase fraction with the ultrasound attenuation coefficient were established by analyzing the interaction between ultrasound and two-phase flow by considering the scattering, absorption and diffusion effect. Experiments were performed to verify the theoretical analysis, and the test results gave good agreement with the theoretical analysis. When the dispersed phase fraction is low, the relationship between ultrasound attenuation coefficient and phase fraction is of monotonic linearity; at higher dispersed phase fraction, ultrasound attenuation coefficient presents an irregular response to the dispersed phase fraction. The presented mechanism models give reasonable explanations about the trend of ultrasound attenuation.

  11. Study on oil-water two-phase flow in horizontal pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Xiao-Xuan [Division of Oilfield Surface Engineering, Petroleum Exploration and Production Research Institute, SINOPEC, 31, Xue yuan Road, Haidian District, Beijing, 100083 (China)

    2007-10-15

    The simultaneous flow of oil and water in pipelines is a common occurrence in the petroleum industry. Water fractions in the output stream increase materially during the producing life of a well and many wells exist from which economic production can still persist with water volume fractions in the liquid phase in excess of 90%. The presence of water must be properly accounted for when designing and predicting the flow behavior in both wells and pipelines. This paper is aimed at giving a brief review on the research of oil-water pipe flows in the past decade. The contents are divided into three sections: (1) flow pattern identification and its transition; (2) phase inversion modeling; (3) pressure drop prediction. It is obvious that oil-water flow patterns, phase inversion prediction and pressure drop have played a great role in the design and running of oil-water flow systems. This paper critically reviews research achievement and presents the current trend in order to offer a guide in future research of the oil-water pipe flows. (author)

  12. An Experimental Study on the Flow Characteristics of OilWater Two-Phase Flow in Horizontal Straight Pipes

    Institute of Scientific and Technical Information of China (English)

    刘文红; 郭烈锦; 吴铁军; 张西民

    2003-01-01

    The flow patterns and their transitions of oil-water two-phase flow in horizontal pipes were studied. The experiments were conducted in two kinds of horizontal tubes, made of plexiglas pipe and stainless steel pipe with 40mm ID respectively. No. 46 mechanical oil and tap water were used as working fluids. The superficial velocity ranges of oil and water were: 0.04-1.2m·s-1 and 0.04-2.2 m·s-1, respectively. The flow patterns were identified by visualization and by transient fluctuation signals of differential pressure drop. The flow patterns were defined according to the relative distribution ofoil and water phases in the pipes. Flow pattern maps were obtained for both pipelines. In addition, semi-theoretical transition criteria for the flow patterns were proposed, and the proposed transitional criteria are in reasonable agreement with available data in liquid-liquid systems.

  13. Thermodynamic modelling of phase equilibrium for water + poly(Ethylene glycol + salt aqueous two-phase systems

    Directory of Open Access Journals (Sweden)

    R.A.G. Sé

    2002-04-01

    Full Text Available The NRTL (nonrandom, two-liquid model, expressed in mass fraction instead of mole fraction, was used to correlate liquid-liquid equilibria for aqueous two-phase polymer-salt solutions. New interaction energy parameters for this model were determined using reported data on the water + poly(ethylene glycol + salt systems, with different molecular masses for PEG and the salts potassium phosphate, sodium sulfate, sodium carbonate and magnesium sulfate. The correlation of liquid-liquid equilibrium is quite satisfactory.

  14. Partition Coefficients of Amino Acids, Peptides, and Enzymes in Dextran + Poly(Ethylene Glycol) + Water Aqueous Two-Phase Systems

    Energy Technology Data Exchange (ETDEWEB)

    Kakisaka, Keijiro.; Shindo, Takashi.; Iwai, Yoshio.; Arai, Yasuhiko. (Kyushu University, Fukuoka (Japan). Department of Chemical Systems and Engineering)

    1998-12-01

    Partition coefficients are measured for five amino acids(aspartic acid, asparagine, methionine, cysteine and histidine) and tow peptides(glycyl-glycine and hexa-glycine) in dextran + poly(ethylene glycol) + water aqueous two-phase system. The partition coefficients of the amino acids and peptides are aorrelated using the osmotic virial equation. The interaction coefficients contained in the equation can be calculated by hydrophilic group parameters. The partition coefficients of [alpha]-amylase calculated by the osmotic virial equation with the hydrophilic group parameters are in fairly good agreement with the experimental data, though a relatively large discrepancy is shown for [beta]-amylase. (author)

  15. Partition Coefficients of Amino Acids, Peptides, and Enzymes in Dextran + Poly(Ethylene Glycol) + Water Aqueous Two-Phase Systems

    Energy Technology Data Exchange (ETDEWEB)

    Kakisaka, Keijiro.; Shindo, Takashi.; Iwai, Yoshio.; Arai, Yasuhiko. [Kyushu University, Fukuoka (Japan). Department of Chemical Systems and Engineering

    1998-12-01

    Partition coefficients are measured for five amino acids(aspartic acid, asparagine, methionine, cysteine and histidine) and tow peptides(glycyl-glycine and hexa-glycine) in dextran + poly(ethylene glycol) + water aqueous two-phase system. The partition coefficients of the amino acids and peptides are aorrelated using the osmotic virial equation. The interaction coefficients contained in the equation can be calculated by hydrophilic group parameters. The partition coefficients of {alpha}-amylase calculated by the osmotic virial equation with the hydrophilic group parameters are in fairly good agreement with the experimental data, though a relatively large discrepancy is shown for {beta}-amylase. (author)

  16. SIMULATION OF OIL-WATER TWO PHASE FLOW AND SEPARATION BEHAVIORS IN COMBINED T JUNCTIONS

    Institute of Scientific and Technical Information of China (English)

    CHEN Jian-lei; HE Li-min; LUO Xiao-ming; BAI Hai-tao; WEI Yan-hai

    2012-01-01

    The combined T junctions used for the oil-water separation have the advantages of compactness in structure,consistency in effects and economy in cost.The mixture k-ε turbulence model and the Eulerian multi-fluid model are used to simulate the flow and phase distribution in the combined T junctions.The effects of structural parameters such as the branched pipe interval and height on the flow distribution and the separation behaviors are studied.The results show that the combined T junctions under fixed inlet and outlet boundary conditions form a single hydraulic equilibrium system in which the fluid energy distributes freely till a balance is achieved.The split-flow promotes the separation of the immiscible oil and the water.The separation efficiency increases with the increase of the branched pipe interval and changes slightly with the increase of the branched pipe height.The structural change of the combined T junctions may change the flow direction in the branched pipes.Simulation results can provide some guidance for the design of the combined T junctions as one kind of oil-water separator.

  17. 利用Fluent软件对植物坝覆盖下二维两相流场的数值模拟%2-D Water-air Two-phase Flow Field Covered by Vegetation Dam Based on Fluent Numerical Simulation

    Institute of Scientific and Technical Information of China (English)

    刘锋; 邱秀云; 周著

    2011-01-01

    In this paper, the hydrodynamic equation about the flow through plants has established the physical model experiment and theory deduction, and the hydraulic characteristics of vegetation dam is simulated with the established equation. And the two-phase flow field of the water sink with plant dam overlay is simulated with CFD software FLUENT, and the free surface is tracked with VOF method, the plant dam overlay districts is simplified with many bores area method, and the infiltration rate is determined with the pressure difference of before or after bores area. And the simulation velocity magnitude are compared with the measured data.%通过物理模型试验及推导建立植物过流水动力学方程,对植物"柔性坝"过流时的水动力学特性进行了数值研究;利用计算流体力学软件FLUENT,用VOF方法追踪自由水面,采用多孔介质域模拟植物坝覆盖区域,以多孔介质前后压强配合空隙率来确定渗透率,对有植物坝覆盖的水槽二维两相流场进行了数值模拟.将数值计算得到的流速值与模型验流速值实测结果进行了比对,两者吻合较好.

  18. Depressurization and two-phase flow of water containing high levels of dissolved nitrogen gas

    Science.gov (United States)

    Simoneau, R. J.

    1981-01-01

    Depressurization of water containing various concentrations of dissolved nitrogen gas was studied. In a nonflow depressurization experiment, water with very high nitrogen content was depressurized at rates from 0.09 to 0.50 MPa per second and a metastable behavior which was a strong function of the depressurization rate was observed. Flow experiments were performed in an axisymmetric, converging diverging nozzle, a two dimensional, converging nozzle with glass sidewalls, and a sharp edge orifice. The converging diverging nozzle exhibited choked flow behavior even at nitrogen concentration levels as low as 4 percent of the saturation level. The flow rates were independent of concentration level. Flow in the two dimensional, converging, visual nozzle appeared to have a sufficient pressure drop at the throat to cause nitrogen to come out of solution, but choking occurred further downstream. The orifice flow motion pictures showed considerable oscillation downstream of the orifice and parallel to the flow. Nitrogen bubbles appeared in the flow at back pressures as high as 3.28 MPa, and the level at which bubbles were no longer visible was a function of nitrogen concentration.

  19. MRI investigation of water-oil two phase flow in straight capillary, bifurcate channel and monolayered glass bead pack.

    Science.gov (United States)

    Liu, Yu; Jiang, Lanlan; Zhu, Ningjun; Zhao, Yuechao; Zhang, Yi; Wang, Dayong; Yang, Mingjun; Zhao, Jiafei; Song, Yongchen

    2015-09-01

    The study of immiscible fluid displacement between aqueous-phase liquids and non-aqueous-phase liquids in porous media is of great importance to oil recovery, groundwater contamination, and underground pollutant migration. Moreover, the attendant viscous, capillary, and gravitational forces are essential to describing the two-phase flows. In this study, magnetic resonance imaging was used to experimentally examine the detailed effects of the viscous, capillary, and gravitational forces on water-oil flows through a vertical straight capillary, bifurcate channel, and monolayered glass-bead pack. Water flooding experiments were performed at atmospheric pressure and 37.8°C, and the evolution of the distribution and saturation of the oil as well as the characteristics of the two-phase flow were investigated and analyzed. The results showed that the flow paths, i.e., the fingers of the displacing phase, during the immiscible displacement in the porous medium were determined by the viscous, capillary, and gravitational forces as well as the sizes of the pores and throats. The experimental results afford a fundamental understanding of immiscible fluid displacement in a porous medium.

  20. The wind-water two-phase erosion and sediment-producing processes in the middle Yellow River basin, China

    Institute of Scientific and Technical Information of China (English)

    许炯心

    2000-01-01

    Based on data from the middle Yellow River basin, a wind-water two-phase mechanism for erosion and sediment-producing processes has been found. By using this mechanism, the extremely strong erosion and sediment yield in the study area can be better explained. The operation of wind and water forces is different in different seasons within a year. During winter and spring, strong wind blows large quantities of eolian sand to gullies and river channels, which are temporally stored there. During the next summer, rainstorms cause runoff that contains much fine loessic material and acts as a powerful force to carry the previously prepared coarse material. As a result, hyperconcentrated flows occur, resulting in high-intensity erosion and sediment yield.

  1. Air/Water Purification

    Science.gov (United States)

    1992-01-01

    After 18 years of research into air/water pollution at Stennis Space Center, Dr. B. C. Wolverton formed his own company, Wolverton Environmental Services, Inc., to provide technology and consultation in air and water treatment. Common houseplants are used to absorb potentially harmful materials from bathrooms and kitchens. The plants are fertilized, air is purified, and wastewater is converted to clean water. More than 100 U.S. communities have adopted Wolverton's earlier water hyacinth and artificial marsh applications. Catfish farmers are currently evaluating the artificial marsh technology as a purification system.

  2. An on-line adaptive estimation method for water holdup measurement in oil-water two-phase flow with a conductance/capacitance sensor

    Science.gov (United States)

    Wu, Hao; Tan, Chao; Dong, Feng

    2016-07-01

    Oil-water two-phase flow widely exists in industrial processes such as petroleum engineering and chemical engineering. Accurate and real-time measurement of water holdup is an important problem requiring urgent solutions. In this work, a conductance and capacitance combination sensor (CCCS) system with four conductance rings and two concave capacitance plates was validated for its measurement performance of in situ water holdup through dynamic experiments. An online adaptive weight Kalman estimation (OAWKE) fusion algorithm for the CCCS system is proposed to fuse the conductance measurement and capacitance measurement. The algorithm has fast and dynamic response for the water holdup measurement of oil-water two-phase flow and has improved measurement precision by the adaptive data fusion method. The OAWKE fusion algorithm also has the ability to deal with the abrupt change of water holdup during the measurement process. Therefore, in the low water conductivity condition (tap water), the CCCS system with the OAWKE fusion algorithm can dynamically estimate the real-time full range water holdup of oil-water two-phase flow, which has prospects in the petroleum industry.

  3. Pressure Loss across Tube Bundles in Two-phase Flow

    Energy Technology Data Exchange (ETDEWEB)

    Sim, Woo Gun; Banzragch, Dagdan [Hannam Univ., Daejon (Korea, Republic of)

    2016-03-15

    An analytical model was developed by Sim to estimate the two-phase damping ratio for upward two-phase flow perpendicular to horizontal tube bundles. The parameters of two-phase flow, such as void fraction and pressure loss evaluated in the model, were calculated based on existing experimental formulations. However, it is necessary to implement a few improvements in the formulations for the case of tube bundles. For the purpose of the improved formulation, we need more information about the two-phase parameters, which can be found through experimental test. An experiment is performed with a typical normal square array of cylinders subjected to the two-phase flow of air-water in the tube bundles, to calculate the two-phase Euler number and the two-phase friction multiplier. The pitch-to-diameter ratio is 1.35 and the diameter of cylinder is 18mm. Pressure loss along the flow direction in the tube bundles is measured with a pressure transducer and data acquisition system to calculate the two-phase Euler number and the two-phase friction multiplier. The void fraction model by Feenstra et al. is used to estimate the void fraction of the two-phase flow in tube bundles. The experimental results of the two phase friction multiplier and two-phase Euler number for homogeneous and non-homogeneous two-phase flows are compared and evaluated against the analytical results given by Sim's model.

  4. Clean Air and Water

    Centers for Disease Control (CDC) Podcasts

    2007-04-10

    The air we breathe and the water we drink are both vital components of our health. Nevertheless, bacteria, pollutants, and other contaminates can alter life-giving air and water into health-threatening hazards. Learn about how scientists at the Centers for Disease Control and Prevention work to protect the public from air and water-related health risks.  Created: 4/10/2007 by CDC National Center for Environmental Health.   Date Released: 4/13/2007.

  5. McClellan Air Force Base operable unit B, two-phase extraction system demonstration test, work implementation plan for McClellan AFB, California. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1994-08-03

    This document is an integrated demonstration and work plan that presents the technical approach for design, implementation, and testing of two-phase extraction as compared with pump and treat technology in Operable Unit B, investigative cluster IC1 at the McClellan Air Force Base. This work is being coordinated with Clean Sites under a cooperative agreement with EPA's Technology Innovation Office and Superfund Innovative Technology Evaluation Program.

  6. Modeling and numerical simulation of oscillatory two-phase flows, with application to boiling water nuclear reactors

    Energy Technology Data Exchange (ETDEWEB)

    Rosa, M.P. [Instituto de Estudos Avancados - CTA, Sao Paolo (Brazil); Podowski, M.Z. [Rensselaer Polytechnic Institute, Troy, NY (United States)

    1995-09-01

    This paper is concerned with the analysis of dynamics and stability of boiling channels and systems. The specific objectives are two-fold. One of them is to present the results of a study aimed at analyzing the effects of various modeling concepts and numerical approaches on the transient response and stability of parallel boiling channels. The other objective is to investigate the effect of closed-loop feedback on stability of a boiling water reactor (BWR). Various modeling and computational issues for parallel boiling channels are discussed, such as: the impact of the numerical discretization scheme for the node containing the moving boiling boundary on the convergence and accuracy of computations, and the effects of subcooled boiling and other two-phase flow phenomena on the predictions of marginal stability conditions. Furthermore, the effects are analyzed of local loss coefficients around the recirculation loop of a boiling water reactor on stability of the reactor system. An apparent paradox is explained concerning the impact of changing single-phase losses on loop stability. The calculations have been performed using the DYNOBOSS computer code. The results of DYNOBOSS validation against other computer codes and experimental data are shown.

  7. Interfacial Area and Interfacial Transfer in Two-Phase Flow Systems (Volume II. Chapters 6-10)

    Energy Technology Data Exchange (ETDEWEB)

    Guo, T.; Park, J.; Kojasoy, G.

    2003-03-15

    Experiments were performed on horizontal air-water bubbly two-phase flow, axial flow, stratified wavy flow, and annular flow. Theoretical studies were also undertaken on interfacial parameters for a horizontal two-phase flow.

  8. Interfacial Area and Interfacial Transfer in Two-Phase Flow Systems (Volume III. Chapters 11-14)

    Energy Technology Data Exchange (ETDEWEB)

    Guo, T.; Park, J.; Kojasoy, G.

    2003-03-15

    Experiments were performed on horizontal air-water bubbly two-phase flow, axial flow, stratified wavy flow, and annular flow. Theoretical studies were also undertaken on interfacial parameters for a horizontal two-phase flow.

  9. Interfacial Area and Interfacial Transfer in Two-Phase Flow Systems (Volume IV. Chapters 15-19)

    Energy Technology Data Exchange (ETDEWEB)

    Guo, T.; Park, J.; Kojasoy, G.

    2003-03-15

    Experiments were performed on horizontal air-water bubbly two-phase flow, axial flow, stratified wavy flow, and annular flow. Theoretical studies were also undertaken on interfacial parameters for a horizontal two-phase flow.

  10. Interfacial Area and Interfacial Transfer in Two-Phase Flow Systems (Volume I. Chapters 1-5)

    Energy Technology Data Exchange (ETDEWEB)

    Guo, T.; Park, J.; Kojasoy, G.

    2003-03-15

    Experiments were performed on horizontal air-water bubbly two-phase flow, axial flow, stratified wavy flow, and annular flow. Theoretical studies were also undertaken on interfacial parameters for a horizontal two-phase flow.

  11. Optimization of two-phase thermophilic anaerobic digestion of biowaste for hydrogen and methane production through reject water recirculation.

    Science.gov (United States)

    Cavinato, C; Bolzonella, D; Fatone, F; Cecchi, F; Pavan, P

    2011-09-01

    The optimization of a two-phase thermophilic anaerobic process treating biowaste for hydrogen and methane production was carried out at pilot scale using two stirred reactors (CSTRs) and without any physical/chemical pre-treatment of inoculum. During the experiment the hydrogen production at low hydraulic retention time (3d) was tested, both with and without reject water recirculation and at two organic loading rate (16 and 21 kgTVS/m3 d). The better yields were obtained with recirculation where the pH reached an optimal value (5.5) thanks to the buffering capacity of the recycle stream. The specific gas production of the first reactor was 51 l/kgVS(fed) and H2 content in biogas 37%. The mixture of gas obtained from the two reactors met the standards for the biohythane mix only when lower loading rate were applied to the first reactor, with a composition of 6.7% H2, 40.1% CO2 and 52.3% CH4 the overall SGP being 0.78 m3/kgVS(fed).

  12. Novel Downhole Electromagnetic Flowmeter for Oil-Water Two-Phase Flow in High-Water-Cut Oil-Producing Wells

    Directory of Open Access Journals (Sweden)

    Yanjun Wang

    2016-10-01

    Full Text Available First, the measuring principle, the weight function, and the magnetic field of the novel downhole inserted electromagnetic flowmeter (EMF are described. Second, the basic design of the EMF is described. Third, the dynamic experiments of two EMFs in oil-water two-phase flow are carried out. The experimental errors are analyzed in detail. The experimental results show that the maximum absolute value of the full-scale errors is better than 5%, the total flowrate is 5–60 m3/d, and the water-cut is higher than 60%. The maximum absolute value of the full-scale errors is better than 7%, the total flowrate is 2–60 m3/d, and the water-cut is higher than 70%. Finally, onsite experiments in high-water-cut oil-producing wells are conducted, and the possible reasons for the errors in the onsite experiments are analyzed. It is found that the EMF can provide an effective technology for measuring downhole oil-water two-phase flow.

  13. Investigation of temperature fluctuation phenomena in a stratified steam-water two-phase flow in a simulating pressurizer spray pipe of a pressurized water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Miyoshi, Koji, E-mail: miyoshi.koj@inss.co.jp; Takenaka, Nobuyuki; Ishida, Taisuke; Sugimoto, Katsumi

    2017-05-15

    Highlights: • Thermal hydraulics phenomena were discussed in a spray pipe of pressurizer. • Temperature fluctuation was investigated in a stratified steam-water two-phase. • Remarkable liquid temperature fluctuations were observed in the liquid layer. • The observed temperature fluctuations were caused by the internal gravity wave. • The temperature fluctuations decreased with increasing dissolved oxygen. - Abstract: Temperature fluctuation phenomena in a stratified steam-water two-phase flow in a horizontal rectangular duct, which simulate a pressurizer spray pipe of a pressurized water reactor, were studied experimentally. Vertical distributions of the temperature and the liquid velocity were measured with water of various dissolved oxygen concentrations. Large liquid temperature fluctuations were observed when the water was deaerated well and dissolved oxygen concentration was around 10 ppb. The large temperature fluctuations were not observed when the oxygen concentration was higher. It was shown that the observed temperature fluctuations were caused by the internal gravity wave since the Richardson numbers were larger than 0.25 and the temperature fluctuation frequencies were around the Brunt-Väisälä frequencies in the present experimental conditions. The temperature fluctuations decreased by the non-condensable gas since the non-condensable gas suppressed the condensation and the temperature difference in the liquid layer was small.

  14. Evaluation of the thermal performance of a solar water heating thermosyphon versus a two-phase closed thermosyphon using different working fluids

    Energy Technology Data Exchange (ETDEWEB)

    Ordaz-Flores, A. [Posgrado en Ingenieria (Energia), Univ. Nacional Autonoma de Mexico, Temixco, Morelos (Mexico); Garcia-Valladares, O.; Gomez, V.H. [Centro de Investigacion en Energia, Univ. Nacional Autonoma de Mexico, Temixco, Morelos (Mexico)

    2008-07-01

    A water heating closed two-phase thermosyphon solar system was designed and built. The system consists of a flat plate solar collector coupled to a thermotank by a continuous copper tubing in which the working fluid circulates. The working fluid evaporates in the collector and condensates in the thermotank transferring its latent heat to the water through a coil heat exchanger. The tested fluids are acetone and R134a. The thermal performance of the proposed systems is compared with a conventional solar water thermosyphon under the same operating conditions. Advantages of a two-phase system include the elimination of freezing, fouling, scaling and corrosion. Geometry and construction materials are the same except for the closed circuit presented in the two-phase system. Data were collected from temperature and pressure sensors throughout the two systems. Early results suggest that R134a may provide a better performance than acetone for this kind of systems. (orig.)

  15. Fast-Neutron Tomography using a Mobile Neutron Generator for Assessment of Steam-Water Distributions in Two-Phase Flows

    OpenAIRE

    Andersson, Peter

    2014-01-01

    This thesis describes the measurement technique of fast-neutron tomography for assessing spatial distributions of steam and water in two-phase flows. This so-called void distribution is of importance both for safe operation and for efficient use of the fuel in light water reactors, which compose the majority of the world’s commercial nuclear reactors. The technique is aimed for usage at thermal-hydraulic test loops, where heated two-phase flows are being investigated under reactor-relevant co...

  16. The influence on response of axial rotation of a six-group local-conductance probe in horizontal oil-water two-phase flow

    Science.gov (United States)

    Weihang, Kong; Lingfu, Kong; Lei, Li; Xingbin, Liu; Tao, Cui

    2017-06-01

    Water volume fraction is an important parameter of two-phase flow measurement, and it is an urgent task for accurate measurement in horizontal oil field development and optimization of oil production. The previous ring-shaped conductance water-cut meter cannot obtain the response values corresponding to the oil field water conductivity for oil-water two-phase flow in horizontal oil-producing wells characterized by low yield liquid, low velocity and high water cut. Hence, an inserted axisymmetric array structure sensor, i.e. a six-group local-conductance probe (SGLCP), is proposed in this paper. Firstly, the electric field distributions generated by the exciting electrodes of SGLCP are investigated by the finite element method (FEM), and the spatial sensitivity distributions of SGLCP are analyzed from the aspect of different separations between two electrodes and different axial rotation angles respectively. Secondly, the numerical simulation responses of SGLCP in horizontal segregated flow are calculated from the aspect of different water cut and heights of the water layer, respectively. Lastly, an SGLCP-based well logging instrument was developed, and experiments were carried out in a horizontal pipe with an inner diameter of 125 mm on the industrial-scale experimental multiphase flow setup in the Daqing Oilfield, China. In the experiments, the different oil-water two-phase flow, mineralization degree, temperature and pressure were tested. The results obtained from the simulation experiments and simulation well experiments demonstrate that the designed and developed SGLCP-based instrument still has a good response characteristic for measuring water conductivity under the different conditions mentioned above. The validity and reliability of obtaining the response values corresponding to the water conductivity through the designed and developed SGLCP-based instrument are verified by the experimental results. The significance of this work can provide an effective

  17. Water holdup measurement of oil-water two-phase flow in a horizontal well using a dual-circle conductance probe array

    Science.gov (United States)

    Xu, Lijun; Zhang, Wen; Cao, Zhang; Zhao, Jiayu; Xie, Ronghua; Liu, Xingbin; Hu, Jinhai

    2016-11-01

    This paper presents a minimum root-mean-square error (RMSE)-based method for a dual-circle conductance probe array to measure the water holdup of an oil-water two-phase flow in a horizontal oil well. The dual-circle conductance probe array consisting of 24 conductance probes, half of which are equidistantly distributed on a 34 mm radius inner circle and the other half on a 48 mm radius outer circle, is used to estimate the oil-water interface and hence the water holdup in the horizontal oil well. For the same water holdup, the number of probes immersed in water may vary with varying the azimuth angle due to the limited number of probes. The limited number of probes and unknown azimuth angle of the probe array in the oil well limit the measurement accuracy of the water holdup. In order to obtain a better water holdup estimate, a water holdup measurement method based on the minimum RMSE was proposed to decrease the effects of the limited number of probes and unknown azimuth angle of the probe array. To verify the proposed method, numerical simulations were carried out and compared with the commonly used equi-weight estimate method; results showed that the RMSE of the water holdup estimates obtained using the proposed method is smaller than that when using the equi-weight estimate method. Experiments were implemented in a 16 m long and 125 mm inner diameter horizontal pipe on an industrial-scale experimental multiphase flow setup in the Daqing Oil Field, China. The RMSEs of water holdup estimates obtained using the proposed and equi-weight estimate methods are 0.0632 and 0.0690, respectively, showing that the proposed method is better than the equi-weight estimate method.

  18. Effect of Inertial Force on Thermal Elastohydrodynamic Lubrication of Oil Film Bearing in Rolling Mill Lubricated by the Oil-water Two-phase Flow

    Science.gov (United States)

    Wang, Tao; Wang, You-Qiang; Wang, Jian; Fan, Xiao-Meng

    2016-05-01

    The oil film bearing in rolling mill as the research object in this paper is established oilwater two-phase flow of thermal elastohydrodynamic lubrication (EHL) model with the inertia force and thermal effect of the Reynolds equation. The oil film bearing in rolling mill in oil-water two-phase flow is analyzed the effect on the pyrolysis with considering inertia force, and the lubricant film pressure, film thickness with the changes in the relationship between water content, rolling force and spindle speed. The results showed that the lubricant film thickness is increased and carrying capacity is also increased with considering inertial force. With the increase of water content, lubricant film thickness is increased and the carrying capacity is decreased.

  19. Liquid-liquid equilibrium of water + PEG 8000 + magnesium sulfate or sodium sulfate aqueous two-phase systems at 35°C: experimental determination and thermodynamic modeling

    Directory of Open Access Journals (Sweden)

    B. D. Castro

    2005-09-01

    Full Text Available Liquid-liquid extraction using aqueous two-phase systems is a highly efficient technique for separation and purification of biomolecules due to the mild properties of both liquid phases. Reliable data on the phase behavior of these systems are essential for the design and operation of new separation processes; several authors reported phase diagrams for polymer-polymer systems, but data on polymer-salt systems are still relatively scarce. In this work, experimental liquid-liquid equilibrium data on water + polyethylene glycol 8000 + magnesium sulfate and water + polyethylene glycol 8000 + sodium sulfate aqueous two-phase systems were obtained at 35°C. Both equilibrium phases were analyzed by lyophilization and ashing. Experimental results were correlated with a mass-fraction-based NRTL activity coefficient model. New interaction parameters were estimated with the Simplex method. The mean deviations between the experimental and calculated compositions in both equilibrium phases is about 2%.

  20. A TWO-PHASE FLOW MODEL FOR SIMULATING AIR ENTRAPMENT DURING MOLD FILLING OF HIGH PRESSURE DIE CASTING PROCESS%应用两相流模型模拟压铸充型过程的卷气现象

    Institute of Scientific and Technical Information of China (English)

    李帅君; 熊守美; Mei Li; John Allison

    2009-01-01

    entrapment. In order to consider the air flow in the die cavity, an incompressible two-phase flow model was presented to simulate the air bubbles entrapped by the free surface of liquid metal during the mold filling stage. Two numerical benchmark tests of fluid dynamics were performed to verify the validity and stability of the model. Furthermore, a high speed water analog experiment similar to real die casting process was designed and carried out to compare the experimental results with the simulation ones. Good agreements obtained demonstrate that the two-phase flow model has acceptable prediction accuracy in modeling the filling behavior of liquid and tracking the entrapped air bubbles.

  1. When water molecules meet air

    OpenAIRE

    Hsie, Cho-Shuen; Campen, R. Kramer; Verde, Ana Vila; Bolhuis, Peter; Nienhuys, Han-Kwang; Bonn, Mischa

    2012-01-01

    About 70% of our planet is covered in water. Most of that water exists as water in the bulk – the neighbors of water molecules are other water molecules – and only a small fraction of molecules are at the air-water interface. Despite the small relative abundance of interfacial water, it is of the utmost importance: it governs the chemistry involving the surface of oceans and seawater aerosols, or the small water droplets forming clouds. Reactions at the air-water interface are directly releva...

  2. Two phase sampling

    CERN Document Server

    Ahmad, Zahoor; Hanif, Muhammad

    2013-01-01

    The development of estimators of population parameters based on two-phase sampling schemes has seen a dramatic increase in the past decade. Various authors have developed estimators of population using either one or two auxiliary variables. The present volume is a comprehensive collection of estimators available in single and two phase sampling. The book covers estimators which utilize information on single, two and multiple auxiliary variables of both quantitative and qualitative nature. Th...

  3. Study of microbial community and biodegradation efficiency for single- and two-phase anaerobic co-digestion of brown water and food waste.

    Science.gov (United States)

    Lim, J W; Chen, C-L; Ho, I J R; Wang, J-Y

    2013-11-01

    The objective of this work was to study the microbial community and reactor performance for the anaerobic co-digestion of brown water and food waste in single- and two-phase continuously stirred tank reactors (CSTRs). Bacterial and archaeal communities were analyzed after 150 days of reactor operation. As compared to single-phase CSTR, methane production in two-phase CSTR was found to be 23% higher. This was likely due to greater extent of solubilization and acidification observed in the latter. These findings could be attributed to the predominance of Firmicutes and greater bacterial diversity in two-phase CSTR, and the lack of Firmicutes in single-phase CSTR. Methanosaeta was predominant in both CSTRs and this correlated to low levels of acetate in their effluent. Insights gained from this study would enhance the understanding of microorganisms involved in co-digestion of brown water and food waste as well as the complex biochemical interactions promoting digester stability and performance.

  4. Contribution to the thermodynamics of sc3+, y3+, la3+ and trivalent lanthanide cations in the two-phase water-nitrobenzene extraction system.

    Science.gov (United States)

    Makrlík, Emanuel; Vaňura, Petr

    2011-06-01

    From the exchange extraction constants corresponding to the general equilibrium M3+(aq) + 3H+(nb) M3+(nb) + 3H+(aq) occurring in the two-phase water-nitrobenzene system (M3+ = Sc3+, Y3+, La3+, Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+, Lu3+; aq = aqueous phase, nb = nitrobenzene phase), the individual extraction constants of 16 trivalent metal cations were calculated. It was found that these individual extraction constants in the mentioned two-phase system increase in the following cation order: Sc3+ < Yb3+< Ho3+ < Er3+ < Tm3+, Lu3+ < Y3+, Dy3+ < Tb3+ < Gd3+ < Eu3+ < Sm3+ < Nd3+ < Pr3+ < La3+, Ce3+.

  5. Two-phase mixture simulation of Al{sub 2}O{sub 3}/water nanofluid heat transfer in a non-uniform heat addition test section

    Energy Technology Data Exchange (ETDEWEB)

    Abbassi, Yasser; Shirani, Amir Saeed [Shahid Beheshti Univ., Teheran (Iran, Islamic Republic of). Dept. of Engineering

    2016-11-15

    Results of a numerical investigation of Al{sub 2}O{sub 3}/Water nanofluid heat transfer are presented. The two-phase mixture model is used to study the effects of Reynolds number and nanoparticle concentrations on nanofluid heat transfer in flow around an annulus test section. Non-uniform heat flux is assumed as heat boundary condition on annuli inner wall. Annuli wall and bulk temperature profiles, Local and averaged heat transfer coefficient profiles, local and averaged Nusselt number profiles are presented as functions of nanoparticle volume concentrations and Reynolds numbers. Both laminar and turbulent flow regimes are simulated.

  6. Investigation on two-phase critical flow for loss-of-coolant accident of pressurized water reactor

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    The previous investigations were mainly conducted under the condition of low pressure,however,the steam-water specific volume and the interphase evaporation rate in high pressure are much different from those in low pressure,Therefore,the new experimental and theoretical investigation are performed in Xi'an Jiaotong University.The investigation results could be directly applied to the analysis of loss-of -coolant accident for pressurized water reacor.The system transition characteristics of cold leg and hot leg break loss-of -coolant tests are described for convective circulation test loop.Two types of loss-of-coolant accident are identified for :hot leg” break,while three types for “cold leg”break and the effect parameters on the break geometries.Tests indicate that the mass flow rate with convergent-divergent nozzle reaches the maximum value among the different break sections at the same inlet fluid condition because the fluid separation does not occur.A wall surface cavity nucleation model is developed for prediction of the critical mass flow rate with water flowing in convergentdivergent nozzles.

  7. 8. Innovative Technologies: Two-Phase Heat Transfer in Water-Based Nanofluids for Nuclear Applications Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Buongiorno, Jacopo; Hu, Lin-wen

    2009-07-31

    Nanofluids are colloidal dispersions of nanoparticles in water. Many studies have reported very significant enhancement (up to 200%) of the Critical Heat Flux (CHF) in pool boiling of nanofluids (You et al. 2003, Vassallo et al. 2004, Bang and Chang 2005, Kim et al. 2006, Kim et al. 2007). These observations have generated considerable interest in nanofluids as potential coolants for more compact and efficient thermal management systems. Potential Light Water Reactor applications include the primary coolant, safety systems and severe accident management strategies, as reported in other papers (Buongiorno et al. 2008 and 2009). However, the situation of interest in reactor applications is often flow boiling, for which no nanofluid data have been reported so far. In this project we investigated the potential of nanofluids to enhance CHF in flow boiling. Subcooled flow boiling heat transfer and CHF experiments were performed with low concentrations of alumina, zinc oxide, and diamond nanoparticles in water (≤ 0.1 % by volume) at atmospheric pressure. It was found that for comparable test conditions the values of the nanofluid and water heat transfer coefficient (HTC) are similar (within ±20%). The HTC increased with mass flux and heat flux for water and nanofluids alike, as expected in flow boiling. The CHF tests were conducted at 0.1 MPa and at three different mass fluxes (1500, 2000, 2500 kg/m2s) under subcooled conditions. The maximum CHF enhancement was 53%, 53% and 38% for alumina, zinc oxide and diamond, respectively, always obtained at the highest mass flux. A post-mortem analysis of the boiling surface reveals that its morphology is altered by deposition of the particles during nanofluids boiling. A confocal-microscopy-based examination of the test section revealed that nanoparticles deposition not only changes the number of micro-cavities on the surface, but also the surface wettability. A simple model was used to estimate the ensuing nucleation site

  8. Pressure drop and heat transfer of a mercury single-phase flow and an air-mercury two-phase flow in a helical tube under a strong magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Minoru E-mail: mtakahas@nr.titech.ac.jp; Momozaki, Yoichi

    2000-11-01

    For the reduction of a large magneto-hydrodynamic (MHD) pressure drop of a liquid metal single-phase flow, a liquid metal two-phase flow cooling system has been proposed. As a fundamental study, MHD pressure drops and heat transfer characteristics of a mercury single-phase flow and an air-mercury two-phase flow were experimentally investigated. A strong transverse magnetic field relevant to the fusion reactor conditions was applied to the mercury single-phase flow and the air-mercury two-phase flow in a helically coiled tube that was inserted in the vertical bore of a solenoidal superconducting magnet. It was found that MHD pressure drops of a mercury single-phase flow in the helically coiled tube were nearly equal to those in a straight tube. The Nusselt number at an outside wall was higher than that at an inside wall both in the mercury single-phase flow in the absence and presence of a magnetic field. The Nusselt number of the mercury single-phase flow decreased, increased and again decreased with an increase in the magnetic flux density. MHD pressure drops did not decrease appreciably by injecting air into a mercury flow and changing the mercury flow into the air-mercury two-phase flow. Remarkable heat transfer enhancement did not appear by the air injection. The injection of air into the mercury flow enhanced heat transfer in the ranges of high mercury flow rate and low magnetic flux density, possibly due to the agitation effect of air bubbles. The air injection deteriorated heat transfer in the range of low mercury flow rates possibly because of the occupation of air near heating wall.

  9. Numerical Simulation for Two-Phase Water Hammer Flows in Pipe by Quasi-Two-Dimensional Model

    Institute of Scientific and Technical Information of China (English)

    Tae Uk Jang; Yuebin Wu; Ying Xu; Qiang Sun

    2016-01-01

    The features of a quasi⁃two⁃dimensional ( quasi⁃2D) model for simulating two⁃phase water hammer flows with vaporous cavity in a pipe are investigated. The quasi⁃2D model with discrete vaporous cavity in the pipe is proposed in this paper. This model uses the quasi⁃2D model for pure liquid zone and one⁃dimensional ( 1D ) discrete vapor cavity model for vaporous cavity zone. The quasi⁃2D model solves two⁃dimensional equations for both axial and radial velocities and 1D equations for both pressure head and discharge by the method of characteristics. The 1D discrete vapor cavity model is used to simulate the vaporous cavity occurred when the pressure in the local pipe is lower than the vapor pressure of the liquid. The proposed model is used to simulate two⁃phase water flows caused by the rapid downstream valve closure in a reservoir⁃pipe⁃valve system. The results obtained by the proposed model are compared with those by the corresponding 1D model and the experimental ones provided by the literature, respectively. The comparison shows that the maximum pressure heads simulated by the proposed model are more accurate than those by the corresponding 1D model.

  10. Flow Boiling Heat Transfer in Two-Phase Micro Channel Heat Sink at Low Water Mass Flux

    Science.gov (United States)

    Kuznetsov, Vladimir V.; Shamirzaev, Alisher S.

    2009-08-01

    Boiling heat transfer at water flow with low mass flux in heat sink which contained rectangular microchannels was studied. The stainless steel heat sink contained ten parallel microchannels with a size of 640 × 2050 μm in cross-section with typical wall roughness of 10-15 μm. The local flow boiling heat transfer coefficients were measured at mass velocity of 17 and 51 kg/m2s, heat flux on 30 to 150 kW/m2 and vapor quality of up to 0.8 at pressure in the channels closed to atmospheric one. It was observed that Kandlikar nucleate boiling correlation is in good agreement with the experimental data at mass flow velocity of 85 kg/m2s. At smaller mass flux the Kandlikar model and Zhang, Hibiki and Mishima model demonstrate incorrect trend of heat transfer coefficients variation with vapor quality.

  11. Modeling and Analysis of Magnetic Nanoparticles Injection in Water-Oil Two-Phase Flow in Porous Media under Magnetic Field Effect

    KAUST Repository

    El-Amin, Mohamed

    2017-08-28

    In this paper, the magnetic nanoparticles are injected into a water-oil, two-phase system under the influence of an external permanent magnetic field. We lay down the mathematical model and provide a set of numerical exercises of hypothetical cases to show how an external magnetic field can influence the transport of nanoparticles in the proposed two-phase system in porous media. We treat the water-nanoparticles suspension as a miscible mixture, whereas it is immiscible with the oil phase. The magnetization properties, the density, and the viscosity of the ferrofluids are obtained based on mixture theory relationships. In the mathematical model, the phase pressure contains additional term to account for the extra pressures due to fluid magnetization effect and the magnetostrictive effect. As a proof of concept, the proposed model is applied on a countercurrent imbibition flow system in which both the displacing and the displaced fluids move in opposite directions. Physical variables, including waternanoparticles suspension saturation, nanoparticles concentration, and pore wall/throat concentrations of deposited nanoparticles, are investigated under the influence of the magnetic field. Two different locations of the magnet are studied numerically, and variations in permeability and porosity are considered.

  12. Heat transfer enhancement using Al{sub 2}O{sub 3}/water nanofluid in a two-phase closed thermosyphon

    Energy Technology Data Exchange (ETDEWEB)

    Noie, S.H. [Chemical Engineering Department, Engineering Faculty, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Heris, S. Zeinali [Chemical Engineering Department, Engineering Faculty, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of)], E-mail: zeinali@ferdowsi.um.ac.ir; Kahani, M.; Nowee, S.M. [Chemical Engineering Department, Engineering Faculty, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of)

    2009-08-15

    A two-phase closed thermosyphon (TPCT) is a device for heat transmission. It consists of an evacuated-close tube filled with a certain amount of working fluid. Fluids with nanoparticles (particles smaller than 100 nm) suspended in them are called nanofluids that they have a great potential in heat transfer enhancement. In the present study, we combined two mentioned techniques for heat transfer enhancement. Nanofluids of aqueous Al{sub 2}O{sub 3} nanoparticles suspensions were prepared in various volume concentration of 1-3% and used in a TPCT as working media. Experimental results showed that for different input powers, the efficiency of the TPCT increases up to 14.7% when Al{sub 2}O{sub 3}/water nanofluid was used instead of pure water. Temperature distributions on TPCT confirm these results too.

  13. The wind-water two-phase erosion and sediment-producing processes in the middle Yellow River basin,China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Based on data from the middle Yellow River basin,a wind-water two-phase mechanism for erosion and sediment-producing processes has been found.By using this mechanism,the extremely strong erosion and sediment yield in the study area can be better explained.The operation of wind and water forces is different in different seasons within a year.During winter and spring,strong wind blows large quantities of eolian sand to gullies and river channels,which are temporally stored there.During the next summer,rainstorms cause runoff that contains much fine loessic material and acts as a powerful force to carry the previously prepared coarse material.As a result,hyperconcentrated flows occur,resulting in high-intensity erosion and sediment yield.

  14. Water-head-driven microfluidic oscillators for autonomous control of periodic flows and generation of aqueous two-phase system droplets.

    Science.gov (United States)

    Dang, Van Bac; Kim, Sung-Jin

    2017-01-17

    Generating periodic flows with an oscillator driven only by water-head pressure has potential for the operation of microfluidic systems without any dynamic off-chip controllers. However, its operational characteristic is not well understood due to complex dynamic interactions of the microfluidic components. Here, we focus on the mechanism of a water-head-driven oscillator and analyze the functions of its flow-switching period (T) and flow rate (Q) in a wide range (0.1 s-5.9 h and 2 μL min(-1)-2 mL min(-1)). We show linear control of T and Q by their corresponding fluidic resistors even with the complex and nonlinear relation of the microfluidic components. This allows independent regulation of T and Q within their operational ranges but we found the two parameters mutually constrain their ranges via fluidic resistance. Also, we characterize the control of T by water-head pressure and present operational ranges of input water-head pressure decrease with increasing output water-head pressure. To show its utility, we apply the oscillator to generate droplets with low interfacial tension aqueous two-phase systems. Our study would be useful and provide the foundation for various functions of water-head-driven microfluidic circuits.

  15. CFD simulations of the single-phase and two-phase coolant flow of water inside the original and modified CANDU 37-element bundles

    Energy Technology Data Exchange (ETDEWEB)

    Abbasian, F.; Hadaller, G.I.; Fortman, R.A. [Stern Laboratories, Hamilton, Ontario (Canada)

    2010-07-01

    Single-phase (inlet temperature of 180° C, outlet pressure of 9 MPa, total power of 2 MW and flow rate of 13.5 Kg/s), and two-phase (inlet temperature of 265° C, outlet pressure of 10 MPa, total power of 7.126 MW and flow rate of 19 Kg/s) water flows inside a CANDU thirty seven element fuel string are simulated using a Computational Fluid Dynamics (CFD) code with parallel processing and results are presented in this paper. The analyses have been performed for the original and modified (11.5 mm center element diameter) designs with skewed cosine axial heat flux distribution and 5.1% diametral creep of the pressure tube. The CFD results are in good agreement with the expected temperature and velocity cross-sectional distributions. The effect of the pressure tube creep on the flow bypass is detected, and the CHF improvement in the core region of the modified design is confirmed. The two-phase flow model reasonably predicted the void distribution and the role of interfacial drag on increasing the pressure drop. In all CFD models, the appendages were shown to enhance the production of cross flows and their corresponding flow mixing and asymmetry. (author)

  16. Releasing intracellular product to prepare whole cell biocatalyst for biosynthesis of Monascus pigments in water-edible oil two-phase system.

    Science.gov (United States)

    Hu, Minglue; Zhang, Xuehong; Wang, Zhilong

    2016-11-01

    Selective releasing intracellular product in Triton X-100 micelle aqueous solution to prepare whole cell biocatalyst is a novel strategy for biosynthesis of Monascus pigments, in which cell suspension culture exhibits some advantages comparing with the corresponding growing cell submerged culture. In the present work, the nonionic surfactant Triton X-100 was successfully replaced by edible plant oils for releasing intracellular Monascus pigments. High concentration of Monascus pigments (with absorbance nearly 710 AU at 470 nm in the oil phase, normalized to the aqueous phase volume approximately 142 AU) was achieved by cell suspension culture in peanut oil-water two-phase system. Furthermore, the utilization of edible oil as extractant also fulfills the demand for application of Monascus pigments as natural food colorant.

  17. Ionic liquid-impregnated agarose film two-phase micro-electrodriven membrane extraction (IL-AF-μ-EME) for the analysis of antidepressants in water samples.

    Science.gov (United States)

    Mohamad Hanapi, Nor Suhaila; Sanagi, Mohd Marsin; Ismail, Abd Khamim; Wan Ibrahim, Wan Aini; Saim, Nor'ashikin; Wan Ibrahim, Wan Nazihah

    2017-03-01

    The aim of this study was to investigate and apply supported ionic liquid membrane (SILM) in two-phase micro-electrodriven membrane extraction combined with high performance liquid chromatography-ultraviolet detection (HPLC-UV) for pre-concentration and determination of three selected antidepressant drugs in water samples. A thin agarose film impregnated with 1-hexyl-3-methylimidazolium hexafluorophosphate, [C6MIM] [PF6], was prepared and used as supported ionic liquid membrane between aqueous sample solution and acceptor phase for extraction of imipramine, amitriptyline and chlorpromazine. Under the optimized extraction conditions, the method provided good linearity in the range of 1.0-1000μgL(-1), good coefficients of determination (r(2)=0.9974-0.9992) and low limits of detection (0.1-0.4μgL(-1)). The method showed high enrichment factors in the range of 110-150 and high relative recoveries in the range of 88.2-111.4% and 90.9-107.0%, for river water and tap water samples, respectively with RSDs of ≤7.6 (n=3). This method was successfully applied to the determination of the drugs in river and tap water samples. It is envisaged that the SILM improved the perm-selectivity by providing a pathway for targeted analytes which resulted in rapid extraction with high degree of selectivity and high enrichment factor.

  18. Efficiency of two-phase methods with focus on a planned population-based case-control study on air pollution and stroke

    Directory of Open Access Journals (Sweden)

    Strömberg Ulf

    2007-11-01

    Full Text Available Abstract Background We plan to conduct a case-control study to investigate whether exposure to nitrogen dioxide (NO2 increases the risk of stroke. In case-control studies, selective participation can lead to bias and loss of efficiency. A two-phase design can reduce bias and improve efficiency by combining information on the non-participating subjects with information from the participating subjects. In our planned study, we will have access to individual disease status and data on NO2 exposure on group (area level for a large population sample of Scania, southern Sweden. A smaller sub-sample will be selected to the second phase for individual-level assessment on exposure and covariables. In this paper, we simulate a case-control study based on our planned study. We develop a two-phase method for this study and compare the performance of our method with the performance of other two-phase methods. Methods A two-phase case-control study was simulated with a varying number of first- and second-phase subjects. Estimation methods: Method 1: Effect estimation with second-phase data only. Method 2: Effect estimation by adjusting the first-phase estimate with the difference between the adjusted and unadjusted second-phase estimate. The first-phase estimate is based on individual disease status and residential address for all study subjects that are linked to register data on NO2-exposure for each geographical area. Method 3: Effect estimation by using the expectation-maximization (EM algorithm without taking area-level register data on exposure into account. Method 4: Effect estimation by using the EM algorithm and incorporating group-level register data on NO2-exposure. Results The simulated scenarios were such that, unbiased or marginally biased ( Conclusion In the setting described here, method 4 had the best performance in order to improve efficiency, while adjusting for varying participation rates across areas.

  19. Applying CFD in the analysis of heavy oil - water two-phase flow in joints by using core annular flow technique

    Directory of Open Access Journals (Sweden)

    T Andrade

    2016-09-01

    Full Text Available In the oil industry the multiphase flow occur throughout the production chain, from reservoir rock until separation units through the production column, risers and pipelines. During the whole process the fluid flows through the horizontal pipes, curves, connections and T joints. Today, technological and economic challenges facing the oil industry is related to heavy oil transportation due to its unfavourable characteristics such as high viscosity and high density that provokes high pressure drop along the flow. The coreflow technique consists in the injection of small amounts of water into the pipe to form a ring of water between the oil and the wall of the pipe which provides the reduction of friction pressure drop along the flow. This paper aim to model and simulate the transient two-phase flow (water-heavy oil in a horizontal pipe and T joint by numerical simulation using the software ANSYS CFX® Release 12.0. Results of pressure and volumetric fraction distribution inside the horizontal pipe and T joint are presented and analysed.

  20. Two-phase flow in refrigeration systems

    CERN Document Server

    Gu, Junjie; Gan, Zhongxue

    2013-01-01

    Two-Phase Flow in Refrigeration Systems presents recent developments from the authors' extensive research programs on two-phase flow in refrigeration systems. This book covers advanced mass and heat transfer and vapor compression refrigeration systems and shows how the performance of an automotive air-conditioning system is affected through results obtained experimentally and theoretically, specifically with consideration of two-phase flow and oil concentration. The book is ideal for university postgraduate students as a textbook, researchers and professors as an academic reference book, and b

  1. Characterizing dynamic hysteresis and fractal statistics of chaotic two-phase flow and application to fuel cells

    Science.gov (United States)

    Burkholder, Michael B.; Litster, Shawn

    2016-05-01

    In this study, we analyze the stability of two-phase flow regimes and their transitions using chaotic and fractal statistics, and we report new measurements of dynamic two-phase pressure drop hysteresis that is related to flow regime stability and channel water content. Two-phase flow dynamics are relevant to a variety of real-world systems, and quantifying transient two-phase flow phenomena is important for efficient design. We recorded two-phase (air and water) pressure drops and flow images in a microchannel under both steady and transient conditions. Using Lyapunov exponents and Hurst exponents to characterize the steady-state pressure fluctuations, we develop a new, measurable regime identification criteria based on the dynamic stability of the two-phase pressure signal. We also applied a new experimental technique by continuously cycling the air flow rate to study dynamic hysteresis in two-phase pressure drops, which is separate from steady-state hysteresis and can be used to understand two-phase flow development time scales. Using recorded images of the two-phase flow, we show that the capacitive dynamic hysteresis is related to channel water content and flow regime stability. The mixed-wettability microchannel and in-channel water introduction used in this study simulate a polymer electrolyte fuel cell cathode air flow channel.

  2. Characterizing dynamic hysteresis and fractal statistics of chaotic two-phase flow and application to fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Burkholder, Michael B.; Litster, Shawn, E-mail: litster@andrew.cmu.edu [Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States)

    2016-05-15

    In this study, we analyze the stability of two-phase flow regimes and their transitions using chaotic and fractal statistics, and we report new measurements of dynamic two-phase pressure drop hysteresis that is related to flow regime stability and channel water content. Two-phase flow dynamics are relevant to a variety of real-world systems, and quantifying transient two-phase flow phenomena is important for efficient design. We recorded two-phase (air and water) pressure drops and flow images in a microchannel under both steady and transient conditions. Using Lyapunov exponents and Hurst exponents to characterize the steady-state pressure fluctuations, we develop a new, measurable regime identification criteria based on the dynamic stability of the two-phase pressure signal. We also applied a new experimental technique by continuously cycling the air flow rate to study dynamic hysteresis in two-phase pressure drops, which is separate from steady-state hysteresis and can be used to understand two-phase flow development time scales. Using recorded images of the two-phase flow, we show that the capacitive dynamic hysteresis is related to channel water content and flow regime stability. The mixed-wettability microchannel and in-channel water introduction used in this study simulate a polymer electrolyte fuel cell cathode air flow channel.

  3. Two phase flow bifurcation due to turbulence: transition from slugs to bubbles

    Science.gov (United States)

    Górski, Grzegorz; Litak, Grzegorz; Mosdorf, Romuald; Rysak, Andrzej

    2015-09-01

    The bifurcation of slugs to bubbles within two-phase flow patterns in a minichannel is analyzed. The two-phase flow (water-air) occurring in a circular horizontal minichannel with a diameter of 1 mm is examined. The sequences of light transmission time series recorded by laser-phototransistor sensor is analyzed using recurrence plots and recurrence quantification analysis. Recurrence parameters allow the two-phase flow patterns to be found. On changing the water flow rate we identified partitioning of slugs or aggregation of bubbles.

  4. Experimental study of a two-phase surface jet

    Science.gov (United States)

    Perret, Matias; Esmaeilpour, Mehdi; Politano, Marcela S.; Carrica, Pablo M.

    2013-04-01

    Results of an experimental study of a two-phase jet are presented, with the jet issued near and below a free surface, parallel to it. The jet under study is isothermal and in fresh water, with air injectors that allow variation of the inlet air volume fraction between 0 and 13 %. Measurements of water velocity have been performed using LDV, and the jet exit conditions measured with PIV. Air volume fraction, bubble velocity and chord length distributions were measured with sapphire optical local phase detection probes. The mean free surface elevation and RMS fluctuations were obtained using local phase detection probes as well. Visualization was performed with laser-induced fluorescence. Measurements reveal that the mean free surface elevation and turbulent fluctuations significantly increase with the injection of air. The water normal Reynolds stresses are damped by the presence of bubbles in the bulk of the liquid, but very close to the free surface the effect is reversed and the normal Reynolds stresses increase slightly for the bubbly flow. The Reynolds shear stresses time it takes the bubbles to pierce the free surface, resulting in a considerable increase in the local air volume fraction. In addition to first explore a bubbly surface jet, the comprehensive dataset reported herein can be used to validate two-phase flow models and computational tools.

  5. Numerical study of water management in the air flow channel of a PEM fuel cell cathode

    Energy Technology Data Exchange (ETDEWEB)

    Quan, Peng; Lai, Ming-Chia [Department of Mechanical Engineering, Wayne State University, Detroit, MI 48202 (United States)

    2007-01-10

    The water management in the air flow channel of a proton exchange membrane (PEM) fuel cell cathode is numerically investigated using the FLUENT software package. By enabling the volume of fraction (VOF) model, the air-water two-phase flow can be simulated under different operating conditions. The effects of channel surface hydrophilicity, channel geometry, and air inlet velocity on water behavior, water content inside the channel, and two-phase pressure drop are discussed in detail. The results of the quasi-steady-state simulations show that: (1) the hydrophilicity of reactant flow channel surface is critical for water management in order to facilitate water transport along channel surfaces or edges; (2) hydrophilic surfaces also increase pressure drop due to liquid water spreading; (3) a sharp corner channel design could benefit water management because it facilitates water accumulation and provides paths for water transport along channel surface opposite to gas diffusion layer; (4) the two-phase pressure drop inside the air flow channel increases almost linearly with increasing air inlet velocity. (author)

  6. Treatment of high salt oxidized modified starch waste water using micro-electrolysis, two-phase anaerobic aerobic and electrolysis for reuse

    Science.gov (United States)

    Yi, Xuenong; Wang, Yulin

    2017-06-01

    A combined process of micro-electrolysis, two-phase anaerobic, aerobic and electrolysis was investigated for the treatment of oxidized modified starch wastewater (OMSW). Optimum ranges for important operating variables were experimentally determined and the treated water was tested for reuse in the production process of corn starch. The optimum hydraulic retention time (HRT) of micro-electrolysis, methanation reactor, aerobic process and electrolysis process were 5, 24, 12 and 3 h, respectively. The addition of iron-carbon fillers to the acidification reactor was 200 mg/L while the best current density of electrolysis was 300 A/m2. The biodegradability was improved from 0.12 to 0.34 by micro-electrolysis. The whole treatment was found to be effective with removal of 96 % of the chemical oxygen demand (COD), 0.71 L/day of methane energy recovery. In addition, active chlorine production (15,720 mg/L) was obtained by electrolysis. The advantage of this hybrid process is that, through appropriate control of reaction conditions, effect from high concentration of salt on the treatment was avoided. Moreover, the process also produced the material needed in the production of oxidized starch while remaining emission-free and solved the problem of high process cost.

  7. Treatment of high salt oxidized modified starch waste water using micro-electrolysis, two-phase anaerobic aerobic and electrolysis for reuse

    Science.gov (United States)

    Yi, Xuenong; Wang, Yulin

    2016-08-01

    A combined process of micro-electrolysis, two-phase anaerobic, aerobic and electrolysis was investigated for the treatment of oxidized modified starch wastewater (OMSW). Optimum ranges for important operating variables were experimentally determined and the treated water was tested for reuse in the production process of corn starch. The optimum hydraulic retention time (HRT) of micro-electrolysis, methanation reactor, aerobic process and electrolysis process were 5, 24, 12 and 3 h, respectively. The addition of iron-carbon fillers to the acidification reactor was 200 mg/L while the best current density of electrolysis was 300 A/m2. The biodegradability was improved from 0.12 to 0.34 by micro-electrolysis. The whole treatment was found to be effective with removal of 96 % of the chemical oxygen demand (COD), 0.71 L/day of methane energy recovery. In addition, active chlorine production (15,720 mg/L) was obtained by electrolysis. The advantage of this hybrid process is that, through appropriate control of reaction conditions, effect from high concentration of salt on the treatment was avoided. Moreover, the process also produced the material needed in the production of oxidized starch while remaining emission-free and solved the problem of high process cost.

  8. Two-phase flow simulation of aeration on stepped spillway

    Institute of Scientific and Technical Information of China (English)

    CHENG Xiangju; LUO Lin; ZHAO Wenqian; LI Ran

    2004-01-01

    Stepped spillways have existed as escape works for a very long time. It is found that water can trap a lot of air when passing through steps and then increasing oxygen content in water body, so stepped spillways can be used as a measure of re-aeration and to improve water quality of water body. However, there is no reliable theoretical method on quantitative calculation of re-aeration ability for the stepped spillways. By introducing an air-water two-phase flow model, this paper used k-ε turbulence model to calculate the characteristic variables of free-surface aeration on stepped spillway. The calculated results fit with the experimental results well. It supports that the numerical modeling method is reasonable and offers firm foundation on calculating re-aeration ability of stepped spillways. The simulation approach can provide a possible optimization tool for designing stepped spillways of more efficient aeration capability.

  9. An interfacial shear term evaluation study for adiabatic dispersed air–water two-phase flow with the two-fluid model using CFD

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, S.L., E-mail: sharma55@purdue.edu [School of Nuclear Engineering, Purdue University, West Lafayette, IN (United States); Hibiki, T.; Ishii, M. [School of Nuclear Engineering, Purdue University, West Lafayette, IN (United States); Schlegel, J.P. [Department of Mining and Nuclear Engineering, Missouri University of Science and Technology, Rolla, MO (United States); Buchanan, J.R.; Hogan, K.J. [Bettis Laboratory, Naval Nuclear Laboratory, West Mifflin, PA (United States); Guilbert, P.W. [ANSYS UK Ltd, Oxfordshire (United Kingdom)

    2017-02-15

    Highlights: • Closure form of the interfacial shear term in three-dimensional form is investigated. • Assessment against adiabatic upward bubbly air–water flow data using CFD. • Effect of addition of the interfacial shear term on the phase distribution. - Abstract: In commercially available Computational Fluid Dynamics (CFD) codes such as ANSYS CFX and Fluent, the interfacial shear term is missing in the field momentum equations. The derivation of the two-fluid model (Ishii and Hibiki, 2011) indicates the presence of this term as a momentum source in the right hand side of the field momentum equation. The inclusion of this term is considered important for proper modeling of the interfacial momentum coupling between phases. For separated flows, such as annular flow, the importance of the shear term is understood in the one-dimensional (1-D) form as the major mechanism by which the wall shear is transferred to the gas phase (Ishii and Mishima, 1984). For gas dispersed two-phase flow CFD simulations, it is important to assess the significance of this term in the prediction of phase distributions. In the first part of this work, the closure of this term in three-dimensional (3-D) form in a CFD code is investigated. For dispersed gas–liquid flow, such as bubbly or churn-turbulent flow, bubbles are dispersed in the shear layer of the continuous phase. The continuous phase shear stress is mainly due to the presence of the wall and the modeling of turbulence through the Boussinesq hypothesis. In a 3-D simulation, the continuous phase shear stress can be calculated from the continuous fluid velocity gradient, so that the interfacial shear term can be closed using the local values of the volume fraction and the total stress of liquid phase. This form also assures that the term acts as an action-reaction force for multiple phases. In the second part of this work, the effect of this term on the volume fraction distribution is investigated. For testing the model two-phase

  10. Magnetic ionic liquid aqueous two-phase system coupled with high performance liquid chromatography: A rapid approach for determination of chloramphenicol in water environment.

    Science.gov (United States)

    Yao, Tian; Yao, Shun

    2017-01-20

    A novel organic magnetic ionic liquid based on guanidinium cation was synthesized and characterized. A new method of magnetic ionic liquid aqueous two-phase system (MILATPs) coupled with high-performance liquid chromatography (HPLC) was established to preconcentrate and determine trace amount of chloramphenicol (CAP) in water environment for the first time. In the absence of volatile organic solvents, MILATPs not only has the excellent properties of rapid extraction, but also exhibits a response to an external magnetic field which can be applied to assist phase separation. The phase behavior of MILATPs was investigated and phase equilibrium data were correlated by Merchuk equation. Various influencing factors on CAP recovery were systematically investigated and optimized. Under the optimal conditions, the preconcentration factor was 147.2 with the precision values (RSD%) of 2.42% and 4.45% for intra-day (n=6) and inter-day (n=6), respectively. The limit of detection (LOD) and limit of quantitation (LOQ) were 0.14ngmL(-1) and 0.42ngmL(-1), respectively. Fine linear range of 12.25ngmL(-1)-2200ngmL(-1) was obtained. Finally, the validated method was successfully applied for the analysis of CAP in some environmental waters with the recoveries for the spiked samples in the acceptable range of 94.6%-99.72%. Hopefully, MILATPs is showing great potential to promote new development in the field of extraction, separation and pretreatment of various biochemical samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Two-phase flow experiments on Counter-Current Flow Limitation in a model of the hot leg of a pressurized water reactor (2015 test series)

    Energy Technology Data Exchange (ETDEWEB)

    Beyer, Matthias; Lucas, Dirk; Pietruske, Heiko; Szalinski, Lutz

    2016-12-15

    Counter-Current Flow Limitation (CCFL) is of importance for PWR safety analyses in several accident scenarios connected with loss of coolant. Basing on the experiences obtained during a first series of hot leg tests now new experiments on counter-current flow limitation were conducted in the TOPFLOW pressure vessel. The test series comprises air-water tests at 1 and 2 bar as well as steam-water tests at 10, 25 and 50 bar. During the experiments the flow structure was observed along the hot leg model using a high-speed camera and web-cams. In addition pressure was measured at several positions along the horizontal part and the water levels in the reactor-simulator and steam-generator-simulator tanks were determined. This report documents the experimental setup including the description of operational and special measuring techniques, the experimental procedure and the data obtained. From these data flooding curves were obtained basing on the Wallis parameter. The results show a slight shift of the curves in dependency of the pressure. In addition a slight decrease of the slope was found with increasing pressure. Additional investigations concern the effects of hysteresis and the frequencies of liquid slugs. The latter ones show a dependency on pressure and the mass flow rate of the injected water. The data are available for CFD-model development and validation.

  12. 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.

  13. Three-dimensional calculation of pollutant migration via compressible two-phase flow, for analysis of the methods of in situ air sparging and soil vapor extraction; Raeumliche Berechnung des Schadstofftransportes mit einer kompressiblen Zweiphasenstroemung zur Untersuchung der Drucklufteinblasung und Bodenluftabsaugung

    Energy Technology Data Exchange (ETDEWEB)

    Kuepper, S.

    1997-12-01

    In this study an analysis method is presented which allows numerical simulation of in situ air sparging coupled with soil vapor extraction. The improved FE-program takes the following phenomena into account: - Two-phase flow of compressible air and incompressible water - convective-dispersive contamination migration with air and water - transfer of volatile components from liquid phase to gas and water phase - sorption of contaminants onto soil - transfer of contaminants between air and water phase - biological processes. By means of back calculations of the results of laboratory experiments made by Eisele (1989) it was shown that with the developed program GWLCOND some of the necessary parameters for the numerical simulation of remedial systems can be determined. (orig./SR) [Deutsch] In dieser Arbeit wird ein Verfahren vorgestellt, mit dem eine numerische Simulation der Drucklufteinblasung und Bodenluftabsaugung durchgefuehrt werden kann. Das weiterentwickelte FE-Programmsystem beinhaltet folgende Ablaeufe: - Zweiphasenstroemung der kompressiblen Luft- und der inkompressiblen Wasserphase - Konvektiv-dispersiver Schadstofftransport mit der Gas- und der Wasserphase - Uebergang fluessiger Schadstoffe in die Gas- und in die Wasserphase - Sorption der Schadstoffe an der Feststoffphase - Uebergang der Schadstoffe zwischen der Gas- und der Wasserphase - Biologischer Abbau. Anhand der Nachrechnung eines Laborversuches von Eisele (1989) wird gezeigt, wie mit dem entwickelten Transportprogramm GWLCOND ein Teil der fuer die numerische Simulation des Sanierungsverfahrens benoetigten Kennwerte ermittelt werden kann. (orig./SR)

  14. Two-phase dusty fluid flow along a cone with variable properties

    Science.gov (United States)

    Siddiqa, Sadia; Begum, Naheed; Hossain, Md. Anwar; Mustafa, Naeem; Gorla, Rama Subba Reddy

    2016-09-01

    In this paper numerical solutions of a two-phase natural convection dusty fluid flow are presented. The two-phase particulate suspension is investigated along a vertical cone by keeping variable viscosity and thermal conductivity of the carrier phase. Comprehensive flow formations of the gas and particle phases are given with the aim to predict the behavior of heat transport across the heated cone. The influence of (1) air with particles, (2) water with particles and (3) oil with particles are shown on shear stress coefficient and heat transfer coefficient. It is recorded that sufficient increment in heat transport rate can be achieved by loading the dust particles in the air. Further, distribution of velocity and temperature of both the carrier phase and the particle phase are shown graphically for the pure fluid (air, water) as well as for the fluid with particles (air-metal and water-metal particle mixture).

  15. Numerical Investigation of Transmission of Low Frequency Sound Through a Smooth Air-water Interface

    Institute of Scientific and Technical Information of China (English)

    Parviz Ghadimi; Alireza Bolghasi; Mohammad A Feizi Chekab; Rahim Zamanian

    2015-01-01

    It is the traditional belief that sound transmission from water to the air is very weak due to a large contrast between air and water impedances. Recently, the enhanced sound transmission and anomalous transparency of air-water interface have been introduced. Anomalous transparency of air-water interface states that the sound generated by a submerged shallow depth monopole point source localized at depths less than 1/10 sound wavelength, can be transmitted into the air with omni-directional pattern. The generated sound has 35 times higher power compared to the classical ray theory prediction. In this paper, sound transmission through air-water interface for a localized underwater shallow depth source is examined. To accomplish this, two-phase coupled Helmholtz wave equations in two-phase media of air-water are solved by the commercial finite element based COMSOL Multiphysics software. Ratios of pressure amplitudes of different sound sources in two different underwater and air coordinates are computed and analyzed against non-dimensional ratio of the source depth (D) to the sound wavelength (λ). The obtained results are compared with the experimental data and good agreement is displayed.

  16. The Effect of Sudden Change in Pipe Diameter on Flow Patterns of Air-Water Two-Phase

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Flow patterns upstream and downstream of a sudden-contraction cross-section in a vertical straight pipe were presented. By comparing with flow patterns in uniform croes-section vertical tubes, the effect of the sudden change in pipe diameter on flow patterns was analyzed. Flow pattern transition mechanisms were discussed and transition criteria for flow pattern transitions were deduced accordingly using the dimensional analysis.

  17. Two-phase and three-dimensional simulations of complex fluid-sediment transport down a slope and impacting water bodies

    Science.gov (United States)

    Pudasaini, Shiva P.; Kattel, Parameshwari; Kafle, Jeevan; Pokhrel, Puskar R.; Khattri, Khim B.

    2014-05-01

    We present a technique that simulates transport and flow of a real two-phase fluid (a mixture of fluid and sediment particles) down three-dimensional slopes and channels. This technique combines novel mechanics formulations and modeling into a unified high-resolution framework, providing a unique opportunity to simulate two-phase subearial landslides and debris flows with dynamically changing concentrations of solid particles. This mixture then impacts downslope with particle-laden fluid reservoirs, rivers, fjords, lakes, or oceans. This results in a super tsunami wave in the fluid body, while the submarine debris flow moves along the bathymetry. The same modelling technique can be applied to simulate rock-ice avalanches and turbidity currents with changing physical properties and mechanical responses of the phases that enhances the flow mobility. These results fundamentally advance our present knowledge associated with the complex mechanics and dynamics of multi-phase geophysical mass flows, including the subearial and submarine sediment transport and deposition processes. Our findings contribute significantly to our understanding of mixing and separation between phases, generation and propagation of special solid and fluid structures, and phase-transitions during the flow process. Finally, these results provide new insights into the evolution of morphodynamics of steep mountain slopes and channels. References Pudasaini, S. P. A general two-phase debris flow model. Journal of Geophysical Research, 117, F03010, 2012. doi: 10.1029/2011JF002186. Pudasaini, S. P. and Miller, S. A. A real two-phase submarine debris flow and tsunami. American Institute of Physics Proceedings, 1479, 197-200, 2012. doi: 10.1063/1.4756096.

  18. Detection of Two-Phase Flow Patterns in a Vertical Minichannel Using the Recurrence Quantification Analysis

    Directory of Open Access Journals (Sweden)

    Mosdorf Romuald

    2015-06-01

    Full Text Available The two-phase flow (water-air occurring in square minichannel (3x3 mm has been analysed. In the minichannel it has been observed: bubbly flow, flow of confined bubbles, flow of elongated bubbles, slug flow and semi-annular flow. The time series recorded by laser-phototransistor sensor was analysed using the recurrence quantification analysis. The two coefficients:Recurrence rate (RR and Determinism (DET have been used for identification of differences between the dynamics of two-phase flow patterns. The algorithm which has been used normalizes the analysed time series before calculating the recurrence plots.Therefore in analysis the quantitative signal characteristicswas neglected. Despite of the neglect of quantitative signal characteristics the analysis of its dynamics (chart of DET vs. RR allows to identify the two-phase flow patterns. This confirms that this type of analysis can be used to identify the two-phase flow patterns in minichannels.

  19. Environmental Chemistry: Air and Water Pollution.

    Science.gov (United States)

    Stoker, H. Stephen; Seager, Spencer L.

    This is a book about air and water pollution whose chapters cover the topics of air pollution--general considerations, carbon monoxide, oxides of nitrogen, hydrocarbons and photochemical oxidants, sulfur oxides, particulates, temperature inversions and the greenhouse effect; and water pollution--general considerations, mercury, lead, detergents,…

  20. Water gun vs air gun: A comparison

    Science.gov (United States)

    Hutchinson, D.R.; Detrick, R. S.

    1984-01-01

    The water gun is a relatively new marine seismic sound source that produces an acoustic signal by an implosive rather than explosive mechanism. A comparison of the source characteristics of two different-sized water guns with those of conventional air guns shows the the water gun signature is cleaner and much shorter than that of a comparable-sized air gun: about 60-100 milliseconds (ms) for an 80-in3. (1.31-liter (I)) water gun compared with several hundred ms for an 80-in3. (1.31-1) air gun. The source spectra of water guns are richer in high frequencies (>200 Hz) than are those of air guns, but they also have less energy than those of air guns at low frequencies. A comparison between water gun and air gun reflection profiles in both shallow (Long Island Sound)-and deep (western Bermuda Rise)-water settings suggests that the water gun offers a good compromise between very high resolution, limited penetration systems (e.g. 3.5-kHz profilers and sparkers) and the large volume air guns and tuned air gun arrays generally used where significant penetration is required. ?? 1984 D. Reidel Publishing Company.

  1. Measurement of local two-phase flow parameters of nanofluids using conductivity double-sensor probe

    Directory of Open Access Journals (Sweden)

    Park Yu sun

    2011-01-01

    Full Text Available Abstract A two-phase flow experiment using air and water-based γ-Al2O3 nanofluid was conducted to observe the basic hydraulic phenomenon of nanofluids. The local two-phase flow parameters were measured with a conductivity double-sensor two-phase void meter. The void fraction, interfacial velocity, interfacial area concentration, and mean bubble diameter were evaluated, and all of those results using the nanofluid were compared with the corresponding results for pure water. The void fraction distribution was flattened in the nanofluid case more than it was in the pure water case. The higher interfacial area concentration resulted in a smaller mean bubble diameter in the case of the nanofluid. This was the first attempt to measure the local two-phase flow parameters of nanofluids using a conductivity double-sensor two-phase void meter. Throughout this experimental study, the differences in the internal two-phase flow structure of the nanofluid were identified. In addition, the heat transfer enhancement of the nanofluid can be resulted from the increase of the interfacial area concentration which means the available area of the heat and mass transfer.

  2. Self-aggregation Phenomenon and Stable Flow Conditions in a Two-Phase Flow Through a Minichannel

    Science.gov (United States)

    Górski, Grzegorz; Litak, Grzegorz; Mosdorf, Romuald; Rysak, Andrzej

    2015-10-01

    By increasing a water flow rate of the two-phase (air-water) flow through a minichannel, both the partitioning of air slugs into air bubbles of different sizes and small air bubbles aggregation into larger air bubbles were identified. These phenomena were studied in detail by using the corresponding sequences of light transmission time series recorded with a laser-phototransistor sensor. To distinguish any instabilities in air slugs along with their break-ups and aggregations, the recurrence plots and recurrence quantification analysis were applied.

  3. 水平井油水两相流含水率解释预测%Water Cut Prediction of Oil-water Two-phase Flow in Horizontal Well

    Institute of Scientific and Technical Information of China (English)

    郑希科; 朴玉琴; 孟凡宇; 王倩

    2012-01-01

    Because of complex flow types, it is difficult to accurately interpret water cut of oil-water two-phase flow of production profile logging in horizontal wells. On the basis of a large number of simulation experiments on nearly horizontal oil-water two-phase flow and the measuring response characteristics of water cut meter of capacitance and resistance, SVR model (support vector machine regression model) is established based on frequency domain eigenvalue of water cut meter response, and this model is used to predict the calibration results of water cut for simulation wells with different angles. Validation results show that higher prediction accuracy can be obtained by using this log interpretation model. Compared with the matching water cut of laboratory experiment, prediction accuracy of water cut can be achieved by using SVR model. In addition, the actual log data is interpreted on the basis of the development of interpretation methods.%水平井油水两相流产液剖面测井解释中流型复杂,准确解释含水率是难点.在进行了大量的近水平油水两相流动模拟实验的基础上,针对电容及阻抗含水率计测量响应特性,建立基于含水率计响应时域及频域特征值的支持向量机回归模型(SVR Model),采用该模型对不同倾斜角度的模拟井动态实验含水率标定结果进行模型预测,模型验证结果表明解释模型可实现较高的含水率预测精度,与室内实验配比含水率比较,达到预测含水率解释精度目标.在解释方法研究的基础上,对实际测井资料进行解释.

  4. Monolayers at air-water interfaces: from origins-of-life to nanotechnology.

    Science.gov (United States)

    Ariga, Katsuhiko; Hill, Jonathan P

    2011-08-01

    The air-water interface presents several interesting features, namely a) a molecularly flat environment, b) a boundary region between two phases with different dielectric constants, c) permits or promotes dynamic interactions within the interface region, and d) a point of interaction between hydrophobic compounds and aqueous molecules. Accordingly, Langmuir monolayers at the air-water interface have several unique characteristics and properties, which require investigation. In this review-type personal account, typical examples of molecular recognition and molecular patterning at air-water interfaces are first introduced, followed by descriptions of specific and unusual properties of monolayers on water. In addition, two examples of our own results concerning Langmuir monolayers are explained. We have selected examples from two apparently unrelated research areas, these being the origin of life and future nanotechnology, in order to emphasize the diverse scientific contribution of research on monolayers at the air-water interface. Copyright © 2011 The Japan Chemical Journal Forum and Wiley Periodicals, Inc.

  5. Optimization of the CFD-based Downhole Oli-water Two-phase Venturimeter%基于CFD的井下油水两相文丘里流量计优选

    Institute of Scientific and Technical Information of China (English)

    黄思; 关玉慧; 冯定; 马卫国

    2012-01-01

    The flowrate condition, change of oil-water ratio and complexity of two-phase flow pattern affect the oil-water two-phase measurement precision and model selection of design concerning the downhole venturime- ter. Considering the problem, a simulation calculation of the oil-water two-phase flow field of three different ventu- rimeters was conducted and the scheme was optimized in different entrance flowrate and different oil-water ratio con- ditions according to the multiphase flow theory. The calculation shows that when the medium is close to oil phase or water phase, the two-phase flow pattern is close to laminar flow or turbulent flow. The characteristic of oil-water two-phase stratification is remarkable when the fluid goes through the venturi throat. According to the requirement of multiphase flow calculation precision and through CFD-based calculation comparison, the design scheme of venturi tube was optimized under small flow with pressure drop changing remarkably with liquid viscosity.%为解决因流量、油水比变化及两相流态的复杂性所带来的井下文丘里管油水两相测量精度和设计选型等问题,根据多相流理论及计算方法,在不同入口流量、不同油水比条件下,模拟计算3种不同文丘里流量计的油水两相流场并进行方案优选。计算结果表明,介质接近油相或水相时,两相流态分别接近层流或湍流。流体经文丘里喉部后,油水两相分层特征显著。根据多相流计量精度的需要,通过CFD计算对比,优选出小流量下压降随液体粘度有显著变化的文丘里管设计方案。

  6. Electrodeposition of magnetic, superhydrophobic, non-stick, two-phase Cu-Ni foam films and their enhanced performance for hydrogen evolution reaction in alkaline water media

    Science.gov (United States)

    Zhang, J.; Baró, M. D.; Pellicer, E.; Sort, J.

    2014-10-01

    Two-phase Cu-Ni magnetic metallic foams (MMFs) with tunable composition have been prepared by electrodeposition taking advantage of hydrogen co-evolution as a source of porosity. It is observed that Ni tends to deposit inside the porous network defined by the Cu building blocks. Contact angle measurements reveal that the prepared porous films show a remarkable superhydrophobicity (contact angle values larger than 150°) and a non-sticking property to aqueous droplets. This behavior is predominately ascribed to the morphology of the films - hierarchical micro/nanoporosity, wall thickness, and spatial arrangement. The electrochemical activity and stability towards hydrogen evolution reaction of the Cu-Ni MMFs has been investigated by cyclic voltammetry in 1 M KOH at 298 K, and the optimal Ni content is found to be 15 at%. Furthermore, all the foam-like films exhibit ferromagnetic behaviour due to the presence of the Ni-rich phase, with coercivity values ranging from 114 Oe to 300 Oe. From the technological point of view, the Cu-Ni MMFs are promising candidates for magnetically-actuated micro/nano-electromechanical systems (MEMS/NEMS) and micro/nanorobotic platforms with a large surface-area to volume ratio or in magnetic sensors or separators.Two-phase Cu-Ni magnetic metallic foams (MMFs) with tunable composition have been prepared by electrodeposition taking advantage of hydrogen co-evolution as a source of porosity. It is observed that Ni tends to deposit inside the porous network defined by the Cu building blocks. Contact angle measurements reveal that the prepared porous films show a remarkable superhydrophobicity (contact angle values larger than 150°) and a non-sticking property to aqueous droplets. This behavior is predominately ascribed to the morphology of the films - hierarchical micro/nanoporosity, wall thickness, and spatial arrangement. The electrochemical activity and stability towards hydrogen evolution reaction of the Cu-Ni MMFs has been investigated

  7. Air-water flow in subsurface systems

    Science.gov (United States)

    Hansen, A.; Mishra, P.

    2013-12-01

    Groundwater traces its roots to tackle challenges of safe and reliable drinking water and food production. When the groundwater level rises, air pressure in the unsaturated Vadose zone increases, forcing air to escape from the ground surface. Abnormally high and low subsurface air pressure can be generated when the groundwater system, rainfall, and sea level fluctuation are favorably combined [Jiao and Li, 2004]. Through this process, contamination in the form of volatile gases may diffuse from the ground surface into residential areas, or possibly move into groundwater from industrial waste sites. It is therefore crucial to understand the combined effects of air-water flow in groundwater system. Here we investigate theoretically and experimentally the effects of air and water flow in groundwater system.

  8. Detailed flow and force measurements in a rotated triangular tube bundle subjected to two-phase cross-flow

    Science.gov (United States)

    Pettigrew, M. J.; Zhang, C.; Mureithi, N. W.; Pamfil, D.

    2005-05-01

    Two-phase cross-flow exists in many shell-and-tube heat exchangers. A detailed knowledge of the characteristics of two-phase cross-flow in tube bundles is required to understand and formulate flow-induced vibration parameters such as damping, fluidelastic instability, and random excitation due to turbulence. An experimental program was undertaken with a rotated-triangular array of cylinders subjected to air/water flow to simulate two-phase mixtures. The array is made of relatively large diameter cylinders (38 mm) to allow for detailed two-phase flow measurements between cylinders. Fiber-optic probes were developed to measure local void fraction. Local flow velocities and bubble diameters or characteristic lengths of the two-phase mixture are obtained by using double probes. Both the dynamic lift and drag forces were measured with a strain gauge instrumented cylinder.

  9. Extraction and separation of tungsten (VI) from aqueous media with Triton X-100-ammonium sulfate-water aqueous two-phase system without any extractant.

    Science.gov (United States)

    Yongqiang Zhang; Tichang Sun; Tieqiang Lu; Chunhuan Yan

    2016-11-25

    An aqueous two-phase system composed of Triton X-100-(NH4)2SO4-H2O was proposed for extraction and separation of tungsten(VI) from aqueous solution without using any extractant. The effects of aqueous pH, concentration of ammonium sulfate, Triton X-100 and tungsten, extracting temperature on the extraction of tungsten were investigated. The extraction of tungsten has remarkable relationship with aqueous pH and are to above 90% at pH=1.0-3.0 under studied pH range (pH=1.0-7.0) and increases gradually with increasing Triton X-100 concentration, but decreases slightly with increasing ammonium sulfate concentration. The extraction percentage of tungsten is hardly relevant to temperature but its distribution coefficient linearly increases with increasing temperature within 303.15-343.15K. The distribution coefficient of tungsten increases with the increase of initial tungsten concentration (0.1-3%) and temperature (303.15 K-333.15K). The solubilization capacity of tungsten in Triton X-100 micellar phase is independent of temperature. FT-IR analysis reveals that there is no evident interaction between polytungstate anion and ether oxygen unit in Triton X-100, and DLS analysis indicates that zeta potential of Triton X-100 micellar phase have a little change from positive to negative after extracting tungsten. Based on the above-mentioned results, it can be deduced that polytungstate anions are solubilized in hydrophilic outer shell of Triton X-100 micelles by electrostatic attraction depending on its relatively high hydrophobic nature. The stripping of tungsten is mainly influenced by temperature and can be easily achieved to 95% in single stage stripping. The tungsten (VI) is separated out from solution containing Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Al(III), Cr(III) and Mn(II) under the suitable conditions.

  10. Two-phase velocity measurements around cylinders using particle image velocimetry

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, Y.A.; Philip, O.G.; Schmidl, W.D. [Texas A& M Univ., College Station, TX (United States)] [and others

    1995-09-01

    The particle Image Velocimetry flow measurement technique was used to study both single-phase flow and two-phase flow across a cylindrical rod inserted in a channel. First, a flow consisting of only a single-phase fluid was studied. The experiment consisted of running a laminar flow over four rods inserted in a channel. The water flow rate was 126 cm{sup 3}/s. Then a two-phase flow was studied. A mixture of water and small air bubbles was used. The water flow rate was 378 cm{sup 3}/s and the air flow rate was approximately 30 cm{sup 3}/s. The data are analyzed to obtain the velocity fields for both experiments. After interpretation of the velocity data, forces acting on a bubble entrained by the vortex were calculated successfully. The lift and drag coefficients were calculated using the velocity measurements and the force data.

  11. 水平长直管内油水两相流流动特性实验研究%An Experimental Study on the Flow Characteristics of Oil-Water Two-Phase Flow in Horizontal Straight Pipes

    Institute of Scientific and Technical Information of China (English)

    刘文红; 郭烈锦; 吴铁军; 张西民

    2003-01-01

    The flow patterns and their transitions of oil-water two-phase flow in horizontal pipes were studied. The experiments were conducted in two kinds of horizontal tubes, made of plexiglas pipe and stainless steel pipe with 40 mm ID respectively. No. 46 mechanical oil and tap water were used as working fluids. The superficial velocity ranges of oil and water were: 0.04-1.2 m.s-1 and 0.04-2.2 m.s-1, respectively. The flow patterns were identified by visualization and by transient fluctuation signals of differential pressure drop. The flow patterns were defined according to the relative distribution of oil and water phases in the pipes. Flow pattern maps were obtained for both pipelines. In addition, semi-theoretical transition criteria for the flow patterns were proposed, and the proposed transitional criteria are in reasonable agreement with available data in liquid-liquid systems.

  12. A numerical study of the gas-liquid, two-phase flow maldistribution in the anode of a high pressure PEM water electrolysis cell

    DEFF Research Database (Denmark)

    Olesen, Anders Christian; Rømer, Carsten; Kær, Søren Knudsen

    2016-01-01

    In this work, the use of a circular-planar, interdigitated flow field for the anode of a high pressure proton exchange membrane (PEM) water electrolysis cell is investigated in a numerical study. While PEM fuel cells have separated flow fields for reactant transport and coolant, it is possible...... causes maldistribution, if land areas of equal width are applied. Moreover, below a water stoichiometry of 350, and at a current density of 1 A/cm2, flow and temperature maldistribution is adversely affected by the presence of the gas phase; particularly gas hold-up near outlet channels can cause...... excessive formation of hotspots. As the water stoichiometry increases, the flow maldistribution increases as well. Nonetheless, its impact on the temperature distribution is counterbalanced by an overall increase in heat capacity of the flow. Hence, a relative uniform temperature distribution is achieved...

  13. The effect of water fluoride concentration on dental caries and fluorosis in five Iran provinces: A multi-center two-phase study

    Science.gov (United States)

    Ramezani, Gholamhossein; Valaie, Nasser; Rakhshan, Vahid

    2015-01-01

    Background: Water fluoride level is unknown in many regions of Iran. Besides, only few non-controlled studies world-wide have assessed the effect of water fluoride on dental fluorosis and caries. We aimed to measure the fluoride level of 76 water supplies in 54 cities and evaluate the effect of fluoride on dental caries and fluorosis in a large multi-project study. Materials and Methods: In the first phase (cross-sectional), fluoride levels of 76 water tanks in 54 cities/villages in five provinces of Iran were randomly evaluated in five subprojects. In the second phase (retrospective cohort), 1127 middle school children (563 cohort and 564 control subjects) in the high and low ends of fluoride concentration in each subproject were visited. Their decayed, missing and filled teeth (DMFT) and fluorosis states were assessed. The data were analyzed using Chi-square, Mann-Whitney U and independent-samples t-test (α = 0.05). Results: Mean fluoride level was 0.298 ± 0.340 mg/L in 54 cities/villages. Only eight water tanks had fluoride levels within the normal range and only one was higher than normal and the rest (67 tanks) were all at low levels. Overall, a significant association was observed between fluoride level and fluorosis. However, this was not the case in all areas, as in 2 of 5 provinces, the effect of fluoride on fluorosis was not confirmed. In 4 of the 5 areas studied, there was a significant link between fluoride level and DMFT. Conclusion: Extremely low fluoride levels in Iran cities are an alarming finding and need attention. Higher fluoride is likely to reduce dental caries while increasing fluorosis. This finding was not confirmed in all the areas studied. PMID:25709672

  14. Application of fast neutron radiography to three-dimensional visualization of steady two-phase flow in a rod bundle

    CERN Document Server

    Takenaka, N; Fujii, T; Mizubata, M; Yoshii, K

    1999-01-01

    Three-dimensional void fraction distribution of air-water two-phase flow in a 4x4 rod-bundle near a spacer was visualized by fast neutron radiography using a CT method. One-dimensional cross sectional averaged void fraction distribution was also calculated. The behaviors of low void fraction (thick water) two-phase flow in the rod bundle around the spacer were clearly visualized. It was shown that the void fraction distributions were visualized with a quality similar to those by thermal neutron radiography for low void fraction two-phase flow which is difficult to visualize by thermal neutron radiography. It is concluded that the fast neutron radiography is efficiently applicable to two-phase flow studies.

  15. Two-Phase Flow Hydrodynamics in Superhydrophobic Channels

    Science.gov (United States)

    Stevens, Kimberly; Crockett, Julie; Maynes, Daniel; Iverson, Brian

    2015-11-01

    Superhydrophobic surfaces promote drop-wise condensation and droplet removal leading to the potential for increased thermal transport. Accordingly, great interest exists in using superhydrophobic surfaces in flow condensing environments, such as power generation and desalination. Adiabatic air-water mixtures were used to gain insight into the effect of hydrophobicity on two-phase flows and the hydrodynamics present in flow condensation. Pressure drop and onset of various flow regimes in hydrophilic, hydrophobic, and superhydrophobic mini (0.5 x 10 mm) channels were explored. Data for air/water mixtures with superficial Reynolds numbers from 20-200 and 250-1800, respectively, were obtained. Agreement between experimentally obtained pressure drops and correlations in literature for the conventional smooth control surfaces was better than 20 percent. Transitions between flow regimes for the hydrophobic and hydrophilic channels were similar to commonly recognized flow types. However, the superhydrophobic channel demonstrated significantly different flow regime behavior from conventional surfaces including a different shape of the air slugs, as discussed in the presentation.

  16. Two-phase viscoelastic jetting

    Energy Technology Data Exchange (ETDEWEB)

    Yu, J-D; Sakai, S.; Sethian, J.A.

    2008-12-10

    A coupled finite difference algorithm on rectangular grids is developed for viscoelastic ink ejection simulations. The ink is modeled by the Oldroyd-B viscoelastic fluid model. The coupled algorithm seamlessly incorporates several things: (1) a coupled level set-projection method for incompressible immiscible two-phase fluid flows; (2) a higher-order Godunov type algorithm for the convection terms in the momentum and level set equations; (3) a simple first-order upwind algorithm for the convection term in the viscoelastic stress equations; (4) central difference approximations for viscosity, surface tension, and upper-convected derivative terms; and (5) an equivalent circuit model to calculate the inflow pressure (or flow rate) from dynamic voltage.

  17. Two phase convective heat transfer augmentation in swirl flow with non-boiling

    Energy Technology Data Exchange (ETDEWEB)

    Cha, K.O. [Myong Ji University, Kyonggi-do (Korea, Republic of); Kim, J.G. [Myongji University Graduate School, Kyonggi-do (Korea, Republic of)

    1995-10-01

    Two phase flow phenomena are observed in many industrial facilities and make much importance of optimum design for nuclear power plant and various heat exchangers. This experimental study has been investigated the classification of the flow pattern, the local void distribution and convective heat transfer in swirl and non-swirl two phase flow under the isothermal and nonisothermal conditions. The convective heat transfer coefficients in the single phase water flow were measured and compared with the calculated results from the Sieder-Tate correlation. These coefficients were used for comparisons with the two-phase heat transfer coefficients in the flow orientations. The experimental results indicate, that the void probe signal and probability density function of void distribution can used into classify the flow patterns, no significant difference in voidage distribution was observed between isothermal and non-isothermal condition in non-swirl flow, the values of two phase heat transfer coefficients increase when superficial air velocities increase, and the enhancement of the values is observed to be most pronounced at the highest superficial water velocity in non-swirl flow. Also two phase heat transfer coefficients in swirl flow are increased when the twist ratios are decreased. (author). 13 refs., 15 figs.

  18. Equations of two-phase flow in spray chamber

    Institute of Scientific and Technical Information of China (English)

    李新禹; 张志红; 金星; 徐杰

    2009-01-01

    The downstream water-air heat and moisture transfer system in a moving coordinate was studied. The relationship between the diameter of the misted droplets and the spray pressure was determined. Based on the theory of the relative velocity,the two-phase flow mode of the spray chamber and the efficiency equation for heat and moisture exchange were established. Corrections were carried out for the efficiency equation with spray pressure of 157 kPa. The results show that the pressure plays an important part in determining the efficiency of heat and moisture exchange. When the spray pressure is less than 157 kPa,better coincidence is noticed between the theoretical analysis and the test results with the error less than 6%. Greater error will be resulted in the case when the spray pressure is beyond 157 kPa. After the correction treatment,the coincidence between the theoretical and the experimental results is greatly improved.

  19. The solidification of two-phase heterogeneous materials: Theory versus experiment

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bin; KIM Tongbeum; LU TianJian

    2009-01-01

    The solidification behavior of two-phase heterogeneous materials such as close-celled aluminum foams was analytically studied. The proposed analytical model can precisely predict the location of solidification front as well as the full solidification time for a two-phase heterogeneous material composed of aluminum melt and non-conducting air pores. Experiments using distilled water simulating the aluminum melt to be solidified (frozen) were subsequently conducted to validate the analytical model for two selected porosities (ε), ε=0 and 0.5. Full numerical simulations with the method of finite difference were also performed to examine the influence of pore shape on solidification. The remarkable agreement between theory and experiment suggests that the delay of solidification in the two-phase heterogeneous material is mainly caused by the reduction of bulk thermal conductivity due to the presence of pores, as this is the sole mechanism accounted for by the analytical model for solidification in a porous medium.

  20. Numerical Simulation and Experimental Studies of Air Treatment Process with Water Spray of One Row Parallel Flow

    Institute of Scientific and Technical Information of China (English)

    倪波

    2001-01-01

    The main purpose of the present work is to make a further insight into the procedure of heat and mass transfer between water droplets sprayed and air stream in a direct evaporative air cooler used in air-conditioning system in textile mills. The thermodynamic models of the two-phase flow in such a air treatment system have been developed for one row parallel flow spray.The fields of temperature and relative humidity in spraylchamber, as well as the trajectories of sprayed drops have been obtained by calculation. A series of experiment aiming at quantifying the system performance and its influence factors have been conducted. It indicates that the increases of air velocity and water/air ratio while the decrease of nozzle density are favorable. Finally, the comparison between numerical simulation and experimental results have been carried out. Good agreements have been found for outlet air temperaturewhile a maximum error of 10% has been observed for air relative humidity.

  1. Korea advanced liquid metal reactor development - Development of measuring techniques of the sodium two-phase flow

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Moo Hwan; Cha, Jae Eun [Pohang University of Science and Technology, Pohang (Korea)

    2000-04-01

    The technology which models and measures the behavior of bubble in liquid sodium is very important to insure the safety of the liquid metal reactor. In this research, we designed/ manufactured each part and loop of experimental facility for sodium two phase flow, and applied a few possible methods, measured characteristic of two phase flow such as bubbly flow. A air-water loop similar to sodium loop on each measuring condition was designed/manufactured. This air-water loop was utilized to acquire many informations which were necessary in designing the two phase flow of sodium and manufacturing experimental facility. Before the manufacture of a electromagnetic flow meter for sodium, the experiment using each electromagnetic flow mete was developed and the air-water loop was performed to understand flow characteristics. Experiments for observing the signal characteristics of flow were performed by flowing two phase mixture into the electromagnetic flow mete. From these experiments, the electromagnetic flow meter was designed and constructed by virtual electrode, its signal processing circuit and micro electro magnet. It was developed to be applicable to low conductivity fluid very successfully. By this experiment with the electromagnetic flow meter, we observed that the flow signal was very different according to void fraction in two phase flow and that probability density function which was made by statistical signal treatment is also different according to flow patterns. From this result, we confirmed that the electromagnetic flow meter could be used to understand the parameters of two phase flow of sodium. By this study, the experimental facility for two phase flow of sodium was constricted. Also the new electromagnetic flow meter was designed/manufactured, and experimental apparatus for two phase flow of air-water. Finally, this study will be a basic tool for measurement of two phase flow of sodium. As the fundamental technique for the applications of sodium at

  2. Two-Phase Technology at NASA/Johnson Space Center

    Science.gov (United States)

    Ungar, Eugene K.; Nicholson, Leonard S. (Technical Monitor)

    1999-01-01

    Since the baseline International Space Station (ISS) External Active Thermal Control System (EATCS) was changed from a two-phase mechanically pumped system to a single phase cascade system in the fall of 1993, two-phase EATCS research has continued at a low level at JSC. One of-the lessons of the ISS EATCS selection was that two-phase thermal control systems must have significantly lower power than comparable single phase systems to overcome their larger radiator area, larger line and fluid mass, and perceived higher technical risk. Therefore, research at JSC has concentrated on low power mechanically pumped two-phase EATCSs. In the presentation, the results of a study investigating the trade of single and two-phase mechanically pumped EATCSs for space vehicles will be summarized. The low power two-phase mechanically pumped EATCS system under development at JSC will be described in detail and the current design status of the subscale test unit will be reviewed. Also, performance predictions for a full size EATCS will be presented. In addition to the discussion of two-phase mechanically pumped EATCS development at JSC, two-phase technologies under development for biological water processing will be discussed. These biological water processor technologies are being prepared for a 2001 flight experiment and subsequent usage on the TransHab module on the International Space Station.

  3. INFLUENCE OF FILLING WATER ON AIR CONCENTRATION

    Institute of Scientific and Technical Information of China (English)

    WU Jian-hua; MA Fei; DAI Hui-chao

    2011-01-01

    The filling water inside the cavity below an aerator occurs for the flow of low Froude number or the small bottom slope of a spillway.The aerator may cease to protect against cavitation damages,and may even act as a generator of cavitation if it is fully filled by water.The experiments were conducted to investigate the influences of the geometric parameters,and then the filling water on the air concentration.The results show that the filling water,or the net cavity length,is closely related to the plunging jet length for a given aerator,and the air concentration at some section is proportional to the ratio Ln/Lj at a fixed Lj for different geometric parameters of aerators.Secondly,at the same ratio of Ln / Lj,the aerator with a larger height or a larger angle of ramp,or a larger bottom slope,would have a larger plunging jet length,and then a larger net cavity length based on the ratio of Ln / Lj.As a result,the large space of cavity,or the high air concentration of the flow could be obtained although the filling water increases also based on the fact that Lf=Lj- Ln.It is the space of the cavity that is the dominant factor to affect the air concentration of the flow.

  4. Unitary water-to-air heat pumps

    Energy Technology Data Exchange (ETDEWEB)

    Christian, J.E.

    1977-10-01

    Performance and cost functions for nine unitary water-to-air heat pumps ranging in nominal size from /sup 1///sub 2/ to 26 tons are presented in mathematical form for easy use in heat pump computer simulations. COPs at nominal water source temperature of 60/sup 0/F range from 2.5 to 3.4 during the heating cycle; during the cooling cycle EERs range from 8.33 to 9.09 with 85/sup 0/F entering water source temperatures. The COP and EER values do not include water source pumping power or any energy requirements associated with a central heat source and heat rejection equipment.

  5. Combined air and water pollution control system

    Science.gov (United States)

    Wolverton, Billy C. (Inventor); Jarrell, Lamont (Inventor)

    1990-01-01

    A bioaquatic air pollution control system for controlling both water and atmospheric pollution is disclosed. The pollution control system includes an exhaust for directing polluted gases out of a furnace and a fluid circulating system which circulates fluid, such as waste water, from a source, past the furnace where the fluid flow entrains the pollutants from the furnace. The combined fluid and pollutants are then directed through a rock/plant/microbial filtering system. A suction pump pumps the treated waste water from the filter system past the exhaust to again entrain more pollutants from the furnace where they are combined with the fluid (waste water) and directed to the filter system.

  6. Experimental study on the two phase flow behavior in PEM fuel cell parallel channels with porous media inserts

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jixin [Mechanical and Aerospace Engineering, University of California, Irvine, Irvine, CA 92697-3975 (United States)

    2010-02-15

    In this study, the air-water two phase flow behavior in PEM fuel cell parallel channels with porous media inserts was experimentally investigated using a self-designed and manufactured transparent assembly. The visualization images of the two phase flow in channels with porous media inserts were presented and three patterns were summarized. Compared with the traditional hollow channel design, the novel configuration featured less severe two phase flow mal-distribution and self-adjustment to water amount in channels, although a higher pressure drop was introduced due to the porous media inserts. The dominant frequency of pressure drop signal was found to be a diagnostic tool for water behavior in channels. The novel flow channel design with porous media inserts may become a solution to the water management problem in PEM fuel cells. (author)

  7. Experimental study on the two phase flow behavior in PEM fuel cell parallel channels with porous media inserts

    Science.gov (United States)

    Chen, Jixin

    In this study, the air-water two phase flow behavior in PEM fuel cell parallel channels with porous media inserts was experimentally investigated using a self-designed and manufactured transparent assembly. The visualization images of the two phase flow in channels with porous media inserts were presented and three patterns were summarized. Compared with the traditional hollow channel design, the novel configuration featured less severe two phase flow mal-distribution and self-adjustment to water amount in channels, although a higher pressure drop was introduced due to the porous media inserts. The dominant frequency of pressure drop signal was found to be a diagnostic tool for water behavior in channels. The novel flow channel design with porous media inserts may become a solution to the water management problem in PEM fuel cells.

  8. 超稠油水在倾斜管路中两相流动的研究%Experimental study for high-viscosity-ratio oil-water two-phase flow in inclined pipes

    Institute of Scientific and Technical Information of China (English)

    刘海飞; 黄三平; 许晶禹; 邓晓辉; 罗东红; 张健

    2012-01-01

    通过实验研究了超稠油(在20°C下,密度为860 kg/m3,黏度为1680mPa.s)、水两相在45°倾斜管中流动的流型和两相压降变化规律.倾斜实验段管线由内径50 mm的透明有机玻璃管组成,向上倾斜管段长为4.5 m.通过实验给出了不同入口条件下实验管段的流型图和两相压降图.结果表明:超稠油水两相在管道中流动流型与低黏度比下的流型具有一定的差异,特别在低入口水相流量下,管道内出现了壁面附着一层油膜而管内部为油水相互掺混流动的流型;油水两相压降随着入口含油率的增加而增加,但在较高入口含油率区域,两相压降出现了一个峰值和峰谷的演变过程.%This work presents experimental studies on flow pattern and pressure drop of high-viscosity-ratio oil-water two-phase flow (oil-to-water viscosity ratio of about 1680:1 at 20℃). The test pipelines, the diameter of which is 50 mm, are made of transparent Perspex pipes to enable the visual observation of the oil-water flow pattern and the length of inclined pipes is 4.5 m. The oil-water two-phase flow pattern and pressure drop graphs were obtained from experimental data. The results indicate that the flow pattern of high-viscosity-ratio oil-water flow in inclined pipes presents different flow characteristics comparing with the low-viscosity-ratio oil-water flow, especially when the inlet water flux is low, a new flow pattern described as oil film at the pipe wall and inner dispersion of oil in water was observed; the oil-water pressure drops increase with increasing the inlet oil fraction, and in those high inlet oil fraction area the pressure drops appears a peak-valley relationship.

  9. Comparison of Experimental and Numerical Two-Phase Flows in a Porous Micro-Model

    Directory of Open Access Journals (Sweden)

    Dustin Crandall

    2009-12-01

    Full Text Available Characterizing two-phase flow in porous media is important to provide estimates of sweep efficiency in enhanced oil recovery and storage estimates in potential geological CO2 sequestration repositories. To further the current understanding of two-phase flow in porous media a micro-model of interconnected channels was designed and fabricated using stereolithography to experimentally study gas-liquid flows. This flowcell was created with a wide variability of throat dimensions to represent naturally occurring porous media. Low flow rate experiments of immiscible two-phase drainage were performed within this cell. Additionally, a computational model for analyzing two-phase flows in the same flowcell was developed and used to simulate conditions not possible with our laboratory settings. The computational model was first tested for the identical conditions used in the experimental studies, and was shown to be in good agreement with the experimentally determined fractal dimension of the invading gas structure, time until breakthrough, and fluid saturation. The numerical model was then used to study two-phase air-water flows in flowcells with the same geometry and different gas-liquid-solid contact angles. The percent saturation of air and the motion of the fluids through the cell were found to vary with changes in these parameters. Finally, to simulate flows expected during geologic carbon sequestration, the fluid properties and interface conditions were set to model the flow of CO2 into a brine-saturated porous medium at representative subsurface conditions. The CO2 flows were shown to have larger gas saturations than the previous air into water studies. Thus the accuracy of the computational model was supported by the flowcell experiments, and the computational model extended the laboratory results to conditions not possible with the apparatus used in the experiments.

  10. Liquid–liquid equilibria in the quinary aqueous two-phase system of poly(ethylene glycol) 6000 + sodium sulfate + water in the presence of glucose and ethanol: Experimental investigation and thermodynamic modeling

    Energy Technology Data Exchange (ETDEWEB)

    Hekayati, Javad; Roosta, Aliakbar, E-mail: aa.roosta@sutech.ac.ir; Javanmardi, Jafar

    2016-02-10

    Highlights: • Quinary LLE phase equilibria involving PEG 6000 + Na{sub 2}SO{sub 4} + H{sub 2}O + glucose + ethanol. • Favorable partition coefficients of ethanol and glucose. • Satisfactory correlation of the LLE experimental data with the original NRTL model. • Root mean squared deviations (RMSDs) of less than 0.6%. - Abstract: Extractive fermentation processes involving aqueous two-phase systems (ATPSs) are considered as viable means of overcoming the problems associated with product inhibition. Practical development of these processes requires accurate knowledge of the liquid–liquid equilibrium (LLE) of the ATPS forming components alongside the substrate and product of the fermentation process. In this work, the quinary aqueous two-phase LLE of poly(ethylene glycol) 6000 + sodium sulfate + water in the presence of glucose and ethanol have been experimentally determined at 298.15 K using spectrophotometric methods. The resulting LLE data were then satisfactorily correlated by the non-random two-liquid (NRTL) activity coefficient model based on mass fractions. In doing so, the binary energy interaction parameters of the NRTL activity coefficient model were obtained and reported. Calculated RMS deviations below 0.6% demonstrate that the original NRTL activity coefficient model can accurately correlate the LLE data of the quinary aqueous biphasic system of interest.

  11. Study of Water Turbine′s Gas-Liquid Two-Phase Flow Based Numerical Simulation%基于气液两相流模型的水轮机数值模拟研究进展

    Institute of Scientific and Technical Information of China (English)

    冯俊; 郑源

    2012-01-01

    随着水电站机组容量不断增大和计算机技术的飞速发展,传统的数值模拟手段已不能满足人们对深入分析水轮机性能的要求,因此更贴近实际、结果更准确的基于气液两相流模型的数值模拟越来越受到人们的关注。介绍了气液两相流动的主要计算模型,概述近年来国内外水轮机气液两相流数值模拟进展,重点阐述在其应用于水轮机空化性能、尾水管压力脉动等方面的研究成果和应用前景,并对需要进一步深入研究的问题及研究中应遵循的一些原则作出初步探讨。%With the development of water turbines′ capacity and computer technology,people start to focus on the need for accurate numerical simulation to analyse turbines′ internal flow.The Gas-Liquid two-phase flow model which is closer to actual is now drawing more and more attention from people.This article will be followed by a brief instruction of main Gas-Liquid two-phase flow models and an overview of latest international progress of water turbine′s Gas-Liquid flow based numerical simulation.Details on applications in water turbines′ cavitation and draft tube′s pressure pulsation are described in later sections.Finally,it shows a discussion on problems and methods to solve them.

  12. Simulation and modeling of two-phase bubbly flows

    Energy Technology Data Exchange (ETDEWEB)

    Sylvain L Pigny; Pierre F Coste [DEN/DER/SSTH, CEA/Grenoble, 38054 Grenoble Cedex 9 (France)

    2005-07-01

    Full text of publication follows: Phenomena related to bubbles in two-phase recirculating flows are investigated, via the computational code SIMMER, concerning an experiment in which air is injected in the lower part of a tank filled of water and initially at rest. Averaged mass and momentum transport equations are solved for air and water. Close to the injector, the formation of individual large bubbles is represented in the calculations, via direct simulation. Small scale phenomena, related to small bubbles behavior or turbulence in the liquid continuous phase, are modeled, in a statistical way, via classical closure laws. In a first calculation, the splitting of large bubbles is not represented. It is shown that this phenomenon, the space scale of which is close to the cell size, cannot be simulated, in view of the present computational resources. Nevertheless, relatively fine meshes are used, for an accurate description of hydrodynamical phenomena, and the splitting phenomenon is too large to be modeled via closure laws. A specific approach for the intermediate scales is therefore developed to represent it. (authors)

  13. Unsteady flow analysis of a two-phase hydraulic coupling

    Science.gov (United States)

    Hur, N.; Kwak, M.; Lee, W. J.; Moshfeghi, M.; Chang, C.-S.; Kang, N.-W.

    2016-06-01

    Hydraulic couplings are being widely used for torque transmitting between separate shafts. A mechanism for controlling the transmitted torque of a hydraulic system is to change the amount of working fluid inside the system. This paper numerically investigates three-dimensional turbulent flow in a real hydraulic coupling with different ratios of charged working fluid. Working fluid is assumed to be water and the Realizable k-ɛ turbulence model together with the VOF method are used to investigate two-phase flow inside the wheels. Unsteady simulations are conducted using the sliding mesh technique. The primary wheel is rotating at a fixed speed of 1780 rpm and the secondary wheel rotates at different speeds for simulating different speed ratios. Results are investigated for different blade angles, speed ratios and also different water volume fractions, and are presented in the form of flow patterns, fluid average velocity and also torques values. According to the results, blade angle severely affects the velocity vector and the transmitted torque. Also in the partially-filled cases, air is accumulated in the center of the wheel forming a toroidal shape wrapped by water and the transmitted torque sensitively depends on the water volume fraction. In addition, in the fully-filled case the transmitted torque decreases as the speed ration increases and the average velocity associated with lower speed ratios are higher.

  14. Numerical flow analyses of a two-phase hydraulic coupling

    Energy Technology Data Exchange (ETDEWEB)

    Hur, N.; Kwak, M.; Moshfeghi, M. [Sogang University, Seoul (Korea, Republic of); Chang, C.-S.; Kang, N.-W. [VS Engineering, Seoul (Korea, Republic of)

    2017-05-15

    We investigated flow characteristics in a hydraulic coupling at different charged water conditions and speed ratios. Hence, simulations were performed for three-dimensional two-phase flow by using the VOF method. The realizable k-ε turbulence model was adopted. To resolve the interaction of passing blades of the primary and secondary wheels, simulations were conducted in the unsteady framework using a sliding grid technique. The results show that the water-air distribution inside the wheel is strongly dependent upon both amount of charged water and speed ratio. Generally, air is accumulated in the center of the wheel, forming a toroidal shape wrapped by the circulating water. The results also show that at high speed ratios, the solid-body-like rotation causes dry areas on the periphery of the wheels and, hence, considerably decreases the circulating flow rate and the transmitted torque. Furthermore, the momentum transfer was investigated through the concept of a mass flux triangle based on the local velocity multiplied by the local mixture density instead of the velocity triangle commonly used in a single-phase turbomachine analysis. Also, the mass fluxes along the radius of the coupling in the partially charged and fully charged cases were found to be completely different. It is shown that the flow rate at the interfacial plane and also the transmitted torque are closely related and are strongly dependent upon both the amount of charged water and speed ratio. Finally, a conceptual categorization together with two comprehensive maps was provided for the torque transmission and also circulating flow rates. These two maps in turn exhibit valuable engineering information and can serve as bases for an optimal design of a hydraulic coupling.

  15. Two Phase Flow Mapping and Transition Under Microgravity Conditions

    Science.gov (United States)

    Parang, Masood; Chao, David F.

    1998-01-01

    In this paper, recent microgravity two-phase flow data for air-water, air-water-glycerin, and air- water-Zonyl FSP mixtures are analyzed for transition from bubbly to slug and from slug to annular flow. It is found that Weber number-based maps are inadequate to predict flow-pattern transition, especially over a wide range of liquid flow rates. It is further shown that slug to annular flow transition is dependent on liquid phase Reynolds number at high liquid flow rate. This effect may be attributed to growing importance of liquid phase inertia in the dynamics of the phase flow and distribution. As a result a new form of scaling is introduced to present data using liquid Weber number based on vapor and liquid superficial velocities and Reynolds number based on liquid superficial velocity. This new combination of the dimensionless parameters seem to be more appropriate for the presentation of the microgravity data and provides a better flow pattern prediction and should be considered for evaluation with data obtained in the future. Similarly, the analysis of bubble to slug flow transition indicates a strong dependence on both liquid inertia and turbulence fluctuations which seem to play a significant role on this transition at high values of liquid velocity. A revised mapping of data using a new group of dimensionless parameters show a better and more consistent description of flow transition over a wide range of liquid flow rates. Further evaluation of the proposed flow transition mapping will have to be made after a wider range of microgravity data become available.

  16. INFLUENCE OF SURFACTANT ON TWO-PHASE FLOW REGIME AND PRESSURE DROP IN UPWARD INCLINED PIPES

    Institute of Scientific and Technical Information of China (English)

    XIA Guo-dong; CHAI Lei

    2012-01-01

    The influence of a surfactant on the two-phase flow regime and the pressure drop in upward inclined pipes is investigated for various gas/liquid flow rates.The air/water and air/100 ppm sodium dodecyl sulphate aqueous solution are used as the working fluids.The influence of the surfactant on the two-phase flow regime in upward inclined pipes is investigated using the electrical tomographic technique.For 0°,2.5° and 5° pipe inclinations,the surfactant has obvious effect on the transition from the stratified wavy flow to the annular flow,and the range of the stratified smooth flow regime is also extended to higher gas velocities.For 10°pipe inclination,no stratified flow regime is observed in the air/water flow.In the air/surfactant solution system,however,the stratified flow regime can be found in the range of USG =10m/s-28m/s and USL =0.07 m/s-0.2 m/s.For all inclination angles,the changes of the pressure gradient characteristics are accompanied with the flow pattern transitions.Adding surfactant in a two-phase flow would reduce the pressure gradient significantly in the slug flow and annular flow regimes.In the annular flow regime,the pressure gradient gradually becomes free of the influence of the upward inclined angle,and is only dependent on the property of the two-phase flow.

  17. Emerging Two-Phase Cooling Technologies for Power Electronic Inverters

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, J.S.

    2005-08-17

    In order to meet the Department of Energy's (DOE's) FreedomCAR and Vehicle Technologies (FVCT) goals for volume, weight, efficiency, reliability, and cost, the cooling of the power electronic devices, traction motors, and generators is critical. Currently the power electronic devices, traction motors, and generators in a hybrid electric vehicle (HEV) are primarily cooled by water-ethylene glycol (WEG) mixture. The cooling fluid operates as a single-phase coolant as the liquid phase of the WEG does not change to its vapor phase during the cooling process. In these single-phase systems, two cooling loops of WEG produce a low temperature (around 70 C) cooling loop for the power electronics and motor/generator, and higher temperature loop (around 105 C) for the internal combustion engine. There is another coolant option currently available in automobiles. It is possible to use the transmission oil as a coolant. The oil temperature exists at approximately 85 C which can be utilized to cool the power electronic and electrical devices. Because heat flux is proportional to the temperature difference between the device's hot surface and the coolant, a device that can tolerate higher temperatures enables the device to be smaller while dissipating the same amount of heat. Presently, new silicon carbide (SiC) devices and high temperature direct current (dc)-link capacitors, such as Teflon capacitors, are available but at significantly higher costs. Higher junction temperature (175 C) silicon (Si) dies are gradually emerging in the market, which will eventually help to lower hardware costs for cooling. The development of high-temperature devices is not the only way to reduce device size. Two-phase cooling that utilizes the vaporization of the liquid to dissipate heat is expected to be a very effective cooling method. Among two-phase cooling methods, different technologies such as spray, jet impingement, pool boiling and submersion, etc. are being developed. The

  18. Air-Water Gas Transfer in Coastal Waters

    Science.gov (United States)

    2016-06-07

    OBJECTIVES In interdisciplinary field experiments the influence of wind forcing, short wind waves, and surfactants on the air-sea gas transfer in coastal...Physicochemical surface conditions ranged from coastal waters with high surfactant concentrations to very clean, deep blue waters close to the Bermuda islands...research project are only the beginning of a new interdisciplinary research area that merges chemistry , applied optics, fluid mechanics, and image

  19. Application of Cross-C orrelation and Calorimetry in Meas urement of Qil-Water Two Phase Flow%相关分析及量热法在油水两相流测量中的应用

    Institute of Scientific and Technical Information of China (English)

    何安定; 李斌; 周芳德; 任长春

    2000-01-01

    用相关分析及量热法相结合用于油水两相流测量,并进行了相应的理论分析和试验研究。利用上下游温升的相关性测量总流流量,再用量热法来测量油水比,从而得到油水两相的各自流量。同时,在以前研究的基础上对实验段进行了必要的改进。结果表明,这有利于提高测量精度。%Cross-correlation and calorimetry were applied in the measurement of oil-water two phase flow. The tot al flow rate was calculated from t he correlativity between two tempe rature probes, and the oil-water r atio was got by means of calorimetry. Thus the flow rate for oil and water was obtained respectively. Moreover, the test segment was imp roved based on the previous studies. And the result showed that the accuracy was improved greatly.

  20. Anomalous Effects in Air While Cooling Water

    CERN Document Server

    Sardo, Rachel

    2008-01-01

    Water is a unique compound with many anomalies and properties not fully understood. Designing an experiment in the laboratory to study such anomalies, we set up a series of experiments where a tube was placed inside a sealed container with thermocouples attached to the outer surface of the tube and in the air adjacent to the tube. Alternately, deionized water and other compounds were added to the tube and cooled to freezing. Several of the thermocouples suspended in the air and adjacent to the tube showed thermal oscillations as the overall temperature of the container was decreasing. The temperature of the thermocouples increased and decreased in a sinusoidal way during part of the cool down to freezing. Thermal oscillations as large as 3 degrees Celsius were recorded with typical frequencies of about 5 oscillations per minute.

  1. 磨料射流固液两相流场的数值模拟%Numerical simulation of liquid-solid two phase flow field for abrasive water jet

    Institute of Scientific and Technical Information of China (English)

    张永利; 于欢; 马玉林

    2011-01-01

    为了解决磨料射流固、液两相流场运动对割缝效果的影响问题,采用数值模拟的方法,通过建立磨料射流固、液两相流场的数学模型,研究了磨料两相射流割缝的速度场和流动场规律。结果表明:磨料射流中割缝速度可达100 m/s左右,有利于有效割缝;有效割缝需要入射压力至少达到25 Mpa;磨料射流割缝过程中会形成了一道“水墙,,阻止磨料射流全部高速射出。产生二次回流。虽然二次加速的效果有限,但二次循环的水和颗粒经过二次加速能够再一次对壁面形成高速打击,提高割缝效率。研究成果对磨料两相射流割缝提高油井采收率具有指导意义。%In order to understand the impact on abrasive hydraulic slotting by liquid-solid two phase flow field, this study has developed a mathematical model of liquid-solid two phase flow field for abrasive water jet, and investigated the velocity field and fluid field of abrasive hydraulic slotting. The study shows that the cutting speed using abrasive water jet can reach approaximately 100 m/s, which is benefical to slot cutting. The incident pressure for an effective slotting is at least 25Mpa. A "water wall" will be formed during the abrasive hydraulic slotting which arrests the high-speed abrasive granules, engender the secondary reverse current. Although the effect of the second acceleration were limited, the recirculate water and granules engender hypervelocity impact on wall face by the second acceleration, which can increase the efficiency of slotting. The findings in this study can provide a guide for improving oil recovery using abrasive hydraulic slotting.

  2. Air expansion in the water rocket

    CERN Document Server

    Romanelli, Alejandro; Madina, Federico González

    2012-01-01

    We study the thermodynamics of the water rocket in the thrust phase, taking into account the expansion of the air with water vapor, vapor condensation and the energy taken from the environment. We set up a simple experimental device with a stationary bottle and verified that the gas expansion in the bottle is well approximated by a polytropic process $PV^\\beta$= constant, where the parameter $\\beta$ depends on the initial conditions. We find an analytical expression for $\\beta $ that only depends on the thermodynamic initial conditions and is in good agreement with the experimental results.

  3. 14 CFR 1260.34 - Clean air and water.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Clean air and water. 1260.34 Section 1260... AGREEMENTS General Provisions § 1260.34 Clean air and water. Clean Air and Water October 2000 (Applicable... the Clean Air Act (42 U.S.C. 1857c-8(c)(1) or the Federal Water Pollution Control Act (33 U.S.C....

  4. Numerical simulation of two-phase flow in offshore environments

    NARCIS (Netherlands)

    Wemmenhove, Rik

    2008-01-01

    Numerical Simulation of Two-Phase Flow in Offshore Environments Rik Wemmenhove Weather conditions on full sea are often violent, leading to breaking waves and lots of spray and air bubbles. As high and steep waves may lead to severe damage on ships and offshore structures, there is a great need for

  5. Dynamics of a two-phase flow through a minichannel: Transition from churn to slug flow

    Science.gov (United States)

    Górski, Grzegorz; Litak, Grzegorz; Mosdorf, Romuald; Rysak, Andrzej

    2016-04-01

    The churn-to-slug flow bifurcations of two-phase (air-water) flow patterns in a 2mm diameter minichannel were investigated. With increasing a water flow rate, we observed the transition of slugs to bubbles of different sizes. The process was recorded by a digital camera. The sequences of light transmission time series were recorded by a laser-phototransistor sensor, and then analyzed using the recurrence plots and recurrence quantification analysis (RQA). Due to volume dependence of bubbles velocities, we observed the formation of periodic modulations in the laser signal.

  6. Advanced Gastric Cancer: Differentiation of Borrmann Type IV versus Borrmann Type III by Two-Phased Dynamic Multi-Detector Row CT with Use of the Water Filling Method

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dae Jung; Yu, Jeong Sik; Lee, Sang Min; Kim, Joo Hee; Chung, Jae Joon; Kim, Ki Whang [Dept. of Radiology, Yonsei University College of Medicine, Gangnam Severance Hospital, Seoul (Korea, Republic of); Kang, Hae Youn [CHA Bundang Medical Center, CHA University, Seongnam (Korea, Republic of)

    2013-02-15

    To characterize Borrmann type IV from Borrmann type III advanced gastric cancer (AGC) by two-phased multi-detector row computed tomography (MDCT) using the water filling method. A total of 143 patients (pathologically confirmed Borrmann type III and IV - 100 and 43 patients), who underwent preoperative MDCT, were enrolled. Two radiologists, retrospectively and independently, determined tumor enhancement pattern using a 5-grade scale without clinical information. A weighted kappa test was applied for interobserver variability. The score of tumor enhancement pattern correlated with Borrmann type as determined by Spearman's correlation coefficient. The accuracy of differentiation of Borrmann type using MDCT was determined by receiver operating characteristic curves. Interobserver agreement (weighted kappa = 0.683) was substantial. The tumor enhancement pattern score showed a significant correlation with Borrmann type (reviewer 1, r = 0.591, p < 0.001; reviewer 2, r = 0.616, p < 0.001). The accuracy for differentiation of Borrmann type on MDCT was 0.86 (p < 0.001) in both reviewers. The sensitivity and specificity of the diagnosis of Borrmann type IV were 79% and 82% in reviewer 1, and 88% and 78% in reviewer 2, respectively. Dual-phased MDCT using the water filling method can differentiate between Borrmann type IV and III AGC with high accuracy.

  7. Two-phase flows during draining of liquefied gases initially undersaturated. Validation by water and CFC11; Ecoulements diphasiques lors de la vidange de gaz liquifies initialement sous satures. Validation par l`eau et le CFC11

    Energy Technology Data Exchange (ETDEWEB)

    May, L.

    1996-12-11

    In petroleum industry, the safety studies require to estimate the two-phase flow during accidental draining of pressurized liquefied gas storages. Meanwhile the mass flow strongly depends of initial conditions. Then it is primordial to be able to reckon it in the case where it is the highest, that is to say when the fluid is initially undersaturated. An experimental installation has been carried out. The used fluids are water and CFC11. The experimental measures show that the thermodynamic conditions at the inlet of the pipe (P at +/- 15 mbar and T at +/- 0.15 degrees Celsius) are well controlled. The measured mass flows are compared to different models. The frictions in the monophase domain have been taken into account. It has been shown that the extensive H.E.M. model perfectly estimates the mass flow (as well as for water than for CFC11) for large deviations to saturation. In order to correctly predict the domain of weak variation to saturation, D.E.M. (out of equilibrium) models or H.R.M. (homogeneous model of relaxation) models have to be used. (O.M.) 50 refs.

  8. Steam-air mixture condensation in a subcooled water pool

    Science.gov (United States)

    Norman, Timothy Linhurst

    2007-12-01

    In any conceptual reactor design under postulated accidental conditions, one parameter that is considered as being highly ranked in determining the thermal-hydraulic conditions of the reactor safety components is the system pressure. To obtain a satisfactory prediction of steam partial pressure, within reasonable uncertainty in the gas space of a confined SP (suppression pool) bounded to the steam source of the break flow, one must establish a means by which local phenomena associated with steam direct contact condensation in the subcooled water pool can be fully addressed to predict the global component thermal response. For this purpose a scaled down, reduced pressure, suppression pool was designed and built to study condensation and mixing phenomena. The scaled test facility represented an idealized trapezoidal cross section, 1/10 sector of the SP with scaled height ratio of 1/4.5 and volume ratio of 1/400. The design and test conditions were based on a hierarchical scaling principle that preserves the transfer of mass, momentum, energy and condensation phenomena. Distributed thermocouples within the pool provided a means to quantify the pool thermal response. The test loop was not only instrumented with thermocouples for monitoring pool stratification but also with high speed photography for flow visualization from which to build a comprehensive database to identify the regions of the pool that were thermally stratified or mixed. Data were obtained for different pool initial subcooling and steam/air mixture flow rates. Dimensionless boundary maps were plotted from several experimental runs of pure steam injection to determine conditions when the pool transits from being homogeneously mixed to being thermally stratified. Steam-air mixture injection cases for single horizontal venting indicated that above a pool temperature of 40°C with airmass flow rates below 0.1 g/s the pool can attain thermal stratification. Models of a single phase liquid

  9. Electrical Capacitance Probe Characterization in Vertical Annular Two-Phase Flow

    Directory of Open Access Journals (Sweden)

    Grazia Monni

    2013-01-01

    Full Text Available The paper presents the experimental analysis and the characterization of an electrical capacitance probe (ECP that has been developed at the SIET Italian Company, for the measurement of two-phase flow parameters during the experimental simulation of nuclear accidents, as LOCA. The ECP is used to investigate a vertical air/water flow, characterized by void fraction higher than 95%, with mass flow rates ranging from 0.094 to 0.15 kg/s for air and from 0.002 to 0.021 kg/s for water, corresponding to an annular flow pattern. From the ECP signals, the electrode shape functions (i.e., the signals as a function of electrode distances in single- and two-phase flows are obtained. The dependence of the signal on the void fraction is derived and the liquid film thickness and the phase’s velocity are evaluated by means of rather simple models. The experimental analysis allows one to characterize the ECP, showing the advantages and the drawbacks of this technique for the two-phase flow characterization at high void fraction.

  10. Test and Analysis on Flow Field in A Two-Phase Flow Water-Sediment Separation Device by PIV Techniques%两相流水沙分离鳃流场的PIV测试及分析

    Institute of Scientific and Technical Information of China (English)

    赵丽娜; 邱秀云; 陈铂; 邹强

    2012-01-01

    利用粒子图像测速技术,测试了两种工况下垂向异重流式水沙分离鳃中水沙两相流的速度场,给出了分离鳃内泥沙运动的流速矢量分布图、流速云图及三维流场分布图.对测试结果的分析表明,分离鳃内部形成了泥沙沿鳃片上表面向下运动,清水沿鳃片下表面向上运动的垂向异重流现象,加速了泥沙的下沉.此分析结果与实际观察现象及理论分析一致,进一步探明了分离鳃的水沙分离机理.%A Particle Image Velocimetry (short for PIV) technology was used to test the velocity field of water-sediment two-phase flow in a vertical-component density flow water-sediment separation device under two working conditions, and the distribution map of velocity vector of sediment movement in separation device,cloud atlas of velocity and distribution map of three-dimentional flow field were presented. Analysis of the test results indicated that a vertical-component density flow was formed in the separation device,and its phenomena was follows as-the sediment moved down along the upper surface of the gill slice and the water moved up along the undersurface oppositely. This analysis result was in accordance with the real observed phenomena and the theoretical analysis result, which further proved the separation mechanism of water and sediment in the separation device.

  11. Two Phase Technology Development Initiatives

    Science.gov (United States)

    Didion, Jeffrey R.

    1999-01-01

    Three promising thermal technology development initiatives, vapor compression thermal control system, electronics cooling, and electrohydrodynamics applications are outlined herein. These technologies will provide thermal engineers with additional tools to meet the thermal challenges presented by increased power densities and reduced architectural options that will be available in future spacecraft. Goddard Space Flight Center and the University of Maryland are fabricating and testing a 'proto- flight' vapor compression based thermal control system for the Ultra Long Duration Balloon (ULDB) Program. The vapor compression system will be capable of transporting approximately 400 W of heat while providing a temperature lift of 60C. The system is constructed of 'commercial off-the-shelf' hardware that is modified to meet the unique environmental requirements of the ULDB. A demonstration flight is planned for 1999 or early 2000. Goddard Space Flight Center has embarked upon a multi-discipline effort to address a number of design issues regarding spacecraft electronics. The program addressed the high priority design issues concerning the total mass of standard spacecraft electronics enclosures and the impact of design changes on thermal performance. This presentation reviews the pertinent results of the Lightweight Electronics Enclosure Program. Electronics cooling is a growing challenge to thermal engineers due to increasing power densities and spacecraft architecture. The space-flight qualification program and preliminary results of thermal performance tests of copper-water heat pipes are presented. Electrohydrodynamics (EHD) is an emerging technology that uses the secondary forces that result from the application of an electric field to a flowing fluid to enhance heat transfer and manage fluid flow. A brief review of current EHD capabilities regarding heat transfer enhancement of commercial heat exchangers and capillary pumped loops is presented. Goddard Space Flight

  12. Implementation of the interfacial area transport equation in trace for boiling two-phase flows

    Science.gov (United States)

    Bernard, Matthew S.

    Correctly predicting the interfacial area concentration (a i) is vital to the overall accuracy of the two-fluid model because ai describes the amount of surface area that exists between the two-phases, and is therefore directly related to interfacial mass, momentum and energy transfer. The conventional method for specifying ai in the two-fluid model is through flow regime-based empirical correlations coupled with regime transition criteria. However, a more physically consistent approach to predicting ai is through the interfacial area transport equation (IATE), which can address the deficiencies of the flow regime-based approach. Some previous studies have been performed to demonstrate the feasibility of IATE in developmental versions of the nuclear reactor systems analysis code, TRACE. However, a full TRACE version capable of predicting boiling two-phase flows with the IATE has not been established. Therefore, the current work develops a version of TRACE that is capable of predicting boiling two-phase flows using the IATE. The development is carried out in stages. First, a version of TRACE which employs the two-group IATE for adiabatic, vertical upward, air-water conditions is developed. An in-depth assessment on the existing experimental database is performed to select reliable experimental data for code assessment. Then, the implementation is assessed against the qualified air-water two-phase flow experimental data. Good agreement is observed between the experimental data for ai and the TRACE code with an average error of +/-9% for all conditions. Following the initial development, one-group IATE models for vertical downward and horizontal two-phase flows are implemented and assessed against qualified data. Finally, IATE models capable of predicting subcooled boiling two-phase flows are implemented. An assessment of the models shows that TRACE is capable of generating ai in subcooled boiling two-phase flows with the IATE and that heat transfer effects dominate

  13. Sensitivity study of poisson corruption in tomographic measurements for air-water flows

    Energy Technology Data Exchange (ETDEWEB)

    Munshi, P. (Fraunhofer Institute for Nondestructive Testing, Saarbrucken (Germany)); Vaidya, M.S. (Indian Institute of Technology, Kanpur (India))

    1993-01-01

    An application of computerized tomography (CT) for measuring void fraction profiles in two-phase air-water flows was reported earlier. Those attempts involved some special radial methods for tomographic reconstruction and the popular convolution backprojection (CBP) method. The CBP method is capable of reconstructing void profiles for nonsymmetric flows also. In this paper, we investigate the effect of corrupted CT data for gamma-ray sources and aCBP algorithm. The corruption in such a case is due to the statistical (Poisson) nature of the source.

  14. Visualization and research of gas-liquid two phase flow structures in cylindrical channel

    Directory of Open Access Journals (Sweden)

    Stefański Sebastian

    2017-01-01

    Full Text Available Two-phase flows are commonly found in many industries, especially in systems, where efficient and correct functioning depend on specific values of flow parameters. In thermal engineering and chemical technology the most popular types of two-phase mixture are gas-liquid or liquid-vapour mixtures. Bubbles can create in flow different structures and determine diverse properties of flow (velocity of phase, void fraction, fluctuations of pressure, pipe vibrations, etc.. That type of flow is difficult to observe, especially in liquid-vapour mixture, where vapour is being made by heating the medium. Production of vapour and nucleation process are very complicated issues, which are important part of two-phase flow phenomenon. Gas-liquid flow structures were observed and described with figures, but type of structure depends on many parameters. Authors of this paper made an attempt to simulate gas-liquid flow with air and water. In the paper there was presented specific test stand built to observe two-phase flow structures, methodology of experiment and conditions which were maintained during observation. The paper presents also the structures which were observed and the analysis of results with reference to theoretical models and diagrams available in literature.

  15. Photodetoxification and purification of water and air

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, M. [Univ. of Wisconsin, Madison, WI (United States); Blake, D.M. [National Renewable Energy Lab., Golden, CO (United States)

    1996-09-01

    The scope of interest in this section is basic research in photochemistry that can remove barriers to the development of photochemical technologies for the removal of hazardous chemicals from contaminated air or water (photodetoxification). Photochemistry is be broadly interpreted to include direct photochemistry, indirect photochemistry (sensitized and photocatalytic), photochemistry of species adsorbed on inert surfaces, and complementary effects of high energy radiation photons and particles. These may occur in either homogeneous or heterogeneous media. The photon source may span the range from ionizing radiation to the near infrared.

  16. Simulating confined swirling gas-solid two phase jet

    Institute of Scientific and Technical Information of China (English)

    金晗辉; 夏钧; 樊建人; 岑可法

    2002-01-01

    A k-ε-kp multi-fluid model was used to simulate confined swirling gas-solid two phase jet comprised of particle-laden flow from a center tube and a swirling air stream entering the test section from the coaxial annular. After considering the drag force between the two phases and gravity, a series of numerical simulations of the two-phase flow of 30μm, 45μm, 60μm diameter particles were performed on a x×r=50×50 mesh grid respectively. The results showed that the k-ε-kp multi-fluid model can be applied to predict moderate swirling multi-phase flow. When the particle diameter is large, the collision of the particles with the wall will influence the prediction accuracy. The bigger the diameter of the particles, the stronger the collision with the wall, and the more obvious the difference between measured and calculated results.

  17. Two-phase flow patterns in adiabatic and diabatic corrugated plate gaps

    Science.gov (United States)

    Polzin, A.-E.; Kabelac, S.; de Vries, B.

    2016-09-01

    Correlations for two-phase heat transfer and pressure drop can be improved considerably, when they are adapted to specific flow patterns. As plate heat exchangers find increasing application as evaporators and condensers, there is a need for flow pattern maps for corrugated plate gaps. This contribution presents experimental results on flow pattern investigations for such a plate heat exchanger background, using an adiabatic visualisation setup as well as a diabatic setup. Three characteristic flow patterns were observed in the considered range of two-phase flow: bubbly flow, film flow and slug flow. The occurrence of these flow patterns is a function of mass flux, void fraction, fluid properties and plate geometry. Two different plate geometries having a corrugation angle of 27° and 63°, respectively and two different fluids (water/air and R365mfc liquid/vapor) have been analysed. A flow pattern map using the momentum flux is presented.

  18. Numerical Simulation and Experimental Studies of Air Treatment Process with Water Spray of One Row Counter Flow

    Institute of Scientific and Technical Information of China (English)

    倪波

    2001-01-01

    The present work is focused on heat and mass transfer in a direct evaporative air cooler of one row counter flow spray. Models of the two-phase flow in such a air treatment system have been developed. The fields of temperature and relative humidity in spray chamber, as well as the trajectories of sprayed drops have been obtained by numerical method. Experiments aiming at quantifying the system performance and its influence factors have been conducted. It indicates that the increase of air velocity and water/air ratio while the decrease of nozzle density are favorable. The performance of the system of parallel flow spray and counter flow spray have been compared by means of humidifying efficiency. Comparison between numerical simulation and experimental results demonstrate good agreement for outlet air temperature with a maximum error of 8% observed for air relative humidity.

  19. 发电厂除灰泵浆体水击压强的计算与分析%The Calculation and Analysis of Water-hammer of Liquid-Solid Two -Phase Flow for Ash-Water Pump in Steam Power Plant

    Institute of Scientific and Technical Information of China (English)

    周云龙; 孙斌; 蒋诚

    2001-01-01

    The calculations and analysis on water hammer pressure of liquid-solid two-phase flow and the round velocity of turning back of the pump on ash-water pump in st e am power plant have been done. Based on the calculation results, some protection s against water-hammer for ash-water pump have been presented.%对某电厂除灰泵进行了浆体水击压强及反向转速的计算与分析,根据计算结果提出了除灰泵的水击防护措施。

  20. Priming procedure for a two-phase water thermosyphon starting from the frozen state; Procedure de demarrage d`un thermosiphon diphasique a eau a partir de l`etat gele

    Energy Technology Data Exchange (ETDEWEB)

    Sartre, V.; Lallemand, M. [Institut National des Sciences Appliquees (INSA), 69 - Villeurbanne (France)

    1996-12-31

    Heat pipe systems have been developed for the cooling of power electronics components used in railway applications. These systems must ensure a temperature lower than 125 deg. C at the component junctions in various functioning conditions. The aim of this work is to study the priming of a frozen water heat pipe made of 7 copper pipes with condensers connected by common flanges and cooled by forced air convection. Tests were performed under a -33 deg. C initial ambient temperature, a 5 m/s air speed and a 3 kW power. A priming procedure has been developed which allows to reach a reproducible stationary state without exceeding the maximum admissible junction temperature. This procedure consists in a delayed start-up of the ventilation system using the temperature instruction. (J.S.) 7 refs.

  1. High-frame rate, fast neutron imaging of two-phase flow in a thin rectangular channel

    CERN Document Server

    Zboray, R; Dangendorf, V; Stark, M; Tittelmeier, K; Cortesi, M; Adams, R

    2015-01-01

    We have demonstrated the feasibility of performing high-frame-rate, fast neutron radiography of air-water two-phase flows in a thin channel with rectangular cross section. The experiments have been carried out at the accelerator facility of the Physikalisch-Technische Bundesanstalt. A polychromatic, high-intensity fast neutron beam with average energy of 6 MeV was produced by 11.5 MeV deuterons hitting a thick Be target. Image sequences down to 10 millisecond exposure times were obtained using a fast-neutron imaging detector developed in the context of fast-neutron resonance imaging. Different two-phase flow regimes such as bubbly slug and churn flows have been examined. Two phase flow parameters like the volumetric gas fraction, bubble size and bubble velocities have been measured. The first results are promising, improvements for future experiments are also discussed.

  2. Food-Growing, Air- And Water-Cleaning Module

    Science.gov (United States)

    Sauer, R. L.; Scheld, H. W.; Mafnuson, J. W.

    1988-01-01

    Apparatus produces fresh vegetables and removes pollutants from air. Hydroponic apparatus performs dual function of growing fresh vegetables and purifying air and water. Leafy vegetables rooted in granular growth medium grow in light of fluorescent lamps. Air flowing over leaves supplies carbon dioxide and receives fresh oxygen from them. Adaptable to production of food and cleaning of air and water in closed environments as in underwater research stations and submarines.

  3. Two-phase flow studies. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kestin, J.; Maeder, P.F.

    1980-08-01

    Progress on the following is reported: literature survey, design of two-phase flow testing facility, design of nozzle loop, thermophysical properties, design manual, and advanced energy conversion systems. (MHR)

  4. Coal-Face Fracture With A Two-Phase Liquid

    Science.gov (United States)

    Collins, E. R., Jr.

    1985-01-01

    In new method for mining coal without explosive, two-phase liquid such as CO2 and water, injected at high pressure into deeper ends of holes drilled in coal face. Liquid permeates coal seam through existing microfractures; as liquid seeps back toward face, pressure eventually drops below critical value at which dissolved gas flashvaporizes, breaking up coal.

  5. Two-phase flow in micro and nanofluidic devices

    NARCIS (Netherlands)

    Shui, Lingling

    2009-01-01

    This thesis provides experimental data and theoretical analysis on two-phase flow in devices with different layouts of micrometer or nanometer-size channels. A full flow diagram is presented for oil and water flow in head-on microfluidic devices. Morphologically different flow regimes (dripping, jet

  6. Two-phase distribution in the vertical flow line of a domestic wet central heating system

    Directory of Open Access Journals (Sweden)

    Ge Y.T.

    2013-04-01

    Full Text Available The theoretical and experimental aspects of bubble distribution in bubbly two-phase flow are reviewed in the context of the micro bubbles present in a domestic gas fired wet central heating system. The latter systems are mostly operated through the circulation of heated standard tap water through a closed loop circuit which often results in water supersaturated with dissolved air. This leads to micro bubble nucleation at the primary heat exchanger wall, followed by detachment along the flow. Consequently, a bubbly two-phase flow characterises the flow line of such systems. The two-phase distribution across the vertical and horizontal pipes was measured through a consideration of the volumetric void fraction, quantified through photographic techniques. The bubble distribution in the vertical pipe in down flow conditions was measured to be quasi homogenous across the pipe section with a negligible reduction in the void fraction at close proximity to the pipe wall. Such a reduction was more evident at lower bulk fluid velocities.

  7. Two-phase distribution in the vertical flow line of a domestic wet central heating system

    Science.gov (United States)

    Fsadni, A.-M.; Ge, Y. T.

    2013-04-01

    The theoretical and experimental aspects of bubble distribution in bubbly two-phase flow are reviewed in the context of the micro bubbles present in a domestic gas fired wet central heating system. The latter systems are mostly operated through the circulation of heated standard tap water through a closed loop circuit which often results in water supersaturated with dissolved air. This leads to micro bubble nucleation at the primary heat exchanger wall, followed by detachment along the flow. Consequently, a bubbly two-phase flow characterises the flow line of such systems. The two-phase distribution across the vertical and horizontal pipes was measured through a consideration of the volumetric void fraction, quantified through photographic techniques. The bubble distribution in the vertical pipe in down flow conditions was measured to be quasi homogenous across the pipe section with a negligible reduction in the void fraction at close proximity to the pipe wall. Such a reduction was more evident at lower bulk fluid velocities.

  8. Two-phase flow and boiling heat transfer in two vertical narrow annuli

    Energy Technology Data Exchange (ETDEWEB)

    Peng Changhong [Department of Nuclear and Thermal Power Engineering, Xi' an Jiaotong University, Xian 710049 (China)]. E-mail: pxm321@163.com; Guo Yun [Department of Nuclear and Thermal Power Engineering, Xi' an Jiaotong University, Xian 710049 (China); Qiu Suizheng [Department of Nuclear and Thermal Power Engineering, Xi' an Jiaotong University, Xian 710049 (China); Jia Dounan [Department of Nuclear and Thermal Power Engineering, Xi' an Jiaotong University, Xian 710049 (China); Nie Changhua [Nuclear Power Institute of China, Chengdu 610041 (China)

    2005-07-01

    Experimental study associated with two-phase flow and heat transfer during flow boiling in two vertical narrow annuli has been conducted. The parameters examined were: mass flux from 38.8 to 163.1 kg/m{sup 2} s; heat flux from 4.9 to 50.7 kW/m{sup 2} for inside tube and from 4.2 to 78.8 kW/m{sup 2} for outside tube; equilibrium mass quality from 0.02 to 0.88; system pressure from 1.5 to 6.0 MPa. It was found that the boiling heat transfer was strongly influenced by heat flux, while the effect of mass velocity and mass quality were not very significant. This suggested that the boiling heat transfer was mainly via nucleate boiling. The data were used to develop a new correlation for boiling heat transfer in the narrow annuli. In the two-phase flow study, the comparison with the correlation of Chisholm [Chisholm, D., 1967. A theoretical basis for the Lockhart-Martinelli correlation for two-phase flow. Int. J. Heat Mass Transfer 10, 1767-1778] and Mishima and Hibiki [Mishima, K., Hibiki, T., 1996. Some characteristics of air-water two-phase flow in small diameter vertical tubes. Int. J. Multiphase Flow 22, 703-712] indicated that the existing correlations could not predict the two-phase multiplier in the narrow annuli well. Based on the experimental data, a new correlation was developed.

  9. Numerical simulation of two-phase turbulent flow in hydraulic and hydropower engineering

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In connection with the specific features of high velocity aerated flow generated by hydraulic engineering structures,the mathematical model is developed for high turbulence air-water two-phase flow with the use of twin flow theoretical model in this paper.Furthermore the numerical method is proposed to treat bubbled flows.In addition,on the basis of air-water stratified twin flow model,the new calculation methods and free surface tracking technique are proposed to describe complicated movements of the free surface.Finally,the proposed model is used to calculate artificial aerated flows.The computed results coincide quite well with experimental results.This means that the proposed method can provide solid basis for practical engineering design.

  10. Prediction of amount of entrained droplets in vertical annular two-phase flow

    Energy Technology Data Exchange (ETDEWEB)

    Sawant, Pravin [Purdue University, School of Nuclear Engineering, 400 Central Dr., West Lafayette, IN 47907-2017 (United States)], E-mail: psawant@purdue.edu; Ishii, Mamoru [Purdue University, School of Nuclear Engineering, 400 Central Dr., West Lafayette, IN 47907-2017 (United States)], E-mail: ishii@purdue.edu; Mori, Michitsugu [Tokyo Electric Power Co. Inc., 4-1 Egasaki-cho, Tsurumi-ku, Yokohama 230-8510 (Japan)], E-mail: michitsugu.mori@tepco.co.jp

    2009-08-15

    Prediction of amount of entrained droplets or entrainment fraction in annular two-phase flow is essential for the estimation of dryout condition and analysis of post dryout heat transfer in light water nuclear reactors and steam boilers. In this study, air-water and organic fluid (Freon-113) annular flow entrainment experiments have been carried out in 9.4 and 10.2 mm diameter test sections, respectively. Both the experiments covered three distinct pressure conditions and wide range of liquid and gas flow conditions. The organic fluid experiments simulated high pressure steam-water annular flow conditions. In each experiment, measurements of entrainment fraction, droplet entrainment rate and droplet deposition rate have been performed by using the liquid film extraction method. A simple, explicit and non-dimensional correlation developed by Sawant [Sawant, P.H., Ishii, M., Mori, M., 2008. Droplet entrainment correlation in vertical upward co-current annular two-phase flow. Nucl. Eng. Des. 238 (6), 1342-1352] for the prediction of entrainment fraction is further improved in this study in order to account for the existence of critical gas and liquid flow rates below which no entrainment is possible. Additionally, a new correlation is proposed for the estimation of minimum liquid film flow rate at the maximum entrainment fraction condition. The improved correlation successfully predicted the newly collected air-water and Freon-113 entrainment fraction data. Furthermore, the correlations satisfactorily compared with the air-water, helium-water and air-genklene experimental data measured by Willetts [Willetts, I.P., 1987. Non-aqueous annular two-phase flow. D.Phil. Thesis, University of Oxford]. However, comparison of the correlations with the steam-water data available in literature showed significant discrepancies. It is proposed that these discrepancies might have been caused due to the inadequacy of the liquid film extraction method used to measure the entrainment

  11. INFLUENCE OF AIR HUMIDITY ON THE SUPPRESSION OF FUGITIVE DUST BY USING A WATER-SPRAYING SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Peter Werner Grundnig; Wilhelm H(o)flinger; Gerd Mauschitz; Zechang Liu; Guiqin Zhang; Zhiqiang Wang

    2006-01-01

    One of the main origins of fugitive dust emission arises from bulk handling in quarries or mines, in particular, from bulk materials falling from a hopper or a conveyor belt. Water-spraying systems, using two-phase nozzles,are one of the methods to suppress such dust emission. In this work we tried to develop a mathematical model to correlate air humidity, water flux through the nozzle and the dust (in particular PM10) emission, in order to improve the application and efficiency of these systems. Sand from the Yellow River in China was dropped from a conveyor belt into a dust chamber at 1 kg·min-1, wherefrom the emitted dust was sucked off and quantified via a cascade impactor. A two-phase nozzle was installed in the dust chamber with a water flux through the nozzle of 1.2 to 3 L·h-1, whereas the relative air humidity changed between 55 and 73%. Dust emission was found to be linearly dependent on relative air humidity. Furthermore model equations were developed to describe the dependence of PM10 emission on water flux and relative air humidity.

  12. Two-Phase flow instrumentation for nuclear accidents simulation

    Science.gov (United States)

    Monni, G.; De Salve, M.; Panella, B.

    2014-11-01

    The paper presents the research work performed at the Energy Department of the Politecnico di Torino, concerning the development of two-phase flow instrumentation and of models, based on the analysis of experimental data, that are able to interpret the measurement signals. The study has been performed with particular reference to the design of power plants, such as nuclear water reactors, where the two-phase flow thermal fluid dynamics must be accurately modeled and predicted. In two-phase flow typically a set of different measurement instruments (Spool Piece - SP) must be installed in order to evaluate the mass flow rate of the phases in a large range of flow conditions (flow patterns, pressures and temperatures); moreover, an interpretative model of the SP need to be developed and experimentally verified. The investigated meters are: Turbine, Venturi, Impedance Probes, Concave sensors, Wire mesh sensor, Electrical Capacitance Probe. Different instrument combinations have been tested, and the performance of each one has been analyzed.

  13. An investigation of channel flow with a smooth air-water interface

    Science.gov (United States)

    Madad, Reza; Elsnab, John; Chin, Cheng; Klewicki, Joseph; Marusic, Ivan

    2015-06-01

    Experiments and numerical simulation are used to investigate fully developed laminar and turbulent channel flow with an air-water interface as the lower boundary condition. Laser Doppler velocimetry measurements of streamwise and wall-normal velocity components are made over a range of Reynolds number based upon channel height and bulk velocity from 1100 to 4300, which encompasses the laminar, transitional and low Reynolds numbers turbulent regimes. The results show that the airflow statistics near the stationary wall are not significantly altered by the air-water moving interface and reflect those found in channel flows. The mean statistics on the water interface side largely exhibit results similar to simulated Poiseuille-Couette flow (PCF) with a solid moving wall. For second-order statistics, however, the simulation and experimental results show some discrepancies near the moving water surface, suggesting that a full two-phase simulation is required. A momentum and energy transport tubes analysis is investigated for laminar and turbulent PCFs. This analysis builds upon the classical notion of a streamtube and indicates that part of the energy from the pressure gradient is transported towards the stationary wall and is dissipated as heat inside the energy tubes, while the remainder is transmitted to the moving wall. For the experiments, the airflow energy is transmitted towards the water to overcome the drag force and drive the water forward; therefore, the amount of energy transferred to the water is higher than the energy transferred to a solid moving wall.

  14. Methylglyoxal at the Air-Water Interface

    Science.gov (United States)

    Wren, S. N.; Gordon, B. P.; McWilliams, L.; Valley, N. A.; Richmond, G.

    2014-12-01

    Recently, it has been suggested that aqueous-phase processing of atmospheric α-dicarbonyl compounds such as methylglyoxal (MG) could constitute an important source of secondary organic aerosol (SOA). The uptake of MG to aqueous particles is higher than expected due to the fact that its carbonyl moieties can hydrate to form diols, as well as the fact that MG can undergo aldol condensation reactions to form larger oligomers in solution. MG is known to be surface active but an improved description of its surface behaviour is crucial to understanding MG-SOA formation, in addition to understanding its gas-to-particle partitioning and cloud forming potential. Here, we employ a combined experimental and theoretical approach involving vibrational sum frequency generation spectroscopy (VSFS), surface tensiometry, molecular dynamics simulations, and density functional theory calculations to study MG's surface adsorption, in both the presence and absence of salts. We are particularly interested in determining MG's hydration state at the surface. Our experimental results indicate that MG slowly adsorbs to the air-water interface and strongly perturbs the water structure there. This perturbation is enhanced in the presence of NaCl. Together our experimental and theoretical results suggest that singly-hydrated MG is the dominant form of MG at the surface.

  15. Flow patterns and their transition characteristicsof the air-water two-phase flow in a horizontal pipe with asudden-changed cross-section area

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Flow patterns in upstream and downstream straight tubes of sudden-changedareas in ahorizontal straight pipe were experimentally examined. Both sudden-expansioncross-section (SECS)and sudden-contraction cross-section (SCCS) were investigated. The flow pattern mapsupstream anddownstream were delineated and compared with those in straight tubes with uniformcross-sections.The effects of the SECS and SCCS on flow patterns were discussed and analyzed.Furthermore, flowpattern transition mechanisms resulting in occurrences of different flow patternswere simplydiscussed and some transition criteria for the flow pattern transitions were deduced byusing the non-dimensionlized analysis method.

  16. Study of two-phase flows in reduced gravity

    Science.gov (United States)

    Roy, Tirthankar

    have been done in the past to understand the global structure of gas-liquid two-phase flows under reduced gravity conditions, using experimental setups aboard drop towers or aircrafts flying parabolic flights, detailed data on local structure of such two-phase flows are extremely rare. Hence experiments were carried out in a 304 mm inner diameter (ID) test facility on earth. Keeping in mind the detailed experimental data base that needs to be generated to evaluate two-fluid model along with IATE, ground based simulations provide the only economic path. Here the reduced gravity condition is simulated using two-liquids of similar densities (water and Therminol 59 RTM in the present case). Only adiabatic two-phase flows were concentrated on at this initial stage. Such a large diameter test section was chosen to study the development of drops to their full extent (it is to be noted that under reduced gravity conditions the stable bubble size in gas-liquid two-phase flows is much larger than that at normal gravity conditions). Twelve flow conditions were chosen around predicted bubbly flow to cap-bubbly flow transition region. Detailed local data was obtained at ten radial locations for each of three axial locations using state-of-the art multi-sensor conductivity probes. The results are presented and discussed. Also one-group as well as two-group, steady state, one-dimensional IATE was evaluated against data obtained here and by other researchers, and the results presented and discussed.

  17. Entropy analysis of CO2-air microchannel evaporator in two-phase flow region%CO2-空气微通道蒸发器两相区熵产分析

    Institute of Scientific and Technical Information of China (English)

    吕静; 石冬冬; 徐峰; 朱思倩

    2014-01-01

    Microchannels have become a hot issue in heat exchanger research. In this paper, the microchannel evaporator with CO2 was taken as research subject. A new entropy mathematical model was proposed for microchannel evaporator with CO2 flowing inside and air flowing outside. Phase transition existed on both sides. Entropy generation numberNs represented the losses due to temperature difference of heat transfer and pressure drop. A steady state distributed parameter model for the microchannel evaporator was established to solve entropy generation number. Comparisons of analytical and existing experimental data were made to verify and validate the model. The effects of mass flow rate of CO2and air, CO2 evaporation temperature and inlet air temperature on system entropy generation number were analyzed. The results from the mathematic model showed that mass flow rate of CO2 had little effect on system entropy generation number. System entropy was mostly caused by temperature difference of heat transfer between CO2 and air sides. With rising inlet air temperature, entropy generation number became larger. While with rising CO2 evaporation temperature, system entropy generation number decreased. With increasing air mass flow rate, system entropy generation number increased. The higher the evaporation temperature, the greater the impact of air mass flow rate on system entropy generation number.%微通道已成为换热器研究领域的热点,以CO2微通道蒸发器为研究对象,建立了CO2微通道蒸发器两相区内、外侧均有相变的熵产模型,通过建立的CO2微通道蒸发器二维分布参数模型求解系统熵产数。分析CO2与空气侧质量流率、空气入口温度及CO2蒸发温度对系统熵产数的影响。结果表明:CO2质量流率对系统熵产数影响很小;系统熵产数主要由CO2与空气两侧温差传热引起;系统熵产数随空气入口温度的增大而增大,随CO2的蒸发温度的增大而减小;随着

  18. Detection and characterization of elongated bubbles and drops in two-phase flow using magnetic fields

    Science.gov (United States)

    Wiederhold, A.; Boeck, T.; Resagk, C.

    2017-08-01

    We report a method to detect and to measure the size and velocity of elongated bubbles or drops in a dispersed two-phase flow. The difference of the magnetic susceptibilities between two phases causes a force on the interface between both phases when it is exposed to an external magnetic field. The force is measured with a state-of-the-art electromagnetic compensation balance. While the front and the back of the bubble pass the magnetic field, two peaks in the force signal appear, which can be used to calculate the velocity and geometry parameters of the bubble. We achieve a substantial advantage over other bubble detection techniques because this technique is contactless, non-invasive, independent of the electrical conductivity and can be applied to opaque or aggressive fluids. The measurements are performed in an inclined channel with air bubbles and paraffin oil drops in water. The bubble length is in the range of 0.1-0.25 m and the bubble velocity lies between 0.02-0.22 m s-1. Furthermore we show that it is possible to apply this measurement principle for nondestructive testing (NDT) of diamagnetic and paramagnetic materials like metal, plastics or glass, provided that defects are in the range of 10‒2 m. This technique opens up new possibilities in industrial applications to measure two-phase flow parameters and in material testing.

  19. The solidification of two-phase heterogeneous materials:Theory versus experiment

    Institute of Scientific and Technical Information of China (English)

    KIM; Tongbeum

    2009-01-01

    The solidification behavior of two-phase heterogeneous materials such as close-celled aluminum foams was analytically studied.The proposed analytical model can precisely predict the location of solidification front as well as the full solidification time for a two-phase heterogeneous material composed of aluminum melt and non-conducting air pores.Experiments using distilled water simulating the aluminum melt to be solidified(frozen)were subsequently conducted to validate the analytical model for two selected porosities(ε),ε=0 and 0.5.Full numerical simulations with the method of finite difference were also performed to examine the influence of pore shape on solidification.The remarkable agreement between theory and experiment suggests that the delay of solidification in the two-phase heterogeneous material is mainly caused by the reduction of bulk thermal conductivity due to the presence of pores,as this is the sole mechanism accounted for by the analytical model for solidification in a porous medium.

  20. Anisotropic diffusion of volatile pollutants at air-water interface

    Institute of Scientific and Technical Information of China (English)

    Li-ping CHEN; Jing-tao CHENG; Guang-fa DENG

    2013-01-01

    The volatile pollutants that spill into natural waters cause water pollution. Air pollution arises from the water pollution because of volatilization. Mass exchange caused by turbulent fluctuation is stronger in the direction normal to the air-water interface than in other directions due to the large density difference between water and air. In order to explore the characteristics of anisotropic diffusion of the volatile pollutants at the air-water interface, the relationship between velocity gradient and mass transfer rate was established to calculate the turbulent mass diffusivity. A second-order accurate smooth transition differencing scheme (STDS) was proposed to guarantee the boundedness for the flow and mass transfer at the air-water interface. Simulations and experiments were performed to study the trichloroethylene (C2HCl3) release. By comparing the anisotropic coupling diffusion model, isotropic coupling diffusion model, and non-coupling diffusion model, the features of the transport of volatile pollutants at the air-water interface were determined. The results show that the anisotropic coupling diffusion model is more accurate than the isotropic coupling diffusion model and non-coupling diffusion model. Mass transfer significantly increases with the increase of the air-water relative velocity at a low relative velocity. However, at a higher relative velocity, an increase in the relative velocity has no effect on mass transfer.

  1. Anisotropic diffusion of volatile pollutants at air-water interface

    Directory of Open Access Journals (Sweden)

    Li-ping CHEN

    2013-04-01

    Full Text Available The volatile pollutants that spill into natural waters cause water pollution. Air pollution arises from the water pollution because of volatilization. Mass exchange caused by turbulent fluctuation is stronger in the direction normal to the air-water interface than in other directions due to the large density difference between water and air. In order to explore the characteristics of anisotropic diffusion of the volatile pollutants at the air-water interface, the relationship between velocity gradient and mass transfer rate was established to calculate the turbulent mass diffusivity. A second-order accurate smooth transition differencing scheme (STDS was proposed to guarantee the boundedness for the flow and mass transfer at the air-water interface. Simulations and experiments were performed to study the trichloroethylene (C2HCl3 release. By comparing the anisotropic coupling diffusion model, isotropic coupling diffusion model, and non-coupling diffusion model, the features of the transport of volatile pollutants at the air-water interface were determined. The results show that the anisotropic coupling diffusion model is more accurate than the isotropic coupling diffusion model and non-coupling diffusion model. Mass transfer significantly increases with the increase of the air-water relative velocity at a low relative velocity. However, at a higher relative velocity, an increase in the relative velocity has no effect on mass transfer.

  2. Influence of water air content on cavitation erosion in distilled water

    CSIR Research Space (South Africa)

    Auret, JG

    1993-12-01

    Full Text Available air content on cavitation erosion in distilled water J. G. Auret,* O. F. R. A. Damm,* G. J. Wright* and F. P. A. Robinson t The influence of increased air content of the cavitating liquid (distilled water... erosion, air (gas) content, distilled water Introduction The existence of cavitation at positive liquid pressures depends on the presence of small gas pockets or nuclei ~. Thus gas (usually air) content is an extremely...

  3. Investigations of two-phase flame propagation under microgravity conditions

    Science.gov (United States)

    Gokalp, Iskender

    2016-07-01

    Investigations of two-phase flame propagation under microgravity conditions R. Thimothée, C. Chauveau, F. Halter, I Gökalp Institut de Combustion, Aérothermique, Réactivité et Environnement (ICARE), CNRS, 1C Avenue de la Recherche Scientifique, 45071 Orléans Cedex 2, France This paper presents and discusses recent results on two-phase flame propagation experiments we carried out with mono-sized ethanol droplet aerosols under microgravity conditions. Fundamental studies on the flame propagation in fuel droplet clouds or sprays are essential for a better understanding of the combustion processes in many practical applications including internal combustion engines for cars, modern aircraft and liquid rocket engines. Compared to homogeneous gas phase combustion, the presence of a liquid phase considerably complicates the physico-chemical processes that make up combustion phenomena by coupling liquid atomization, droplet vaporization, mixing and heterogeneous combustion processes giving rise to various combustion regimes where ignition problems and flame instabilities become crucial to understand and control. Almost all applications of spray combustion occur under high pressure conditions. When a high pressure two-phase flame propagation is investigated under normal gravity conditions, sedimentation effects and strong buoyancy flows complicate the picture by inducing additional phenomena and obscuring the proper effect of the presence of the liquid droplets on flame propagation compared to gas phase flame propagation. Conducting such experiments under reduced gravity conditions is therefore helpful for the fundamental understanding of two-phase combustion. We are considering spherically propagating two-phase flames where the fuel aerosol is generated from a gaseous air-fuel mixture using the condensation technique of expansion cooling, based on the Wilson cloud chamber principle. This technique is widely recognized to create well-defined mono-size droplets

  4. Two-phase relative permeability models in reservoir engineering calculations

    Energy Technology Data Exchange (ETDEWEB)

    Siddiqui, S.; Hicks, P.J.; Ertekin, T.

    1999-01-15

    A comparison of ten two-phase relative permeability models is conducted using experimental, semianalytical and numerical approaches. Model predicted relative permeabilities are compared with data from 12 steady-state experiments on Berea and Brown sandstones using combinations of three white mineral oils and 2% CaCl1 brine. The model results are compared against the experimental data using three different criteria. The models are found to predict the relative permeability to oil, relative permeability to water and fractional flow of water with varying degrees of success. Relative permeability data from four of the experimental runs are used to predict the displacement performance under Buckley-Leverett conditions and the results are compared against those predicted by the models. Finally, waterflooding performances predicted by the models are analyzed at three different viscosity ratios using a two-dimensional, two-phase numerical reservoir simulator. (author)

  5. Computational methods for two-phase flow and particle transport

    CERN Document Server

    Lee, Wen Ho

    2013-01-01

    This book describes mathematical formulations and computational methods for solving two-phase flow problems with a computer code that calculates thermal hydraulic problems related to light water and fast breeder reactors. The physical model also handles the particle and gas flow problems that arise from coal gasification and fluidized beds. The second part of this book deals with the computational methods for particle transport.

  6. Two-Phase Cavitating Flow in Turbomachines

    Directory of Open Access Journals (Sweden)

    Sandor I. Bernad

    2012-11-01

    Full Text Available Cavitating flows are notoriously complex because they are highly turbulent and unsteady flows involving two species (liquid/vapor with a large density difference. These features pose a unique challenge to numerical modeling works. The study briefly reviews the methodology curently employed for industrial cavitating flow simulations using the two-phase mixture model. The two-phase mixture model is evaluated and validated using benchmark problem where experimental data are available. A 3D cavitating flow computation is performed for the GAMM Francis runner. The model is able to qualitatively predict the location and extent of the 3D cavity on the blade, but further investigation are needed to quatitatively assess the accuracy for real turbomachinery cavitating flows.

  7. Review of two-phase instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Han Ok; Seo, Han Ok; Kang, Hyung Suk; Cho, Bong Hyun; Lee, Doo Jeong

    1997-06-01

    KAERI is carrying out a development of the design for a new type of integral reactors. The once-through helical steam generator is important design features. The study on designs and operating conditions which prevent flow instability should precede the introduction of one-through steam generator. Experiments are currently scheduled to understand two-phase instability, evaluate the effect of each design parameter on the critical point, and determine proper inlet throttling for the prevention of instability. This report covers general two-phase instability with review of existing studies on this topics. The general classification of two phase flow instability and the characteristics of each type of instability are first described. Special attention is paid to BWR core flow instability and once-through steam generator instability. The reactivity feedback and the effect of system parameters are treated mainly for BWR. With relation to once-through steam generators, the characteristics of convective heating and dryout point oscillation are first investigated and then the existing experimental studies are summarized. Finally chapter summarized the proposed correlations for instability boundary conditions. (author). 231 refs., 5 tabs., 47 figs

  8. Critical thinking: a two-phase framework.

    Science.gov (United States)

    Edwards, Sharon L

    2007-09-01

    This article provides a comprehensive review of how a two-phase framework can promote and engage nurses in the concepts of critical thinking. Nurse education is required to integrate critical thinking in their teaching strategies, as it is widely recognised as an important part of student nurses becoming analytical qualified practitioners. The two-phase framework can be incorporated in the classroom using enquiry-based scenarios or used to investigate situations that arise from practice, for reflection, analysis, theorising or to explore issues. This paper proposes a two-phase framework for incorporation in the classroom and practice to promote critical thinking. Phase 1 attempts to make it easier for nurses to organise and expound often complex and abstract ideas that arise when using critical thinking, identify more than one solution to the problem by using a variety of cues to facilitate action. Phase 2 encourages nurses to be accountable and responsible, to justify a decision, be creative and innovative in implementing change.

  9. Experimental Study on Two-Phase Flow in Horizontal Rectangular Minichannel with Y-Junction

    Directory of Open Access Journals (Sweden)

    Agus Santoso

    2016-03-01

    Full Text Available An experimental study was conducted to investigate two-phase air-water flow characteristics, in horizontal rectangular minichannel with Y-junction. The width (W, the height (H and the hydraulic diameter (DH of the rectangular cross section for the upstream side of the junction are 4.60 mm, 2.50 mm and 3.24 mm, while those for the downstream side are 2.36 mm, 2.50 mm and 2.43 mm. The entire test section was machined from transparent acrylic block, so that the flow structure could be visualized. Liquid single-phase and air-liquid twophase flow experiments were conducted at room temperature. The flow pattern, the bubble velocity, the bubble length, and the void fraction were measured with a high-speed video camera. Pressure profile upstream and downstream from the junction was also measured for the respective flows, and the pressure loss due to the contraction at the junction was determined from the pressure profiles. Two flow patterns, i.e., slug and annular flows, were observed in the fully-developed region apart from the junction. In the analysis, the frictional pressure drop data, the two-phase frictional multiplier data, bubble velocity data, bubble length data and void fraction data were compared with calculations by some correlations in literatures. In addition, new pressure loss coefficient correlations for the pressure drop at the junction has been proposed. Results of such experiment and analysis are described in the present paper.

  10. Numerical Simulations of Two-Phase Flow in a Dorr-Oliver Flotation Cell Model

    Directory of Open Access Journals (Sweden)

    Hassan Fayed

    2013-08-01

    Full Text Available Two-phase (water and air flow in the forced-air mechanically-stirred Dorr-Oliver machine has been investigated using computational fluid dynamics (CFD. A 6 m3 model is considered. The flow is modeled by the Euler-Euler approach, and transport equations are solved using software ANSYS-CFX5. Unsteady simulations are conducted in a 180-degree sector with periodic boundary conditions. Air is injected into the rotor at the rate of 2.63 m3/min, and a uniform bubble diameter is specified. The effects of bubble diameter on velocity field and air volume fraction are determined by conducting simulations for three diameters of 0.5, 1.0, and 2.0 mm. Air volume fraction contours, velocity profiles, and turbulent kinetic energy profiles in different parts of the machine are presented and discussed. Results have been compared to experimental data, and good agreement is obtained for the mean velocity and turbulent kinetic energy profiles in the rotor-stator gap and in the jet region outside stator blades.

  11. ATMOSPHERIC MOISTURE CONDENSATION TO WATER RECOVERY BY HOME AIR CONDITIONERS

    Directory of Open Access Journals (Sweden)

    Amir Hossein Mahvi

    2013-01-01

    Full Text Available Earth’s atmosphere contains billion cubic meters of fresh water, which is considerable as a reliable water resource, especially in sultry areas. What is important in this context, how to extract the water, in an economic manner. In order to extract water from air conditioner, no need to spend any cost, because water produced as a by-product and trouble production. This cross-sectional study was conducted to evaluate the quantity and chemical quality of water obtained from Bandar Abbas air conditioners; at intervals beginning of March to early December of 2010. Sixty six samples were taken in cluster random plan. Bandar Abbas divided into four clusters; based on distance to shore and population density. Chemical tests which included: Turbidity, alkalinity, total hardness, Dissolved Solids (TDS and Electrical Conductivity (EC and quantity measurement were performed on them. Obtained water had slightly acidic pH, near to neutral range. Total dissolved solids, electrical conductivity, total hardness and alkalinity of extracted water were in low rate. Each air conditioner produced 36 liter per day averagely. Split types obtained more water to window air conditioners. With regard to some assumptions, approximately 4680 to 9360 cubic meter per day water is obtainable which is suitable for many municipal and industrial water applications.

  12. Ferry Engine Repower to Provide Benefits for Air and Water

    Science.gov (United States)

    EPA’s Diesel Emission Reduction Act grant to the Delaware River and Bay Authority is bringing new clean air technology to the Cape May-Lewes Ferry, thereby reducing air pollution emissions and contributing to cleaner water in the Chesapeake Bay.

  13. Experimental Assessment of the Two-Phase Flow in a Large Inclined Channel

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Thanh Hung; Song, Ki Won; Revankar, Shripad T; Park, Hyun Sun [Pohang University of Science and Technology, Pohang (Korea, Republic of)

    2014-10-15

    In order to assess the cooling performance of the core catcher system, a model facility has been constructed in POSTECH using scaling analysis. This facility consists of horizontal, inclined and vertical section. To investigate the flow parameters in each section, the instrumentation is developed to measure two-phase characteristics such as local void fraction, bubble velocity and bubble size. To date, there has been a considerable amount of research conducted on the internal structure of two-phase flow in pipe. However, the number of attempts made on the experiment regarding large inclined channels has been still limited. One of the reasons for this lack of data is the difficulty in constructing experimental facility. In this paper, the parameters of the flow in the inclined section are presented. The inclined channel is 10 degree from the horizontal with the rectangular cross section of 300 cm{sup 2}. The distributions of local parameters are evaluated through the data of double sensor conductivity probes installed at different locations along the inclined section. The data sets of the structure of two-phase flow in an inclined large channel was acquired. The air was injected through the metal foam installed on the top surface wall of the inclined section. Water level was kept below the top of the inclined section so the amount of water was fixed during the experiment. 9 probes set up at the different locations to get the data of local two-phase parameters. The measurement at each location was conducted in 5 minutes to determine the mean value of each parameter. The result of local void fraction profiles at different locations indicates that the void distribution primarily changes along the height of the inclined section. The slug flow occurs in the channel which results in most bubbles attached to the top surface wall. This fact explains the high local void fraction near the top wall and its rapid decline towards the bottom wall of the inclined section. The

  14. Air flotation treatment of salmon processing waste water

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This paper discusses methods for the reduction of the pollution strength of salmon processing waste water. Past research has indicated the success of air pressure...

  15. Relating water and air flow characteristics in coarse granular materials

    DEFF Research Database (Denmark)

    Andreasen, Rune Røjgaard; Canga, Eriona; Poulsen, Tjalfe Gorm

    2013-01-01

    Water pressure drop as a function of velocity controls w 1 ater cleaning biofilter operation 2 cost. At present this relationship in biofilter materials must be determined experimentally as no 3 universal link between pressure drop, velocity and filter material properties have been established. 4...... Pressure drop - velocity in porous media is much simpler and faster to measure for air than for water. 5 For soils and similar materials, observations show a strong connection between pressure drop – 6 velocity relations for air and water, indicating that water pressure drop – velocity may be estimated 7...... from air flow data. The objective of this study was, therefore, to investigate if this approach is valid 8 also for coarse granular biofilter media which usually consists of much larger particles than soils. In 9 this paper the connection between the pressure drop – velocity relationships for air...

  16. Coupling two-phase fluid flow with two-phase darcy flow in anisotropic porous media

    KAUST Repository

    Chen, J.

    2014-06-03

    This paper reports a numerical study of coupling two-phase fluid flow in a free fluid region with two-phase Darcy flow in a homogeneous and anisotropic porous medium region. The model consists of coupled Cahn-Hilliard and Navier-Stokes equations in the free fluid region and the two-phase Darcy law in the anisotropic porous medium region. A Robin-Robin domain decomposition method is used for the coupled Navier-Stokes and Darcy system with the generalized Beavers-Joseph-Saffman condition on the interface between the free flow and the porous media regions. Obtained results have shown the anisotropic properties effect on the velocity and pressure of the two-phase flow. 2014 Jie Chen et al.

  17. Interactive Effect of Air-Water Ratio and Temperature on the Air ...

    African Journals Online (AJOL)

    Windows User

    KEYWORDS: Interactive effect, air-water ratio, temperature, volatile organic ... VOCs removal from wastewater by increasing the surface ... surface area (m2). ... where α and n are constants, DL is liquid diffusion coefficient .... Packing volume.

  18. Role of air on local water retention behavior in the shallow heterogeneous vadose zone

    Science.gov (United States)

    Sakaki, T.; Limsuwat, A.; Illangasekare, T. H.

    2009-12-01

    In the presence of a subsurface source, air flowing through the unsaturated soil can transport toxic vapor into subsurface structures due to pressure gradients created by, e.g., a pressure drop within the building. Development of dynamic air pathways in the subsurface are largely controlled by the geological heterogeneity and the spatial and temporal distribution of soil moisture. To better understand how these air pathways are developed, it is crucial to know how water is retained in heterogeneous medium at spatial resolutions that are finer than those adopted in typical hydrologic and soil physics applications. Although methods for soil water pressure measurement can be readily found in literature, a technique for measuring “air pressure” in wet soil is not well-established or documented. Hydrophobic porous ceramic cups have been used to measure non-wetting NAPL phase pressure in two-phase systems. However, our preliminary tests using the hydrophobic ceramic cups installed in highly wet soil showed that under conditions of fast drainage of the wetting fluid that is replaced by air, it typically took some time before the cups responded to register the air pressure. Therefore, an attempt was made to develop a more robust method where the time lag is minimized. The tested materials were; 1) ceramic porous cups, 2) sintered stainless steel cups, 3) porous glass discs, and 4) non-woven PTFE fabric. The ceramic cups, sintered stainless steel cups and sintered porous glass discs required hydrophobic treatment, whereas the non-woven PTFE fabric is hydrophobic by itself. To treat the ceramic porous cups, the method proposed by Parker and Lenhard [1988] was adopted. The sintered porous stainless steel cups and porous glass discs were treated by a commercially available water repellant compound. For those four materials, contact angle, water entry pressure, and time lag to respond to an imposed pressure were measured. The best performing material was then tested in a

  19. Water management in capillary gas chromatographic air monitoring systems

    Energy Technology Data Exchange (ETDEWEB)

    Ryan, J.F.; Tippler, A.; Seeley, I. [Perkin-Elmer Corp., Wilton, CT (United States)

    1995-12-31

    Determining the identity and quantities of volatile organic compounds in air samples at trace levels often requires large sample sizes to achieve part-per-billion (ppb) detection levels. Given the volatile nature of many of low molecular weight chemical species, some form of cooling or adsorbent trapping of the organics is required. Unfortunately, cooling air samples below ambient temperature causes large amounts of water to be removed along with the organics. This paper investigates the magnitude of the problem and examines various alternatives for managing trapped water. The application of some of these techniques is demonstrated in a method for determining volatile polar and non-polar compounds in ambient air.

  20. Large eddy simulation and PIV experiments of air-water mixing tanks

    Science.gov (United States)

    Zamankhan, Piroz

    2010-06-01

    The simulations and experiments of a turbulent bubbly flow are carried out in a cylindrical mixing vessel. Dynamics of the turbulent bubbly flow is visualized using a novel two-phase particle image velocimetry (PIV) with a combination of back lighting, digital masking and fluorescent tracer particles. Using an advanced technique, Mie's scattering at surfaces of bubbles is totally filtered out and, henceforth, images of tracer particles and of bubbles are obtained with high quality. In parallel to the comprehensive experimental studies, numerical results are obtained from large eddy simulations (LES) of the two-phase air-water mixer. The impeller-induced flow at the blade tip radius is modeled by using sliding mesh method. The results demonstrate the existence of large structures such as tip-vortex tips, and also some finer details. In addition, the stability of the jet is found to be connected with the fluctuations of the tip vortices whose dynamics are affected by the presence of bubbles. Numerical results are used to interpret the measurement data and to guide the refinement of consistent theoretical analyses. Such information is invaluable in the development of advanced theories capable of describing bubbly flows in the presence of complex liquid flow. This detailed information is of real significance in facilitating the design and scale-up of practical stirred tanks.

  1. Microgravity Two-Phase Flow Transition

    Science.gov (United States)

    Parang, M.; Chao, D.

    1999-01-01

    Two-phase flows under microgravity condition find a large number of important applications in fluid handling and storage, and spacecraft thermal management. Specifically, under microgravity condition heat transfer between heat exchanger surfaces and fluids depend critically on the distribution and interaction between different fluid phases which are often qualitatively different from the gravity-based systems. Heat transfer and flow analysis in two-phase flows under these conditions require a clear understanding of the flow pattern transition and development of appropriate dimensionless scales for its modeling and prediction. The physics of this flow is however very complex and remains poorly understood. This has led to various inadequacies in flow and heat transfer modeling and has made prediction of flow transition difficult in engineering design of efficient thermal and flow systems. In the present study the available published data for flow transition under microgravity condition are considered for mapping. The transition from slug to annular flow and from bubbly to slug flow are mapped using dimensionless variable combination developed in a previous study by the authors. The result indicate that the new maps describe the flow transitions reasonably well over the range of the data available. The transition maps are examined and the results are discussed in relation to the presumed balance of forces and flow dynamics. It is suggested that further evaluation of the proposed flow and transition mapping will require a wider range of microgravity data expected to be made available in future studies.

  2. Continued development of a semianalytical solution for two-phase fluid and heat flow in a porous medium

    Energy Technology Data Exchange (ETDEWEB)

    Doughty, C.; Pruess, K. [Lawrence Berkeley Lab., CA (United States)

    1991-06-01

    Over the past few years the authors have developed a semianalytical solution for transient two-phase water, air, and heat flow in a porous medium surrounding a constant-strength linear heat source, using a similarity variable {eta} = r/{radical}t. Although the similarity transformation approach requires a simplified geometry, all the complex physical mechanisms involved in coupled two-phase fluid and heat flow can be taken into account in a rigorous way, so that the solution may be applied to a variety of problems of current interest. The work was motivated by adverse to predict the thermohydrological response to the proposed geologic repository for heat-generating high-level nuclear wastes at Yucca Mountain, Nevada, in a partially saturated, highly fractured volcanic formation. The paper describes thermal and hydrologic conditions near the heat source; new features of the model; vapor pressure lowering; and the effective-continuum representation of a fractured/porous medium.

  3. Why air bubbles in water glow so easily

    NARCIS (Netherlands)

    Brenner, M.; Hilgenfeldt, Sascha; Lohse, Detlef

    1996-01-01

    Sound driven gas bubbles in water can emit light pulses (sonoluminescence). Experiments show a strong dependence on the type of gas dissolved in water. Air is found to be one of the most friendly gases towards this phenomenon. Recently, \\cite{loh96} have suggested a chemical mechanism to account for

  4. Minimizing the water and air impacts of unconventional energy extraction

    Science.gov (United States)

    Jackson, R. B.

    2014-12-01

    Unconventional energy generates income and, done well, can reduce air pollution compared to other fossil fuels and even water use compared to fossil fuels and nuclear energy. Alternatively, it could slow the adoption of renewables and, done poorly, release toxic chemicals into water and air. Based on research to date, some primary threats to water resources come from surface spills, wastewater disposal, and drinking-water contamination through poor well integrity. For air resources, an increase in volatile organic compounds and air toxics locally is a potential health threat, but the switch from coal to natural gas for electricity generation will reduce sulfur, nitrogen, mercury, and particulate pollution regionally. Critical needs for future research include data for 1) estimated ultimate recovery (EUR) of unconventional hydrocarbons; 2) the potential for further reductions of water requirements and chemical toxicity; 3) whether unconventional resource development alters the frequency of well-integrity failures; 4) potential contamination of surface and ground waters from drilling and spills; and 5) the consequences of greenhouse gases and air pollution on ecosystems and human health.

  5. Air-to-water heat pumps for the home

    Energy Technology Data Exchange (ETDEWEB)

    Bodzin, S. [ed.

    1997-07-01

    Heat pump water heaters may be on the rise again. Retrofitters have shied away from this form of water heating due to concerns about cost, moise, efficiency, and maintaenance. Recent advances have overcome some of these problems and are helping the technology find a niche in both hot and cold climates. The topics covered in this article include the following: how heat pump water heaters work; air source from where to where, including air conditioning, heat recovery ventilation, hybrid systems; nuisances; maintenance; costs; to install or not to install; performance: a trick to quantify. 2 figs.

  6. Two-phase flow pattern recognition in a varying section based on void fraction and pressure measurements

    Science.gov (United States)

    de Kerret, F.; Benito, I.; Béguin, C.; Pelletier, D.; Etienne, S.

    2016-11-01

    In a hydroelectric turbine, the air injected during operation has an impact on the yield of the machine leading to important losses of energy. To understand those losses and be able to reduce them, a first step is to understand the pattern of the two-phase flows and describe their characteristics in the turbine. Those two-phase flows can be bubbly, intermittent, or annular, with different types of intermittent flow possible. Two-phase flow patterns are well defined in classical geometries such as cylinders with reliable descriptions available [5]. But, there is a critical lack of knowledge for flow patterns in other geometries. In our present work we take interest into a geometry that is a pipe with periodical changes of the section and realize a flow pattern map. To realize this map, we measure the pressure variations and void fraction fluctuations while changing the flow rates of water and air in our test section. We then use our physical understanding of the phenomena to analyze data and identify different flow patterns, characterize them, and build a new flow pattern map.

  7. Cold water aquifer storage. [air conditioning

    Science.gov (United States)

    Reddell, D. L.; Davison, R. R.; Harris, W. B.

    1980-01-01

    A working prototype system is described in which water is pumped from an aquifer at 70 F in the winter time, chilled to a temperature of less than 50 F, injected into a ground-water aquifer, stored for a period of several months, pumped back to the surface in the summer time. A total of 8.1 million gallons of chilled water at an average temperature of 48 F were injected. This was followed by a storage period of 100 days. The recovery cycle was completed a year later with a total of 8.1 million gallons recovered. Approximately 20 percent of the chill energy was recovered.

  8. Droplet Manipulations in Two Phase Flow Microfluidics

    Directory of Open Access Journals (Sweden)

    Arjen M. Pit

    2015-11-01

    Full Text Available Even though droplet microfluidics has been developed since the early 1980s, the number of applications that have resulted in commercial products is still relatively small. This is partly due to an ongoing maturation and integration of existing methods, but possibly also because of the emergence of new techniques, whose potential has not been fully realized. This review summarizes the currently existing techniques for manipulating droplets in two-phase flow microfluidics. Specifically, very recent developments like the use of acoustic waves, magnetic fields, surface energy wells, and electrostatic traps and rails are discussed. The physical principles are explained, and (potential advantages and drawbacks of different methods in the sense of versatility, flexibility, tunability and durability are discussed, where possible, per technique and per droplet operation: generation, transport, sorting, coalescence and splitting.

  9. Two phase decision algorithm of replica allocation

    Institute of Scientific and Technical Information of China (English)

    Zuo Chaoshu; Liu Xinsong; Wang Zheng; Li Yi

    2006-01-01

    In distributed parallel server system, location and redundancy of replicas have great influence on availability and efficiency of the system. In order to improve availahility and efficiency of the system, two phase decision algorithm of replica allocation is proposed. The algorithm which makes use of auto-regression model dynamically predicts the future count of READ and WRITE operation, and then determines location and redundancy of replicas by considering availability, CPU and bands of the network. The algorithm can not only ensure the requirement of availability, but also reduce the system resources consumed by all the operations in a great scale. Analysis and test show that communication complexity and time complexity of the algorithm satisfy O( n ), resource optimizing scale increases with the increase of READ count.

  10. Plants Clean Air and Water for Indoor Environments

    Science.gov (United States)

    2007-01-01

    Wolverton Environmental Services Inc., founded by longtime government environmental scientist B.C. "Bill" Wolverton, is an environmental consulting firm that gives customers access to the results of his decades of cutting-edge bioremediation research. Findings about how to use plants to improve indoor air quality have been published in dozens of NASA technical papers and in the book, "How to Grow Fresh Air: 50 Houseplants That Purify Your Home or Office." The book has now been translated into 12 languages and has been on the shelves of bookstores for nearly 10 years. A companion book, "Growing Clean Water: Nature's Solution to Water Pollution," explains how plants can clean waste water. Other discoveries include that the more air that is allowed to circulate through the roots of the plants, the more effective they are at cleaning polluted air; and that plants play a psychological role in welfare in that people recover from illness faster in the presence of plants. Wolverton Environmental is also working in partnership with Syracuse University, to engineer systems consisting of modular wicking filters tied into duct work and water supplies, essentially tying plant-based filters into heating, ventilation, and air conditioning (HVAC) systems. Also, the company has recently begun to assess the ability of the EcoPlanter to remove formaldehyde from interior environments. Wolverton Environmental is also in talks with designers of the new Stennis Visitor's Center, who are interested in using its designs for indoor air-quality filters

  11. Interrelationships of petiole air canal architecture, water depth and convective air flow in Nymphaea odorata (Nymphaeaceae)

    Science.gov (United States)

    Premise of the study--Nymphaea odorata grows in water up to 2 m deep, producing fewer, larger leaves in deeper water. This species has a convective flow system that moves gases from younger leaves through submerged parts to older leaves, aerating submerged parts. Petiole air canals are in the conv...

  12. Aqueous Nanofluid as a Two-Phase Coolant for PWR

    Directory of Open Access Journals (Sweden)

    Pavel N. Alekseev

    2012-01-01

    Full Text Available Density fluctuations in liquid water consist of two topological kinds of instant molecular clusters. The dense ones have helical hydrogen bonds and the nondense ones are tetrahedral clusters with ice-like hydrogen bonds of water molecules. Helical ordering of protons in the dense water clusters can participate in coherent vibrations. The ramified interface of such incompatible structural elements induces clustering impurities in any aqueous solution. These additives can enhance a heat transfer of water as a two-phase coolant for PWR due to natural forming of nanoparticles with a thermal conductivity higher than water. The aqueous nanofluid as a new condensed matter has a great potential for cooling applications. It is a mixture of liquid water and dispersed phase of extremely fine quasi-solid particles usually less than 50 nm in size with the high thermal conductivity. An alternative approach is the formation of gaseous (oxygen or hydrogen nanoparticles in density fluctuations of water. It is possible to obtain stable nanobubbles that can considerably exceed the molecular solubility of oxygen (hydrogen in water. Such a nanofluid can convert the liquid water in the nonstoichiometric state and change its reduction-oxidation (RedOx potential similarly to adding oxidants (or antioxidants for applying 2D water chemistry to aqueous coolant.

  13. Microencapsulation using an oil-in-water-in-air 'dry water emulsion'.

    Science.gov (United States)

    Carter, Benjamin O; Weaver, Jonathan V M; Wang, Weixing; Spiller, David G; Adams, Dave J; Cooper, Andrew I

    2011-08-07

    We describe the first example of a tri-phasic oil-in-water-in-air 'dry water emulsion'. The method combines highly stable oil-in-water emulsions prepared using branched copolymer surfactants, with aqueous droplet encapsulation using 'dry water' technology.

  14. Investigations of hydraulic operating conditions of air lift pump with three types of air-water mixers

    Directory of Open Access Journals (Sweden)

    Kalenik Marek

    2015-03-01

    Full Text Available Investigations of hydraulic operating conditions of air lift pump with three types of air-water mixers. The paper presents the analysis of results of the investigations concerning the influence of various constructive solutions of the air-water mixers on hydraulic operating conditions of the air lift pump. The scope of the investigations encompassed the determination of characteristics of delivery head and delivery rate for three types of air-water mixers applied in the constructed air lift pump. Using the obtained results, the efficiency of the three types of air-water mixers applied in this air lift pump was determined. The analysis was carried out and there was checked whether the improved analytical Stenning-Martin model can be used to design air lift pumps with the air-water mixers of these types. The highest capacity in the water transport was reached by the air lift pump with the 1st type air-water mixer, the lowest one – with the 3rd type air-water mixer. The water flow in the air lift pump increases along with the rise in the air flow. The lower are the hydraulic losses generated during flow of the air flux by the air-water mixer, the higher is the air lift pump capacity. Along with the rise in the water delivery head, the capacity of the air lift pump decreases. The highest efficiency is reached by the air lift pump with the 1st type air-water mixer, the lowest – with the 3st type air-water mixer. The efficiency of the air lift pump for the three investigated types of air-water mixers decreases along with the rise in air flow rate and water delivery head. The values of submergence ratio (h/L of the delivery pipe, calculated with the use of the improved analytical Stenning-Martin model, coincide quite well with the values of h/L determined from the measurements.

  15. Analysis of free-surface flows through energy considerations: Single-phase versus two-phase modeling.

    Science.gov (United States)

    Marrone, Salvatore; Colagrossi, Andrea; Di Mascio, Andrea; Le Touzé, David

    2016-05-01

    The study of energetic free-surface flows is challenging because of the large range of interface scales involved due to multiple fragmentations and reconnections of the air-water interface with the formation of drops and bubbles. Because of their complexity the investigation of such phenomena through numerical simulation largely increased during recent years. Actually, in the last decades different numerical models have been developed to study these flows, especially in the context of particle methods. In the latter a single-phase approximation is usually adopted to reduce the computational costs and the model complexity. While it is well known that the role of air largely affects the local flow evolution, it is still not clear whether this single-phase approximation is able to predict global flow features like the evolution of the global mechanical energy dissipation. The present work is dedicated to this topic through the study of a selected problem simulated with both single-phase and two-phase models. It is shown that, interestingly, even though flow evolutions are different, energy evolutions can be similar when including or not the presence of air. This is remarkable since, in the problem considered, with the two-phase model about half of the energy is lost in the air phase while in the one-phase model the energy is mainly dissipated by cavity collapses.

  16. A mixed air/air and air/water heat pump system ensures the air-conditioning of a cinema; Un systeme mixte PAC air/air et air/eau climatise un cinema

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2001-03-01

    This article presents the air conditioning system of a new cinema complex of Boulogne (92, France) which comprises a double-flux air processing plant and two heat pumps. Each heat pump has two independent refrigerating loops: one with a air condenser and the other with a water condenser. This system allows to limit the power of the loop and to reduce the size of the cooling tower and of the vertical ducts. This article describes the technical characteristics of the installation: thermodynamic units, smoke clearing, temperature control, air renewing. (J.S.)

  17. Degradation of chloramphenicol in aqueous solution using ozone oxidation in a two-phase system of water/loaded ozone organic solvent%水/载O3有机溶剂两相臭氧氧化法降解水体中氯霉素

    Institute of Scientific and Technical Information of China (English)

    李时银; 史震宇; 陆继来; 邹敏; 张利民

    2011-01-01

    Using a two-phase system of water/perfluorodecalin organic solvent loaded ozone, degradation of chloramphenicol in aqueous solution was conducted. Due to perfluorodecalin has a high ozone stability and solubility, chloramphenicol was used to examine the efficiency of the two-phase ozonation system. During the experiments, effects of initial pH and free radical scavenger on the removal rate of chloramphenicol were investigated respectively. The results showed that the efficiency of two-phase ozonation was increased with the increase of initial pH in water. It was also observed that free radical scavenger had no significant negative effect in two-phase ozonation.%以水/载O3有机溶剂(全氟萘烷)为新型两相臭氧氧化体系,研究了臭氧在全氟萘烷中的溶解度和稳定性,并考察了pH、NaHCO3和叔丁醇对两相体系中臭氧稳定性的影响;以水体中氯霉素为研究对象,考察了初始pH值和自由基抑制剂对两相臭氧氧化体系降解氯霉素效果的影响.结果表明:初始水相pH增大有利于氯霉素的降解;自由基抑制剂对两相体系氧化降解氯霉素影响不显著.

  18. Numerical investigation of confined swirling gas-solid two phase jet

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This paper presents a k-ε-kp multi-fluid model for simulating confined swirling gas-solid two phase jet comprised of particle-laden flow from a center tube and a swirling air stream entering the test section from the coaxial annular. A series of numerical simulations of the two-phase flow of 30 μm, 45 μm, 60 μm diameter particles respectively yielded results fitting well with published experimental data.

  19. Numerical Simulation of Swirling Gas-solid Two Phase Flow through a Pipe Expansion

    Institute of Scientific and Technical Information of China (English)

    Jin Hanhui; Xia Jun; Fan Jianren; Cen Kefa

    2001-01-01

    A k- ε -kp multi-fluid model is stated and adopted to simulate swirling gas-solid two phase flow. A particle-laden flow from a center tube and a swirling air stream from the coaxial annular enter the test section. A series of numerical simulations of the two-phase flow are performed based on 30 μ m, 45 μ m, 60 μ m diameter particles respectively. The results fit well with published experimental data.

  20. Numerical investigation of confined swirling gas-solid two phase jet

    Institute of Scientific and Technical Information of China (English)

    金晗辉; 夏钧; 樊建人; 岑可法

    2002-01-01

    This paper presents a k-e-kp multi-fluid model for simulating confined swirling gas-solid two phase jet comprised of particle-laden flow from a center tube and a swirling air stream entering the test section from the coaxial annular. A series of numerical simulations of the two-phase flow of 30μm, 45μm, 60μm diameter particles respectively yielded results fitting well with published experimental data.

  1. A Hydrodynamic Model for Slug Frequency in Horizontal Gas-Liquid Two-Phase Flow

    Institute of Scientific and Technical Information of China (English)

    刘磊; 孙贺东; 胡志华; 周芳德

    2003-01-01

    The prediction of slug frequency has important significance on gas-liquid two-phase flow. A hydrodynamic model was put forward to evaluate slug frequency for horizontal two-phase flow, based on the dependence of slug frequency on the frequency of unstable interfacial wave. Using air and water, experimental verification of the model was carried out in a large range of flow parameters. Six electrical probes were installed at different positions of a horizontal plexiglass pipe to detect slug frequency development. The pipe is 30 m long and its inner diameter is 24 ram. It is observed experimentally that the interracial wave frequency at the inlet is about i to 3 times the frequency of stable slug. The slug frequencies predicted by the model fit well with Tronconi (1990) model and the experimental data. The combination of the hydrodynamic model and the experimental data results in a conclusion that the frequency of equilibrium liquid slug is approximately half the minimum frequency of interfacial wave.

  2. Two Phase Compressible Flow Fields in One Dimensional and Eulerian Grid Framework

    Science.gov (United States)

    Lee, Sungsu; Park, Chan Wook

    2008-11-01

    Numerical investigation for two phase compressible flow fields of air-water in one dimensional tube are performed in the fixed Eulerian grid framework. Using an equation of states of Tait's type for a multiphase cell, the two phase compressible flow is modeled as equivalent single phase which is discretized using the Roe`s approximate Riemann solver, while the phase interface is captured via volume fractions of each phase. The most common problem found in the computational approaches in compressible multiphase flow is occurrence of the pressure oscillation at the phase interface. In order to suppress that phenomenon, tried are two approaches; a passive advection of volume fraction and a direct pressure relaxation with the compressible form of volume fraction equation. The results show that the direct pressure equalizing method suppresses pressure oscillation successfully and generates sharp discontinuities, transmitting and reflecting acoustic waves naturally at the phase interface. This work was supported by a research fund granted from Agency for Defense Development, South Korea

  3. Study of the gas content in two-phase downflow in a sieve-plate column

    Energy Technology Data Exchange (ETDEWEB)

    Utkin, V.A.; Chekhov, O.S.; Stepanov, A.M.

    1986-04-10

    This paper presents a thorough study of the gas content in two-phase downflow in a column sectioned by sieve plates. The air-water system was used in the experiments and the mass flow rates of the gas and liquid in the column were varied in the ranges of 0.5-10 and 200-900 kg m/sup -2/.sec/sup -1/, respectively. The gas content of the stream was determined by gamma radioscopy. A scintilalation counter was used as the gamma-radiation detector. Determination of the gas content over the height of the apparatus showed that the flow structure is formed immediately after the first plate and then remains constant. The influence of the viscosity of the liquid on the gas content of the stream was studied with the use of plates of 40.5% open cross section. Statistical analysis of the experimental data revealed the existence of two patterns of two-phase flow in the apparatus.

  4. Sea water air conditioning : a cost effective alternative

    Energy Technology Data Exchange (ETDEWEB)

    Elsafty, A.F. [Arab Academy for Science, Technology and Maritime Transport, Alexandria (Egypt). Dept. of Mechanical Engineering, College of Engineering and Technology; Saeid, L. [National Gas Company, Cairo (Egypt). GIS and Design Section

    2009-07-01

    The 2 main types of air conditioning systems are vapor compression systems which are electrically operated, and absorption systems which are heat operated. This paper presented a new air conditioning technique for use in the Middle East. The Sea Water Air Conditioning (SWAC) system uses deep cold ocean and sea water as a renewable energy source to air-condition buildings. A technical and economical assessment was performed to determine the advantages of the SWAC system over conventional vapor compression systems to air-condition hotels and resorts at a new tourists resort in Egypt. Meteorological data for the region was used to estimate the gross cooling load for the hotels using the HVAC Load Explorer program. The major components of the SWAC system were sized and analyzed to the determine its operational performance and to estimate the probable costs. The economic analysis was based on two different methods, notably the net present value (NPV) and the simple pay back method. Three options were investigated in the economic study. The first was the use of a conventional air conditioning system to provide a baseline for the other options being investigated. The second option was the use of deep sea water only, and the third option involved the use of a hybrid system using both a sea water air conditioning system and a conventional chiller in series. The SWAC system was the preferred option for its minimum net present value as well as the short pay back period. The energy savings approached 80 per cent of conventional air-conditioners. It was concluded that in addition to reducing electricity use, the SWAC systems can contribute to a reduction in greenhouse gases. 11 refs., 7 tabs., 6 figs.

  5. Reynolds stress turbulence model applied to two-phase pressurized thermal shocks in nuclear power plant

    Energy Technology Data Exchange (ETDEWEB)

    Mérigoux, Nicolas, E-mail: nicolas.merigoux@edf.fr; Laviéville, Jérôme; Mimouni, Stéphane; Guingo, Mathieu; Baudry, Cyril

    2016-04-01

    Highlights: • NEPTUNE-CFD is used to model two-phase PTS. • k-ε model did produce some satisfactory results but also highlights some weaknesses. • A more advanced turbulence model has been developed, validated and applied for PTS. • Coupled with LIM, the first results confirmed the increased accuracy of the approach. - Abstract: Nuclear power plants are subjected to a variety of ageing mechanisms and, at the same time, exposed to potential pressurized thermal shock (PTS) – characterized by a rapid cooling of the internal Reactor Pressure Vessel (RPV) surface. In this context, NEPTUNE-CFD is used to model two-phase PTS and give an assessment on the structural integrity of the RPV. The first available choice was to use standard first order turbulence model (k-ε) to model high-Reynolds number flows encountered in Pressurized Water Reactor (PWR) primary circuits. In a first attempt, the use of k-ε model did produce some satisfactory results in terms of condensation rate and temperature field distribution on integral experiments, but also highlights some weaknesses in the way to model highly anisotropic turbulence. One way to improve the turbulence prediction – and consequently the temperature field distribution – is to opt for more advanced Reynolds Stress turbulence Model. After various verification and validation steps on separated effects cases – co-current air/steam-water stratified flows in rectangular channels, water jet impingements on water pool free surfaces – this Reynolds Stress turbulence Model (R{sub ij}-ε SSG) has been applied for the first time to thermal free surface flows under industrial conditions on COSI and TOPFLOW-PTS experiments. Coupled with the Large Interface Model, the first results confirmed the adequacy and increased accuracy of the approach in an industrial context.

  6. Strongly coupled dispersed two-phase flows; Ecoulements diphasiques disperses fortement couples

    Energy Technology Data Exchange (ETDEWEB)

    Zun, I.; Lance, M.; Ekiel-Jezewska, M.L.; Petrosyan, A.; Lecoq, N.; Anthore, R.; Bostel, F.; Feuillebois, F.; Nott, P.; Zenit, R.; Hunt, M.L.; Brennen, C.E.; Campbell, C.S.; Tong, P.; Lei, X.; Ackerson, B.J.; Asmolov, E.S.; Abade, G.; da Cunha, F.R.; Lhuillier, D.; Cartellier, A.; Ruzicka, M.C.; Drahos, J.; Thomas, N.H.; Talini, L.; Leblond, J.; Leshansky, A.M.; Lavrenteva, O.M.; Nir, A.; Teshukov, V.; Risso, F.; Ellinsen, K.; Crispel, S.; Dahlkild, A.; Vynnycky, M.; Davila, J.; Matas, J.P.; Guazelli, L.; Morris, J.; Ooms, G.; Poelma, C.; van Wijngaarden, L.; de Vries, A.; Elghobashi, S.; Huilier, D.; Peirano, E.; Minier, J.P.; Gavrilyuk, S.; Saurel, R.; Kashinsky, O.; Randin, V.; Colin, C.; Larue de Tournemine, A.; Roig, V.; Suzanne, C.; Bounhoure, C.; Brunet, Y.; Tanaka, A.T.; Noma, K.; Tsuji, Y.; Pascal-Ribot, S.; Le Gall, F.; Aliseda, A.; Hainaux, F.; Lasheras, J.; Didwania, A.; Costa, A.; Vallerin, W.; Mudde, R.F.; Van Den Akker, H.E.A.; Jaumouillie, P.; Larrarte, F.; Burgisser, A.; Bergantz, G.; Necker, F.; Hartel, C.; Kleiser, L.; Meiburg, E.; Michallet, H.; Mory, M.; Hutter, M.; Markov, A.A.; Dumoulin, F.X.; Suard, S.; Borghi, R.; Hong, M.; Hopfinger, E.; Laforgia, A.; Lawrence, C.J.; Hewitt, G.F.; Osiptsov, A.N.; Tsirkunov, Yu. M.; Volkov, A.N.

    2003-07-01

    flow, current distribution and mass transfer along a vertical gas evolving electrode; a two-way coupled model for dilute multiphase flows. Topic 3: turbulence modulation by particles, droplets or bubbles in dense systems: influence of particles on the transition to turbulence in pipe flow; comparison between a point particle model and a finite-diameter-model for the particle turbulence interaction in a suspension; the effect on turbulence by bubbles rising through it under buoyancy; the physical mechanisms of modifying the structure of turbulent homogeneous shear flows by dispersed particles; influence of hydrodynamic interactions between particles on the turbulent flow in a suspension; review of relationships between Lagrangian and Eulerian scales; a two-point PDF for modelling turbulent dispersed two-phase flows and derivation of a two field model; mathematical and numerical modeling of two-phase compressible flows with micro-inertia. Topic 4: collective effects in dispersed two-phase flows clustering and phase distribution: hydrodynamic structure of downward bubbly flow; influence of gravity on the dynamics of a turbulent bubbly pipe flow; experimental study of two-phase flows; particle clusters formed in dispersed gas-solid flows: simulations and experiments; experimental study of the turbulence in bubbly flows at high void fraction; first step in the study of the correlation between air/water flow fluctuations and random buffering forces; clustering and settling velocity of micro-droplets in a grid turbulence. Topic 5: large scale instabilities and gravity driven dispersed flows: new 'non-isothermal' linear instability modes in fluidized beds and bubbly flows; large scale instability in a confined buoyant shear layer; convective instability in uniform dispersed layers; structures in gravity driven bubbly flows; effects of concentration profiles on velocity profiles in sewer; pyroclastic density currents viewed as mammoth scale two-phase flows; mixing and

  7. Water management in capillary gas chromatographic air monitoring systems

    Energy Technology Data Exchange (ETDEWEB)

    Tipler, A. [Perkin Elmer Corp., Norwalk, CT (United States). Fresh Aire Lab.

    1994-12-31

    Capillary gas chromatography is an excellent technique for the speciated quantitation of low-level volatile organic compounds (VOCs) in ambient air. Although GC detectors have excellent sensitivity, some sample pre-concentration will be necessary to enable detection of VOCs at sub-ppb levels. This process normally employs a cooled and/or adsorbent trap to retain the analytes from a large volume of sample air. For very volatile VOCs, a very retentive trap is used and this may also retain water present as vapor in the sample. This trapped water causes significant problems with the chromatography and detector operation and methods must be sought to remove it or eliminate its effects. This paper investigates the magnitude of the problem and examines the various alternatives for managing the trapped water. The application of some of these techniques is demonstrated in a method for the determination of volatile polar and non-polar toxic organic compounds in ambient air.

  8. Influence of Water Salinity on Air Purification from Hydrogen Sulfide

    Directory of Open Access Journals (Sweden)

    Leybovych L.I.

    2015-12-01

    Full Text Available Mathematical modeling of «sliding» water drop motion in the air flow was performed in software package FlowVision. The result of mathematical modeling of water motion in a droplet with diameter 100 microns at the «sliding» velocity of 15 m/s is shown. It is established that hydrogen sulfide oxidation occurs at the surface of phases contact. The schematic diagram of the experimental setup for studying air purification from hydrogen sulfide is shown. The results of the experimental research of hydrogen sulfide oxidation by tap and distilled water are presented. The dependence determining the share of hydrogen sulfide oxidized at the surface of phases contact from the dimensionless initial concentration of hydrogen sulfide in the air has been obtained.

  9. Water Resources Investigations at Edwards Air Force Base since 1988

    Science.gov (United States)

    Sneed, Michelle; Nishikawa, Tracy; Martin, Peter

    2006-01-01

    Edwards Air Force Base (EAFB) in southern California (fig. 1) has relied on ground water to meet its water-supply needs. The extraction of ground water has led to two major problems that can directly affect the mission of EAFB: declining water levels (more than 120 ft since the 1920s) and land subsidence, a gradual downward movement of the land surface (more than 4 ft since the late 1920s). As water levels decline, this valuable resource becomes depleted, thus requiring mitigating measures. Land subsidence has caused cracked (fissured) runways and accelerated erosion on Rogers lakebed. In 1988, the U.S. Geological Survey (USGS), in cooperation with the U.S. Air Force, began investigations of the effects of declining water levels and land subsidence at EAFB and possible mitigation measures, such as the injection of imported surface water into the ground-water system. The cooperative investigations included data collection and analyses, numerical simulations of ground-water flow and land subsidence, and development of a preliminary simulation-optimization model. The results of these investigations indicate that the injection of imported water may help to control land subsidence; however, the potential ground-water-quality impacts are unknown.

  10. A real two-phase submarine debris flow and tsunami

    Energy Technology Data Exchange (ETDEWEB)

    Pudasaini, Shiva P.; Miller, Stephen A. [Department of Geodynamics and Geophysics, Steinmann Institute, University of Bonn Nussallee 8, D-53115, Bonn (Germany)

    2012-09-26

    The general two-phase debris flow model proposed by Pudasaini is employed to study subaerial and submarine debris flows, and the tsunami generated by the debris impact at lakes and oceans. The model, which includes three fundamentally new and dominant physical aspects such as enhanced viscous stress, virtual mass, and generalized drag (in addition to buoyancy), constitutes the most generalized two-phase flow model to date. The advantage of this two-phase debris flow model over classical single-phase, or quasi-two-phase models, is that the initial mass can be divided into several parts by appropriately considering the solid volume fraction. These parts include a dry (landslide or rock slide), a fluid (water or muddy water; e.g., dams, rivers), and a general debris mixture material as needed in real flow simulations. This innovative formulation provides an opportunity, within a single framework, to simultaneously simulate the sliding debris (or landslide), the water lake or ocean, the debris impact at the lake or ocean, the tsunami generation and propagation, the mixing and separation between the solid and fluid phases, and the sediment transport and deposition process in the bathymetric surface. Applications of this model include (a) sediment transport on hill slopes, river streams, hydraulic channels (e.g., hydropower dams and plants); lakes, fjords, coastal lines, and aquatic ecology; and (b) submarine debris impact and the rupture of fiber optic, submarine cables and pipelines along the ocean floor, and damage to offshore drilling platforms. Numerical simulations reveal that the dynamics of debris impact induced tsunamis in mountain lakes or oceans are fundamentally different than the tsunami generated by pure rock avalanches and landslides. The analysis includes the generation, amplification and propagation of super tsunami waves and run-ups along coastlines, debris slide and deposition at the bottom floor, and debris shock waves. It is observed that the

  11. Water Tank with Capillary Air/Liquid Separation

    Science.gov (United States)

    Ungar, Eugene K.; Smith, Frederick; Edeen, Gregg; Almlie, Jay C.

    2010-01-01

    A bladderless water tank (see figure) has been developed that contains capillary devices that allow it to be filled and emptied, as needed, in microgravity. When filled with water, the tank shields human occupants of a spacecraft against cosmic radiation. A membrane that is permeable by air but is hydrophobic (neither wettable nor permeable by liquid water) covers one inside surface of the tank. Grooves between the surface and the membrane allow air to flow through vent holes in the surface as the tank is filled or drained. A margin of wettable surface surrounds the edges of the membrane, and all the other inside tank surfaces are also wettable. A fill/drain port is located in one corner of the tank and is covered with a hydrophilic membrane. As filling begins, water runs from the hydrophilic membrane into the corner fillets of the tank walls. Continued filling in the absence of gravity will result in a single contiguous air bubble that will be vented through the hydrophobic membrane. The bubble will be reduced in size until it becomes spherical and smaller than the tank thickness. Draining the tank reverses the process. Air is introduced through the hydrophobic membrane, and liquid continuity is maintained with the fill/drain port through the corner fillets. Even after the tank is emptied, as long as the suction pressure on the hydrophilic membrane does not exceed its bubble point, no air will be drawn into the liquid line.

  12. Two-phase flow research. Phase 1: Two-phase nozzle research

    Science.gov (United States)

    Toner, S. J.

    1981-07-01

    Experimental performance of converging-diverging nozzles operating on air-water mixtures is presented for a wide range of parameters. Thrust measurements characterized the performance and photographic documentation was used to visually observe the off-design regimes. Thirty-six nozzle configurations were tested to determine the effects of convergence angle, area ratio, and nozzle length. In addition, the pressure ratio and mass flowrate ratio were varied to experimentally map off-design performance. The test results indicate the effects of wall friction and infer temperature and velocity differences between phases and the effect on nozzle performance. The slip ratio between the phases, gas velocity to liquid velocity, is shown to be below about 4 or 5.

  13. Air-water transfer of hydrogen sulfide

    DEFF Research Database (Denmark)

    Yongsiri, C.; Vollertsen, J.; Rasmussen, M. R.

    2004-01-01

    The emissions process of hydrogen sulfide was studied to quantify air–water transfer of hydrogen sulfide in sewer networks. Hydrogen sulfide transfer across the air–water interface was investigated at different turbulence levels (expressed in terms of the Froude number) and pH using batch...... experiments. By means of the overall mass–transfer coefficient (KLa), the transfer coefficient of hydrogen sulfide (KLaH2S), referring to total sulfide, was correlated to that of oxygen (KLaO2) (i.e., the reaeration coefficient). Results demonstrate that both turbulence and pH in the water phase play...... a significant role for KLaH2S. An exponential expression is a suitable representation for the relationship between KLaH2S and the Froude number at all pH values studied (4.5 to 8.0). Because of the dissociation of hydrogen sulfide, KLaH2S increased with decreasing pH at a constant turbulence level. Relative...

  14. Two-Phase Quality/Flow Meter

    Science.gov (United States)

    Moerk, J. Steven (Inventor); Youngquist, Robert C. (Inventor); Werlink, Rudy J. (Inventor)

    1999-01-01

    A quality and/or flow meter employs a capacitance probe assembly for measuring the dielectric constant of flow stream, particularly a two-phase flow stream including liquid and gas components.ne dielectric constant of the flow stream varies depending upon the volume ratios of its liquid and gas components, and capacitance measurements can therefore be employed to calculate the quality of the flow, which is defined as the volume ratio of liquid in the flow to the total volume ratio of gas and liquid in the flow. By using two spaced capacitance sensors, and cross-correlating the time varying capacitance values of each, the velocity of the flow stream can also be determined. A microcontroller-based processing circuit is employed to measure the capacitance of the probe sensors.The circuit employs high speed timer and counter circuits to provide a high resolution measurement of the time interval required to charge each capacitor in the probe assembly. In this manner, a high resolution, noise resistant, digital representation of each of capacitance value is obtained without the need for a high resolution A/D converter, or a high frequency oscillator circuit. One embodiment of the probe assembly employs a capacitor with two ground plates which provide symmetry to insure that accurate measurements are made thereby.

  15. Characteristics of drift-flux models for the 3' diameter vertical-upward air-water flow condition

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, V. T.; Euh, D. J.; Song, C. H. [KAERI, Daejeon (Korea, Republic of)

    2009-07-01

    One of the more complex aspects of two-phase flow calculations is the determination of the void fraction. An accurate estimation of this parameter is important for understanding and predicting the behavior of systems during a wide variety of transient conditions. The drift-flux models are based on correlations to compute the void fraction distribution and slip in a two-phase flow needed to obtain the relative velocity between the phases. Thus, the accuracy of the correlation has a decisive role in determining the correct transport of the two-phases in the system. In this paper, the assessment of 7 correlations based on the Zuber-Findlay model has been done by using the experimental data which were performed on the 3' diameter vertical-upward air-water test facility in KAERI. The void fraction was measured by using the impedance void meter which has a good dynamic resolution to get the values directly without any further data treatment. A total of 28 flow conditions have been performed at 2 bar and 3 bar inlet pressure conditions with temperature of 30 .deg. C, superficial liquid and gas velocity range of 0.5-2.8 m/s and 0.044-1.025 m/s. Some physical phenomena relevant to inlet flow condition and pressure effect were investigated. The results of assessment show a good predictive capability of Bestion model, which is currently used in the system code CATHARE.

  16. Economics of water injected air screw compressor systems

    Science.gov (United States)

    Venu Madhav, K.; Kovačević, A.

    2015-08-01

    There is a growing need for compressed air free of entrained oil to be used in industry. In many cases it can be supplied by oil flooded screw compressors with multi stage filtration systems, or by oil free screw compressors. However, if water injected screw compressors can be made to operate reliably, they could be more efficient and therefore cheaper to operate. Unfortunately, to date, such machines have proved to be insufficiently reliable and not cost effective. This paper describes an investigation carried out to determine the current limitations of water injected screw compressor systems and how these could be overcome in the 15-315 kW power range and delivery pressures of 6-10 bar. Modern rotor profiles and approach to sealing and cooling allow reasonably inexpensive air end design. The prototype of the water injected screw compressor air system was built and tested for performance and reliability. The water injected compressor system was compared with the oil injected and oil free compressor systems of the equivalent size including the economic analysis based on the lifecycle costs. Based on the obtained results, it was concluded that water injected screw compressor systems could be designed to deliver clean air free of oil contamination with a better user value proposition than the oil injected or oil free screw compressor systems over the considered range of operations.

  17. Experimental study of two-phase natural circulation circuit

    Energy Technology Data Exchange (ETDEWEB)

    Lemos, Wanderley Freitas; Su, Jian, E-mail: wlemos@lasme.coppe.ufrj.br, E-mail: sujian@nuclear.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Faccini, Jose Luiz Horacio, E-mail: faccini@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), RIo de Janeiro, RJ (Brazil). Lab. de Termo-Hidraulica Experimental

    2012-07-01

    This paper reports an experimental study on the behavior of fluid flow in natural circulation under single-and two-phase flow conditions. The natural circulation circuit was designed based on concepts of similarity and scale in proportion to the actual operating conditions of a nuclear reactor. This test equipment has similar performance to the passive system for removal of residual heat presents in Advanced Pressurized Water Reactors (A PWR). The experiment was carried out by supplying water to primary and secondary circuits, as well as electrical power resistors installed inside the heater. Power controller has available to adjust the values for supply of electrical power resistors, in order to simulate conditions of decay of power from the nuclear reactor in steady state. Data acquisition system allows the measurement and control of the temperature at different points by means of thermocouples installed at several points along the circuit. The behavior of the phenomenon of natural circulation was monitored by a software with graphical interface, showing the evolution of temperature measurement points and the results stored in digital format spreadsheets. Besides, the natural circulation flow rate was measured by a flowmeter installed on the hot leg. A flow visualization technique was used the for identifying vertical flow regimes of two-phase natural circulation. Finally, the Reynolds Number was calculated for the establishment of a friction factor correlation dependent on the scale geometrical length, height and diameter of the pipe. (author)

  18. A numerical study of steady-state two-phase flow in porous media

    Energy Technology Data Exchange (ETDEWEB)

    Knudsen, Henning Arendt

    2002-07-01

    Two-phase flow in porous media means the simultaneous flow of two phases, say two liquids, e.g., oil and water. This flow is restrained to be within a porous medium. For example sandstone and limestone are typical porous stones that can contain oil and gas in nature. In the extraction of oil from reservoirs, oil is usually displaced by water. So on a large scale we can consider it to be a displacement process. However, on pore scale the ''mix'' and flow processes are complicated. Idealistically, one might consider the search for truth a sufficient motivation for work in this field. Nevertheless, from an economic and technological point of view, enhanced oil recovery is the main motivation for the study of two-phase flow in porous media. Luckily, there are additional systems in real world that falls into this category. One such system is the flow of water and pollutants in aquifers. General knowledge in the field might be beneficial for preserving ground water reserves in the future. In the laboratory one often encounters artificially made porous media. For example glass beads between two glass plates. Therein, one of the phases flowing may be a mixture of glycerol and water. The other phase can be air which then is the non-wetting phase; air does not wet glass. It can also be silicone oil, and in that case the water/glycerol is normally the nonwetting phase. There are other possibilities. In general, laboratory studies are performed on systems on pore scale. The flow properties on the various length scales found in flow systems in nature depend on these properties on pore scale. The so-called upscaling problem concerns how to relate pore scale properties with properties on larger scales. The scope of this thesis is the study of properties on pore scale. The upscaling problem, which is a large research field in itself, is thus outside the scope of this thesis. The results of Paper 3 is an exception since they may infer also to larger scales than

  19. Interactive Effect of Air-Water Ratio and Temperature on the Air Stripping of Benzene

    Directory of Open Access Journals (Sweden)

    M. E. Abdullahi

    2014-06-01

    Full Text Available High cost of pilot scale studies has led engineers to use simulation to study the factors that affect process performance. This study focuses on the interactive effect of air water ratio and temperature on the removal of volatile organic compounds from polluted water using packed column air stripper taking benzene as a case study. The process governing equations developed based on two-film model of mass transfer were solved using MATLAB and a surface response plot was done. The mass transfer coefficient increased from 0.1237x10-5 to 0.1932x10-5 s-1 as the temperature was raised from 293 to 323 K. Also, the Henry’s constant increased from 228.59 to 883.36 K as the temperature was raised from 293 to 323 K. Benzene removal efficiencies of over 99% were obtained for all combinations of temperature and air-water ratio. The result also indicated that air stripping of benzene from wastewater is most dependent on temperature and moderately on air-water ratio.

  20. Two-phase flow interfacial structures in a rod bundle geometry

    Science.gov (United States)

    Paranjape, Sidharth S.

    Interfacial structure of air-water two-phase flow in a scaled nuclear reactor rod bundle geometry was studied in this research. Global and local flow regimes were obtained for the rod bundle geometry. Local two-phase flow parameters were measured at various axial locations in order to understand the transport of interfacial structures. A one-dimensional two-group interfacial area transport model was evaluated using the local parameter database. Air-water two-phase flow experiments were performed in an 8 X 8 rod bundle test section to obtain flow regime maps at various axial locations. Area averaged void fraction was measured using parallel plate type impedance void meters. The cumulative probability distribution functions of the signals from the impedance void meters were used along with a self organizing neural network to identify flow regimes. Local flow regime maps revealed the cross-sectional distribution of flow regimes in the bundle. Local parameters that characterize interfacial structure, that is, void fraction alpha, interfacial area concentration, ai, bubble Sauter mean diameter, DSm and bubble velocity, vg were measured using four sensor conductivity probe technique. The local data revealed the distribution of the interfacial structure in the radial direction, as well as its development in the axial direction. In addition to this, the effect of spacer grid on the flow structure at different gas and liquid velocities was revealed by local parameter measurements across the spacer grids. A two-group interfacial area transport equation (IATE) specific to rod bundle geometry was derived. The derivation of two-group IATE required certain assumption on the bubble shapes in the subchannels and the bubbles spanning more than a subchannel. It was found that the geometrical relationship between the volume and the area of a cap bubble distorted by rods was similar to the one derived for a confined channel under a specific geometrical transformation. The one

  1. Numerical simulation of the two-phase flows in a hydraulic coupling by solving VOF model

    Science.gov (United States)

    Luo, Y.; Zuo, Z. G.; Liu, S. H.; Fan, H. G.; Zhuge, W. L.

    2013-12-01

    The flow in a partially filled hydraulic coupling is essentially a gas-liquid two-phase flow, in which the distribution of two phases has significant influence on its characteristics. The interfaces between the air and the liquid, and the circulating flows inside the hydraulic coupling can be simulated by solving the VOF two-phase model. In this paper, PISO algorithm and RNG k-ɛ turbulence model were employed to simulate the phase distribution and the flow field in a hydraulic coupling with 80% liquid fill. The results indicate that the flow forms a circulating movement on the torus section with decreasing speed ratio. In the pump impeller, the air phase mostly accumulates on the suction side of the blades, while liquid on the pressure side; in turbine runner, air locates in the middle of the flow passage. Flow separations appear near the blades and the enclosing boundaries of the hydraulic coupling.

  2. Correlation of air temperature above water-air sections with the forecasted low level clouds

    Science.gov (United States)

    Huseynov, N. Sh.; Malikov, B. M.

    2009-04-01

    As a case study approach the development of low clouds forecasting methods in correlation with air temperature transformational variations on the sections "water-air" is surveyed. It was evident, that transformational variations of air temperature mainly depend on peculiarities and value of advective variations of temperature. DT is the differences of initial temperature on section water-air in started area, from contrast temperature of water surface along a trajectory of movement of air masses and from the temperature above water surface in a final point of a trajectory. Main values of transformational variations of air temperature at advection of a cold masses is 0.530C•h, and at advection of warm masses is -0.370C•h. There was dimensionless quantity K determined and implemented into practice which was characterized with difference of water temperature in forecasting point and air temperature in an initial point in the ratio of dew-points deficiency at the forecasting area. It follows, that the appropriate increasing or decreasing of K under conditions of cold and warm air masses advection, contributes decreasing of low clouds level. References: Abramovich K.G.: Conditions of development and forecasting of low level clouds. vol. #78, 124 pp., Hydrometcenter USSR 1973. Abramovich K.G.: Variations of low clouds level // Meteorology and Hydrology, vol. # 5, 30-41, Moscow, 1968. Budiko M.I.: Empirical assessment of climatic changes toward the end of XX century // Meteorology and Hydrology, vol. #12, 5-13, Moscow, 1999. Buykov M.V.: Computational modeling of daily evolutions of boundary layer of atmosphere at the presence of clouds and fog // Meteorology and Hydrology, vol. # 4, 35-44, Moscow, 1981. Huseynov N.Sh. Transformational variations of air temperature above Caspian Sea / Proceedings of Conference On Climate And Protection of Environment, 118-120, Baku, 1999. Huseynov N.Sh.: Consideration of advective and transformational variations of air temperature in

  3. The application of water-soluble ruthenium catalysts for the hydrogenation of the dichloromethane soluble fraction of fast pyrolysis oil and related model compounds in a two phase aqueous-organic system

    NARCIS (Netherlands)

    Mahfud, F.H.; Bussemaker, S.; Kooi, B.J.; ten Brink, Gert; Heeres, H.J.

    2007-01-01

    The hydrogenation of a dichloromethane soluble fraction of flash pyrolysis oil (bio-oil, BO), obtained by treatment of BO with a water–dichloromethane solvent mixture, was investigated using a water-soluble homogeneous ruthenium catalyst (RuCl3·3H2O/tris(m-sulfonatophenyl)phosphine, TPPTS). The

  4. Earth, Air, Fire and Water in Our Elements

    Science.gov (United States)

    Lievesley, Tara

    2007-01-01

    The idea that everything is made of the four "elements", earth, air, fire and water, goes back to the ancient Greeks. In this article, the author talks about the origins of ideas about the elements. The author provides an account that attempts to summarise thousands of years of theoretical development of the elements in a thousand words or so.

  5. Propagation of density disturbances in air-water flow

    Science.gov (United States)

    Nassos, G. P.

    1969-01-01

    Study investigated the behavior of density waves propagating vertically in an atmospheric pressure air-water system using a technique based on the correlation between density change and electric resistivity. This information is of interest to industries working with heat transfer systems and fluid power and control systems.

  6. Water, air, Earth and cosmic radiation.

    Science.gov (United States)

    Bassez, Marie-Paule

    2015-06-01

    In the context of the origin of life, rocks are considered mainly for catalysis and adsorption-desorption processes. Here it is shown how some rocks evolve in energy and might induce synthesis of molecules of biological interest. Radioactive rocks are a source of thermal energy and water radiolysis producing molecular hydrogen, H2. Mafic and ultramafic rocks evolve in water and dissolved carbon dioxide releasing thermal energy and H2. Peridotites and basalts contain ferromagnesian minerals which transform through exothermic reactions with the generation of heat. These reactions might be triggered by any heating process such as radioactive decay, hydrothermal and subduction zones or post-shock of meteorite impacts. H2 might then be generated from endothermic hydrolyses of the ferromagnesian minerals olivine and pyroxene. In both cases of mafic and radioactive rocks, production of CO might occur through high temperature hydrogenation of CO2. CO, instead of CO2, was proven to be necessary in experiments synthesizing biological-type macromolecules with a gaseous mixture of CO, N2 and H2O. In the geological context, N2 is present in the environment, and the activation source might arise from cosmic radiation and/or radionuclides. Ferromagnesian and radioactive rocks might consequently be a starting point of an hydrothermal chemical evolution towards the abiotic formation of biological molecules. The two usually separate worlds of rocks and life are shown to be connected through molecular and thermodynamic chemical evolution. This concept has been proposed earlier by the author (Bassez J Phys: Condens Matter 15:L353-L361, 2003, 2008a, 2008b; Bassez Orig Life Evol Biosph 39(3-4):223-225, 2009; Bassez et al. 2011; Bassez et al. Orig Life Evol Biosph 42(4):307-316, 2012, Bassez 2013) without thermodynamic details. This concept leads to signatures of prebiotic chemistry such as radionuclides and also iron and magnesium carbonates associated with serpentine and/or talc

  7. Water, Air, Earth and Cosmic Radiation

    Science.gov (United States)

    Bassez, Marie-Paule

    2015-06-01

    In the context of the origin of life, rocks are considered mainly for catalysis and adsorption-desorption processes. Here it is shown how some rocks evolve in energy and might induce synthesis of molecules of biological interest. Radioactive rocks are a source of thermal energy and water radiolysis producing molecular hydrogen, H2. Mafic and ultramafic rocks evolve in water and dissolved carbon dioxide releasing thermal energy and H2. Peridotites and basalts contain ferromagnesian minerals which transform through exothermic reactions with the generation of heat. These reactions might be triggered by any heating process such as radioactive decay, hydrothermal and subduction zones or post-shock of meteorite impacts. H2 might then be generated from endothermic hydrolyses of the ferromagnesian minerals olivine and pyroxene. In both cases of mafic and radioactive rocks, production of CO might occur through high temperature hydrogenation of CO2. CO, instead of CO2, was proven to be necessary in experiments synthesizing biological-type macromolecules with a gaseous mixture of CO, N2 and H2O. In the geological context, N2 is present in the environment, and the activation source might arise from cosmic radiation and/or radionuclides. Ferromagnesian and radioactive rocks might consequently be a starting point of an hydrothermal chemical evolution towards the abiotic formation of biological molecules. The two usually separate worlds of rocks and life are shown to be connected through molecular and thermodynamic chemical evolution. This concept has been proposed earlier by the author (Bassez J Phys: Condens Matter 15:L353-L361, 2003, 2008a, 2008b; Bassez Orig Life Evol Biosph 39(3-4):223-225, 2009; Bassez et al. 2011; Bassez et al. Orig Life Evol Biosph 42(4):307-316, 2012, Bassez 2013) without thermodynamic details. This concept leads to signatures of prebiotic chemistry such as radionuclides and also iron and magnesium carbonates associated with serpentine and/or talc, which

  8. Air-water transfer of hydrogen sulfide

    DEFF Research Database (Denmark)

    Yongsiri, C.; Vollertsen, J.; Rasmussen, M. R.

    2004-01-01

    experiments. By means of the overall mass–transfer coefficient (KLa), the transfer coefficient of hydrogen sulfide (KLaH2S), referring to total sulfide, was correlated to that of oxygen (KLaO2) (i.e., the reaeration coefficient). Results demonstrate that both turbulence and pH in the water phase play...... a significant role for KLaH2S. An exponential expression is a suitable representation for the relationship between KLaH2S and the Froude number at all pH values studied (4.5 to 8.0). Because of the dissociation of hydrogen sulfide, KLaH2S increased with decreasing pH at a constant turbulence level. Relative...... differences in KLaH2S at pH values between 4.5 and 8.0 became larger as the turbulence level increased, whereas those at pH between 4.5 and 7.0 did not statistically show any change. At constant pH, KLaH2S/KLaO2 was observed not to be dependent on the turbulence range studied. KLaH2S/KLaO2 ratio was 0...

  9. Vapor Compressor Driven Hybrid Two-Phase Loop Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project will demonstrate a vapor compressor driven hybrid two-phase loop technology. The hybrid two-phase loop...

  10. Thermo-fluid dynamics of two-phase flow

    CERN Document Server

    Ishii, Mamoru; Ishii, Mamoru; Ishii, M

    2006-01-01

    Provides a very systematic treatment of two phase flow problems from a theoretical perspectiveProvides an easy to follow treatment of modeling and code devlopemnt of two phase flow related phenomenaCovers new results of two phase flow research such as coverage of fuel cells technology.

  11. Experimental study of two phase flow in inclined channel

    Energy Technology Data Exchange (ETDEWEB)

    Park, Goon Cherl; Lee, Tae Ho; Lee, Sang Won [Seoul National University, Seoul (Korea, Republic of)

    1997-07-01

    Local two-phase flow parameters were measured to investigate the internal flow structures of steam-water boiling flow in an inclined channel. The vapor phase local flow parameters, such as void fraction, bubble frequency, vapor velocity, interfacial area concentration and chord length, were measured, using two conductivity probe method, and local liquid phase velocity was measured by pitot tube. In order to investigate the effects of channel inclination on two phase flow structure, the experiments were conducted for three angles of inclination; 0 degree(vertical), 30 degree and 60 degree. The experimental flow conditions were confined to the liquid superficial velocities less than 1.4 m/sec and nearly atmospheric pressure, and the flow regime was limited to the subcooled boiling. Using the measured distributions of the local phasic parameters, correlations for the drift-flux parameters such as distribution parameter and drift velocity were proposed. Those correlations were compared with the available correlation applicable to the inclined channel by the calculation of average void fraction using the present data. 44 refs., 4 tabs., 88 figs. (author)

  12. Correlations for predicting single phase and two-phase flow pressure drop in pebble bed flow channels

    Energy Technology Data Exchange (ETDEWEB)

    Bai Bofeng, E-mail: bfbai@mail.xjtu.edu.cn [State Key Laboratory of Multiphase Flow in Power Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Liu Maolong; Lv Xiaofei; Yan Junjie [State Key Laboratory of Multiphase Flow in Power Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Yan Xiao; Xiao Zejun [Lab of Bubble Physics and Natural Circulation, Nuclear Power Institute of China, Chengdu 610041 (China)

    2011-12-15

    An experimental study was conducted on the pressure drop of the single phase and the air-water two-phase flow in the bed of rectangular cross sections densely filled with uniform spheres. Three kinds of glass spheres with different equivalent diameters (3 mm, 6 mm, and 8 mm) were used for the establishment of the test sections. The Reynolds number in the experiment ranged from a dozen to thousands for the single-phase flow and from hundreds to tens of thousands for the two-phase flow. In the present flow-regime model, the bed was subdivided into a near-wall region and a central region in order to take the wall effect into account to improve the prediction at low tube-to-particle diameter ratios. Improved correlations are obtained based on the previous study to consider the single-phase flow pressure drops for finite pebble beds with spherical particles and nonspherical particles by fitting the coefficients of that equation to both the database and the present experiment. The correlation is consistent with the observed physical behavior which explains its comparatively good agreement with the experimental data. A new empirical correlation for the prediction of two-phase flow pressure drops was proposed based on the gas phase relative permeability as a function of the gas phase saturation and the void fraction. The correlation fit well for both experimental data of spherical particles and nonspherical particles.

  13. 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.

  14. Why air bubbles in water glow so easily

    CERN Document Server

    Brenner, M; Lohse, D; Brenner, Michael; Hilgenfeldt, Sascha; Lohse, Detlef

    1996-01-01

    Sound driven gas bubbles in water can emit light pulses (sonoluminescence). Experiments show a strong dependence on the type of gas dissolved in water. Air is found to be one of the most friendly gases towards this phenomenon. Recently, \\cite{loh96} have suggested a chemical mechanism to account for the strong dependence on the gas mixture: the dissociation of nitrogen at high temperatures and its subsequent chemical reactions to highly water soluble gases such as NO, NO$_2$, and/or NH$_3$. Here, we analyze the consequences of the theory and offer detailed comparison with the experimental data of Putterman's UCLA group. We can quantitatively account for heretofore unexplained results. In particular, we understand why the argon percentage in air is so essential for the observation of stable SL.

  15. Nonlinear Acoustics at the Air-Water Free Surface

    Science.gov (United States)

    Pree, Seth; Naranjo, Brian; Putterman, Seth

    2016-11-01

    According to linear acoustics, airborne sound incident on a water surface transmits only a tenth of a percent of its energy. This difficulty of transmitting energy across the water surface limits the feasibility of standoff ultrasound imaging. We propose to overcome this long standing problem by developing new methods of coupling into the medium at standoff. In particular, we believe that the acoustic nonlinearity of both the air and the medium may yield a range of effects in the vicinity of the surface permitting an efficient transmission of ultrasound from the air into the medium. The recent commercial availability of parametric speakers that deliver modulated 100kHz ultrasound at 135dB to nonlinearly generate music at 95dB provides an interesting platform with which to revisit the transmission of sound across acoustic impedance mismatches. We show results of experimental studies of the behavior of the air-water free surface when subjected to large amplitude acoustic pressures from the air. This work was supported by the ARO STIR program.

  16. INTERPRETATION CORRECTION OF THE OXYGEN ACTIVATED WELL LOGGING UNDER THE CONDITION OF OIL-WATER TWO-PHASE FLOWS OF HORIZONTAL WELLS%水平井油水两相流条件下氧活化测井解释校正

    Institute of Scientific and Technical Information of China (English)

    梁庆宝

    2012-01-01

    由于脉冲中子氧活化测井在水平井油水两相流条件下测量结果的相对误差随着含水率的减小而增大,因此有必要研究氧活化测井解释校正方法.根据放射性衰减规律以及物质对伽马射线的吸收规律,分析了理想测量条件下井内介质含水率对测量结果的影响,利用函数回归方法对水平井油水两相流条件下脉冲中子氧活化测井的解释结果进行了校正,并给出了与含水率相关的解释结果校正公式.当井内为油水两相流体时,采用该方法能够有效提高氧活化测井的解释精度.%Due to the deterioration of the relative errors of the measured results of the oxygen activated well logging under the conditions of oil-water two-phases flow in horizontal well with the decrease of the water cut, it is necessary to study on the correcting method of the above well logging interpretation. According to the laws of both radioactive decay and the absorption of gamma ray by substances, the influences of the water cuts of the downhole media on the measured results under the ideal operating conditions are analyzed. With the help of function regression method, the well logging interpretation results are corrected for the horizontal well in oil-water two-phase flows. In addition, the correcting formula of the interpretation results relating with the water cuts is presented. When there are two-phase oil-water flows in the well, the method can effectively improve the interpretation accuracy of oxygen activation well logging.

  17. Experimental study on transient behavior of semi-open two-phase thermosyphon

    Institute of Scientific and Technical Information of China (English)

    朱华; 王建新; 张巧惠; 屠传经

    2004-01-01

    An experimental system was set up to measure the temperature, pressure, heat transfer rate and mass flow rate in a semi-open two-phase thermosyphon. The behaviors of a semi-open two-phase thermosyphon during startup, shutdown and lack of water were studied to get complete understanding of its thermal characteristics. The variation of wall temperature, heat-exchange condition and pressure fluctuations of semi-open two-phase thermosyphons showed that the startup of SOTPT needs about 60-70 min; the startup speed of SOTPT is determined by the startup speed of the condensation section; the average pressure in the heat pipe is equal to the environmental pressure usually; the shutdown of SOTPT needs about 30-50min; a semi-open two-phase thermosyphon has good response to lack of water accident.

  18. Reynolds transport theorem for a two-phase flow

    Science.gov (United States)

    Collado, Francisco J.

    2007-01-01

    Transport equations for one-dimensional (1d), steady, two-phase flow have been proposed based on the fact that if the phases have different velocities, they cannot cover the same distance (the control volume length) in the same time. Thus, working in the same control volume for the two phases, the time scales of the phases have to be different. From this approach, transport balances for 1D, steady, two-phase flow have been already derived, supplying acceptable correlations for two-phase flow. Here, based on the strict application of the Reynolds transport theorem, general transport balances for two-phase flow are suggested.

  19. A Mass Conservative Numerical Solution for Two-Phase Flow in Porous Media With Application to Unsaturated Flow

    DEFF Research Database (Denmark)

    Celia, Michael A.; Binning, Philip John

    1992-01-01

    . Numerical results also demonstrate the potential importance of air phase advection when considering contaminant transport in unsaturated soils. Comparison to several other numerical algorithms shows that the modified Picard approach offers robust, mass conservative solutions to the general equations......A numerical algorithm for simulation of two-phase flow in porous media is presented. The algorithm is based on a modified Picard linearization of the governing equations of flow, coupled with a lumped finite element approximation in space and dynamic time step control. Numerical results indicate...... that the algorithm produces solutions that are essentially mass conservative and oscillation free, even in the presence of steep infiltrating fronts. When the algorithm is applied to the case of air and water flow in unsaturated soils, numerical results confirm the conditions under which Richards's equation is valid...

  20. Connecting Water Quality With Air Quality Through Microbial Aerosols

    Science.gov (United States)

    Dueker, M. Elias

    Aerosol production from surface waters results in the transfer of aquatic materials (including nutrients and bacteria) to air. These materials can then be transported by onshore winds to land, representing a biogeochemical connection between aquatic and terrestrial systems not normally considered. In urban waterfront environments, this transfer could result in emissions of pathogenic bacteria from contaminated waters. Despite the potential importance of this link, sources, near-shore deposition, identity and viability of microbial aerosols are largely uncharacterized. This dissertation focuses on the environmental and biological mechanisms that define this water-air connection, as a means to build our understanding of the biogeochemical, biogeographical, and public health implications of the transfer of surface water materials to the near-shore environment in both urban and non-urban environments. The effects of tidal height, wind speed and fog on coastal aerosols and microbial content were first quantified on a non-urban coast of Maine, USA. Culture-based, culture-independent, and molecular methods were used to simultaneously sample microbial aerosols while monitoring meteorological parameters. Aerosols at this site displayed clear marine influence and high concentrations of ecologically-relevant nutrients. Coarse aerosol concentrations significantly increased with tidal height, onshore wind speed, and fog presence. Tidal height and fog presence did not significantly influence total microbial aerosol concentrations, but did have a significant effect on culturable microbial aerosol fallout. Molecular analyses of the microbes settling out of near-shore aerosols provided further evidence of local ocean to terrestrial transport of microbes. Aerosol and surface ocean bacterial communities shared species and in general were dominated by organisms previously sampled in marine environments. Fog presence strengthened the microbial connection between water and land through

  1. CFD Code Validation against Stratified Air-Water Flow Experimental Data

    Directory of Open Access Journals (Sweden)

    F. Terzuoli

    2008-01-01

    Full Text Available Pressurized thermal shock (PTS modelling has been identified as one of the most important industrial needs related to nuclear reactor safety. A severe PTS scenario limiting the reactor pressure vessel (RPV lifetime is the cold water emergency core cooling (ECC injection into the cold leg during a loss of coolant accident (LOCA. Since it represents a big challenge for numerical simulations, this scenario was selected within the European Platform for Nuclear Reactor Simulations (NURESIM Integrated Project as a reference two-phase problem for computational fluid dynamics (CFDs code validation. This paper presents a CFD analysis of a stratified air-water flow experimental investigation performed at the Institut de Mécanique des Fluides de Toulouse in 1985, which shares some common physical features with the ECC injection in PWR cold leg. Numerical simulations have been carried out with two commercial codes (Fluent and Ansys CFX, and a research code (NEPTUNE CFD. The aim of this work, carried out at the University of Pisa within the NURESIM IP, is to validate the free surface flow model implemented in the codes against experimental data, and to perform code-to-code benchmarking. Obtained results suggest the relevance of three-dimensional effects and stress the importance of a suitable interface drag modelling.

  2. Carbon and Noble Gas Isotope Banks in Two-Phase Flow: Changes in Gas Composition During Migration

    Science.gov (United States)

    Sathaye, K.; Larson, T.; Hesse, M. A.

    2015-12-01

    In conjunction with the rise of unconventional oil and gas production, there has been a recent rise in interest in noble gas and carbon isotope changes that can occur during the migration of natural gas. Natural gas geochemistry studies use bulk hydrocarbon composition, carbon isotopes, and noble gas isotopes to determine the migration history of gases from source to reservoir, and to trace fugitive gas leaks from reservoirs to shallow groundwater. We present theoretical and experimental work, which helps to explain trends observed in gas composition in various migration scenarios. Noble gases are used as tracers for subsurface fluid flow due to distinct initial compositions in air-saturated water and natural gases. Numerous field studies have observed enrichments and depletions of noble gases after gas-water interaction. A theoretical two-phase gas displacement model shows that differences in noble gas solubility will cause volatile gas components will become enriched at the front of gas plumes, leaving the surrounding residual water stripped of dissolved gases. Changes in hydrocarbon gas composition are controlled by gas solubility in both formation water and residual oil. In addition to model results, we present results from a series of two-phase flow experiments. These results demonstrate the formation of a noble gas isotope banks ahead of a main CO2 gas plume. Additionally, we show that migrating hydrocarbon gas plumes can sweep biogenic methane from groundwater, significantly altering the isotope ratio of the gas itself. Results from multicomponent, two-phase flow experiments qualitatively agree with the theoretical model, and previous field studies. These experimentally verified models for gas composition changes can be used to aid source identification of subsurface gases.

  3. Studies of Two-Phase Flow Dynamics and Heat Transfer at Reduced Gravity Conditions

    Science.gov (United States)

    Witte, Larry C.; Bousman, W. Scott; Fore, Larry B.

    1996-01-01

    The ability to predict gas-liquid flow patterns is crucial to the design and operation of two-phase flow systems in the microgravity environment. Flow pattern maps have been developed in this study which show the occurrence of flow patterns as a function of gas and liquid superficial velocities as well as tube diameter, liquid viscosity and surface tension. The results have demonstrated that the location of the bubble-slug transition is affected by the tube diameter for air-water systems and by surface tension, suggesting that turbulence-induced bubble fluctuations and coalescence mechanisms play a role in this transition. The location of the slug-annular transition on the flow pattern maps is largely unaffected by tube diameter, liquid viscosity or surface tension in the ranges tested. Void fraction-based transition criteria were developed which separate the flow patterns on the flow pattern maps with reasonable accuracy. Weber number transition criteria also show promise but further work is needed to improve these models. For annular gas-liquid flows of air-water and air- 50 percent glycerine under reduced gravity conditions, the pressure gradient agrees fairly well with a version of the Lockhart-Martinelli correlation but the measured film thickness deviates from published correlations at lower Reynolds numbers. Nusselt numbers, based on a film thickness obtained from standard normal-gravity correlations, follow the relation, Nu = A Re(sup n) Pr(exp l/3), but more experimental data in a reduced gravity environment are needed to increase the confidence in the estimated constants, A and n. In the slug flow regime, experimental pressure gradient does not correlate well with either the Lockhart-Martinelli or a homogeneous formulation, but does correlate nicely with a formulation based on a two-phase Reynolds number. Comparison with ground-based correlations implies that the heat transfer coefficients are lower at reduced gravity than at normal gravity under the same

  4. Use of Surfactants to Decrease Air-Water Interfacial Tension During Sparging

    Science.gov (United States)

    Air sparging is a remediation procedure of injecting air into polluted ground water. The primary intention of air sparging is to promote biodegradation of volatile organic compounds (VOCs) in the groundwater passing through the treatment sector. Sparging treatment efficiency dep...

  5. Use of Surfactants to Decrease Air-Water Interfacial Tension During Sparging (OKC, OK)

    Science.gov (United States)

    Air sparging is a remediation procedure of injecting air into polluted ground water. The primary intention of air sparging is to promote biodegradation of volatile organic compounds (VOCs) in the groundwater passing through the treatment sector. Sparging treatment efficiency dep...

  6. Two-phase microfluidics: thermophysical fundamentals and engineering concepts

    Science.gov (United States)

    Kuznetsov, V. V.

    2016-10-01

    Thermophysical fundamentals and engineering concepts of the two-phase microfluidic devises based on controlled liquid decay are discussed in this paper. The results of an experimental study of the explosive evaporation at a thin film heater of the MEMS devise in application to thermal inkjet printing are presented. The peculiarities of homogeneous nucleation and bubble growth in the liquid subjected to pulse heating are discussed. Using experimental data a simple equation suitable for predicting the growth rate of a vapor bubble in a non-uniformly superheated liquid was obtained and used to complete a mathematical model of the self-consistent nucleation and vapor bubbles growth in the induced pressure field. The results of numerical calculations according to the proposed model showed good agreement with the experimental data on a time of nucleation and duration of the initial stage of an explosive evaporation of water.

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

    Energy Technology Data Exchange (ETDEWEB)

    Spann, J.F. (Morgantown Energy Technology Center, U.S. Department of Energy, P.O. Box 880, Morgantown, West Virginia 26507-0880 (United States)); Maloney, D.J.; Lawson, W.F.; Casleton, K.H. (Morgantown Energy Technology Center, U.S. Department of Energy, P.O. Box 880, Morgantown, West Virginia 26507-0880 (United States))

    1993-04-20

    The response of two-phase droplets to intense radiant heating is studied to determine the incident power that is required for causing explosive boiling in the liquid phase. The droplets studied consist of strongly absorbing coal particles dispersed in a weakly absorbing water medium. Experiments are performed by confining droplets (radii = 37, 55, and 80 [mu]m) electrodynamically and irradiating them from two sides with pulsed laser beams. Emphasis is placed on the transition region from accelerated droplet vaporization to droplet superheating and explosive boiling. The time scale observed for explosive boiling is more than 2 orders of magnitude longer than published values for pure liquids. The delayed response is the result of energy transfer limitations between the absorbing solid phase and the surrounding liquid.

  8. Flooding in counter-current two-phase flow

    Energy Technology Data Exchange (ETDEWEB)

    Ragland, W.A.; Ganic, E.N.

    1982-01-01

    Flooding is a phenomenon which is best described as the transition from counter-current to co-current flow. Early notice was taken of this phenomenon in the chemical engineering industry. Flooding also plays an important role in the field of two-phase heat transfer since it is a limit for many systems involving counter-current flow. Practical applications of flooding limited processes include wickless thermosyphons and the emergency core cooling system (ECCS) of pressurized water nuclear reactors. The phenomenon of flooding also is involved in the behavior of nuclear reactor core materials during severe accident conditions where flooding is one of the mechanisms governing the motion of the molten fuel pin cladding.

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

    Science.gov (United States)

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

    1993-01-01

    The response of two-phase droplets to intense radiant heating is studied to determine the incident power that is required for causing explosive boiling in the liquid phase. The droplets studied consist of strongly absorbing coal particles dispersed in a weakly absorbing water medium. Experiments are performed by confining droplets (radii of 37, 55, and 80 microns) electrodynamically and irradiating them from two sides with pulsed laser beams. Emphasis is placed on the transition region from accelerated droplet vaporization to droplet superheating and explosive boiling. The time scale observed for explosive boiling is more than 2 orders of magnitude longer than published values for pure liquids. The delayed response is the result of energy transfer limitations between the absorbing solid phase and the surrounding liquid.

  10. 阻抗传感器在近水平油水两相管流的实验研究%Experimental Study on Impedance Sensor in Oil-water Two-phase Flow of Near-horizontal Pipe

    Institute of Scientific and Technical Information of China (English)

    倪莉; 刘兴斌; 胡金海

    2009-01-01

    生产测井动态监测中水平井受井身结构、井简流动状态、重力影响等因素影响使得流动介质分布、速度分布、流体的流型、流速削面、油水的分布状态等与垂直井有很大的不同.设计了小管径多相流实验装置,实验介质是柴油和水,设置了分别为3~60 m3/d的10种流量,含水率变化范围10%~100%;分别为85°、88°、90°、92°、95°等近水平状态下的5个角度对阻抗传感器进行了实验.实验结果表明,流量大于10 m3/d时的流型是分相的泡状流,阻抗的相埘响应不受角度的影响,响应规律与垂直井类似;流量低于10 m3/d时的流型是层流,阻抗的相对响应同时受到流量、含水率、角度的影响,在同一角度下受流量和含水率的影响;受油水滑脱现象影响.低流量下的相对响应高于高流量的,持水率高于含水率;受角度的影响,在90°、92°、95°时输出的相对响应出现了向下的趋势,85°、88°时输出的相对响应出现了向上的趋势.实验传感器是仪器短节,排除了集流伞漏失对流体流型的影响,完全反映流体在传感器内流道的真实流动状态,高速摄像机记录了流体随流量和含水率的变化.%In performance monitoring of production log, since the horizontal wells are often affected by well structures, borehole fluid flow states and gravity, the flow media distributions, flowing velocities and fluid types, flowing velocity profiles and oil/water distributions in the horizontal wells are quite dif-ferent from those in the vertical wells. Designed is a small diameter multiphase flow test device. The test media are diesel fuel and water with 10 different flow rates and from 10% to 100% range of watercut changess; Experiments of impedance sensor were conducted in the device at five near-horizontal angles or inclinations (i. e., 85°,88°,90°,92°and 95°). The flow pattern is dispersed bubble flow when the flow rate is over 10 m3/d, the

  11. Study on constant-pressure specific heat of non-equi- librium phase change process in gas-liquid two-phase flow system

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this paper, the air-water vapor-water system is taken as an example, and the formula of constantpressure specific heat during non-equilibrium phase change process in the two-phase flow system is deduced using the theory of two-phase flow and thermophysics. The constant-pressure specific heat of non-equilibrium phase change process is calculated with the corresponding numerical model, and the numerical results are compared to those of the equilibrium phase change process. It is shown that in evaporation process, the variational rate of the non-equilibrium specific heat increases with increasing initial fluid temperature and particle mass fraction. The smaller particle radius is, the faster the variational rate is. Meanwhile, the constant-pressure specific heat of equilibrium process is higher than that of the non-equilibrium process all the time.

  12. Rarefaction Waves at the Outlet of the Supersonic Two-Phase Flow Nozzle

    Science.gov (United States)

    Nakagawa, Masafumi; Miyazaki, Hiroki; Harada, Atsushi

    Two-phase flow nozzles are used in the total flow system for geothermal power plants and in the ejector of the refrigerant cycle, etc. One of the most important functions of a two-phase flow nozzle is to convert the thermal energy to the kinetic energy of the two-phase flow. The kinetic energy of the two-phase flow exhausted from a nozzle is available for all applications of this type. There exist the shock waves or rarefaction waves at the outlet of a supersonic nozzle in the case of non-best fitting expansion conditions when the operation conditions of the nozzle are widely chosen. Those waves affect largely on the energy conversion efficiency of the two-phase flow nozzle. The purpose of the present study is to elucidate the character of the rarefaction waves at the outlet of the supersonic two-phase flow nozzle. The high pressure hot water blow down experiment has been carried out. The decompression curves by the rarefaction waves are measured by changing the flow rate of the nozzle and inlet temperature of the hot water. The back pressures of the nozzle are also changed in those experiments. The divergent angles of the two-phase flow flushed out from the nozzle are measured by means of the photograph. The experimental results show that the recompression curves are different from those predicted by the isentropic homogenous two-phase flow. The regions where the rarefaction waves occur become wide due to the increased outlet speed of two-phase flow. The qualitative dependency of this expansion character is the same as the isotropic homogenous flow, but the values obtained from the experiments are quite different. When the back pressure of the nozzle is higher, these regions do not become small in spite of the super sonic two-phase flow. This means that the disturbance of the down-stream propagate to the up-stream. It is shown by the present experiments that the rarefaction waves in the supersonic two-phase flow of water have a subsonic feature. The measured

  13. Expansion Waves at the Outlet of the Supersonic Two-Phase Flow Nozzle

    Science.gov (United States)

    Nakagawa, Masafumi; Miyazaki, Hiroki; Harada, Atsushi; Ibragimov, Zokirjon

    Two-phase flow nozzles are used in the total flow system of geothermal power plants and in the ejector of the refrigeration cycle, etc. One of the most important functions of the two-phase flow nozzle is converting two-phase flow thermal energy into kinetic energy. The kinetic energy of the two-phase flow exhausted from a nozzle is available for all applications of this type. In the case of non-best fitting expansion conditions, when the operation conditions of the supersonic nozzle are widely chosen, there exist shock waves or expansion waves at the outlet of the nozzle. Those waves affect largely the energy conversion efficiency of the two-phase flow nozzle. The purpose of the present study is to elucidate character of the expansion waves at the outlet of the supersonic two-phase flow nozzle. High-pressure hot water blowdown experiments have been carried out. The decompression curves of the expansion waves are measured by changing the flowrate in the nozzle and inlet temperature of the hot water. The back pressures of the nozzle are also changed in those experiments. The expansion angles of the two-phase flow flushed out from the nozzle are measured by means of the photograph. The experimental results show that the decompression curves are different from those predicted by the isentropic homogeneous two-phase flow theory. The regions where the expansion waves occur become wide due to the increased outlet speed of the two-phase flow. The qualitative dependency of this expansion character is the same as the isentropic homogeneous flow, but the values obtained from the experiments are quite different. When the back pressure of the nozzle is higher, these regions do not become small in spite of the supersonic two-phase flow. This means that the disturbance in the downstream propagates to the upstream. It is shown by the present experiments that the expansion waves in the supersonic two-phase flow of water have a subsonic feature. The measured expansion angles become

  14. Thermal performance of closed two-phase thermosyphon using nanofluids

    Energy Technology Data Exchange (ETDEWEB)

    Khandekar, Sameer; Mehta, Balkrishna [Department of Mechanical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Joshi, Yogesh M. [Department of Chemical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016 (India)

    2008-06-15

    Nanofluids, stabilized suspensions of nanoparticles typically <100 nm in conventional fluids, are evolving as potential enhanced heat transfer fluids due to their improved thermal conductivity, increase in single phase heat transfer coefficient and significant increase in critical boiling heat flux. In the present paper, we investigate the overall thermal resistance of closed two-phase thermosyphon using pure water and various water based nanofluids (of Al{sub 2}O{sub 3}, CuO and laponite clay) as working fluids. We observe that all these nanofluids show inferior thermal performance than pure water. Furthermore, we observe that the wettability of all nanofluids on copper substrate, having the same average roughness as that of the thermosyphon container pipe, is better than that of pure water. A scaling analysis is presented which shows that the increase in wettability and entrapment of nanoparticles in the grooves of the surface roughness cause decrease in evaporator side Peclet number that finally leads to poor thermal performance. (author)

  15. Bacterial Swimming at Air/Water and Oil/Water Interfaces

    Science.gov (United States)

    Morse, Michael; Huang, Athena; Li, Guanglai; Tang, Jay

    2012-02-01

    The microbes inhabiting the planet over billions of years have adapted to diverse physical environments of water, soil, and interfaces between water and either solid or air. Following recent studies on bacterial swimming and accumulation near solid surfaces, we turn our attention to the behavior of Caulobacter crescentus, a singly flagellated bacterium, at water/air and water/oil interfaces. The latter is motivated by relevance to microbial degradation of crude oil in light of the recent oil spill in the Gulf of Mexico. Our ongoing study suggests that Caulobacter swarmer cells tend to get physically trapped at both water/air and water/oil interfaces, accumulating at the surface to a greater degree than boundary confinement properties like that of solid surfaces would predict. At the water/air interface, swimmers move in tight circles at half the speed of swimmers in the bulk fluid. At the water/oil interface, swimming circles are even tighter with further reduced swimming speed. We report experimental data and present preliminary analysis of the findings based on low Reynolds number hydrodynamics, the known surface tension, and surface viscosity at the interface. The analysis will help determine properties of the bacterium such as their surface charge and hydrophobicity.

  16. Modeling of membrane processes for air revitalization and water recovery

    Science.gov (United States)

    Lange, Kevin E.; Foerg, Sandra L.; Dall-Bauman, Liese A.

    1992-01-01

    Gas-separation and reverse-osmosis membrane models are being developed in conjunction with membrane testing at NASA JSC. The completed gas-separation membrane model extracts effective component permeabilities from multicomponent test data, and predicts the effects of flow configuration, operating conditions, and membrane dimensions on module performance. Variable feed- and permeate-side pressures are considered. The model has been applied to test data for hollow-fiber membrane modules with simulated cabin-air feeds. Results are presented for a membrane designed for air drying applications. Extracted permeabilities are used to predict the effect of operating conditions on water enrichment in the permeate. A first-order reverse-osmosis model has been applied to test data for spiral wound membrane modules with a simulated hygiene water feed. The model estimates an effective local component rejection coefficient under pseudosteady-state conditions. Results are used to define requirements for a detailed reverse-osmosis model.

  17. Estimating the radon concentration in water and indoor air.

    Science.gov (United States)

    Maged, A F

    2009-05-01

    The paper presents the results of radon concentration measurements in the vicinity of water, indoor air and in contact to building walls. The investigations were carried out using CR-39 track detectors. Samples of ground water flowing out of many springs mostly in Arabian Gulf area except one from Germany have been studied. The results are compared with international recommendations and the values are found to be lower than the recommended value. Measuring the mean indoor radon concentrations in air and in contact to building walls in the dwellings of Kuwait University Campus were found 24.2 +/- 7.7, and 462 +/- 422 Bq m(-3) respectively. These values lead to average effective dose equivalent rates of 1.3 +/- 0.4 and 23 +/- 21 mSv year(-1), respectively.

  18. Economics of water injected air screw compressor systems

    OpenAIRE

    Madhav, K. V.; Kovacevic, A.

    2015-01-01

    There is a growing need for compressed air free of entrained oil to be used in industry. In many cases it can be supplied by oil flooded screw compressors with multi stage filtration systems, or by oil free screw compressors. However, if water injected screw compressors can be made to operate reliably, they could be more efficient and therefore cheaper to operate. Unfortunately, to date, such machines have proved to be insufficiently reliable and not cost effective. This paper describes an in...

  19. Eenergy Extraction from air or Water by Vibrations

    Science.gov (United States)

    Viba, J.; Shtals, L.; Eiduks, M.

    2009-01-01

    The paper considers the possibility to derive energy from air or water in a non-traditional way (without using rotating equipment). For this purpose, the authors studied variations in the additional area of a vibrating object in a definite sequence found as the solution of an optimisation problem. In the work, stably moving mechatronic systems were synthesised and modelled, whose control is very simple (not requiring calibration), being a function of the changing sign of phase coordinates.

  20. Numerical investigation on the characteristics of two-phase flow in fuel assemblies with spacer grid

    Energy Technology Data Exchange (ETDEWEB)

    Chen, D.; Yang, Z.; Zhong, Y.; Xiao, Y.; Hu, L. [Chongqing Univ. (China). Key Lab. of Low-grade Energy Utilization Technologies and Systems

    2016-07-15

    In pressurized water reactors (PWRs), the spacer grids of the fuel assembly has significant impact on the thermal-hydraulic performance of the fuel assembly. Particularly, the spacer grids with the mixing vanes can dramatically enhance the secondary flow and have significant effect on the void distribution in the fuel assembly. In this paper, the CFD study has been carried out to analyze the effects of the spacer grid with the steel contacts, dimples and mixing vanes on the boiling two-phase flow characteristics, such as the two-phase flow field, the void distribution, and so on. Considered the influence of the boiling phase change on two-phase flow, a boiling model was proposed and applied in the CFD simulation by using the UDF (User Defined Function) method. Furthermore, in order to analyze the effects of the spacer grid with mixing vanes, the adiabatic (without boiling) two-phase flow has also been investigated as comparison with the boiling two-phase flow in the fuel assembly with spacer grids. The CFD simulation on two-phase flow in the fuel assembly with the proposed boiling model can predict the characteristics of two-phase flow better.

  1. Polydopamine Films from the Forgotten Air/Water Interface.

    Science.gov (United States)

    Ponzio, Florian; Payamyar, Payam; Schneider, Anne; Winterhalter, Mathias; Bour, Jérôme; Addiego, Frédéric; Krafft, Marie-Pierre; Hemmerle, Joseph; Ball, Vincent

    2014-10-02

    The formation of polydopamine under mild oxidation conditions from dopamine solutions with mechanical agitation leads to the formation of films that can functionalize all kinds of materials. In the absence of stirring of the solution, we report the formation of polydopamine films at the air/water interface (PDA A/W) and suggest that it arises from an homogeneous nucleation process. These films grow two times faster than in solution and can be deposited on hydrophilic or hydrophobic substrates by the Langmuir-Schaeffer technique. Thanks to this new method, porous and hydrophobic materials like polytetrafluoroethylene (PTFE) membranes can be completely covered with a 35 nm thick PDA A/W film after only 3h of reaction. Finally the oxidation of a monomer followed by a polymerization in water is not exclusive to polydopamine since we also transferred polyaniline functional films from the air/water interface to solid substrates. These findings suggest that self-assembly from a solution containing hydrophilic monomers undergoing a chemical transformation (here oxidation and oligomerization) could be a general method to produce films at the liquid/air interface.

  2. New research on bioregenerative air/water purification systems

    Science.gov (United States)

    Johnson, Anne H.; Ellender, R. D.; Watkins, Paul J.

    1991-01-01

    For the past several years, air and water purification systems have been developed and used. This technology is based on the combined activities of plants and microorganisms as they function in a natural environment. More recently, researchers have begun to address the problems associated with indoor air pollution. Various common houseplants are currently being evaluated for their abilities to reduce concentrations of volatile organic compounds (VOCS) such as formaldehyde and benzene. With development of the Space Exploration Initiative, missions will increase in duration, and problems with resupply necessitates implementation of regenerative technology. Aspects of bioregenerative technology have been included in a habitat known as the BioHome. The ultimate goal is to use this technology in conjunction with physicochemical systems for air and water purification within closed systems. This study continued the risk assessment of bioregenerative technology with emphasis on biological hazards. In an effort to evaluate the risk for human infection, analyses were directed at enumeration of fecal streptococci and enteric viruses with the BioHome waste water treatment system.

  3. Energy and air emission effects of water supply.

    Science.gov (United States)

    Stokes, Jennifer R; Horvath, Arpad

    2009-04-15

    Life-cycle air emission effects of supplying water are explored using a hybrid life-cycle assessment For the typically sized U.S. utility analyzed, recycled water is preferable to desalination and comparable to importation. Seawater desalination has an energy and air emission footprint that is 1.5-2.4 times larger than that of imported water. However, some desalination modes fare better; brackish groundwater is 53-66% as environmentally intensive as seawater desalination. The annual water needs (326 m3) of a typical Californian that is met with imported water requires 5.8 GJ of energy and creates 360 kg of CO2 equivalent emissions. With seawater desalination, energy use would increase to 14 GJ and 800 kg of CO2 equivalent emissions. Meeting the water demand of California with desalination would consume 52% of the state's electricity. Supply options were reassessed using alternative electricity mixes, including the average mix of the United States and several renewable sources. Desalination using solar thermal energy has lower greenhouse gas emissions than that of imported and recycled water (using California's electricity mix), but using the U.S. mix increases the environmental footprint by 1.5 times. A comparison with a more energy-intensive international scenario shows that CO2 equivalent emissions for desalination in Dubai are 1.6 times larger than in California. The methods, decision support tool (WEST), and results of this study should persuade decision makers to make informed water policy choices by including energy consumption and material use effects in the decision-making process.

  4. The water-filled versus air-filled status of vessels cut open in air: the 'Scholander assumption' revisited

    Science.gov (United States)

    M.T. Tyree; H. Cochard; P. Cruziat

    2003-01-01

    When petioles of transpiring leaves are cut in the air, according to the 'Scholander assumption', the vessels cut open should fill with air as the water is drained away by continued transpiration, The distribution of air-filled vessels versus distance from the cut surface should match the distribution of lengths of 'open vessels', i.e. vessels cut...

  5. AirSWOT: An Airborne Platform for Surface Water Monitoring

    Science.gov (United States)

    Rodriguez, E.; Moller, D.; Smith, L. C.; Pavelsky, T. M.; Alsdorf, D. E.

    2010-12-01

    The SWOT mission, expected to launch in 2020, will provide global measurements of surface water extent and elevation from which storage change and discharge can be derived. SWOT-like measurements are not routinely used by the hydrology community, and their optimal use and associated errors are areas of active research. The purpose of AirSWOT, a system that has been proposed to NASA’s Instrument Incubator Program, is to provide SWOT-like measurements to the hydrology and ocean community to be used to advance the understanding and use of SWOT data in the pre-launch phase. In the post-launch phase, AirSWOT will be used as the SWOT calibration/validation platform. The AirSWOT payload will consist of Kaspar, a multi-beam Ka-band radar interferometer able to produce elevations over a 5 km swath with centimetric precision. The absolute elevation accuracy of the AirSWOT system will be achieved with a combination of high precision Inertial Motion Units (IMUs), ground calibration points, and advanced calibration techniques utilizing a priori knowledge. It is expected that the accuracy of AirSWOT will exceed or match SWOT’s accuracy requirements. In addition to elevation measurements, the AirSWOT payload will include a near-infrared camera able to provide coincident high-resolution optical imagery of the water bodies imaged by the radar. In its initial hydrology deployments, AirSWOT will investigate four field sites: the Ohio-Mississippi confluence, the lower Atchafalaya River on the Mississippi River Delta, the Yukon River basin near Fairbanks, and the Sacramento River, California. The Ohio-Mississippi confluence is targeted for its large discharge, modest slope, and control structures that modulate Ohio but not Mississippi River slopes and elevations. The lower Atchafalaya River includes low slopes, wetlands with differing vegetation types, and some open lakes. Vegetation includes Cyprus forests, floating macrophytes, and grass marshes, all of which impact radar returns

  6. Molecular Dynamics Simulation of Water Nanodroplets on Silica Surfaces at High Air Pressures

    DEFF Research Database (Denmark)

    Zambrano, Harvey A; Jaffe, Richard Lawrence; Walther, Jens Honore

    2010-01-01

    e.g., nanobubbles. In the present work we study the role of air on the wetting of hydrophilic systems. We conduct molecular dynamics simulations of a water nanodroplet on an amorphous silica surface at different air pressures. The interaction potentials describing the silica, water, and air...... are obtained from the literature. The silica surface is modeled by a large 32 ⨯ 32 ⨯ 2 nm amorphous SiO2 structure consisting of 180000 atoms. The water consists of 18000 water molecules surrounded by N2 and O2 air molecules corresponding to air pressures of 0 bar (vacuum), 50 bar, 100 bar and 200 bar. We...... perform extensive simulations of the water- air equilibrium and calibrate the water-air interaction to match the experimental solubility of N2 and O2 in water. For the silica-water system we calibrate the water-silica interaction to match the experimental contact angle of 27º. We subsequently study...

  7. Experimental Study of the Interfacial Waves in Horizontal Stratified Gas-liquid Two-phase Flows by Using the Developed Image Processing Technique

    CERN Document Server

    Kuntoro, Hadiyan Yusuf; Dinaryanto, Okto; Deendarlianto,; Indarto,

    2015-01-01

    Experimental series of stratified gas-liquid two-phase flows had been carried out in a 26 mm i.d. transparent acrylic horizontal pipe. The study was aimed to determine the interfacial wave characteristics of the flow and to develop a high quality database of it. The longitudinal section of the pipe was used as the reference section of image recording. Air and water were used as the test fluids, flowing co-currently inside the pipe. The flow behavior was recorded by using a high-speed video camera around 5 m in axial distance from the inlet pipe to ensure the fully-developed stratified gas-liquid two-phase flow. To correct the refraction due to the acrylic pipe, a correction box was employed in the visualization test section. The group of stratified smooth and wavy two-phase flows were successfully recorded and classified on the basis of the visualization study from 24 couples of test condition of superficial water and air velocities. Digital image processing technique was then used to perform quantitative ana...

  8. 航空发动机滚动轴承内油气两相流动与温度场的数值模拟%Numerical Simulation of Oil-air Two-phase Flow and Temperature Field inside the Aero-engine Rolling Bearing

    Institute of Scientific and Technical Information of China (English)

    徐让书; 李骏; 牛玲; 常柱宇

    2014-01-01

    基于VOF方法和滑移网格技术,研究喷射润滑下主轴承内部压力、温度场及油气体积比随转子转速及滑油流量的变化规律。给出滑油在轴承内的相界面分布,描述轴承内油膜分布及运动。结果表明:轴承内压力和油气两相在轴承内分布不均匀;油液体积分数随转速的升高而降低,随供油量的增加而增加,呈非线性关系;轴承内最高工作温度随主轴转速的增加而增加;轴承润滑效果与供油量有直接的关系,不同的转速下对应不同的最佳供油量。%Based on the volume of fluid(VOF)method and sliding mesh technique,the effect of rotor speed and the oil inlet flow rate on the pressure,temperature field and oil volume fraction in the rolling bearing with spay lubrication were in-vestigated.The film distribution and movement in oil and air interface were showed.The results show that the pressure and the oil-air two-phase flow distribution is not homogenized in the bearing.The oil volume fractionis decreased with the in-crease of revolution speed,and is increased with speeding up the lubrication flow rate nonlinearly.The highest temperature of the bearing is increased with the increase of revolution speed.The effect of the bearing lubrication is directly related with the lubrication flow rate,and an optimum oil feeding rate exists at different rotor speed.

  9. Properties of disturbance waves in vertical annular two-phase flow

    Energy Technology Data Exchange (ETDEWEB)

    Sawant, Pravin [Purdue University, School of Nuclear Engineering, 400 Central Dr., West Lafayette, IN 47907-2017 (United States)], E-mail: psawant@purdue.edu; Ishii, Mamoru [Purdue University, School of Nuclear Engineering, 400 Central Dr., West Lafayette, IN 47907-2017 (United States); Hazuku, Tatsuya; Takamasa, Tomoji [Faculty of Marine Technology, Tokyo University of Marine Science and Technology, Etchujima, Koto-ku, Tokyo 135-8533 (Japan); Mori, Michitsugu [Tokyo Electric Power Co., Inc., 4-1 Egasaki-cho, Tsurumi-ku, Yokohama 230-8510 (Japan)

    2008-12-15

    Disturbance waves play an important role in interfacial transfer of mass, momentum and energy in annular two-phase flow. In spite of their importance, majority of the experimental data available in literature on disturbance wave properties such as velocity, frequency, wavelength and amplitude are limited to near atmospheric conditions (Azzopardi, B.J., 1997. Drops in annular two-phase flow. International Journal of Multiphase Flow, 23, 1-53). In view of this, air-water annular flow experiments have been conducted at three pressure conditions (1.2, 4.0 and 5.8 bar) in a tubular test section having an inside diameter 9.4 mm. At each pressure condition liquid and gas phase flow rates are varied over a large range so that the effects of density ratio, liquid flow rate and gas flow rate on disturbance wave properties can be studied systematically. A liquid film thickness is measured by two flush mounted ring shaped conductance probes located 38.1 mm apart. Disturbance wave velocity, frequency, amplitude and wavelength are estimated from the liquid film thickness measurements by following the statistical analysis methods. Parametric trends in variations of disturbance wave properties are analyzed using the non-dimensional numbers; liquid phase Reynolds number (Re{sub f}), gas phase Reynolds number (Re{sub g}), Weber number (We) and Strouhal number (Sr). Finally, the existing correlations available for the prediction of disturbance wave velocity and frequency are analyzed and a new, improved correlation is proposed for the prediction of disturbance wave frequency. The new correlation satisfactorily predicted the current data and the data available in literature.

  10. Reversible, on-demand generation of aqueous two-phase microdroplets

    Energy Technology Data Exchange (ETDEWEB)

    Collier, Charles Patrick; Retterer, Scott Thomas; Boreyko, Jonathan Barton; Mruetusatorn, Prachya

    2017-08-15

    The present invention provides methods of on-demand, reversible generation of aqueous two-phase microdroplets core-shell microbeads, microparticle preparations comprising the core-shell microbeads, and drug delivery formulation comprising the microparticle preparations. Because these aqueous microdroplets have volumes comparable to those of cells, they provide an approach to mimicking the dynamic microcompartmentation of biomaterial that naturally occurs within the cytoplasm of cells. Hence, the present methods generate femtoliter aqueous two-phase droplets within a microfluidic oil channel using gated pressure pulses to generate individual, stationary two-phase microdroplets with a well-defined time zero for carrying out controlled and sequential phase transformations over time. Reversible phase transitions between single-phase, two-phase, and core-shell microbead states are obtained via evaporation-induced dehydration and water rehydration.

  11. Research of Characteristics of Gas-liquid Two-phase Pressure Drop in Microreactor

    Directory of Open Access Journals (Sweden)

    Li Dan

    2015-01-01

    Full Text Available With the research system of nitrogen and deionized water, this paper researches the pressure drop of gas-liquid two-phase flow in the circular microchannel with an inner diameter which is respectively 0.9mm and 0.5mm, analyzes the effect of microchannel diameter on gas-liquid two-phase frictional pressure drop in the microchannel reactor, and compares with the result of frictional pressure drop and the predicting result of divided-phase flow pattern. The result shows that, the gas-liquid two-phase frictional pressure drop in the microchannel significantly increases with the decreasing microchannel diameter; Lockhart-Martinelli relationship in divided-phase flow pattern can preferably predict the gas-liquid two-phase frictional pressure drop in the microchannel, but the Tabular constant needs to be corrected.

  12. Quantitative study on experimentally observed poroelastic behavior of Berea sandstone in two-phase fluid system

    Science.gov (United States)

    Goto, Hiroki; Aichi, Masaatsu; Tokunaga, Tomochika; Yamamoto, Hajime; Ogawa, Toyokazu; Aoki, Tomoyuki

    2014-08-01

    Coupled two-phase fluid flow and poroelastic deformation of Berea sandstone is studied through laboratory experiment and numerical simulation. In the experiment, compressed air was infiltrated from the bottom of a water-saturated cylindrical Berea sandstone sample under hydrostatic external stress condition. Both axial and circumferential strains at half the height of the sample showed sudden extension and monotonic and gradual extension afterward. Numerical simulation based on thermodynamically consistent constitutive equations was conducted in order to quantitatively analyze the experimental results. In a simulation assuming isotropy of material properties, the volumetric discharge rate of water at the outlet and one of the axial, circumferential, and volumetric strains at half the height of the sample were reproduced well by each parameter set, while the other two strains were not. When introducing transverse isotropy, all the experimental data were reproduced well. In addition, the effect of saturation dependency of Bishop's effective stress coefficient on the deformation behavior of porous media was discussed, and it was found that strains, both axial and circumferential, are sensitive to the coefficient.

  13. Langmuir films of petroleum at the air-water interface.

    Science.gov (United States)

    Vieira, Vinícius C C; Severino, Divinomar; Oliveira, Osvaldo N; Pavinatto, Felippe J; Zaniquelli, Maria E D; Ramos, Ana Paula; Baptista, Maurício S

    2009-11-03

    Understanding the behavior of petroleum films at the air/water interface is crucial for dealing with oil slicks and reducing the damages to the environment, which has normally been attempted with studies of Langmuir films made of fractions of petroleum. However, the properties of films from whole petroleum samples may differ considerably from those of individual fractions. Using surface pressure and surface potential measurements and Brewster angle and fluorescence microscopy, we show that petroleum forms a nonhomogeneous Langmuir film at the air-water interface. The surface pressure isotherms for petroleum Langmuir films exhibit gas (G), liquid-expanded (LE), and liquid-condensed phases, with almost no hysteresis in the compression-decompression cycles. Domains formed upon compression from the G to the LE phase were accompanied by an increase in fluorescence intensity with excitation at 400-440 nm owing to an increase in the surface density of the chromophores in the petroleum film. The surface pressure and the fluorescence microscopy data pointed to self-assembling domains into a pseudophase in thermodynamic equilibrium with other less emitting petroleum components. This hypothesis was supported by Brewster angle microscopy images, whereby the appearance of water domains even at high surface pressures confirms the tendency of petroleum to stabilize emulsion systems. The results presented here suggest that, for understanding the interaction with water, it may be more appropriate to use the whole petroleum samples rather than its fractions.

  14. Next steps in two-phase flow: executive summary

    Energy Technology Data Exchange (ETDEWEB)

    DiPippo, R.

    1980-09-01

    The executive summary includes the following topics of discussion: the state of affairs; the fundamental governing equations; the one-dimensional mixture model; the drift-flux model; the Denver Research Institute two-phase geothermal flow program; two-phase flow pattern transition criteria; a two-fluid model under development; the mixture model as applied to geothermal well flow; DRI downwell instrumentation; two-phase flow instrumentation; the Sperry Research Corporation downhole pump and gravity-head heat exchanger systems; and the Brown University two-phase flow experimental program. (MHR)

  15. Passive Two-Phase Cooling of Automotive Power Electronics: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, G.; Jeffers, J. R.; Narumanchi, S.; Bennion, K.

    2014-08-01

    Experiments were conducted to evaluate the use of a passive two-phase cooling strategy as a means of cooling automotive power electronics. The proposed cooling approach utilizes an indirect cooling configuration to alleviate some reliability concerns and to allow the use of conventional power modules. An inverter-scale proof-of-concept cooling system was fabricated, and tests were conducted using the refrigerants hydrofluoroolefin HFO-1234yf and hydrofluorocarbon HFC-245fa. Results demonstrated that the system can dissipate at least 3.5 kW of heat with 250 cm3 of HFC-245fa. An advanced evaporator design that incorporates features to improve performance and reduce size was conceived. Simulation results indicate its thermal resistance can be 37% to 48% lower than automotive dual side cooled power modules. Tests were also conducted to measure the thermal performance of two air-cooled condensers--plain and rifled finned tube designs. The results combined with some analysis were then used to estimate the required condenser size per operating conditions and maximum allowable system (i.e., vapor and liquid) temperatures.

  16. Air/water oxydesulfurization of coal: laboratory investigation

    Energy Technology Data Exchange (ETDEWEB)

    Warzinski, R. P.; Friedman, S.; Ruether, J. A.; LaCount, R. B.

    1980-08-01

    Air/water oxidative desulfurization has been demonstrated in autoclave experiments at the Pittsburgh Energy Technology Center for various coals representative of the major US coal basins. This experimentation has shown that the reaction proceeds effectively for pulverized coals at temperatures of 150 to 200/sup 0/C with air at a total system pressure of 500 to 1500 psig. Above 200/sup 0/C, the loss of coal and product heating value increases due to oxidative consumption of carbon and hydrogen. The pyritic sulfur solubilization reactions are typically complete (95 percent removal) within 15 to 40 minutes at temperature; however, significant apparent organic sulfur removal requires residence times of up to 60 minutes at the higher temperatures. The principal products of the reaction are sulfuric acid, which can be neutralized with limestone, and iron oxide. Under certain conditions, especially for high pyritic sulfur coals, the precipitation of sulfur-containing compounds from the products of the pyrite reaction may cause anomalous variations in the sulfur form data. The influence of various parameters on the efficiency of sulfur removal from coal by air/water oxydesulfurization has been studied.

  17. Study on Two-Phase Flow in Heterogeneous Porous Media by Light Transmission Method

    Science.gov (United States)

    Qiao, W.

    2015-12-01

    The non-aqueous phase liquid (NAPL) released to the subsurface can form residual ganglia and globules occupying pores and also accumulate and form pools, in which multiphase system forms. Determining transient fluid saturations in a multiphase system is essential to understand the flow characteristics of systems and to perform effective remediation strategies. As a non-destructive and non-invasive laboratory technique utilized for the measurement of liquid saturation in porous media, light transmission is of the lowest cost and safe. Utilization of Coupled Charge Device camera in light transmission systems provides a nearly instantaneous high-density array of spatial measurements over a very large dynamic range. The migration of NAPL and air spariging technique applied to remove NAPL in aquifer systems are typically two-phase flow problem. Because of the natural aquifer normally being heterogeneous, two 2-D sandboxes (Length55cm×width1.3cm×hight45cm) are set up to study the migration of gas and DNAPL in heterogeneous porous media based on light transmission method and its application in two-phase flow. Model D for water/gas system developed by Niemet and Selker (2001) and Model NW-A for water/NAPL system developed by Zhang et al. (2014) are applied for the calculation of fluid saturation in the two experiments, respectively. The gas injection experiments show that the gas moves upward in the irregular channels, piling up beneath the low permeability lenses and starting lateral movement. Bypassing the lenses, the gas moves upward and forms continuous distribution in the top of the sandbox. The faster of gas injects, the wider of gas migration will be. The DNAPL infiltration experiment shows that TCE mainly moves downward as the influence of gravity, stopping vertical infiltration when reaching the low permeability lenses because of its failure to overcome the capillary pressure. Then, TCE accumulates on the surface and starts transverse movement. Bypassing the

  18. Development of an ex-vessel corium debris bed with two-phase natural convection in a flooded cavity

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eunho; Lee, Mooneon; Park, Hyun Sun, E-mail: hejsunny@postech.ac.kr; Moriyama, Kiyofumi; Park, Jin Ho

    2016-03-15

    Highlights: • For ex-vessel severe accidents in LWRs with wet-cavity strategy, development of debris bed with two-phase natural convection flow due to thermal characteristics of prototypic corium particles was investigated experimentally by using simulant particles and local air bubble control system. • Based on the experimental results of this study, an analytical model was established to describe the spreading of the debris bed in terms of two-phase flow and the debris injection parameters. • This model was then used to analyze the formation of debris beds at the reactor scale, and a sensitivity analysis was carried out based on key accident parameters. - Abstract: During severe accidents of light water reactors (LWRs), the coolability of relocated corium from the reactor vessel is a significant safety issue and a threat to the integrity of containment. With a flooded cavity, a porous debris bed is expected to develop on the bottom of the pool due to breakup and fragmentation of the melt jet. As part of the coolability assessment under accident conditions, the geometrical configuration of the debris bed is important. The Debris Bed Research Apparatus for Validation of the Bubble-Induced Natural Convection Effect Issue (DAVINCI) experimental apparatus facility was constructed to investigate the formation of debris beds under the influence of a two-phase flow induced by steam generation due to the decay heat of the debris bed. Using this system, five kilograms of stainless steel simulant debris were injected from the top of the water level, while air bubbles simulating the vapor flow were injected from the bottom of the particle catcher plate. The airflow rate was determined based on the quantity of settled debris, which will form a heat source due to the decay of corium. The radial distribution of the settled debris was examined using a ‘gap–tooth’ approach. Based on the experimental results of this study, an analytical model was established to

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

    Science.gov (United States)

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

    1993-04-01

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

  20. Two Phases of Coherent Structure Motions in Turbulent Boundary Layer

    Institute of Scientific and Technical Information of China (English)

    LIU Jian-Hua; JIANG Nan

    2007-01-01

    Two phases of coherent structure motion are acquired after obtaining conditional phase-averaged waveforms for longitudinal velocity of coherent structures in turbulent boundary layer based on Harr wavelet transfer. The correspondences of the two phases to the two processes (i.e. ejection and sweep) during a burst are determined.

  1. Experimental Study of Air Vessel Behavior for Energy Storage or System Protection in Water Hammer Events

    OpenAIRE

    Mohsen Besharat; Maria Teresa Viseu; Helena M. Ramos

    2017-01-01

    An experimental assessment of an air pocket (AP), confined in a compressed air vessel (CAV), has been investigated under several different water hammer (WH) events to better define the use of protection devices or compressed air energy storage (CAES) systems. This research focuses on the size of an AP within an air vessel and tries to describe how it affects important parameters of the system, i.e., the pressure in the pipe, stored pressure, flow velocity, displaced volume of water and water ...

  2. Thermal Marangoni Convection of Two-phase Dusty Fluid Flow along a Vertical Wavy Surface

    Directory of Open Access Journals (Sweden)

    S. Siddiqa

    2017-01-01

    Full Text Available The paper considers the influence of thermal Marangoni convection on boundary layer flow of two-phase dusty fluid along a vertical wavy surface. The dimensionless boundary layer equations for two-phase problem are reduced to a convenient form by primitive variable transformations (PVF and then integrated numerically by employing the implicit finite difference method along with the Thomas Algorithm. The effect of thermal Marangoni convection, dusty water and sinusoidal waveform are discussed in detail in terms of local heat transfer rate, skin friction coefficient, velocity and temperature distributions. This investigation reveals the fact that the water-particle mixture reduces the rate of heat transfer, significantly.

  3. STUDIES OF TWO-PHASE PLUMES IN STRATIFIED ENVIRONMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Scott A. Socolofsky; Brian C. Crounse; E. Eric Adams

    1998-11-18

    Two-phase plumes play an important role in the more practical scenarios for ocean sequestration of CO{sub 2}--i.e. dispersing CO{sub 2} as a buoyant liquid from either a bottom-mounted or ship-towed pipeline. Despite much research on related applications, such as for reservoir destratification using bubble plumes, our understanding of these flows is incomplete, especially concerning the phenomenon of plume peeling in a stratified ambient. To address this deficiency, we have built a laboratory facility in which we can make fundamental measurements of plume behavior. Although we are using air, oil and sediments as our sources of buoyancy (rather than CO{sub 2}), by using models, our results can be directly applied to field scale CO{sub 2} releases to help us design better CO{sub 2} injection systems, as well as plan and interpret the results of our up-coming international field experiment. The experimental facility designed to study two-phase plume behavior similar to that of an ocean CO{sub 2} release includes the following components: 1.22 x 1.22 x 2.44 m tall glass walled tank; Tanks and piping for the two-tank stratification method for producing step- and linearly-stratified ambient conditions; Density profiling system using a conductivity and temperature probe mounted to an automated depth profiler; Lighting systems, including a virtual point source light for shadowgraphs and a 6 W argon-ion laser for laser induced fluorescence (LIF) imaging; Imaging system, including a digital, progressive scanning CCD camera, computerized framegrabber, and image acquisition and analysis software; Buoyancy source diffusers having four different air diffusers, two oil diffusers, and a planned sediment diffuser; Dye injection method using a Mariotte bottle and a collar diffuser; and Systems integration software using the Labview graphical programming language and Windows NT. In comparison with previously reported experiments, this system allows us to extend the parameter range of

  4. Proton Transfers at the Air-Water Interface

    Science.gov (United States)

    Mishra, Himanshu

    Proton transfer reactions at the interface of water with hydrophobic media, such as air or lipids, are ubiquitous on our planet. These reactions orchestrate a host of vital phenomena in the environment including, for example, acidification of clouds, enzymatic catalysis, chemistries of aerosol and atmospheric gases, and bioenergetic transduction. Despite their importance, however, quantitative details underlying these interactions have remained unclear. Deeper insight into these interfacial reactions is also required in addressing challenges in green chemistry, improved water quality, self-assembly of materials, the next generation of micro-nanofluidics, adhesives, coatings, catalysts, and electrodes. This thesis describes experimental and theoretical investigation of proton transfer reactions at the air-water interface as a function of hydration gradients, electrochemical potential, and electrostatics. Since emerging insights hold at the lipid-water interface as well, this work is also expected to aid understanding of complex biological phenomena associated with proton migration across membranes. Based on our current understanding, it is known that the physicochemical properties of the gas-phase water are drastically different from those of bulk water. For example, the gas-phase hydronium ion, H3O +(g), can protonate most (non-alkane) organic species, whereas H 3O+(aq) can neutralize only relatively strong bases. Thus, to be able to understand and engineer water-hydrophobe interfaces, it is imperative to investigate this fluctuating region of molecular thickness wherein the 'function' of chemical species transitions from one phase to another via steep gradients in hydration, dielectric constant, and density. Aqueous interfaces are difficult to approach by current experimental techniques because designing experiments to specifically sample interfacial layers (quantum mechanics and molecular dynamics to simulate our experiments toward gaining insight at the

  5. 14 CFR 1274.926 - Clean Air-Water Pollution Control Acts.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Clean Air-Water Pollution Control Acts...-Water Pollution Control Acts. Clean Air-Water Pollution Control Acts July 2002 If this cooperative... 91-604) and section 308 of the Federal Water Pollution Control Act, as amended (33 U.S.C. 1251 et...

  6. Ionic liquids for two-phase systems and their application for purification, extraction and biocatalysis.

    Science.gov (United States)

    Oppermann, Sebastian; Stein, Florian; Kragl, Udo

    2011-02-01

    The development of biotechnological processes using novel two-phase systems based on molten salts known as ionic liquids (ILs) got into the focus of interest. Many new approaches for the beneficial application of the interesting solvent have been published over the last years. ILs bring beneficial properties compared to organic solvents like nonflammability and nonvolatility. There are two possible ways to use the ILs: first, the hydrophobic ones as a substitute for organic solvents in pure two-phase systems with water and second, the hydrophilic ones in aqueous two-phase systems (ATPS). To effectively utilise IL-based two-phase systems or IL-based ATPS in biotechnology, extensive experimental work is required to gain the optimal system parameters to ensure selective extraction of the product of interest. This review will focus on the most actual findings dealing with the basic driving forces for the target extraction in IL-based ATPS as well as presenting some selected examples for the beneficial application of ILs as a substitute for organic solvents. Besides the research focusing on IL-based two-phase systems, the "green aspect" of ILs, due to their negligible vapour pressure, is widely discussed. We will present the newest results concerning ecotoxicity of ILs to get an overview of the state of the art concerning ILs and their utilisation in novel two-phase systems in biotechnology.

  7. Sea/Lake Water Air Conditioning at Naval Facilities.

    Science.gov (United States)

    1980-05-01

    r-AO89 262 CIVIL ENGINEERING LAS (NAVY) PONT HUJENEME CA F/6 13/1 SEA/LAKF WATER AIR CONDITIONING AT N4AVAL FACILITIES.u MAY S0 .J B CIAN...AROICC. Brooklyn NY: CO; C’ode (NP (LCDR ATJ Stewart): C’ode 10)28. RDT&ELO. Philadelphia PA: Code III (Castranovo) Philadelphia. PA: Design Div. (R...Governor’s Council On Energy) NEW MEXICO SOLAR ENERGY INST. Dr. Zwibcl Las Cruces NM NY CITY COMMUNITY COLLEGE BROOKLYN , NY (LIBRARY) NYS ENERGY OFFICE

  8. Path instabilities of air bubbles rising in clean water

    CERN Document Server

    Wu, M; Wu, Mingming; Gharib, Moteza

    1998-01-01

    Experiments are conducted to study the path and shape of single air bubbles (diameter range 0.10- 0.20cm) rising freely in clean water. The experimental results demonstrate that the bubble shape has a bistable state, i. e. the bubble chooses to be in spherical or ellipsoidal shape depending on its generation mechanism. The path of a spherical/ellipsoidal bubble is found to change from a straight path to a zigzag/spiral path via a supercritical/subcritical bifurcation when the Reynolds number of the bubble exceeds a threshold.

  9. Inactivation of the biofilm by the air plasma containing water

    Science.gov (United States)

    Suganuma, Ryota; Yasuoka, Koichi; Yasuoka Takeuchi lab Team

    2014-10-01

    Biofilms are caused by environmental degradation in food factory and medical facilities. Inactivation of biofilm has the method of making it react to chemicals including chlorine, hydrogen peroxide, and ozone. Although inactivation by chemicals has the problem that hazardous property of a residual substance and hydrogen peroxide have slow reaction velocity. We achieved advanced oxidation process (AOP) with air plasma. Hydrogen peroxide and ozone, which were used for the formation of OH radicals in our experiment, were able to be generated selectively by adjusting the amount of water supplied to the plasma. We inactivated Pseudomonas aeruginosa biofilm in five minutes with OH radicals generated by using hydrogen peroxide and ozone.

  10. Instrumented Water Tanks can Improve Air Shower Detector Sensitivity

    CERN Document Server

    Atkins, R; Berley, D; Chen, M L; Coyne, D G; Delay, R S; Dingus, B L; Dorfan, D E; Ellsworth, R W; Evans, D; Falcone, A D; Fleysher, L; Fleysher, R; Gisler, G; Goodman, J A; Haines, T J; Hoffman, C M; Hugenberger, S; Kelley, L A; Leonor, I; Macri, J R; McConnell, M; McCullough, J F; McEnery, J E; Miller, R S; Mincer, A I; Morales, M F; Némethy, P; Ryan, J M; Schneider, M; Shen, B; Shoup, A L; Sinnis, G; Smith, A J; Sullivan, G W; Thompson, T N; Tümer, T O; Wang, K; Wascko, M O; Westerhoff, S; Williams, D A; Yang, T; Yodh, G B

    1999-01-01

    Previous works have shown that water Cherenkov detectors have superior sensitivity to those of scintillation counters as applied to detecting extensive air showers (EAS). This is in large part due to their much higher sensitivity to EAS photons which are more than five times more numerous than EAS electrons. Large area water Cherenkov detectors can be constructed relatively cheaply and operated reliably. A sparse detector array has been designed which uses these types of detectors to substantially increase the area over which the Milagro Gamma Ray Observatory collects EAS information. Improvements to the Milagro detector's performance characteristics and sensitivity derived from this array and preliminary results from a prototype array currently installed near the Milagro detector will be presented.

  11. Powder wettability at a static air-water interface.

    Science.gov (United States)

    Dupas, Julien; Forny, Laurent; Ramaioli, Marco

    2015-06-15

    The reconstitution of a beverage from a dehydrated powder involves several physical mechanisms that determine the practical difficulty to obtain a homogeneous drink in a convenient way and within an acceptable time for the preparation of a beverage. When pouring powder onto static water, the first hurdle to overcome is the air-water interface. We propose a model to predict the percentage of powder crossing the interface in 45 s, namely the duration relevant for this application. We highlight theoretically the determinant role of the contact angle and of the particle size distribution. We validate experimentally the model for single spheres and use it to predict the wettability performance of commercial food powders for different contact angles and particles sizes. A good agreement is obtained when comparing the predictions and the wettability of the tested powders.

  12. Correlations between the two-phase gas/liquid spray atomization and the Stokes/aerodynamic Weber numbers

    Science.gov (United States)

    Rahman, Mohammad A.; Heidrick, Ted; Fleck, Brian A.

    2009-02-01

    The The effects of air-to-liquid ratio (β) and void fraction (α) on Sauter mean diameter (SMD or D32), arithmetic mean diameter (D10), surface mean diameter (D20), volume mean diameter (VMD or D20), and radial velocity profiles were experimentally investigated for a two-phase gas/liquid (TPGL) nozzle with a hybrid design of classical twin-fluid and effervescent nozzles. Radial spray profiles were measured using a Phase-Doppler-Particle-Anemometer (PDPA) system on 15Dn, 30Dn, 60Dn, 120Dn;(Dn represents nozzle diameter = 3.10,mm) axial distances. In addition, the effects of spray break-up patterns were analyzed with changing axial distances. The average void fraction in the feeding conduit (FC) was measured by a pneumatic controlled quick-closing-valve (QCV). The experiments were performed using mixtures of air with water at water flow rates of 1.50 to 7.50 kg/min and air-to-liquid mass ratios (β) of 0.30 to 10;%. The length and diameter of the FC was 36.8,cm and 6.35,mm, respectively. Result indicates that as the St number reaches the value of one, no more break-up continues, thus the droplets start to coalesce each other forming bigger droplets (higher D10 values) with increasing radial distances. Knowledge from this study will provide better understanding that ensures an increase in plant efficiency and product yield in oil sands bitumen upgrading.

  13. Two-Phase Master Sintering Curve for 17-4 PH Stainless Steel

    Science.gov (United States)

    Jung, Im Doo; Ha, Sangyul; Park, Seong Jin; Blaine, Deborah C.; Bollina, Ravi; German, Randall M.

    2016-11-01

    The sintering behavior of 17-4 PH stainless steel has been efficiently characterized by a two-phase master sintering curve model (MSC). The activation energy for the sintering of gas-atomized and water-atomized 17-4 PH powders is derived using the mean residual method, and the relative density of both powders is well predicted by the two-phase MSC model. The average error between dilatometry data and MSC model has been reduced by 68 pct for gas-atomized powder and by 45 pct for water-atomized powder through the consideration of phase transformation of 17-4 PH in MSC model. The effect of δ-ferrite is considered in the two-phase MSC model, leading to excellent explanation of the sintering behavior for 17-4 PH stainless steel. The suggested model is useful in predicting the densification and phase change phenomenon during sintering of 17-4 PH stainless steel.

  14. Use of Air2Air Technology to Recover Fresh-Water from the Normal Evaporative Cooling Loss at Coal-Based Thermoelectric Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Ken Mortensen

    2009-06-30

    This program was undertaken to build and operate the first Air2Air{trademark} Water Conservation Cooling Tower at a power plant, giving a validated basis and capability for water conservation by this method. Air2Air{trademark} water conservation technology recovers a portion of the traditional cooling tower evaporate. The Condensing Module provides an air-to-air heat exchanger above the wet fill media, extracting the heat from the hot saturated moist air leaving in the cooling tower and condensing water. The rate of evaporate water recovery is typically 10%-25% annually, depending on the cooling tower location (climate).

  15. Relationship between Formation Water Rate, Equivalent Penetration Rate and Volume Flow Rate of Air in Air Drilling

    Institute of Scientific and Technical Information of China (English)

    Wang Kexiong; Zhang Laibin; Jiang Hongwei

    2007-01-01

    Formation water invasion is the most troublesome problem associated with air drilling. However, it is not economical to apply mist drilling when only a small amount of water flows into wellbore from formation during air drilling. Formation water could be circulated out of the wellbore through increasing the gas injection rate. In this paper,the Angel model was modified by introducing Nikurade friction factor for the flow in coarse open holes and translating formation water rate into equivalent penetration rate. Thus the distribution of annular pressure and the relationship between minimum air injection rate and formation water rate were obtained. Real data verification indicated that the modified model is more accurate than the Angel model and can provide useful information for air drilling.

  16. 77 FR 47282 - Safety Zone; Milwaukee Air and Water Show, Lake Michigan, Milwaukee, WI

    Science.gov (United States)

    2012-08-08

    ... safety zone during this year's air show. This safety zone is intended to restrict vessels from a portion... spectators and vessels from the hazards associated with an air show over water. DATES: This rule will be... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Milwaukee Air and Water Show, Lake Michigan...

  17. 75 FR 19307 - Safety Zone; Milwaukee Air and Water Show, Milwaukee, Lake Michigan, Milwaukee, WI

    Science.gov (United States)

    2010-04-14

    ... surrounding public and their vessels from the hazards associated with a large-scale air show and fireworks... ensure the safety of the public and vessels from the hazards associated with the Milwaukee Air and Water... vessels and people during the Milwaukee Air and Water show. The safety zone is a 4,000 yard by 1,000 yard...

  18. Air humidity and water pressure effects on the performance of air-cathode microbial fuel cell cathodes

    KAUST Repository

    Ahn, Yongtae

    2014-02-01

    To better understand how air cathode performance is affected by air humidification, microbial fuel cells were operated under different humidity conditions or water pressure conditions. Maximum power density decreased from 1130 ± 30 mW m-2 with dry air to 980 ± 80 mW m -2 with water-saturated air. When the cathode was exposed to higher water pressures by placing the cathode in a horizontal position, with the cathode oriented so it was on the reactor bottom, power was reduced for both with dry (1030 ± 130 mW m-2) and water-saturated (390 ± 190 mW m-2) air. Decreased performance was partly due to water flooding of the catalyst, which would hinder oxygen diffusion to the catalyst. However, drying used cathodes did not improve performance in electrochemical tests. Soaking the cathode in a weak acid solution, but not deionized water, mostly restored performance (960 ± 60 mW m-2), suggesting that there was salt precipitation in the cathode that was enhanced by higher relative humidity or water pressure. These results showed that cathode performance could be adversely affected by both flooding and the subsequent salt precipitation, and therefore control of air humidity and water pressure may need to be considered for long-term MFC operation. © 2013 Elsevier B.V. All rights reserved.

  19. Air humidity and water pressure effects on the performance of air-cathode microbial fuel cell cathodes

    Science.gov (United States)

    Ahn, Yongtae; Zhang, Fang; Logan, Bruce E.

    2014-02-01

    To better understand how air cathode performance is affected by air humidification, microbial fuel cells were operated under different humidity conditions or water pressure conditions. Maximum power density decreased from 1130 ± 30 mW m-2 with dry air to 980 ± 80 mW m-2 with water-saturated air. When the cathode was exposed to higher water pressures by placing the cathode in a horizontal position, with the cathode oriented so it was on the reactor bottom, power was reduced for both with dry (1030 ± 130 mW m-2) and water-saturated (390 ± 190 mW m-2) air. Decreased performance was partly due to water flooding of the catalyst, which would hinder oxygen diffusion to the catalyst. However, drying used cathodes did not improve performance in electrochemical tests. Soaking the cathode in a weak acid solution, but not deionized water, mostly restored performance (960 ± 60 mW m-2), suggesting that there was salt precipitation in the cathode that was enhanced by higher relative humidity or water pressure. These results showed that cathode performance could be adversely affected by both flooding and the subsequent salt precipitation, and therefore control of air humidity and water pressure may need to be considered for long-term MFC operation.

  20. Patterns and properties of polarized light in air and water.

    Science.gov (United States)

    Cronin, Thomas W; Marshall, Justin

    2011-03-12

    Natural sources of light are at best weakly polarized, but polarization of light is common in natural scenes in the atmosphere, on the surface of the Earth, and underwater. We review the current state of knowledge concerning how polarization and polarization patterns are formed in nature, emphasizing linearly polarized light. Scattering of sunlight or moonlight in the sky often forms a strongly polarized, stable and predictable pattern used by many animals for orientation and navigation throughout the day, at twilight, and on moonlit nights. By contrast, polarization of light in water, while visible in most directions of view, is generally much weaker. In air, the surfaces of natural objects often reflect partially polarized light, but such reflections are rarer underwater, and multiple-path scattering degrades such polarization within metres. Because polarization in both air and water is produced by scattering, visibility through such media can be enhanced using straightforward polarization-based methods of image recovery, and some living visual systems may use similar methods to improve vision in haze or underwater. Although circularly polarized light is rare in nature, it is produced by the surfaces of some animals, where it may be used in specialized systems of communication.

  1. Environmental application of nanotechnology: air, soil, and water.

    Science.gov (United States)

    Ibrahim, Rusul Khaleel; Hayyan, Maan; AlSaadi, Mohammed Abdulhakim; Hayyan, Adeeb; Ibrahim, Shaliza

    2016-07-01

    Global deterioration of water, soil, and atmosphere by the release of toxic chemicals from the ongoing anthropogenic activities is becoming a serious problem throughout the world. This poses numerous issues relevant to ecosystem and human health that intensify the application challenges of conventional treatment technologies. Therefore, this review sheds the light on the recent progresses in nanotechnology and its vital role to encompass the imperative demand to monitor and treat the emerging hazardous wastes with lower cost, less energy, as well as higher efficiency. Essentially, the key aspects of this account are to briefly outline the advantages of nanotechnology over conventional treatment technologies and to relevantly highlight the treatment applications of some nanomaterials (e.g., carbon-based nanoparticles, antibacterial nanoparticles, and metal oxide nanoparticles) in the following environments: (1) air (treatment of greenhouse gases, volatile organic compounds, and bioaerosols via adsorption, photocatalytic degradation, thermal decomposition, and air filtration processes), (2) soil (application of nanomaterials as amendment agents for phytoremediation processes and utilization of stabilizers to enhance their performance), and (3) water (removal of organic pollutants, heavy metals, pathogens through adsorption, membrane processes, photocatalysis, and disinfection processes).

  2. Non-isothermal two-phase flow in low-permeable porous media

    Science.gov (United States)

    Kolditz, O.; De Jonge, J.

    In this paper, we consider non-isothermal two-phase flow of two components (air and water) in gaseous and liquid phases in extremely low-permeable porous media through the use of the finite element method (FEM). Interphase mass transfer of the components between any of the phases is evaluated by assuming local thermodynamic equilibrium between the phases. Heat transfer occurs by conduction and multiphase advection. General equations of state for phase changes (Clausius-Clapeyron and Henry law) as well as multiphase properties for the low-permeable bentonites are implemented in the code. Additionally we consider the impact of swelling/shrinking processes on porosity and permeability changes. The numerical model is implemented in the context of the simulator RockFlow/RockMech (RF/RM), which is based on object-oriented programming techniques. The finite element formulations are written in terms of dimensionless quantities. This has proved to be advantageous for preconditioning composite system matrices of coupled multi-field problems. Three application examples are presented. The first one examines differences between the Richards' approximation and the multicomponent/multiphase approach, and between two numerical coupling schemes. The second example serves as partial verification against experimental results and to demonstrate coherence between different element types. The last example shows simultaneous desaturation and resaturation in one system.

  3. Flow regimes of adiabatic gas-liquid two-phase under rolling conditions

    Science.gov (United States)

    Yan, Chaoxing; Yan, Changqi; Sun, Licheng; Xing, Dianchuan; Wang, Yang; Tian, Daogui

    2013-07-01

    Characteristics of adiabatic air/water two-phase flow regimes under vertical and rolling motion conditions were investigated experimentally. Test sections are two rectangular ducts with the gaps of 1.41 and 10 mm, respectively, and a circular tube with 25 mm diameter. Flow regimes were recorded by a high speed CCD-camera and were identified by examining the video images. The experimental results indicate that the characteristics of flow patterns in 10 mm wide rectangular duct under vertical condition are very similar to those in circular tube, but different from the 1.41 mm wide rectangular duct. Channel size has a significant influence on flow pattern transition, boundary of which in rectangular channels tends asymptotically towards that in the circular tube with increasing the width of narrow side. Flow patterns in rolling channels are similar to each other, nevertheless, the effect of rolling motion on flow pattern transition are significantly various. Due to the remarkable influences of the friction shear stress and surface tension in the narrow gap duct, detailed flow pattern maps of which under vertical and rolling conditions are indistinguishable. While for the circular tube with 25 mm diameter, the transition from bubbly to slug flow occurs at a higher superficial liquid velocity and the churn flow covers more area on the flow regime map as the rolling period decreases.

  4. Experimental Study on Interfacial Area Transport of Two-Phase Flow under Vibration Conditions

    Directory of Open Access Journals (Sweden)

    Xiu Xiao

    2017-01-01

    Full Text Available An experimental study on air-water two-phase flow under vibration condition has been conducted using double-sensor conductivity probe. The test section is an annular geometry with hydraulic diameter of 19.1 mm. The vibration frequency ranges from 0.47 Hz to 2.47 Hz. Local measurements of void fraction, interfacial area concentration (IAC, and Sauter mean diameter have been performed along one radius in the vibration direction. The result shows that local parameters fluctuate continuously around the base values in the vibration cycle. Additional bubble force due to inertia is used to explain lateral bubble motions. The fluctuation amplitudes of local void fraction and IAC increase significantly with vibration frequency. The radial distribution of local parameters at the maximum vibration displacement is specifically analyzed. In the void fraction and IAC profiles, the peak near the inner wall is weakened or even disappearing and a strong peak skewed to outer wall is gradually observed with the increase of vibration frequency. The nondimensional peak void fraction can reach a maximum of 49% and the mean relative variation of local void fraction can increase to more than 29% as the vibration frequency increases to 2.47 Hz. But the increase of vibration frequency does not bring significant change to bubble diameter.

  5. CFD Simulation of Polydispersed Bubbly Two-Phase Flow around an Obstacle

    Directory of Open Access Journals (Sweden)

    E. Krepper

    2009-01-01

    Full Text Available This paper concerns the model of a polydispersed bubble population in the frame of an ensemble averaged two-phase flow formulation. The ability of the moment density approach to represent bubble population size distribution within a multi-dimensional CFD code based on the two-fluid model is studied. Two different methods describing the polydispersion are presented: (i a moment density method, developed at IRSN, to model the bubble size distribution function and (ii a population balance method considering several different velocity fields of the gaseous phase. The first method is implemented in the Neptune_CFD code, whereas the second method is implemented in the CFD code ANSYS/CFX. Both methods consider coalescence and breakup phenomena and momentum interphase transfers related to drag and lift forces. Air-water bubbly flows in a vertical pipe with obstacle of the TOPFLOW experiments series performed at FZD are then used as simulations test cases. The numerical results, obtained with Neptune_CFD and with ANSYS/CFX, allow attesting the validity of the approaches. Perspectives concerning the improvement of the models, their validation, as well as the extension of their applicability range are discussed.

  6. An adaptive level set approach for incompressible two-phase flows

    Energy Technology Data Exchange (ETDEWEB)

    Sussman, M.; Almgren, A.S.; Bell, J.B. [and others

    1997-04-01

    In Sussman, Smereka and Osher, a numerical method using the level set approach was formulated for solving incompressible two-phase flow with surface tension. In the level set approach, the interface is represented as the zero level set of a smooth function; this has the effect of replacing the advection of density, which has steep gradients at the interface, with the advection of the level set function, which is smooth. In addition, the interface can merge or break up with no special treatment. The authors maintain the level set function as the signed distance from the interface in order to robustly compute flows with high density ratios and stiff surface tension effects. In this work, they couple the level set scheme to an adaptive projection method for the incompressible Navier-Stokes equations, in order to achieve higher resolution of the interface with a minimum of additional expense. They present two-dimensional axisymmetric and fully three-dimensional results of air bubble and water drop computations.

  7. Assessment of methane biodegradation kinetics in two-phase partitioning bioreactors by pulse respirometry.

    Science.gov (United States)

    Ordaz, Alberto; López, Juan C; Figueroa-González, Ivonne; Muñoz, Raúl; Quijano, Guillermo

    2014-12-15

    Biological methane biodegradation is a promising treatment alternative when the methane produced in waste management facilities cannot be used for energy generation. Two-phase partitioning bioreactors (TPPBs), provided with a non-aqueous phase (NAP) with high affinity for the target pollutant, are particularly suitable for the treatment of poorly water-soluble compounds such as methane. Nevertheless, little is known about the influence of the presence of the NAP on the resulting biodegradation kinetics in TPPBs. In this study, an experimental framework based on the in situ pulse respirometry technique was developed to assess the impact of NAP addition on the methane biodegradation kinetics using Methylosinus sporium as a model methane-degrading microorganism. A comprehensive mass transfer characterization was performed in order to avoid mass transfer limiting scenarios and ensure a correct kinetic parameter characterization. The presence of the NAP mediated significant changes in the apparent kinetic parameters of M. sporium during methane biodegradation, with variations of 60, 120, and 150% in the maximum oxygen uptake rate, half-saturation constant and maximum specific growth rate, respectively, compared with the intrinsic kinetic parameters retrieved from a control without NAP. These significant changes in the kinetic parameters mediated by the NAP must be considered for the design, operation and modeling of TPPBs devoted to air pollution control.

  8. On the convergence of the weakly compressible sharp-interface method for two-phase flows

    Science.gov (United States)

    Schranner, Felix S.; Hu, Xiangyu; Adams, Nikolaus A.

    2016-11-01

    A weakly compressible sharp-interface framework for two-phase flows is presented. Special emphasis is on investigating its convergence properties. For this purpose a well-defined set of benchmark configurations is introduced. These may serve as future references for the verification of sharp-interface methods. Global mass and momentum conservation is ensured by the conservative sharp-interface method. Viscous and capillary stresses are considered directly at the interface. A low-dissipation weakly compressible Roe Riemann solver, in combination with a 5th-order WENO scheme, leads to high spatial accuracy. A wavelet-based adaptive multi-resolution approach permits to combine computational efficiency with physical consistency. The first test configuration is a Rayleigh-Taylor instability at moderate Reynolds number and infinite Eötvös number. A second group of benchmark cases are isolated air bubbles rising in water at high Eötvös numbers, and low to high Reynolds numbers. With these test cases, three distinct types of complex interface evolution, which are typical for a wide range of industrial applications, are realized.

  9. Pressure transient analysis of two-phase flow problems

    Energy Technology Data Exchange (ETDEWEB)

    Chu, W.C.; Reynolds, A.C.; Raghavan, R.

    1986-04-01

    This paper considers the analysis of pressure drawdown and buildup data for two-phase flow problems. Of primary concern is the analysis of data influenced by saturation gradients that exist within the reservoir. Wellbore storage effects are assumed to be negligible. The pressure data considered are obtained from a two-dimensional (2D) numerical coning model for an oil/water system. The authors consider constant-rate production followed by a buildup period and assume that the top, bottom, and outer boundaries of the reservoir are sealed. First, they consider the case where the producing interval is equal to the total formation thickness. Second, they discuss the effect of partial penetration. In both cases, they show that average pressure can be estimated by the Matthews-Brons-Hazebroek method and consider the computation of the skin factor. They also show that a reservoir limit test can estimate reservoir PV only if the total mobility adjacent to the wellbore does not vary with time.

  10. Two-Phase Flow Field Simulation of Horizontal Steam Generators

    Directory of Open Access Journals (Sweden)

    Ataollah Rabiee

    2017-02-01

    Full Text Available The analysis of steam generators as an interface between primary and secondary circuits in light water nuclear power plants is crucial in terms of safety and design issues. VVER-1000 nuclear power plants use horizontal steam generators which demand a detailed thermal hydraulics investigation in order to predict their behavior during normal and transient operational conditions. Two phase flow field simulation on adjacent tube bundles is important in obtaining logical numerical results. However, the complexity of the tube bundles, due to geometry and arrangement, makes it complicated. Employment of porous media is suggested to simplify numerical modeling. This study presents the use of porous media to simulate the tube bundles within a general-purpose computational fluid dynamics code. Solved governing equations are generalized phase continuity, momentum, and energy equations. Boundary conditions, as one of the main challenges in this numerical analysis, are optimized. The model has been verified and tuned by simple two-dimensional geometry. It is shown that the obtained vapor volume fraction near the cold and hot collectors predict the experimental results more accurately than in previous studies.

  11. Dynamic behavior of pipes conveying gas–liquid two-phase flow

    Energy Technology Data Exchange (ETDEWEB)

    An, Chen, E-mail: anchen@cup.edu.cn [Offshore Oil/Gas Research Center, China University of Petroleum-Beijing, Beijing 102249 (China); Su, Jian, E-mail: sujian@lasme.coppe.ufrj.br [Nuclear Engineering Program, COPPE, Universidade Federal do Rio de Janeiro, CP 68509, Rio de Janeiro 21941-972 (Brazil)

    2015-10-15

    Highlights: • Dynamic behavior of pipes conveying gas–liquid two-phase flow was analyzed. • The generalized integral transform technique (GITT) was applied. • Excellent convergence behavior and long-time stability were shown. • Effects of volumetric quality and volumetric flow rate on dynamic behavior were studied. • Normalized volumetric-flow-rate stability envelope of dynamic system was determined. - Abstract: In this paper, the dynamic behavior of pipes conveying gas–liquid two-phase flow was analytically and numerically investigated on the basis of the generalized integral transform technique (GITT). The use of the GITT approach in the analysis of the transverse vibration equation lead to a coupled system of second order differential equations in the dimensionless temporal variable. The Mathematica's built-in function, NDSolve, was employed to numerically solve the resulting transformed ODE system. The characteristics of gas–liquid two-phase flow were represented by a slip-ratio factor model that was devised and used for similar problems. Good convergence behavior of the proposed eigenfunction expansions is demonstrated for calculating the transverse displacement at various points of pipes conveying air–water two-phase flow. Parametric studies were performed to analyze the effects of the volumetric gas fraction and the volumetric flow rate on the dynamic behavior of pipes conveying air–water two-phase flow. Besides, the normalized volumetric-flow-rate stability envelope for the dynamic system was obtained.

  12. Thermo-Fluid Dynamics of Two-Phase Flow

    CERN Document Server

    Ishii, Mamrou

    2011-01-01

    "Thermo-fluid Dynamics of Two-Phase Flow, Second Edition" is focused on the fundamental physics of two-phase flow. The authors present the detailed theoretical foundation of multi-phase flow thermo-fluid dynamics as they apply to: Nuclear reactor transient and accident analysis; Energy systems; Power generation systems; Chemical reactors and process systems; Space propulsion; Transport processes. This edition features updates on two-phase flow formulation and constitutive equations and CFD simulation codes such as FLUENT and CFX, new coverage of the lift force model, which is of part

  13. Critical transport velocity in two-phase, horizontal pipe flow

    Energy Technology Data Exchange (ETDEWEB)

    Sommerville, D. (U.S. Army Chemical Research, Development and Engineering Center, Aberdeen Proving Grounds, MD (US))

    1991-02-01

    This paper reports on the suspension of solid particles or entrainment of liquid droplets in two- phase flow. Theoretical and empirical relationships have been derived for both instances without any consideration to the similarities between the two. However, a general relation for two-phase flow is desirable since there are systems that cannot be readily defined due to the dual (solid/liquid) nature of the transported material, such as colloids, pulp, slurries, and sludge. Using turbulence theory, one general equation can be derived to predict critical transport velocities for two-phase horizontal flow.

  14. What types of investors generate the two-phase phenomenon?

    Science.gov (United States)

    Ryu, Doojin

    2013-12-01

    We examine the two-phase phenomenon described by Plerou, Gopikrishnan, and Stanley (2003) [1] in the KOSPI 200 options market, one of the most liquid options markets in the world. By analysing a unique intraday dataset that contains information about investor type for each trade and quote, we find that the two-phase phenomenon is generated primarily by domestic individual investors, who are generally considered to be uninformed and noisy traders. In contrast, our empirical results indicate that trades by foreign institutions, who are generally considered informed and sophisticated investors, do not exhibit two-phase behaviour.

  15. Tunable two-phase coexistence in half-doped manganites

    Indian Academy of Sciences (India)

    P Chaddah; A Banerjee

    2008-02-01

    We discuss our very interesting experimental observation that the low-temperature two-phase coexistence in half-doped manganites is multi-valued (at any field) in that we can tune the coexisting antiferromagnetic-insulating (AF-I) and the ferromagnetic-metallic (FM-M) phase fractions by following different paths in (; ) space. We have shown experimentally that the phase fraction, in this two-phase coexistence, can take continuous infinity of values. All but one of these are metastable, and two-phase coexistence is not an equilibrium state.

  16. Experimental study on two-phase gas-liquid flow patterns at normal and reduced gravity conditions

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Experimental studies have been performed for horizontal two-phase air-water flows at nor-mal and reduced gravity conditions in a square cross-section channel. The experiments at reducedgravity are conducted on board the Russian IL-76 reduced gravity airplane. Four flow patterns, namelybubble, slug, slug-annular transition and annular flows, are observed depending on the liquid and gassuperficial velocities at both conditions. Semi-theoretical Weber number model is developed to includethe shape influence on the slug-annular transition. It is shown that its prediction is in reasonable agree-ment with the experimental slug-annular transition under both conditions. For the case of two-phasegas-liquid flow with large value of the Froude number, the drift-flux model can predict well the observedboundary between bubble and slug flows.

  17. Evaluating the impact of ambient benzene vapor concentrations on product water from Condensation Water From Air technology.

    Science.gov (United States)

    Kinder, Katherine M; Gellasch, Christopher A; Dusenbury, James S; Timmes, Thomas C; Hughes, Thomas M

    2017-07-15

    Globally, drinking water resources are diminishing in both quantity and quality. This situation has renewed interest in Condensation Water From Air (CWFA) technology, which utilizes water vapor in the air to produce water for both potable and non-potable purposes. However, there are currently insufficient data available to determine the relationship between air contaminants and the rate at which they are transferred from the air into CWFA untreated product water. This study implemented a novel experimental method utilizing an environmental test chamber to evaluate how air quality and temperature affects CWFA untreated product water quality in order to collect data that will inform the type of water treatment required to protect human health. This study found that temperature and benzene air concentration affected the untreated product water from a CWFA system. Benzene vapor concentrations representing a polluted outdoor environment resulted in benzene product water concentrations between 15% and 23% of the USEPA drinking water limit of 5μg/l. In contrast, product water benzene concentrations representing an indoor industrial environment were between 1.4 and 2.4 times higher than the drinking water limit. Lower condenser coil temperatures were correlated with an increased concentration of benzene in the product water. Environmental health professionals and engineers can integrate the results of this assessment to predict benzene concentrations in the product water and take appropriate health protective measures.

  18. Film boiling on spheres in single- and two-phase flows.

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.; Theofanous, T. G.

    2000-08-29

    Film boiling on spheres in single- and two-phase flows was studied experimentally and theoretically with an emphasis on establishing the film boiling heat transfer closure law, which is useful in the analysis of nuclear reactor core melt accidents. Systematic experimentation of film boiling on spheres in single-phase water flows was carried out to investigate the effects of liquid subcooling (from 0 to 40 C), liquid velocity (from 0 to 2 m/s), sphere superheat (from 200 to 900 C), sphere diameter (from 6 to 19 mm), and sphere material (stainless steel and brass) on film boiling heat transfer. Based on the experimental data a general film boiling heat transfer correlation is developed. Utilizing a two-phase laminar boundary-layer model for the unseparated front film region and a turbulent eddy model for the separated rear region, a theoretical model was developed to predict the film boiling heat transfer in all single-phase regimes. The film boiling from a sphere in two-phase flows was investigated both in upward two-phase flows (with void fraction from 0.2 to 0.65, water velocity from 0.6 to 3.2 m/s, and steam velocity from 3.0 to 9.0 m/s) and in downward two-phase flows (with void fraction from 0.7 to 0.95, water velocity from 1.9 to 6.5 m/s, and steam velocity from 1.1 to 9.0 m/s). The saturated single-phase heat transfer correlation was found to be applicable to the two-phase film boiling data by making use of the actual water velocity (water phase velocity), and an adjustment factor of (1 - {alpha}){sup 1/4} (with a being the void fraction) for downward flow case only. Slight adjustments of the Reynolds number exponents in the correlation provided an even better interpretation of the two-phase data. Preliminary experiments were also conducted to address the influences of multi-sphere structure on the film boiling heat transfer in single- and two-phase flows.

  19. Bubble Generation in a Flowing Liquid Medium and Resulting Two-Phase Flow in Microgravity

    Science.gov (United States)

    Pais, S. C.; Kamotani, Y.; Bhunia, A.; Ostrach, S.

    1999-01-01

    The present investigation reports a study of bubble generation under reduced gravity conditions, using both a co-flow and a cross-flow configuration. This study may be used in the conceptual design of a space-based thermal management system. Ensuing two-phase flow void fraction can be accurately monitored using a single nozzle gas injection system within a continuous liquid flow conduit, as utilized in the present investigation. Accurate monitoring of void fraction leads to precise control of heat and mass transfer coefficients related to a thermal management system; hence providing an efficient and highly effective means of removing heat aboard spacecraft or space stations. Our experiments are performed in parabolic flight aboard the modified DC-9 Reduced Gravity Research Aircraft at NASA Lewis Research Center, using an air-water system. For the purpose of bubble dispersion in a flowing liquid, we use both a co-flow and a cross-flow configuration. In the co-flow geometry, air is introduced through a nozzle in the same direction with the liquid flow. On the other hand, in the cross-flow configuration, air is injected perpendicular to the direction of water flow, via a nozzle protruding inside the two-phase flow conduit. Three different flow conduit (pipe) diameters are used, namely, 1.27 cm, 1.9 cm and 2.54 cm. Two different ratios of nozzle to pipe diameter (D(sub N))sup * are considered, namely (D(sub N))sup * = 0.1 and 0.2, while superficial liquid velocities are varied from 8 to 70 cm/s depending on flow conduit diameter. It is experimentally observed that by holding all other flow conditions and geometry constant, generated bubbles decrease in size with increase in superficial liquid velocity. Detached bubble diameter is shown to increase with air injection nozzle diameter. Likewise, generated bubbles grow in size with increasing pipe diameter. Along the same lines, it is shown that bubble frequency of formation increases and hence the time to detachment of a

  20. Oscillation of a rigid catenary riser due to the internal two-phase flow

    Energy Technology Data Exchange (ETDEWEB)

    Bordalo, Sergio N.; Morooka, Celso K.; Cavalcante, Cesar C.P. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil); Matt, Cyntia G.C.; Franciss, Ricardo [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas

    2008-07-01

    Production of petroleum reservoirs from deep and ultra-deep waters is of paramount importance in Brazil, and several researches are necessary to develop appropriated equipment and risers for those operational conditions. Risers are suspended pipes used to transport the petroleum fluids between the seabed and the floating production unit. The structural flexibility of riser's lines is conferred by its length when compared with the diameter, characterizing it as a slender body. The risers are submitted to large static and dynamic loads originated from its own weight, waves, currents, platform motions and the internal flow. These loadings may threaten, by fatigue, the structural integrity of the system, compromising its useful life, and so they must be considered in the riser's project. There is a large amount of knowledge in the literature about the effects of external loadings on these systems, but the effect of the internal flow remains vastly unexplored. The variation of the flow mass and momentum inside the riser causes a dynamic loading on this system, originating an oscillatory motion. Furthermore, the gas-liquid two-phase flow may assume several flow patterns (bubble, slug, intermittent or annular), each one possessing completely different characteristics. In this work, the influence of the internal flow on the oscillatory motion (whipping motion) of catenary risers is analyzed. To provide a better understanding of this physical phenomenon, a scaled apparatus was designed and built. The material used to manufacture the riser's model was a flexible silicone tube, and air and water were used to simulate the two-phase flow. The instrumentation used to measure the fluids flow rates and the sustaining force at the top of the model was installed in the apparatus. A video acquisition system was used to determine the displacements, and frequency spectrum, of color targets positioned throughout the model, under several flow conditions. The flow patterns

  1. Time dependent two phase flows in Magnetohydrodynamics: A ...

    African Journals Online (AJOL)

    Journal of the Nigerian Association of Mathematical Physics ... Open Access DOWNLOAD FULL TEXT Subscription or Fee Access. Time dependent two phase flows in Magnetohydrodynamics: A Greens function approach. BK Jha, HM Jibril ...

  2. Gravity Independence of Microchannel Two-Phase Flow Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Most of the amassed two-phase flow and heat transfer knowledge comes from experiments conducted in Earth’s gravity. Space missions span varying gravity levels,...

  3. Vapor Compressor Driven Hybrid Two-Phase Loop Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Phase I project successfully demonstrated the feasibility of the vapor compression hybrid two-phase loop (VCHTPL). The test results showed the high...

  4. TWO PHASE FLOW SPLIT MODEL FOR PARALLEL CHANNELS

    African Journals Online (AJOL)

    Ifeanyichukwu Onwuka

    The equations are solved using the Broyden'smethod ... channel system subjected to a two-phase flow transient, and the results have been very .... system pressure, the heat addition rates inside ... three dimensional flows in the LP.

  5. Particle modulations to turbulence in two-phase round jets

    Institute of Scientific and Technical Information of China (English)

    Bing Wang; Huiqiang Zhang; Yi Liu; Xiaofen Yan; Xilin Wang

    2009-01-01

    The particle modulations to turbulence in round jets were experimentally studied by means of two-phase velocity measurements with Phase Doppler Anemometer (PDA). Laden with very large particles, no significant attenuations of turbulence intensities were measured in the far-fields, due to small two-phase slip velocities and particle Reynolds number. The gas-phase turbulence is enhanced by particles in the near-fields, but it is significantly attenuated by the small particles in the far-fields. The smaller particles have a more profound effect on the attenuation of turbulence intensities. The enhancements or attenuations of turbulence intensities in the far-fields depends on the energy production, transport and dissipation mechanisms between the two phases, which are determined by the particle prop-erties and two-phase velocity slips. The non-dimensional parameter CTI is introduced to represent the change of turbulence intensity.

  6. Transient two-phase performance of LOFT reactor coolant pumps

    Energy Technology Data Exchange (ETDEWEB)

    Chen, T.H.; Modro, S.M.

    1983-01-01

    Performance characteristics of Loss-of-Fluid Test (LOFT) reactor coolant pumps under transient two-phase flow conditions were obtained based on the analysis of two large and small break loss-of-coolant experiments conducted at the LOFT facility. Emphasis is placed on the evaluation of the transient two-phase flow effects on the LOFT reactor coolant pump performance during the first quadrant operation. The measured pump characteristics are presented as functions of pump void fraction which was determined based on the measured density. The calculated pump characteristics such as pump head, torque (or hydraulic torque), and efficiency are also determined as functions of pump void fractions. The importance of accurate modeling of the reactor coolant pump performance under two-phase conditions is addressed. The analytical pump model, currently used in most reactor analysis codes to predict transient two-phase pump behavior, is assessed.

  7. Scaling of Two-Phase Systems Across Gravity Levels Project

    Data.gov (United States)

    National Aeronautics and Space Administration — There is a defined need for long term earth based testing for the development and deployment of two-phase flow systems in reduced-gravity, including lunar gravity,...

  8. Numerical Simulation of Hydrodynamic Wave Loading by a Compressible Two-Phase Model

    NARCIS (Netherlands)

    Wemmenhove, R.; Loots, G.E.; Veldman, A.E.P.

    2006-01-01

    The numerical simulation of hydrodynamic wave loading on different types of offshore structures is important to predict forces on and water motion around these structures. This paper presents a numerical study of the effects of two-phase flow on an offshore structure subject to breaking waves. The

  9. Nonequilibrium capillarity effects in two-phase flow through porous media at different scales

    NARCIS (Netherlands)

    Bottero, S.; Hassanizadeh, S.M.; Kleingeld, P.J.; Heimovaara, T.J.

    2011-01-01

    A series of primary drainage experiments was carried out in order to investigate nonequilibrium capillarity effects in two-phase flow through porous media. Experiments were performed with tetrachloroethylene (PCE) and water as immiscible fluids in a sand column 21 cm long. Four drainage experiments

  10. Gas-driven subharmonic waves in a vibrated two-phase granular material.

    Science.gov (United States)

    Matas, J-P; Uehara, J; Behringer, R P

    2008-04-01

    Vibrated powders exhibit striking phenomena: subharmonic waves, oscillons, convection, heaping, and even bubbling. We demonstrate novel rectangular profile subharmonic waves for vibrated granular material, that occur uniquely in the two-phase case of grains, and a fluid, such as air. These waves differ substantially from those for the gas-free case, exhibit different dispersion relations, and occur for specific shaking parameters and air pressure, understandable with gas-particle flow models. These waves occur when the gas diffusively penetrates the granular layer in a time comparable to the shaker period. As the pressure is lowered towards P =0, the granular-gas system exhibits a Knudsen regime. This instability provides an opportunity to quantitatively test models of two-phase flow.

  11. Modeling of Immiscible, Two-Phase Flows in a Natural Rock Fracture

    Energy Technology Data Exchange (ETDEWEB)

    Crandall, Dustin; Ahmadi, Goodarz; Smith, Duane H

    2009-01-01

    One potential method of geologically sequestering carbon dioxide (CO2) is to inject the gas into brine-filled, subsurface formations. Within these low-permeability rocks, fractures exist that can act as natural fluid conduits. Understanding how a less viscous fluid moves when injected into an initially saturated rock fracture is important for the prediction of CO2 transport within fractured rocks. Our study examined experimentally and numerically the motion of immiscible fluids as they were transported through models of a fracture in Berea sandstone. The natural fracture geometry was initially scanned using micro-computerized tomography (CT) at a fine volume-pixel (voxel) resolution by Karpyn et al. [1]. This CT scanned fracture was converted into a numerical mesh for two-phase flow calculations using the finite-volume solver FLUENT® and the volume-of-fluid method. Additionally, a translucent experimental model was constructed using stereolithography. The numerical model was shown to agree well with experiments for the case of a constant rate injection of air into the initially water-saturated fracture. The invading air moved intermittently, quickly invading large-aperture regions of the fracture. Relative permeability curves were developed to describe the fluid motion. These permeability curves can be used in reservoir-scale discrete fracture models for predictions of fluid motion within fractured geological formations. The numerical model was then changed to better mimic the subsurface conditions at which CO2 will move into brine saturated fractures. The different fluid properties of the modeled subsurface fluids were shown to increase the amount of volume the less-viscous invading gas would occupy while traversing the fracture.

  12. Two-phase cooling fluids; Les fluides frigoporteurs diphasiques

    Energy Technology Data Exchange (ETDEWEB)

    Lallemand, A. [Institut National des Sciences Appliquees (INSA), 69 - Lyon (France)

    1997-12-31

    In the framework of the diminution of heat transfer fluid consumption, the concept of indirect refrigerating circuits, using cooling intermediate fluids, is reviewed and the fluids that are currently used in these systems are described. Two-phase cooling fluids advantages over single-phase fluids are presented with their thermophysical characteristics: solid fraction, two-phase mixture enthalpy, thermal and rheological properties, determination of heat and mass transfer characteristics, and cold storage through ice slurry

  13. Experimental study of the decrease in the temperature of an air/water-cooled turbine blade

    Science.gov (United States)

    Ryzhov, A. A.; Sereda, A. V.; Shaiakberov, V. F.; Iskakov, K. M.; Shatalov, Iu. S.

    Results of the full-scale testing of an air/water-cooled deflector-type turbine blade are reported. Data on the decrease in the temperature of the cooling air and of the blade are presented and compared with the calculated values. An analysis of the results indicates that the use of air/water cooling makes it possible to significantly reduce the temperature of the cooling air and of the blade with practically no increase in the engine weight and dimensions.

  14. Influence of Cooling to Heating Load Ratio on Optimal Supply Water and Air Temperatures in an Air Conditioning System

    Science.gov (United States)

    Karino, Naoki; Shiba, Takashi; Yokoyama, Ryohei; Ito, Koichi

    In planning an air conditioning system, supply water and air temperatures are important factors from the viewpoint of energy saving and cost reduction. For example, lower temperature supply water and air for space cooling reduce the coefficient of performance of a refrigeration machine, and increase the thickness of heat insulation material. However, they enable larger temperature differences, and reduce equipment sizes and power demand. It is also an important subject to evaluate the effect of the supply water and air temperatures on energy saving and cost reduction on the annual basis by considering not only cooling but also heating loads. The purposes of this paper are to propose an optimal planning method for an air conditioning system with large temperature difference, and to analyze the effect of supply water and air temperatures on the long-term economics through a numerical study for an office building. As a result, it is shown that the proposed method effectively determines supply water and air temperatures, and the influence of the cooling to heating load ratio on the long-term economics is clarified.

  15. THE ASSESSMENT OF AIR AND WATER QUALITY OF SHARRA LANDFILL

    Directory of Open Access Journals (Sweden)

    A. Bani

    2011-04-01

    Full Text Available The waste disposal site of Sharra represents the first landfill for the management of solid wastes in Albania designed in accordance to the European Union standards for the management and administration of solid wastes. The objective of this study was to realize a general assessment of the environmental state in the areas nearby Sharra, after the implementation of the landfill as a remediation method. Water and air samples have been periodically collected and analyzed before and after the remediation of the waste disposal site of Sharra, respectively on the years 2008 and 2009. Results show that the measured indicators used to assess the quality of air such as; solid particles, PM10, NO2, H2S, CH4 reach the respective average values of 372 μg m-3, 216 μg m-3, 97 μg m-3, 0.8 μg m-3, 350 μg m-3 in 2008 and 72 μg m-3, 30 μg m-3, 29 μg m-3, 0.22 μg m-3, 41 μg m-3, in the year 2009. Before the remediation, except H2S the concentrations of all the other components in air exceed the Albanian and European Union limits whereas in 2009 these values have dropped under the mentioned limits. The concentration of heavy metals (mg L-1 in the surface waters exceeds the allowed limits for Ni (0.002-0.08, Mn (0.6, Cr (0.19-0.33 and Fe (0.2-3.5. As regards to the quality of surface water; some of the indicators such as EC, Cl-, NO2- resulted to surpass the above mentioned limits even after the implementation of the landfill. Based on the obtained results, further actions should be considered to be carried out in order to assure the collection and remediation of the landfill leaching prior they join the Erzeni River.

  16. 15 CFR 923.45 - Air and water pollution control requirements.

    Science.gov (United States)

    2010-01-01

    ... 15 Commerce and Foreign Trade 3 2010-01-01 2010-01-01 false Air and water pollution control....45 Air and water pollution control requirements. The program must incorporate, by reference or otherwise, all requirements established by the Federal Water Pollution Control Act, as amended (Clean...

  17. 45 CFR 2543.86 - Clean Air Act and the Federal Water Pollution Control Act.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 4 2010-10-01 2010-10-01 false Clean Air Act and the Federal Water Pollution... Water Pollution Control Act. Contracts and subgrants of amounts in excess of $100,000 shall contain a... regulations issued pursuant to the Clean Air Act (42 U.S.C. 7401 et seq.) and the Federal Water...

  18. Investigation on two-phase flow instability in steam generator of integrated nuclear reactor

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    In the pressure range of 3-18MPa,high pressure steam-water two-phase flow density wave instability in vertical upward parallel pipes with inner diameter of 12mm is studied experimentally.The oscillation curves of two-phase flow instability and the effects of several parameters on the oscillation threshold of the system are obtained.Based on the small pertubation linearization method and the stability principles of automatic control system,a mathematical model is developed to predict the characteristics of density wave instability threshold.The predictions of the model are in good agreement with the experimental results.

  19. Research of Characteristics of Gas-liquid Two-phase Pressure Drop in Microreactor

    OpenAIRE

    Li Dan

    2015-01-01

    With the research system of nitrogen and deionized water, this paper researches the pressure drop of gas-liquid two-phase flow in the circular microchannel with an inner diameter which is respectively 0.9mm and 0.5mm, analyzes the effect of microchannel diameter on gas-liquid two-phase frictional pressure drop in the microchannel reactor, and compares with the result of frictional pressure drop and the predicting result of divided-phase flow pattern. The result shows that, the gas-liquid two-...

  20. Experimental Study of Air Vessel Behavior for Energy Storage or System Protection in Water Hammer Events

    Directory of Open Access Journals (Sweden)

    Mohsen Besharat

    2017-01-01

    Full Text Available An experimental assessment of an air pocket (AP, confined in a compressed air vessel (CAV, has been investigated under several different water hammer (WH events to better define the use of protection devices or compressed air energy storage (CAES systems. This research focuses on the size of an AP within an air vessel and tries to describe how it affects important parameters of the system, i.e., the pressure in the pipe, stored pressure, flow velocity, displaced volume of water and water level in the CAV. Results present a specific range of air pockets based on a dimensionless parameter extractable for other real systems.

  1. Hearing in birds: what changes from air to water.

    Science.gov (United States)

    Dooling, Robert J; Therrien, Sara C

    2012-01-01

    We reviewed what is known about hearing in birds, including the effects of anthropogenic noise, to speculate on the nature of underwater hearing in diving birds. Taking into consideration changes inhuman hearing underwater, the effects of changes in middle ear pressure on hearing in humans, and the protective effects against acoustic overexposure in birds from changes in middle ear pressure, we suggest that if similar patterns hold for diving birds, they may not hear well underwater. Moreover,the frequency of best hearing sensitivity may shift to frequencies below 2 and 4 kHz. Trapped air may allow the middle ear cavity of birds to function much as the swim bladder functions in fish.Diving birds present important auditory and environmental issues. To resolve these issues properly requires comparative anatomical investigations of the middle and inner ears of diving birds.More importantly, behavioral measures of hearing in diving birds must be conducted both in air and in water. Finally, behavioral studies of these animals in their natural habitats are required to deter-mine whether they use sound underwater for communication, foraging, predator avoidance, or other behaviors.

  2. Interfacial structure in an air-water planar bubble jet

    Science.gov (United States)

    Sun, X.; Vasavada, S.; Choi, S. W.; Kim, S.; Ishii, M.; Beus, S. G.

    2005-04-01

    The objective of the current study is to better understand the interfacial structure and its development in an air-water planar bubble jet, as well as to provide a unique benchmark data set for a 3D thermal-hydraulic analysis code. Both flow visualization and local measurements were performed in three characteristic flow conditions at four elevations along a test section with a cross section of 200 mm in width and 10 mm in gap. A high-speed digital video camera was applied in the flow visualization study to capture the flow structures and bubble interaction phenomena, while a miniaturized four-sensor conductivity probe was used to acquire the time-averaged local void fraction, interfacial velocity, and bubble number frequency. Also, the interfacial area concentration and the averaged bubble Sauter mean diameter were obtained from the local measurements. The lateral bubble transport and bubble interaction mechanisms were clearly demonstrated in the acquired data.

  3. Reacting chemistry at the air-water interface

    Science.gov (United States)

    Murakami, Tomoyuki; Morgan, Thomas; Huwel, Lutz; Graham, William

    2016-09-01

    Plasma interaction with gas-liquid interfaces is becoming increasingly important in biological applications, chemical analysis and medicine. It introduces electrons, new ionic species and reactive species and contributes to chemical and electrical self-organization at the interface. To provide insight into the associated physics and chemistry at work in the evolution of the plasma in the air-water interface (AWI), a time-dependent one-dimensional modelling has been developed. The numerical simulation is used to solve the kinetic equations and help identify the important reaction mechanisms and describe the phenomena associated with hundreds of reacting pathways in gas-phase and liquid-phase AWI chemistry. This work was partly supported by JSPS KAKENHI Grant Number 16K04998.

  4. Measuring the benefits of clean air and water

    Energy Technology Data Exchange (ETDEWEB)

    Kneese, A.V.

    1984-01-01

    Methods are discussed for quantitatively estimating the benefits derived from the maintenance or improvement of air and water quality. Investigations are centered on two broad approaches. The first approach involves methods based, however indirectly, on observed human behavior with respect to environmental good, including travel to recreational opportunities of varying quality and prices paid for houses in different locations. The second approach involves questioning respondents about their willingness to pay for various hypothetical changes in environmental quality. Included in this book is the current state of the art regarding benefits assessment, including such tools as bidding games, surveys, property-value studies, wage differentials, risk-reduction evaluation, and mortality and morbidity cost estimation.

  5. Gas-liquid two-phase flow across a bank of micropillars

    Science.gov (United States)

    Krishnamurthy, Santosh; Peles, Yoav

    2007-04-01

    Adiabatic nitrogen-water two-phase flow across a bank of staggered circular micropillars, 100μm long with a diameter of 100μm and a pitch-to-diameter ratio of 1.5, was investigated experimentally for Reynolds number ranging from 5 to 50. Flow patterns, void fraction, and pressure drop were obtained, discussed, and compared to large scale as well as microchannel results. Two-phase flow patterns were determined by flow visualization, and a flow map was constructed as a function of gas and liquid superficial velocities. Significant deviations from conventional scale systems, with respect to flow patterns and trend lines, were observed. A unique flow pattern, driven by surface tension, was observed and termed bridge flow. The applicability of conventional scale models to predict the void fraction and two-phase frictional pressure drop was also assessed. Comparison with a conventional scale void fraction model revealed good agreement, but was found to be in a physically wrong form. Thus, a modified physically based model for void fraction was developed. A two-phase frictional multiplier was found to be a strong function of mass flux, unlike in previous microchannel studies. It was observed that models from conventional scale systems did not adequately predict the two-phase frictional multiplier at the microscale, thus, a modified model accounting for mass flux was developed.

  6. Drag reduction by polymer addition in single and two-phase gas-liquid flows in pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Bizotto, Vanessa Cristina; Paes, Diogo Melo; Franca, Fernando de Almeida [Universidade Estadual de Campinas, SP (Brazil). Centro de Estudos de Petroleo. LabPetro]. E-mails: vanessa@cepetro.unicamp.br; diogopaes10@hotmail.com; Sabadini, Edvaldo [Universidade Estadual de Campinas, SP (Brazil). Inst. de Quimica]. E-mails: sabadini@iqm.unicamp.br; ffranca@fem.unicamp.br

    2008-07-01

    Turbulence mechanisms, as the eddies formation frequency and size, promote energy dissipation that appears as pressure drop in pipe flows. Adding minute amounts of polymers - ppm - of high molecular weight to the solution can lead to the reduction of the viscous dissipation. The formed macromolecules interact with the eddies, cause the eddies coherence breakdown, damp the energy transport and reduces the pressure drop. This phenomenon is known as the hydrodynamic drag reduction (DR, for short). Thus, for a given pipe flow rate there is decrease in pressure head, which is a desired operating strategy when transporting liquids. Studies on the hydrodynamic drag reduction in polymeric systems have been carried out in collaboration by the Chemistry Institute and the Petroleum Laboratory - LabPetro, UNICAMP. These studies have allowed microscopic approaches to the engineering scales, tackling the most usual processes - single phase flows, as well as gas-liquid two-phase flows in pipelines, which are quite common in the chemical and the petroleum industries. Tests conducted in the Chemistry Institute comprised over-the-bench experimentations made with a rotational double-gap type rheometer. These quick performed tests used small amount of polymers, and provided information on the additive concentration, the drag reduction and the solution mechanical stability along a turbulent shearing process. The results indicated that 17% is the limiting drag reduction achieved when a 2 ppm aqueous solution of polyacrylamide - PAM - was tested. These tests, besides giving preliminary estimations, are limited in terms of engineering application due to the low shearing rates applied by the viscometer. The tests performed at LabPetro comprised pressure drop measurements in actual pipe flows, both water single and air-water two-phase flows, using the previous knowledge acquired with the viscometer tests. In the former case, the Prandtl-von Karman map has been drawn to show the %DR in terms

  7. Water- and Air-Quality Monitoring of the Sweetwater Reservoir Watershed, San Diego County, California-Phase One Results, Continued, 1999-2001

    Science.gov (United States)

    Mendez, Gregory O.; Foreman, William T.; Sidhu, Jagdeep S.; Majewski, Michael S.

    2007-01-01

    In 1998, the U.S. Geological Survey, in cooperation with the Sweetwater Authority, began a study to assess the overall health of the Sweetwater watershed with respect to chemical contamination. The study included regular sampling of air and water at Sweetwater Reservoir for chemical contaminants, including volatile organic compounds, polycyclic aromatic hydrocarbons, pesticides, and major and trace elements. Background water samples were collected at Loveland Reservoir for volatile organic compounds and pesticides. The purpose of this study was to monitor changes in contaminant composition and concentration in the air and water resulting from the construction and operation of State Route 125 near Sweetwater Reservoir. To accomplish this, the study was divided into two phases. Phase One sampling was designed to establish baseline conditions for target compounds in terms of detection frequency and concentration in air and water. Phase Two sampling is planned to continue at the established monitoring sites during and after construction of State Route 125 to assess the chemical impact this roadway alignment project may have on the water quality in the reservoir. In addition to the ongoing data collection, several special studies were initiated to assess the occurrence of specific chemicals of concern, such as low-use pesticides, trace metals, and wastewater compounds. This report describes the study design, and the sampling and analytical methods, and presents the results for the second and third years of the study (October 1999 to September 2001). Data collected during the first year of sampling (October 1998 to September 1999) were published in 2002.

  8. Time dependent FTIR spectra of mineral waters after contact with air

    CERN Document Server

    Kondyurin, Alexey

    2010-01-01

    FTIR spectra of mineral waters of Slavyanovskaya, Aqua Montana, Bad Harzburger and Christinen with time from first contact of water with open air were analysed. The kinetic of spectral changes of Slavyanovskaya mineral water in the regions of stretch, deformation and intermolecular vibrations was measured. The spectral changes do not correlate with chemical contamination of mineral water and degassing process. The observed spectral changes could be due to different structure of mineral water in liquid state, which is destroyed after air contact. The observed spectral behaviour of Slavyanovskaya is correlated with the catalytic activity of mineral water, which was saved without contact with air. The characteristic time of spectral dependence (669 seconds) is close to the characteristic time of catalytic activity loss (600 seconds) of mineral water at air contact. The spectra results support the medical studies that show the activity of mineral water near spring, and the loosing activity of water after long tim...

  9. Disponibilidad de agua-aire en sustratos para plantas Water-air availability in plant substrates

    Directory of Open Access Journals (Sweden)

    Lilia Beatriz Vence

    2008-12-01

    Full Text Available Las propiedades físicas de los sustratos especialmente las relacionadas con la disponibilidad de agua-aire para las raíces de las plantas son las más importantes dentro del estudio de estos materiales usados en cultivos en contenedores. Para un óptimo crecimiento de la planta un sustrato debe contener suficiente cantidad de agua y aire y ambos estar disponibles. A nivel mundial el estudio de las propiedades que determinan esta disponibilidad comenzó desde las ciencias del suelo y fue adaptándose a las características propias de la amplia gama de productos que pueden ser utilizados, surgiendo así variables y métodos de medida específicos para la caracterización física de sustratos. En la Argentina el estudio de sustratos para plantas constituye un área de conocimiento nueva y en desarrollo, por ello exige un trabajo interdisciplinario donde hay que concordar un lenguaje común de términos técnicos, la elección de los métodos analíticos de referencia específicos y una legislación actualizada para sustratos. Haciendo un estudio crítico de la gran cantidad de información al respecto que proviene de otros países se podrán adaptar a nuestra realidad y a nuestros materiales. En esta revisión se enumeran resumidamente los más importantes conceptos a tener en cuenta para la evaluación física de sustratos a fin de que puedan servir de base para una mejor comprensión y discusión del tema.The study of the physical properties of substrates for container plant production is very important because the water and air availability for plant roots is involved. A substrate must contain a sufficient amount of available water and air to produce an optimum plant growth and development. Worldwide, the study of the properties that determine the water and air availability started from soil sciences and has been evolving to the present existence of a great variety of products that can be used, concomitant with the identification of parameters

  10. Effects of air vessel on water hammer in high-head pumping station

    Science.gov (United States)

    Wang, L.; Wang, F. J.; Zou, Z. C.; Li, X. N.; Zhang, J. C.

    2013-12-01

    Effects of air vessel on water hammer process in a pumping station with high-head were analyzed by using the characteristics method. The results show that the air vessel volume is the key parameter that determines the protective effect on water hammer pressure. The maximum pressure in the system declines with increasing air vessel volume. For a fixed volume of air vessel, the shape of air vessel and mounting style, such as horizontal or vertical mounting, have little effect on the water hammer. In order to obtain good protection effects, the position of air vessel should be close to the outlet of the pump. Generally, once the volume of air vessel is guaranteed, the water hammer of a entire pipeline is effectively controlled.

  11. Experiments and Characterization of the Two-Phase Flow Driven Particulate Debris Spreading in the Pool

    OpenAIRE

    Konovalenko, Alexander; Basso, Simone; Kudinov, Pavel

    2014-01-01

    Melt fragmentation, quenching and long term coolability in a deep pool of water under reactor vessel are employed as a severe accident mitigation strategy in several designs of light water reactors. Success of the strategy is contingent upon effectiveness of natural circulation in removing the decay heat generated by the porous debris bed. Geometrical configuration of the bed is one of the factors which affect coolability of the bed. Boiling and two-phase turbulent flows in the pool serve as ...

  12. Modeling and simulation of nanoparticles transport in a two-phase flow in porous media

    KAUST Repository

    El-Amin, Mohamed

    2012-01-01

    In the current paper, a mathematical model to describe the nanoparticles transport carried by a two-phase flow in a porous medium is presented. Both capillary forces as well as Brownian diffusion are considered in the model. A numerical example of countercurrent water-oil imbibition is considered. We monitor the changing of the fluid and solid properties due to the addition of the nanoparticles using numerical experiments. Variation of water saturation, nanoparticles concentration and porosity ratio are investigated.

  13. Liquid Steel at Low Pressure: Experimental Investigation of a Downward Water Air Flow

    Science.gov (United States)

    Thumfart, Maria

    2016-07-01

    In the continuous casting of steel controlling the steel flow rate to the mould is critical because a well-defined flow field at the mould level is essential for a good quality of the cast product. The stopper rod is a commonly used device to control this flow rate. Agglomeration of solid material near the stopper rod can lead to a reduced cross section and thus to a decreased casting speed or even total blockage (“clogging”). The mechanisms causing clogging are still not fully understood. Single phase considerations of the flow in the region of the stopper rod result in a low or even negative pressure at the smallest cross section. This can cause degassing of dissolved gases from the melt, evaporation of alloys and entrainment of air through the porous refractory material. It can be shown that the degassing process in liquid steel is taking place mainly at the stopper rod tip and its surrounding. The steel flow around the stopper rod tip is highly turbulent. In addition refractory material has a low wettability to liquid steel. So the first step to understand the flow situation and transport phenomena which occur near the stopper is to understand the behaviour of this two phase (steel, gas) flow. To simulate the flow situation near the stopper rod tip, water experiments are conducted using a convergent divergent nozzle with three different wall materials and three different contact angles respectively. These experiments show the high impact of the wettability of the wall material on the actual flow structure at a constant gas flow rate.

  14. Experimental research on continuous metering method of oil-water two-phase flow in low-yield oil wells%低产液油井油水两相流连续计量方法实验研究

    Institute of Scientific and Technical Information of China (English)

    于靖民

    2016-01-01

    针对传统油井多相流地面分离计量方法的缺点,研究出了经旋流气相分离后油水两相流参数连续测量方法。基于低流量条件下油、水两相分离特点,在一个容积已知的环形空间内,利用仪器上位于油、水区域的两个阀门的不断切换,自动测量油相和水相排出该空间所用的时间来计算油井油水两相流条件下的流量和含水率。%Aimed at the shortcomings of traditional oil-well multiphase flow separation and metering method above the ground,a continuous metering method of oil-well two-phase flow after cyclonic gas-separation is studied in this paper.The flow rate and water content in oil wells can be calculated by this method.

  15. The Effect of Rain on Air-Water Gas Exchange

    Science.gov (United States)

    Ho, David T.; Bliven, Larry F.; Wanninkhof, Rik; Schlosser, Peter

    1997-01-01

    The relationship between gas transfer velocity and rain rate was investigated at NASA's Rain-Sea Interaction Facility (RSIF) using several SF, evasion experiments. During each experiment, a water tank below the rain simulator was supersaturated with SF6, a synthetic gas, and the gas transfer velocities were calculated from the measured decrease in SF6 concentration with time. The results from experiments with IS different rain rates (7 to 10 mm/h) and 1 of 2 drop sizes (2.8 or 4.2 mm diameter) confirm a significant and systematic enhancement of air-water gas exchange by rainfall. The gas transfer velocities derived from our experiment were related to the kinetic energy flux calculated from the rain rate and drop size. The relationship obtained for mono-dropsize rain at the RSIF was extrapolated to natural rain using the kinetic energy flux of natural rain calculated from the Marshall-Palmer raindrop size distribution. Results of laboratory experiments at RSIF were compared to field observations made during a tropical rainstorm in Miami, Florida and show good agreement between laboratory and field data.

  16. Visualization of two-phase gas-liquid flow regimes in horizontal and slightly-inclined circular tubes

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Livia Alves [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil); Nuclear Engineering Institute (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)], E-mail: livia@lasme.coppe.ufrj.br; Cunha Filho, Jurandyr; Su, Jian [Coordenacao dos Programas de Pos-Graduacao de Engenharia (COPPE/UFRJ), RJ (Brazil). Nuclear Engineering Program], Emails: cunhafilho@lasme.coppe.ufrj.br, sujian@lasme.coppe.ufrj.br; Faccini, Jose Luiz Horacio [Nuclear Engineering Institute (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)], E-mail: faccini@ien.gov.br

    2010-07-01

    In this paper a flow visualization study was performed for two-phase gas-liquid flow in horizontal and slightly inclined tubes. The test section consists of a 2.54 cm inner diameter stainless steel circular tube, followed by a transparent acrylic tube with the same inner diameter. The working fluids were air and water, with liquid superficial velocities ranging from 0:11 to 3:28 m/s and gas superficial velocities ranging from 0:27 to 5:48 m/s. Flow visualization was executed for upward flow at 5 deg and 10 deg and downward flow at 2:5 deg, 5 deg and 10 deg, as well as for horizontal flow. The visualization technique consists of a high-speed digital camera that records images at rates of 125 and 250 frames per second of a concurrent air-water mixture through a transparent part of the tube. From the obtained images, the flow regimes were identified (except for annular flow), observing the effect of inclination angles on flow regime transition boundaries. Finally, the experimental results were compared with empirical and theoretical flow pattern maps available in literature. (author)

  17. The effects of surface tension on flooding in counter-current two-phase flow in an inclined tube

    Energy Technology Data Exchange (ETDEWEB)

    Deendarlianto [Department of Mechanical and Industrial Engineering, Faculty of Engineering, Gadjah Mada University, Jalan Grafika No.2 Yogyakarta 55281 (Indonesia); Forschungszentrum Dresden-Rossendorf e.V., Institute of Safety Research, P.O. Box 510 119, D-01314 Dresden (Germany); Ousaka, Akiharu [Department of Mechanical Engineering, The University of Tokushima, 2-1 Minami Josanjima, Tokushima 770-8506 (Japan); Indarto [Department of Mechanical and Industrial Engineering, Faculty of Engineering, Gadjah Mada University, Jalan Grafika No.2 Yogyakarta 55281 (Indonesia); Kariyasaki, Akira [Department of Chemical Engineering, Fukuoka University, 8-19-1, Jyonan-ku, Fukuoka 814-0180 (Japan); Lucas, Dirk; Vallee, Christophe [Forschungszentrum Dresden-Rossendorf e.V., Institute of Safety Research, P.O. Box 510 119, D-01314 Dresden (Germany); Vierow, Karen; Hogan, Kevin [Department of Nuclear Engineering Texas A and M University, 129 Zachry Engineering Center, 3133 TAMU College Station, TX 77843-3133 (United States)

    2010-10-15

    The purpose of the present study is to investigate the effects of surface tension on flooding phenomena in counter-current two-phase flow in an inclined tube. Previous studies by other researchers have shown that surface tension has a stabilizing effect on the falling liquid film under certain conditions and a destabilizing or unclear trend under other conditions. Experimental results are reported herein for air-water systems in which a surfactant has been added to vary the liquid surface tension without altering other liquid properties. The flooding section is a tube of 16 mm in inner diameter and 1.1 m length, inclined at 30-60 from horizontal. The flooding mechanisms were observed by using two high-speed video cameras and by measuring the time variation of liquid hold-up along the test tube. The results show that effects of surface tension are significant. The gas velocity needed to induce flooding is lower for a lower surface tension. There was no upward motion of the air-water interfacial waves upon flooding occurrence, even for lower a surface tension. Observations on the liquid film behavior after flooding occurred suggest that the entrainment of liquid droplets plays an important role in the upward transport of liquid. Finally, an empirical correlation for flooding velocities is proposed that includes functional dependencies on surface tension and tube inclination. (author)

  18. Flow regime transition criteria for two-phase flow in a vertical annulus

    Energy Technology Data Exchange (ETDEWEB)

    Julia, J. Enrique, E-mail: bolivar@emc.uji.es [Departamento de Ingenieria Mecanica y Construccion, Universitat Jaume I., Campus de Riu Sec, 12071 Castellon (Spain); Hibiki, Takashi [School of Nuclear Engineering, Purdue University, 400 Central Dr., West Lafayette, IN 47907-2017 (United States)

    2011-10-15

    Highlights: > Flow regime transition model is presented for two-phase flows in a vertical annulus. > The transition criteria is easy to be implemented in computational codes. > Final equations do not need experimental input. > New developed model shows better predicting capabilities than existing correlations. > New developed model shows good predicting capabilities in boiling flow. - Abstract: In this work, a new flow regime transition model is proposed for two-phase flows in a vertical annulus. Following previous works, the flow regimes considered are bubbly (B), slug (S) or cap-slug (CS), churn (C) and annular (A). The B to CS transition is modeled using the maximum bubble package criteria of small bubbles. The S to C transition takes place for small annulus perimeter flow channels and it is assumed to occur when the mean void fraction over the entire region exceeds that over the slug-bubble section. If the annulus perimeter is larger that the distorted bubble limit the cap-slug flow regime will be considered since in these conditions it is not possible to distinguish between cap and partial-slug bubbles. The CS to C transition is modeled using the maximum bubble package criteria. However, this transition considers the coalescence of cap and spherical bubbles in order to take into account the flow channel geometry. Finally, the C to A transition is modeled assuming two different mechanisms, (a) flow reversal in the liquid film section along large bubbles; (b) destruction on liquid slugs or large waves by entrainment or deformation. In the S to C and C to A flow regime transitions the annulus flow channel is considered as a rectangular flow channel with no side walls. In all the modeled transitions the drift-flux model is used to obtain the final correlations. The final equations for every flow regime transition are easy to be implemented in computational codes and not experimental input is needed. The prediction accuracy of the newly developed model has been

  19. Wind driven vertical transport in a vegetated, wetland water column with air-water gas exchange

    Science.gov (United States)

    Poindexter, C.; Variano, E. A.

    2010-12-01

    Flow around arrays of cylinders at low and intermediate Reynolds numbers has been studied numerically, analytically and experimentally. Early results demonstrated that at flow around randomly oriented cylinders exhibits reduced turbulent length scales and reduced diffusivity when compared to similarly forced, unimpeded flows (Nepf 1999). While horizontal dispersion in flows through cylinder arrays has received considerable research attention, the case of vertical dispersion of reactive constituents has not. This case is relevant to the vertical transfer of dissolved gases in wetlands with emergent vegetation. We present results showing that the presence of vegetation can significantly enhance vertical transport, including gas transfer across the air-water interface. Specifically, we study a wind-sheared air-water interface in which randomly arrayed cylinders represent emergent vegetation. Wind is one of several processes that may govern physical dispersion of dissolved gases in wetlands. Wind represents the dominant force for gas transfer across the air-water interface in the ocean. Empirical relationships between wind and the gas transfer coefficient, k, have been used to estimate spatial variability of CO2 exchange across the worlds’ oceans. Because wetlands with emergent vegetation are different from oceans, different model of wind effects is needed. We investigated the vertical transport of dissolved oxygen in a scaled wetland model built inside a laboratory tank equipped with an open-ended wind tunnel. Plastic tubing immersed in water to a depth of approximately 40 cm represented emergent vegetation of cylindrical form such as hard-stem bulrush (Schoenoplectus acutus). After partially removing the oxygen from the tank water via reaction with sodium sulfite, we used an optical probe to measure dissolved oxygen at mid-depth as the tank water re-equilibrated with the air above. We used dissolved oxygen time-series for a range of mean wind speeds to estimate the

  20. Mathematical modeling of disperse two-phase flows

    CERN Document Server

    Morel, Christophe

    2015-01-01

    This book develops the theoretical foundations of disperse two-phase flows, which are characterized by the existence of bubbles, droplets or solid particles finely dispersed in a carrier fluid, which can be a liquid or a gas. Chapters clarify many difficult subjects, including modeling of the interfacial area concentration. Basic knowledge of the subjects treated in this book is essential to practitioners of Computational Fluid Dynamics for two-phase flows in a variety of industrial and environmental settings. The author provides a complete derivation of the basic equations, followed by more advanced subjects like turbulence equations for the two phases (continuous and disperse) and multi-size particulate flow modeling. As well as theoretical material, readers will discover chapters concerned with closure relations and numerical issues. Many physical models are presented, covering key subjects including heat and mass transfers between phases, interfacial forces and fluid particles coalescence and breakup, a...

  1. Velocity and energy relaxation in two-phase flows

    CERN Document Server

    Meyapin, Yannick; Gisclon, Marguerite

    2009-01-01

    In the present study we investigate analytically the process of velocity and energy relaxation in two-phase flows. We begin our exposition by considering the so-called six equations two-phase model [Ishii1975, Rovarch2006]. This model assumes each phase to possess its own velocity and energy variables. Despite recent advances, the six equations model remains computationally expensive for many practical applications. Moreover, its advection operator may be non-hyperbolic which poses additional theoretical difficulties to construct robust numerical schemes |Ghidaglia et al, 2001]. In order to simplify this system, we complete momentum and energy conservation equations by relaxation terms. When relaxation characteristic time tends to zero, velocities and energies are constrained to tend to common values for both phases. As a result, we obtain a simple two-phase model which was recently proposed for simulation of violent aerated flows [Dias et al, 2010]. The preservation of invariant regions and incompressible li...

  2. A SAS Package for Logistic Two-Phase Studies

    Directory of Open Access Journals (Sweden)

    Walter Schill

    2014-04-01

    Full Text Available Two-phase designs, in which for a large study a dichotomous outcome and partial or proxy information on risk factors is available, whereas precise or complete measurements on covariates have been obtained only in a stratified sub-sample, extend the standard case-control design and have been proven useful in practice. The application of two-phase designs, however, seems to be hampered by the lack of appropriate, easy-to-use software. This paper introduces sas-twophase-package, a collection of SAS-macros, to fulfill this task. sas-twophase-package implements weighted likelihood, pseudo likelihood and semi- parametric maximum likelihood estimation via the EM algorithm and via profile likelihood in two-phase settings with dichotomous outcome and a given stratification.

  3. A mechanical erosion model for two-phase mass flows

    CERN Document Server

    Pudasaini, Shiva P

    2016-01-01

    Erosion, entrainment and deposition are complex and dominant, but yet poorly understood, mechanical processes in geophysical mass flows. Here, we propose a novel, process-based, two-phase, erosion-deposition model capable of adequately describing these complex phenomena commonly observed in landslides, avalanches, debris flows and bedload transport. The model is based on the jump in the momentum flux including changes of material and flow properties along the flow-bed interface and enhances an existing general two-phase mass flow model (Pudasaini, 2012). A two-phase variably saturated erodible basal morphology is introduced and allows for the evolution of erosion-deposition-depths, incorporating the inherent physical process including momentum and rheological changes of the flowing mixture. By rigorous derivation, we show that appropriate incorporation of the mass and momentum productions or losses in conservative model formulation is essential for the physically correct and mathematically consistent descript...

  4. Experimental study of air-cooled water condensation in slightly inclined circular tube using infrared temperature measurement technique

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyungdae [Nuclear Engineering Department, Kyung Hee University, Yongin (Korea, Republic of); Kwon, Tae-Soon [Korea Atomic Energy Research Institute, Daedeok-daero 989-111, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Kim, Dong Eok, E-mail: dekim@knu.ac.kr [Department of Precision Mechanical Engineering, Kyungpook National University, Sangju (Korea, Republic of)

    2016-11-15

    Highlights: • Air-cooled condensation experiments in an inclined Pyrex glass tube were performed. • High-resolution wall temperature data and flow regime formations could be obtained. • The local heat flux was strongly dependent on the air-side heat transfer. • A CFD analysis was conducted for calculating the local heat flux distribution. - Abstract: This study presents the results of an investigation of the air-cooled water condensation heat transfer characteristics inside a slightly inclined circular tube made of transparent Pyrex glass. The high-resolution wall temperature data and stratified film formations could be obtained with the assistance of an infrared (IR) thermometry technique and side-view visualization using a CCD camera. In all experimental cases, the condensation flow patterns were in the fully-stratified flow region. In addition, the experimentally measured void fraction corresponded well with the logarithmic mean void fraction model. The local temperature differences in the cooling air flow across the condenser tube and high-resolution temperature profiles on the tube’s outer wall were obtained in the experimental measurements. Under the experimental conditions of this study, the local heat flux distributions in the longitudinal direction of the test tube were strongly dependent on the cooling air velocity. And, with the help of IR thermometry, the tube outer wall temperature data at 45 local points could be measured. From the data, the asymmetry distribution of the local wall temperatures and the accurate location of the transition from two-phase mixture to single phase liquid inside the tube could be obtained. Also, the analysis of the thermal resistances by condensation, wall conduction and air convection showed that the air convective heat transfer behavior can play a dominant role to the local heat transfer characteristics. Finally, in order to obtain the local heat flux distribution along the tube’s outer wall, a two

  5. Patterns of a slow air-water flow in a semispherical container

    DEFF Research Database (Denmark)

    Balci, Adnan; Brøns, Morten; Herrada, Miguel A.

    2016-01-01

    This numerical study analyzes the development of eddies in a slow steady axisymmetric air-water flow in a sealed semispherical container, driven by a rotating top disk. As the water height, Hw, increases, new flow cells emerge in both water and air. First, an eddy emerges near the axis-bottom int......This numerical study analyzes the development of eddies in a slow steady axisymmetric air-water flow in a sealed semispherical container, driven by a rotating top disk. As the water height, Hw, increases, new flow cells emerge in both water and air. First, an eddy emerges near the axis...... on the air flow. In contrast to flows in cylindrical and conical containers, there is no interaction with Moffatt corner vortices here....

  6. 77 FR 49349 - Safety Zone; Chicago Air and Water Show, Lake Michigan, Chicago, IL

    Science.gov (United States)

    2012-08-16

    ... this year's air show. This safety zone is intended to restrict vessels from a portion of Lake Michigan during the Chicago Air and Water Show. This safety zone is necessary to protect spectators and vessels... necessary to ensure the safety of spectators and vessels during the air show. This zone will be enforced...

  7. Improvement to Air2Air Technology to Reduce Fresh-Water Evaporative Cooling Loss at Coal-Based Thermoelectric Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Ken Mortensen

    2011-12-31

    This program was undertaken to enhance the manufacturability, constructability, and cost of the Air2Air{TM} Water Conservation and Plume Abatement Cooling Tower, giving a validated cost basis and capability. Air2Air{TM} water conservation technology recovers a portion of the traditional cooling tower evaporate. The Condensing Module provides an air-to-air heat exchanger above the wet fill media, extracting the heat from the hot saturated moist air leaving in the cooling tower and condensing water. The rate of evaporate water recovery is typically 10% - 25% annually, depending on the cooling tower location (climate). This program improved the efficiency and cost of the Air2Air{TM} Water Conservation Cooling Tower capability, and led to the first commercial sale of the product, as described.

  8. Dynamic Modeling of Phase Crossings in Two-Phase Flow

    DEFF Research Database (Denmark)

    Madsen, Søren; Veje, Christian; Willatzen, Morten

    2012-01-01

    of the variables and are usually very slow to evaluate. To overcome these challenges, we use an interpolation scheme with local refinement. The simulations show that the method handles crossing of the saturation lines for both liquid to two-phase and two-phase to gas regions. Furthermore, a novel result obtained...... in this work, the method is stable towards dynamic transitions of the inlet/outlet boundaries across the saturation lines. Results for these cases are presented along with a numerical demonstration of conservation of mass under dynamically varying boundary conditions. Finally we present results...

  9. Shock wave of vapor-liquid two-phase flow

    Institute of Scientific and Technical Information of China (English)

    Liangju ZHAO; Fei WANG; Hong GAO; Jingwen TANG; Yuexiang YUAN

    2008-01-01

    The shock wave of vapor-liquid two-phase flow in a pressure-gain steam injector is studied by build-ing a mathematic model and making calculations. The results show that after the shock, the vapor is nearly com-pletely condensed. The upstream Mach number and the volume ratio of vapor have a great effect on the shock. The pressure and Mach number of two-phase shock con-form to the shock of ideal gas. The analysis of available energy shows that the shock is an irreversible process with entropy increase.

  10. Two Phase Flow and Space-Based Applications

    Science.gov (United States)

    McQuillen, John

    1999-01-01

    A reduced gravity environment offers the ability to remove the effect of buoyancy on two phase flows whereby density differences that normally would promote relative velocities between the phases and also alter the shape of the interface are removed. However, besides being a potent research tool, there are also many space-based technologies that will either utilize or encounter two-phase flow behavior, and as a consequence, several questions must be addressed. This paper presents some of these technologies missions. Finally, this paper gives a description of web-sites for some funding.

  11. Surface, Water, and Air Biocharacterization (SWAB) Flight Experiment

    Science.gov (United States)

    Castro, V. A.; Ott, C. M.; Pierson, D. L.

    2012-01-01

    The determination of risk from infectious disease during spaceflight missions is composed of several factors including both the concentration and characteristics of the microorganisms to which the crew are exposed. Thus, having a good understanding of the microbial ecology aboard spacecraft provides the necessary information to mitigate health risks to the crew. While preventive measures are taken to minimize the presence of pathogens on spacecraft, medically significant organisms have been isolated from both the Mir and International Space Station (ISS). Historically, the method for isolation and identification of microorganisms from spacecraft environmental samples depended upon their growth on culture media. Unfortunately, only a fraction of the organisms may grow on a specific culture medium, potentially omitting those microorganisms whose nutritional and physical requirements for growth are not met. To address this bias in our understanding of the ISS environment, the Surface, Water, and Air Biocharacterization (SWAB) Flight Experiment was designed to investigate and develop monitoring technology to provide better microbial characterization. For the SWAB flight experiment, we hypothesized that environmental analysis using non-culture-based technologies would reveal microorganisms, allergens, and microbial toxins not previously reported in spacecraft, allowing for a more complete health assessment. Key findings during this experiment included: a) Generally, advanced molecular techniques were able to reveal a few organisms not recovered using culture-based methods; however, there is no indication that current monitoring is "missing" any medically significant bacteria or fungi. b) Molecular techniques have tremendous potential for microbial monitoring, however, sample preparation and data analysis present challenges for spaceflight hardware. c) Analytical results indicate that some molecular techniques, such as denaturing gradient gel electrophoresis (DGGE), can

  12. NONUNIFORMITIES OF TWO-PHASE COOLANT DISTRIBUTION IN A HEAT GENERATING PARTICLES BED

    Directory of Open Access Journals (Sweden)

    V. V. Sorokin

    2014-01-01

    Full Text Available Sufficient atomic power generation safety increase may be done with microfuel adapting to reactor plants with water coolant. Microfuel particle is a millimeter size grain containing fission material core in a protecting coverage. The coverage protects fuel contact with coolant and provides isolation of fission products inside. Well thermophysical properties of microfuel bed in a direct contact with water coolant excludes fuel overheating when accidents. Microfuel use was suggested for a VVER, а direct flow reactor for superheat steam generation, a reactor with neutron spectra adjustment by the steam partial content varying in the coolant.Nonuniformities of two-phase coolant distribution in a heat generating particles bed are predicted by calculations in this text. The one is due to multiple-valuedness of pressure drop across the bed on the steam quality dependency. The nonuniformity decreases with flow rate and particle size growths absolute pressure diminishing while porosity effect is weak. The worse case is for pressure quality of order of one. Some pure steam filled pores appears parallel to steam water mixture filled pores, latter steam quality is less than the mean of the bed. Considering this regime for the direct flow reactor for superheat steam generation we predict some water drops at the exit flow. The two-phase coolant filtration with subcooled water feed is unstable to strong disturbance effects are found. Uniformity of two-phase coolant distribution is worse than for one-phase in the same radial type reactor.

  13. Water infiltration in an aquifer recharge basin affected by temperature and air entrapment

    Directory of Open Access Journals (Sweden)

    Loizeau Sébastien

    2017-09-01

    Full Text Available Artificial basins are used to recharge groundwater and protect water pumping fields. In these basins, infiltration rates are monitored to detect any decrease in water infiltration in relation with clogging. However, miss-estimations of infiltration rate may result from neglecting the effects of water temperature change and air-entrapment. This study aims to investigate the effect of temperature and air entrapment on water infiltration at the basin scale by conducting successive infiltration cycles in an experimental basin of 11869 m2 in a pumping field at Crepieux-Charmy (Lyon, France. A first experiment, conducted in summer 2011, showed a strong increase in infiltration rate; which was linked to a potential increase in ground water temperature or a potential dissolution of air entrapped at the beginning of the infiltration. A second experiment was conducted in summer, to inject cold water instead of warm water, and also revealed an increase in infiltration rate. This increase was linked to air dissolution in the soil. A final experiment was conducted in spring with no temperature contrast and no entrapped air (soil initially water-saturated, revealing a constant infiltration rate. Modeling and analysis of experiments revealed that air entrapment and cold water temperature in the soil could substantially reduce infiltration rate over the first infiltration cycles, with respective effects of similar magnitude. Clearly, both water temperature change and air entrapment must be considered for an accurate assessment of the infiltration rate in basins.

  14. Molecular Dynamics Simulation of Water Nanodroplets on Silica Surfaces at High Air Pressures

    DEFF Research Database (Denmark)

    Zambrano, Harvey A; Jaffe, Richard Lawrence; Walther, Jens Honore

    2010-01-01

    e.g., nanobubbles. In the present work we study the role of air on the wetting of hydrophilic systems. We conduct molecular dynamics simulations of a water nanodroplet on an amorphous silica surface at different air pressures. The interaction potentials describing the silica, water, and air...... not been reached. Contact angle measurements of droplets on solid surfaces offer useful quantitative measurements of the physiochemical properties of the solid-liquid interface. For hydrophobic systems the properties the solid- liquid interface are now known to be strongly influenced by the presence of air...... are obtained from the literature. The silica surface is modeled by a large 32 ⨯ 32 ⨯ 2 nm amorphous SiO2 structure consisting of 180000 atoms. The water consists of 18000 water molecules surrounded by N2 and O2 air molecules corresponding to air pressures of 0 bar (vacuum), 50 bar, 100 bar and 200 bar. We...

  15. Spreading of oil from protein stabilised emulsions at air/water interfaces

    NARCIS (Netherlands)

    Schokker, E.P.; Bos, M.A.; Kuijpers, A.J.; Wijnen, M.E.; Walstra, P.

    2002-01-01

    Spreading of a drop of an emulsion made with milk proteins on air/water interfaces was studied. From an unheated emulsion, all oil molecules could spread onto the air/water interface, indicating that the protein layers around the oil globules in the emulsion droplet were not coherent enough to

  16. Structure and dynamics of egg white ovalbumin adsorbed at the air/water interface

    NARCIS (Netherlands)

    Kudryashova, E.V.; Meinders, M.B.J.; Visser, A.J.W.G.; Hoek, A. van; Jongh, H.H.J. de

    2003-01-01

    The molecular properties of egg white ovalbumin adsorbed at the air/water interface were studied using infrared reflection absorption spectroscopy (IRRAS) and time-resolved fluorescence anisotropy (TRFA) techniques. Ovalbumin adsorbed at the air/ water interface adopts a characteristic partially unf

  17. Managing the Drivers of Air Flow and Water Vapor Transport in Existing Single Family Homes (Revised)

    Energy Technology Data Exchange (ETDEWEB)

    Cummings, J.; Withers, C.; Martin, E.; Moyer, N.

    2012-10-01

    This document focuses on managing the driving forces which move air and moisture across the building envelope. While other previously published Measure Guidelines focus on elimination of air pathways, the ultimate goal of this Measure Guideline is to manage drivers which cause air flow and water vapor transport across the building envelope (and also within the home), control air infiltration, keep relative humidity (RH) within acceptable limits, avoid combustion safety problems, improve occupant comfort, and reduce house energy use.

  18. Prediction of Three-Phase Capillary Pressure using a Network Model Anchored to Two-Phase Data

    OpenAIRE

    Dale, Elisabeth Iren; Dijke, Marinus I. J. van; Skauge, Arne

    2008-01-01

    Three-phase capillary pressure is difficult to measure experimentally and therefore has to be estimated by other methods. In this work a network model was applied to generate a consistent set of two-phase and three-phase capillary pressure curves. Experimental data for two-phase, gas-oil and oil-water, capillary pressure from a North Sea reservoir was used in this study. The network model was anchored to the measured two-phase data, and three-phase capillary pressure was constr...

  19. Air-water oxygen exchange in a large whitewater river

    Science.gov (United States)

    Hall, Robert O.; Kennedy, Theodore A.; Rosi-Marshall, Emma J.

    2012-01-01

    Air-water gas exchange governs fluxes of gas into and out of aquatic ecosystems. Knowing this flux is necessary to calculate gas budgets (i.e., O2) to estimate whole-ecosystem metabolism and basin-scale carbon budgets. Empirical data on rates of gas exchange for streams, estuaries, and oceans are readily available. However, there are few data from large rivers and no data from whitewater rapids. We measured gas transfer velocity in the Colorado River, Grand Canyon, as decline in O2 saturation deficit, 7 times in a 28-km segment spanning 7 rapids. The O2 saturation deficit exists because of hypolimnetic discharge from Glen Canyon Dam, located 25 km upriver from Lees Ferry. Gas transfer velocity (k600) increased with slope of the immediate reach. k600 was -1 in flat reaches, while k600 for the steepest rapid ranged 3600-7700 cm h-1, an extremely high value of k600. Using the rate of gas exchange per unit length of water surface elevation (Kdrop, m-1), segment-integrated k600 varied between 74 and 101 cm h-1. Using Kdrop we scaled k600 to the remainder of the Colorado River in Grand Canyon. At the scale corresponding to the segment length where 80% of the O2 exchanged with the atmosphere (mean length = 26.1 km), k600 varied 4.5-fold between 56 and 272 cm h-1 with a mean of 113 cm h-1. Gas transfer velocity for the Colorado River was higher than those from other aquatic ecosystems because of large rapids. Our approach of scaling k600 based on Kdrop allows comparing gas transfer velocity across rivers with spatially heterogeneous morphology.

  20. Modelling two-phase transport of 3H/3He

    NARCIS (Netherlands)

    Visser, A.; Schaap, J.D.; Leijnse, T.; Broers, H.P.; Bierkens, M.F.P.

    2008-01-01

    Degassing of groundwater by excess denitrification of agricultural pollution complicates the interpretation of 3H/3He data and hinders the estimation of travel times in nitrate pollution studies. In this study we used a two-phase flow and transport model (STOMP) to evaluate the method presented by

  1. Two-phase alkali-metal experiments in reduced gravity

    Energy Technology Data Exchange (ETDEWEB)

    Antoniak, Z.I.

    1986-06-01

    Future space missions envision the use of large nuclear reactors utilizing either a single or a two-phase alkali-metal working fluid. The design and analysis of such reactors require state-of-the-art computer codes that can properly treat alkali-metal flow and heat transfer in a reduced-gravity environment. A literature search of relevant experiments in reduced gravity is reported on here, and reveals a paucity of data for such correlations. The few ongoing experiments in reduced gravity are noted. General plans are put forth for the reduced-gravity experiments which will have to be performed, at NASA facilities, with benign fluids. A similar situation exists regarding two-phase alkali-metal flow and heat transfer, even in normal gravity. Existing data are conflicting and indequate for the task of modeling a space reactor using a two-phase alkali-metal coolant. The major features of past experiments are described here. Data from the reduced-gravity experiments with innocuous fluids are to be combined with normal gravity data from the two-phase alkali-metal experiments. Analyses undertaken here give every expectation that the correlations developed from this data base will provide a valid representation of alkali-metal heat transfer and pressure drop in reduced gravity.

  2. Modelling two-phase transport of 3H/3He

    NARCIS (Netherlands)

    Visser, A.; Schaap, J.D.; Leijnse, T.; Broers, H.P.; Bierkens, M.F.P.

    2008-01-01

    Degassing of groundwater by excess denitrification of agricultural pollution complicates the interpretation of 3H/3He data and hinders the estimation of travel times in nitrate pollution studies. In this study we used a two-phase flow and transport model (STOMP) to evaluate the method presented by V

  3. Experimental Investigation of two-phase nitrogen Cryo transfer line

    Science.gov (United States)

    Singh, G. K.; Nimavat, H.; Panchal, R.; Garg, A.; Srikanth, GLN; Patel, K.; Shah, P.; Tanna, V. L.; Pradhan, S.

    2017-02-01

    A 6-m long liquid nitrogen based cryo transfer line has been designed, developed and tested at IPR. The test objectives include the thermo-hydraulic characteristics of Cryo transfer line under single phase as well as two phase flow conditions. It is always easy in experimentation to investigate the thermo-hydraulic parameters in case of single phase flow of cryogen but it is real challenge when one deals with the two phase flow of cryogen due to availibity of mass flow measurements (direct) under two phase flow conditions. Established models have been reported in the literature where one of the well-known model of Lockhart-Martenelli relationship has been used to determine the value of quality at the outlet of Cryo transfer line. Under homogenous flow conditions, by taking the ratio of the single-phase pressure drop and the two-phase pressure drop, we estimated the quality at the outlet. Based on these equations, vapor quality at the outlet of the transfer line was predicted at different heat loads. Experimental rresults shown that from inlet to outlet, there is a considerable increment in the pressure drop and vapour quality of the outlet depending upon heat load and mass flow rate of nitrogen flowing through the line.

  4. TWO-PHASE EJECTOR of CARBON DIOXIDE HEAT PUMP CALCULUS

    Directory of Open Access Journals (Sweden)

    Sit B.M.

    2010-12-01

    Full Text Available It is presented the calculus of the two-phase ejector for carbon dioxide heat pump. The method of calculus is based on the method elaborated by S.M. Kandil, W.E. Lear, S.A. Sherif, and is modified taking into account entrainment ratio as the input for the calculus.

  5. Experimental Studies of Two-Phase Round Turbulent Jet Coherent Structures

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Coherent structures of a two-phase round turbulent jet have been studied experimentally. The flow profiles at different Reynold's numbers and various positions from the jet exit are visualized using a sheet laser source. The jets include two types,an air jet laden with incense smoke and an air jet laden with two kinds of solid particles, glass beads and catalytic cracking beads. The developments of both the large eddy structures of the round turbulent jet and the local particle dispersion in the vortex structures were recorded with a high-speed movie camera. Free and excited jet conditions were tested. Analysis of the video pictures suggests a critical intrinsic frequency exists in the helical coherent structures of the air phase. In the spectral space the clockwise and counter-clockwise helical structures occupy different positions. Large scale structures exsit in the two-phase jet. The patterns are similar to those of the air jet with the Stokes numbers in the range of 1-8.32.

  6. Influence of water depth on the sound generated by air-bubble vibration in the water musical instrument

    Science.gov (United States)

    Ohuchi, Yoshito; Nakazono, Yoichi

    2014-06-01

    We have developed a water musical instrument that generates sound by the falling of water drops within resonance tubes. The instrument can give people who hear it the healing effect inherent in the sound of water. The sound produced by falling water drops arises from air- bubble vibrations. To investigate the impact of water depth on the air-bubble vibrations, we conducted experiments at varying values of water pressure and nozzle shape. We found that air-bubble vibration frequency does not change at a water depth of 50 mm or greater. Between 35 and 40 mm, however, the frequency decreases. At water depths of 30 mm or below, the air-bubble vibration frequency increases. In our tests, we varied the nozzle diameter from 2 to 4 mm. In addition, we discovered that the time taken for air-bubble vibration to start after the water drops start falling is constant at water depths of 40 mm or greater, but slower at depths below 40 mm.

  7. MICROGRAVITY EXPERIMENTS OF TWO-PHASE FLOW PATTERNS ABOARD MIR SPACE STATION

    Institute of Scientific and Technical Information of China (English)

    赵建福; 解京昌; 林海; 胡文瑞; A.V. Ivanov; A.Yu. Belyaev

    2001-01-01

    A first experimental study on two-phase flow patterns at a long-term,steady microgravity condition was conducted on board the Russian Space Station "MIR" in August 1999. Carbogal and air are used as the liquid and the gas phase,respectively. Bubble, slug, slug-annular transitional, and annular flows are observed.A new region of annular flow with lower liquid superficial velocity is discovered,and the region of the slug-annular transitionalfiow is wider than that observed by experiments on board the parabolic aircraft. The main patterns are bubble, slug annular transitional and annular flows based on the experiments on board MIR space station. Some influences on the two-phase flow patterns in the present experiments are discussed.

  8. Effect of grain size reduction on high temperature oxidation ofbinary two-phase alloys

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The effect of grain size reduction on the high temperature oxidation of binary two-phase alloys was discussed based on the recent research progress. The results show that for those two-phase alloys with coarse grain prepared by the conventional methods, complex oxide scales are easily formed after oxidation under high oxygen pressure or under oxygen pressure below the stability limit of the less reactive component oxides. On the contrary, for the nano-sized alloys, an exclusive external oxidation of the most reactive component usually occurs during oxidation in air or pure oxygen even for much lower content of the most reactive component. So the gain size reduction is not always beneficial to improve the oxidation resistance of the materials, but exhibits different effects depending mainly on the protective feature of the scales. The transition mechanisms between the different oxidation modes are discussed with respect to the thermodynamic and dynamic aspects.

  9. Co-current air-water flow in downward sloping pipes: Transport of capacity reducing gas pockets in wastewater mains

    NARCIS (Netherlands)

    Pothof, I.W.M.

    2011-01-01

    Air-water flow is an undesired condition in many systems for the transportation of water or wastewater. Air in storm water tunnels may get trapped and negatively affect the system. Air pockets in hydropower tunnels or sewers may cause blow-back events and inadmissible pressure spikes. Water pipes an

  10. 48 CFR 52.247-52 - Clearance and Documentation Requirements-Shipments to DOD Air or Water Terminal Transshipment...

    Science.gov (United States)

    2010-10-01

    ... Documentation Requirements-Shipments to DOD Air or Water Terminal Transshipment Points. 52.247-52 Section 52.247... and Documentation Requirements—Shipments to DOD Air or Water Terminal Transshipment Points. As... Requirements—Shipments to DOD Air or Water Terminal Transshipment Points (FEB 2006) All shipments to water...

  11. Preliminary Two-Phase Terry Turbine Nozzle Models for RCIC Off-Design Operation Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Haihua [Idaho National Lab. (INL), Idaho Falls, ID (United States); O' Brien, James [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2017-06-12

    This report presents the effort to extend the single-phase analytical Terry turbine model to cover two-phase off-design conditions. The work includes: (1) adding well-established two-phase choking models – the Isentropic Homogenous Equilibrium Model (IHEM) and Moody’s model, and (2) theoretical development and implementation of a two-phase nozzle expansion model. The two choking models provide bounding cases for the two-phase choking mass flow rate. The new two-phase Terry turbine model uses the choking models to calculate the mass flow rate, the critical pressure at the nozzle throat, and steam quality. In the divergent stage, we only consider the vapor phase with a similar model for the single-phase case by assuming that the liquid phase would slip along the wall with a much slower speed and will not contribute the impulse on the rotor. We also modify the stagnation conditions according to two-phase choking conditions at the throat and the cross-section areas for steam flow at the nozzle throat and at the nozzle exit. The new two-phase Terry turbine model was benchmarked with the same steam nozzle test as for the single-phase model. Better agreement with the experimental data is observed than from the single-phase model. We also repeated the Terry turbine nozzle benchmark work against the Sandia CFD simulation results with the two-phase model for the pure steam inlet nozzle case. The RCIC start-up tests were simulated and compared with the single-phase model. Similar results are obtained. Finally, we designed a new RCIC system test case to simulate the self-regulated Terry turbine behavior observed in Fukushima accidents. In this test, a period inlet condition for the steam quality varying from 1 to 0 is applied. For the high quality inlet period, the RCIC system behaves just like the normal operation condition with a high pump injection flow rate and a nominal steam release rate through the turbine, with the net addition of water to the primary system; for

  12. Droplet entrainment correlation in vertical upward co-current annular two-phase flow

    Energy Technology Data Exchange (ETDEWEB)

    Sawant, Pravin [Purdue University, School of Nuclear Engineering, 400 Central Dr., West Lafayette, IN 47907-2017 (United States)], E-mail: psawant@purdue.edu; Ishii, Mamoru [Purdue University, School of Nuclear Engineering, 400 Central Dr., West Lafayette, IN 47907-2017 (United States); Mori, Michitsugu [Tokyo Electric Power Co., Inc., R and D Center, 4-1 Egasaki-cho, Tsurumi-ku, Yokohama 230-8510 (Japan)], E-mail: michitsugu.mori@tepco.co.jp

    2008-06-15

    Upward annular two-phase flow in a vertical tube is characterized by the presence of liquid film on the tube wall and entrained droplet laden gas phase flowing through the tube core. Entrainment fraction in annular flow is defined as a fraction of the total liquid flow flowing in the form of droplets through the central gas core. Its prediction is important for the estimation of pressure drop and dryout in annular flow. In the following study, measurements of entrainment fraction have been obtained in vertical upward co-current air-water annular flow covering wide ranges of pressure and flow conditions. Comparison of the experimental data with the existing entrainment fraction prediction correlations revealed their inadequacies in simulating the trends observed under high flow and high pressure conditions. Furthermore, several correlations available in the literature are implicit and require iterative calculations. Analysis of the experimental data showed that the non-dimensional numbers, Weber number (We = {rho}{sub g}{sup 2}D/{sigma}({delta}{rho}/{rho}{sub g}){sup 1/4}) and liquid phase Reynolds number (Re{sub f} = {rho}{sub f}D/{mu}{sub f}), successfully collapse the data. In view of this, simple, explicit correlation was developed based on these non-dimensional numbers for the prediction of entrainment fraction. The new correlation successfully predicted the trends under the high flow and high pressure conditions observed in the current experimental data and the data available in open literature. However, in order to use the proposed correlation it is necessary to predict the maximum possible entrainment fraction (or limiting entrainment fraction). In the current analysis, an experimental data based correlation was used for this purpose. However, a better model or correlation is necessary for the maximum possible entrainment fraction. A theoretical discussion on the mechanism and modeling of the maximum possible entrainment fraction

  13. Interfacial area and two-phase flow structure development measured by a double-sensor probe

    Energy Technology Data Exchange (ETDEWEB)

    Leung, Waihung; Revankar, S.T.; Ishii, Yoshihiko; Ishii, Mamoru

    1992-06-01

    In this report, we studied the local phasic characters of dispersed flow regime both at the entrance and at the fully developed regions. Since the dispersed phase is distributed randomly in the medium and enclosed in relatively small interfaces, the phasic measurement becomes difficult to obtain. Local probe must be made with a miniaturized sensor in order to reduce the interface distortion. The double-sensor resistivity probe has been widely used in local void fraction and interface velocity measurements because the are small in comparison with the interfaces. It has been tested and proved to be an accurate local phasic measurement tool. In these experiments, a double-sensor probe was employed to measure the local void fraction and interface velocity in an air-water system. The test section was flow regime can be determined by visualization. Furthermore, local phasic measurements can be verified by photographic studies. We concentrated our study on the bubbly flow regime only. The local measurements were conducted at two axial locations, L/D = 8 and 60, in which the first measurement represents the entrance region where the flow develops, and the second measurement represents the fully developed flow region where the radial profile does not change as the flow moves along the axial direction. Four liquid flow rates were chosen in combination with four different gas injection rates. The superficial liquid velocities were j{sub t} = 1.0, 0.6,0.4, and 0.1 m/s and superficial gas velocities were j{sub g} = 0.0965, 0.0696, 0.0384, and 0.0192 m/s. These combinations put the two-phase flow well in the bubbly flow regime. In this sequence of phenomenological studies, the local void fraction, interface area concentration, sauter mean diameter, bubble velocity and bubble frequency were measured.

  14. Intermediate scales between simulation and modeling of two-phase flows

    Energy Technology Data Exchange (ETDEWEB)

    Pigny, Sylvain L., E-mail: sylvain.pigny@cea.f [CEA/DEN, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France)

    2011-03-15

    Research highlights: Simulation and modeling of bubbles are done at high Reynolds number. Intermediate scales between simulation and modeling are of importance. Specific approaches can be envisaged in accurate multiphase codes. An attempt leads to agreement with experimental data. We establish a link between multiphase codes and DNS ones. - Abstract: Phenomena related to two-phase flows in an experiment in which air is injected in the lower part of a tank filled with water are investigated, via the SIMMER-IV software. The Reynolds and Weber numbers of the bubbly flow have high values. Small scale phenomena, related to small bubbles behavior or turbulence in the liquid continuous phase, are modeled via classical closure laws. An attempt to represent the formation of individual large bubbles, close to the injector, via direct simulation is done. In a first calculation, the large bubbles break-up is not represented. This phenomenon, the space scale of which is close to the cell size, cannot be simulated, with the present computational resources. Nevertheless, relatively fine meshes are used, for an accurate description of hydrodynamical phenomena, and these phenomena are too large to be modeled via closure laws. The case is therefore useful to underline some basic limits in the potentialities of direct simulation and modeling and to propose an attempt to face the problem. The breakup of bubbles is now represented. Finally the validity of the approach is checked directly by simulating a single bubble experiment. The problem of the convergence between multiphase codes and direct simulation ones is pointed.

  15. Extraction performance of blend surfactant two-phase aqueous system for determination of malachite green in aquaculture water%混合表面活性剂双水相体系对养殖水中孔雀石绿的萃取测定

    Institute of Scientific and Technical Information of China (English)

    沙鸥; 张婷; 马卫兴; 丁军楠; 陈丽

    2012-01-01

    The extraction performance of blend surfactant two - phase aqueous system composed of sodium dodecyl sulfate ( SDS) and hexadecyltrimethylammonium bromide ( CTAB ) for determination of malachite green in aquaculture water was studied by adopting the spectrophotometric method. Results showed that when amount of CTAB with concentration of 2.74 × 10-2 mol · L-1 and amount of SDS with concentration of 0. 17 mol · L-1 is 0. 65 ~0. 90 mL and 0. 90 ~ 1. 20 mL respectively,the two - phase aqueous system can be formed in presence of NaCl. The system can be used for quantitative extraction of malachite green in medium of pH =7. 0 Britton - Robinson buffer solution,and the maximum absorbance appears at wavelength of 628 nm. When the mass concentration of malachite green ranges in 0. 146 ~ 14. 6 mg · L-1 ,good linearity relationship between the mass concentration and the absorbance appears with a regression equation as A = 0. 190 2p -0. 028 3, and correlation coefficient is 0. 999 6. This developed method was used for the extraction and determination of malachite green in the aquaculture water samples with satisfactory results. The spiked recovery rates are in the range of 95% ~ 106% .%采用分光光度法考察了十六烷基三甲基溴化铵(CTAB) -十二烷基硫酸钠(SDS)双水相体系对水中孔雀石绿的萃取性能.研究发现,2.74×10-2 mol·L-1的CTAB用量在0.65 ~0.90 mL,0.17 mol·L-1的SDS用量在0.90 ~ 1.20 mL时,CTAB-SDS在有NaCl存在下形成双水相体系,该体系在pH =7.0的B-R缓冲液中可对孔雀石绿进行定量萃取,并在628 nm波长处产生最大吸收.萃取相中孔雀石绿质量浓度ρ=0.146~14.6 mg·L-1时与吸光度A有良好的线性关系,线性方程为A =0.190 2ρ -0.028 3,线性相关系数为0.999 6,孔雀石绿的平均萃取率为99.1%.该法用于养殖鱼池水样中孔雀石绿的萃取分析测定,回收率为95%~106%.

  16. Design of Helical Capacitance Sensor for Holdup Measurement in Two-Phase Stratified Flow: A Sinusoidal Function Approach

    Directory of Open Access Journals (Sweden)

    Lam Ghai Lim

    2016-07-01

    Full Text Available A 360° twisted helical capacitance sensor was developed for holdup measurement in horizontal two-phase stratified flow. Instead of suppressing nonlinear response, the sensor was optimized in such a way that a ‘sine-like’ function was displayed on top of the linear function. This concept of design had been implemented and verified in both software and hardware. A good agreement was achieved between the finite element model of proposed design and the approximation model (pure sinusoidal function, with a maximum difference of ±1.2%. In addition, the design parameters of the sensor were analysed and investigated. It was found that the error in symmetry of the sinusoidal function could be minimized by adjusting the pitch of helix. The experiments of air-water and oil-water stratified flows were carried out and validated the sinusoidal relationship with a maximum difference of ±1.2% and ±1.3% for the range of water holdup from 0.15 to 0.85. The proposed design concept therefore may pose a promising alternative for the optimization of capacitance sensor design.

  17. Evaluating the efficiency of two phase partitioning stirred tank bio-reactor for treating xylene vapors from the airstreamthrough a bed of Pseudomonas Putida

    Directory of Open Access Journals (Sweden)

    F. Golbabaei

    2015-04-01

    Conclusion: Overall, the results of the present research revealed that the application of two phase stirred tank bioreactors (TPPBs containing pure strains of Pseudomonas putida was successful for treatment of air streams with xylene.

  18. Laser-induced damage thresholds of gold, silver and their alloys in air and water

    Science.gov (United States)

    Starinskiy, Sergey V.; Shukhov, Yuri G.; Bulgakov, Alexander V.

    2017-02-01

    The nanosecond-laser-induced damage thresholds of gold, silver and gold-silver alloys of various compositions in air and water have been measured for single-shot irradiation conditions. The experimental results are analyzed theoretically by solving the heat flow equation for the samples irradiated in air and in water taking into account vapor nucleation at the solid-water interface. The damage thresholds of Au-Ag alloys are systematically lower than those for pure metals, both in air and water that is explained by lower thermal conductivities of the alloys. The thresholds measured in air agree well with the calculated melting thresholds for all samples. The damage thresholds in water are found to be considerably higher, by a factor of ∼1.5, than the corresponding thresholds in air. This cannot be explained, in the framework of the used model, neither by the conductive heat transfer to water nor by the vapor pressure effect. Possible reasons for the high damage thresholds in water such as scattering of the incident laser light by the vapor-liquid interface and the critical opalescence in the superheated water are suggested. Optical pump-probe measurements have been performed to study the reflectance dynamics of the surface irradiated in air and water. Comparison of the transient reflectance signal with the calculated nucleation dynamics provides evidence that the both suggested scattering mechanisms are likely to occur during metal ablation in water.

  19. A splitting technique for analytical modelling of two-phase multicomponent flow in porous media

    DEFF Research Database (Denmark)

    Pires, A.P.; Bedrikovetsky, P.G.; Shapiro, Alexander

    2006-01-01

    In this paper we discuss one-dimensional models for two-phase Enhanced Oil Recovery (EOR) floods (oil displacement by gases, polymers, carbonized water, hot water, etc.). The main result presented here is the splitting of the EOR mathematical model into thermodynamical and hydrodynamical parts....... The introduction of a potential associated with one of the conservation laws and its use as a new independent coordinate reduces the number of equations by one. The (n)x(n) conservation law model for two-phase n-component EOR flows in new coordinates is transformed into a reduced (n-1)x(n-1) auxiliary system...... containing just thermodynamical variables (equilibrium fractions of components, sorption isotherms) and one lifting equation containing just hydrodynamical parameters (phase relative permeabilities and viscosities). The algorithm to solve analytically the problem includes solution of the reduced auxiliary...

  20. NUMERICAL CALCULATION OF SOLID-LIQUID TWO PHASE FLOW BETWEEN STAY VANES IN HYDRAULIC TURBINE

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper, an energy equation of silt-laden water flow is educed based on the energy equation of continuum fluid flow. The dissipation functions of liquid phase and solid phase are presented respectively. Then the extremity law of energy dissipation rate is introduced for the research of the silt-laden water flow and a new mathematical model is developed. The corresponding procedure based on the finite difference method (FDM) is developed to calculate the two phase flow in hydraulic turbine. The method is applied to analyze the silt-laden water flow between stay vanes, and the numerical results are in good agreement with the experimental ones.

  1. Detachment of deposited colloids by advancing and receding air-water interfaces.

    Science.gov (United States)

    Aramrak, Surachet; Flury, Markus; Harsh, James B

    2011-08-16

    Moving air-water interfaces can detach colloidal particles from stationary surfaces. The objective of this study was to quantify the effects of advancing and receding air-water interfaces on colloid detachment as a function of interface velocity. We deposited fluorescent, negatively charged, carboxylate-modified polystyrene colloids (diameter of 1 μm) into a cylindrical glass channel. The colloids were hydrophilic with an advancing air-water contact angle of 60° and a receding contact angle of 40°. After colloid deposition, two air bubbles were sequentially introduced into the glass channel and passed through the channel at different velocities (0.5, 7.7, 72, 982, and 10,800 cm/h). The passage of the bubbles represented a sequence of receding and advancing air-water interfaces. Colloids remaining in the glass channel after each interface passage were visualized with confocal microscopy and quantified by image analysis. The advancing air-water interface was significantly more effective in detaching colloids from the glass surface than the receding interface. Most of the colloids were detached during the first passage of the advancing air-water interface, while the subsequent interface passages did not remove significant amounts of colloids. Forces acting on the colloids calculated from theory corroborate our experimental results, and confirm that the detachment forces (surface tension forces) during the advancing air-water interface movement were stronger than during the receding movement. Theory indicates that, for hydrophilic colloids, the advancing interface movement generally exerts a stronger detachment force than the receding, except when the hysteresis of the colloid-air-water contact angle is small and that of the channel-air-water contact angle is large.

  2. One- and two-phase anaerobic digestion of ley crop silage with and without liquid recirculation

    Energy Technology Data Exchange (ETDEWEB)

    Nordberg, Aa.

    1996-10-01

    In this study the effects of liquid recirculation on hydrolysis and methanogenesis in one- and two-phase biogas processes were investigated in comparison with water-diluted processes. The operation of a water-diluted one-phase process resulted in process imbalances at a low loading rate. In a water-diluted two-phase process the fibre degrading capability was lost. The reason for the poor process performance was due to a deficiency in trace elements, since the supplementation of cobalt resulted in an increased conversion rate of acetate. The recirculation of process liquid resulted in an accumulation of different compounds which initially stabilized one-phase processes and stimulated the hydrolysis and the methane production in the liquefaction-acidogenesis stage of a two-phase process. However, upon continuous recirculation the concentration of free ammonia reached toxic levels, which resulted in a decrease in the methane yield both in the methanogenic reactor of the two-phase process and in the one-phase process. Due to the decreased methane production, acids started to accumulate which subsequently inhibited the hydrolysis in the one-phase process. The systematic variation in the processes were evaluated using principal component analysis and principal component regression. The interpretation of the dynamic behaviour of the processes was facilitated by the use of score plots and loading plots. The results indicate that ley crops do not meet the nutrient requirements of the bacteria in anaerobic digestion. Thus, the low content of trace elements and the high content of protein which subsequently will cause toxic levels of ammonia in digesting system with low water consumption, suggests co-digestion with supplementary feedstocks. 95 refs, 5 figs, 3 tabs

  3. Surface Tension of Ab Initio Liquid Water at the Water-Air Interface

    CERN Document Server

    Nagata, Yuki; Bonn, Mischa; Kühne, Thomas D

    2016-01-01

    We report calculations of the surface tension of the water-air interface using ab initio molecular dynamics (AIMD) simulations. We investigate the simulation cell size dependence of the surface tension of water from force field molecular dynamics (MD) simulations, which show that the calculated surface tension increases with increasing simulation cell size, thereby illustrating that a correction for finite size effects is required for the small system used in the AIMD simulation. The AIMD simulations reveal that the double-{\\xi} basis set overestimates the experimentally measured surface tension due to the Pulay stress, while the triple and quadruple-{\\xi} basis sets give similar results. We further demonstrate that the van der Waals corrections critically affect the surface tension. AIMD simulations without the van der Waals correction substantially underestimate the surface tension, while van der Waals correction with the Grimme's D2 technique results in the value for the surface tension that is too high. T...

  4. Water-Air Volatilization Factors to Determine Volatile Organic Compound (VOC Reference Levels in Water

    Directory of Open Access Journals (Sweden)

    Vicenç Martí

    2014-06-01

    Full Text Available The goal of this work is the modeling and calculation of volatilization factors (VFs from water to air for volatile organic compounds (VOCs in order to perform human health risk-based reference levels (RLs for the safe use of water. The VF models have been developed starting from the overall mass-transfer coefficients (Koverall concept from air to water for two interaction geometries (flat surface and spherical droplets in indoor and outdoor scenarios. For a case study with five groups of risk scenarios and thirty VOCs, theoretical VFs have been calculated by using the developed models. Results showed that Koverall values for flat and spherical surface geometries were close to the mass transfer coefficient for water (KL when Henry’s law constant (KH was high. In the case of spherical drop geometry, the fraction of volatilization (fV was asymptotical when increasing KH with fV values also limited due to Koverall. VFs for flat surfaces were calculated from the emission flux of VOCs, and results showed values close to 1000KH for the most conservative indoor scenarios and almost constant values for outdoor scenarios. VFs for spherical geometry in indoor scenarios followed also constant VFs and were far from 1000KH. The highest calculated VF values corresponded to the E2A, E2B, E3A and E5A scenarios and were compared with experimental and real results in order to check the goodness of flat and sphere geometry models. Results showed an overestimation of calculated values for the E2A and E2B scenarios and an underestimation for the E3A and E5A scenarios. In both cases, most of the calculated VFs were from 0.1- to 10-times higher than experimental/real values.

  5. 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.

  6. Separation flow field and characteristics of oil-water two phases in tangential single and double entrance hydrocyclones%切向单双入口旋流器油-水两相分离流场及特性研究

    Institute of Scientific and Technical Information of China (English)

    王军; 戴海鹏; 姜胜辉; 陈宁

    2014-01-01

    运用雷诺应力模型(RSM)及两相流 MIXTURE 混合模型和 SIMPLEC 算法对切向单、双入口旋流器内的流场进行模拟分析。采用作图法描述了锥段中间截面处的切向速度、径向速度、湍动能及湍能耗散率,使内部复杂旋流流场的分析得以简化。模拟结果表明:单入口旋流器内流场具有不对称性,呈现偏心结构,双入口旋流器流场具有较好的对称性;油-水分离时,切向双入口旋流器中的分离效率为96%,高于单入口旋流器的94%,但同时增大了能量消耗。实验测试结果显示:流量为3 m3/ h 时的实际分离效率为90%,与模拟结果的平均误差为5%,处理流量相同时,采用切向双入口旋流器更能提高分离效率。%Reynolds stress model(RSM),two-phase flow mixture model and SIMPLEC algorithm are applied to the simulation of flow field in tangential single,double entrance hydrocyclones. The method describes the inter-mediate section cone tangential velocity,radial velocity,turbulent kinetic energy and turbulent energy dissipation rate,and makes the analysis of the internal complex swirling flow field simplified. The results show that the flow field in a hydrocyclone single entrance is asymmetric,having the eccentric structure;the flow field of double en-trance hydrocyclone has higher symmetry. The tangential separation efficiency of double entrance hydrocyclone for oil water separation is 96% ,higher than that of single entrance cyclone,which is 94% ,but energy consump-tion is increased at the same time. Experimental result shows that,when the flow rate is 3m3 / h,the actual sepa-ration efficiency is 90% ,and the average error of the simulation is 5% . For the same flow,the tangential double entrance hydrocyclone can improve the oil water separation efficiency.

  7. Construction and execution of experiments at the multi-purpose thermal hydraulic test facility TOPFLOW for generic investigations of two-phase flows and the development and validation of CFD codes - Final report

    OpenAIRE

    2010-01-01

    The works aimed at the further development and validation of models for CFD codes. For this reason, the new thermal-hydraulic test facility TOPFLOW was erected and equipped with wire-mesh sensors with high spatial and time resolution. Vertical test sections with nominal diameters of DN50 and DN200 operating with air-water as well as steam-water two-phase flows provided results on the evaluation of flow patterns, on the be¬haviour of the interfacial area as well as on interfacial momentum and ...

  8. Computer simulation of two-phase flow in nuclear reactors

    Energy Technology Data Exchange (ETDEWEB)

    Wulff, W.

    1992-09-01

    Two-phase flow models dominate the economic resource requirements for development and use of computer codes for analyzing thermohydraulic transients in nuclear power plants. Six principles are presented on mathematical modeling and selection of numerical methods, along with suggestions on programming and machine selection, all aimed at reducing the cost of analysis. Computer simulation is contrasted with traditional computer calculation. The advantages of run-time interactive access operation in a simulation environment are demonstrated. It is explained that the drift-flux model is better suited for two-phase flow analysis in nuclear reactors than the two-fluid model, because of the latter`s closure problem. The advantage of analytical over numerical integration is demonstrated. Modeling and programming techniques are presented which minimize the number of needed arithmetical and logical operations and thereby increase the simulation speed, while decreasing the cost.

  9. Computer simulation of two-phase flow in nuclear reactors

    Energy Technology Data Exchange (ETDEWEB)

    Wulff, W.

    1992-01-01

    Two-phase flow models dominate the economic resource requirements for development and use of computer codes for analyzing thermohydraulic transients in nuclear power plants. Six principles are presented on mathematical modeling and selection of numerical methods, along with suggestions on programming and machine selection, all aimed at reducing the cost of analysis. Computer simulation is contrasted with traditional computer calculation. The advantages of run-time interactive access operation in a simulation environment are demonstrated. It is explained that the drift-flux model is better suited for two-phase flow analysis in nuclear reactors than the two-fluid model, because of the latter's closure problem. The advantage of analytical over numerical integration is demonstrated. Modeling and programming techniques are presented which minimize the number of needed arithmetical and logical operations and thereby increase the simulation speed, while decreasing the cost.

  10. Two-phase Flow Distribution in Heat Exchanger Manifolds

    OpenAIRE

    Vist, Sivert

    2004-01-01

    The current study has investigated two-phase refrigerant flow distribution in heat exchange manifolds. Experimental data have been acquired in a heat exchanger test rig specially made for measurement of mass flow rate and gas and liquid distribution in the manifolds of compact heat exchangers. Twelve different manifold designs were used in the experiments, and CO2 and HFC-134a were used as refrigerants.

  11. Viscosity Solutions for the two-phase Stefan Problem

    CERN Document Server

    Kim, Inwon C

    2010-01-01

    We introduce a notion of viscosity solutions for the two-phase Stefan problem, which incorporates possible existence of a mushy region generated by the initial data. We show that a comparison principle holds between viscosity solutions, and investigate the coincidence of the viscosity solutions and the weak solutions defined via integration by parts. In particular, in the absence of initial mushy region, viscosity solution is the unique weak solution with the same boundary data.

  12. Recent advances in two-phase flow numerics

    Energy Technology Data Exchange (ETDEWEB)

    Mahaffy, J.H.; Macian, R. [Pennsylvania State Univ., University Park, PA (United States)

    1997-07-01

    The authors review three topics in the broad field of numerical methods that may be of interest to individuals modeling two-phase flow in nuclear power plants. The first topic is iterative solution of linear equations created during the solution of finite volume equations. The second is numerical tracking of macroscopic liquid interfaces. The final area surveyed is the use of higher spatial difference techniques.

  13. Single- and Two-Phase Flow Characterization Using Optical Fiber Bragg Gratings

    Directory of Open Access Journals (Sweden)

    Virgínia H.V. Baroncini

    2015-03-01

    Full Text Available Single- and two-phase flow characterization using optical fiber Bragg gratings (FBGs is presented. The sensor unit consists of the optical fiber Bragg grating positioned transversely to the flow and fixed in the pipe walls. The hydrodynamic pressure applied by the liquid or air/liquid flow to the optical fiber induces deformation that can be detected by the FBG. Given that the applied pressure is directly related to the mass flow, it is possible to establish a relationship using the grating resonance wavelength shift to determine the mass flow when the flow velocity is well known. For two phase flows of air and liquid, there is a significant change in the force applied to the fiber that accounts for the very distinct densities of these substances. As a consequence, the optical fiber deformation and the correspondent grating wavelength shift as a function of the flow will be very different for an air bubble or a liquid slug, allowing their detection as they flow through the pipe. A quasi-distributed sensing tool with 18 sensors evenly spread along the pipe is developed and characterized, making possible the characterization of the flow, as well as the tracking of the bubbles over a large section of the test bed. Results show good agreement with standard measurement methods and open up plenty of opportunities to both laboratory measurement tools and field applications.

  14. Estimating disease prevalence in two-phase studies.

    Science.gov (United States)

    Alonzo, Todd A; Pepe, Margaret Sullivan; Lumley, Thomas

    2003-04-01

    Disease prevalence is ideally estimated using a 'gold standard' to ascertain true disease status on all subjects in a population of interest. In practice, however, the gold standard may be too costly or invasive to be applied to all subjects, in which case a two-phase design is often employed. Phase 1 data consisting of inexpensive and non-invasive screening tests on all study subjects are used to determine the subjects that receive the gold standard in the second phase. Naive estimates of prevalence in two-phase studies can be biased (verification bias). Imputation and re-weighting estimators are often used to avoid this bias. We contrast the forms and attributes of the various prevalence estimators. Distribution theory and simulation studies are used to investigate their bias and efficiency. We conclude that the semiparametric efficient approach is the preferred method for prevalence estimation in two-phase studies. It is more robust and comparable in its efficiency to imputation and other re-weighting estimators. It is also easy to implement. We use this approach to examine the prevalence of depression in adolescents with data from the Great Smoky Mountain Study.

  15. Experimental validation of a local dehumidification system based on cold water droplets and air-to-air heat exchanger

    NARCIS (Netherlands)

    Janssen, E.G.O.N.; Hammink, H.A.J.; Hendriksen, L.J.A.M.

    2015-01-01

    Excessive humidity is a problem in Dutch growing circumstances. A traditional solution is heating and natural ventilation. To save energy a number of energy efficient dehumidification methods are developed, like mechanical ventilation with dry outside air or a curtain of cold water droplets. In this

  16. Influence of Air Humidity and Water Particles on Dust Control Using Ultrasonic Atomization

    Science.gov (United States)

    Okawa, Hirokazu; Nishi, Kentaro; Shindo, Dai; Kawamura, Youhei

    2012-07-01

    The influence of air humidity and water particles on dust control was examined using ultrasonic atomization at 2.4 MHz, an acrylic box (61 L), and four types of ore dust samples: green tuff (4 µm), green tuff (6 µm), kaolin, and silica. It was clearly demonstrated that ultrasonic atomization was effective in raising humidity rapidly. However, at high relative air humidity, the water particles remained stable in the box without changing to water vapor. Ultrasonic atomization was applied to suppress dust dispersion and 40-95% dust reduction was achieved at 83% relative air humidity. Dust dispersion was more effective with ultrasonic atomization than without.

  17. Predicting Air-Water Geysers and Their Implications on Reducing Combined Sewer Overflows

    Science.gov (United States)

    Choi, Y.; Leon, A.; Apte, S.

    2014-12-01

    An air-water geyser in a closed conduit system is characterized by an explosive jetting of a mixture of air and water through drop-shafts. In this study, three scenarios of geysers are numerically simulated using a 3D computational fluid dynamics (CFD) model. The three tested scenarios are comprised of a drop shaft that is closed at its bottom and partially or fully open at the top. Initially, the lower section of the drop shaft is filled with pressurized air, the middle section with stagnant water and the upper section with air at atmospheric pressure. The pressure and volume of the pressurized air, and hence the stored energy, is different for all three test cases. The volume of the stagnant water and the air at atmospheric pressure are kept constant in the tests. The numerical simulations aim to identify the correlation between dimensionless energy stored in the pressurized air pocket and dimensionless maximum pressure reached at the outlet. This dimensionless correlation could be used to determine the energy threshold that does not produce air-water geyser, which in turn could be used in the design of combined sewer systems for minimizing geysers.

  18. Application of stereology for two-phase flow structure validation in fluidized bed reactors

    Directory of Open Access Journals (Sweden)

    Anweiler Stanisław

    2016-01-01

    Full Text Available Paper describes a novel method for two-phase gas-solid flow structure validation in fluidized bed reactors. Investigation is based on application of stereology techniques. This is an innovative approach in the field of fluidization phenomena research. Study is focused on the analysis of flow structure images, obtained with high-speed visualization of the fluidization process. Fluidization is conducted in transparent narrow channel, where plastic balls are fluidized by air. Applied stereological analysis is grounded on the linear method and on the method of random and directed secants. This enables 2-dimensional image measurement and 3-dimensional stereological extrapolation. The major result is that for each two-phase gas-solid flow structure a set of stereological parameters exists. This enables quantification of the process. It has been found that the observation of inter-relation of all stereological parameters, during the changing of the flow structure, can be used for system control. The basic conclusion is that knowledge about the character of the changes may be used for constant process adjustment for various two phase systems such as gas-solid or gas-liquid.

  19. Numerical Simulation of Flow Field in the New Reactor with Two-Phase Fluid

    Directory of Open Access Journals (Sweden)

    Shu Xu

    2013-03-01

    Full Text Available On the basic of the PIV flows field measurement, mature commercial software to fit and test heat plate reactor momentum transfer mathematical model are used and the flow field in various operation conditions of heat plate reactor is simulated. The transfer process of two-phases flow is complicated, the ideal even bubbles model is used to simulate, analyze and calculate, the deviation values of temperature profile of two-phases flow and flow profile of H2O-Air are minor, but they are high than that of homogeneous phase flow. We use the mature business software (CFX of CFD not only to fit, prove the momentum and heat transfer model in reactor with the experiment data of flow profile and temperature profile, but also to simulate the whole flow profile and temperature profile of two-phase fluids, their deviation values between the calculated values and experiment value are lower than the values simulated by traditional empirical formula, these will provide analysis of the transfer process in reactor with reliable mechanism model and computing method.

  20. Competing Air Quality and Water Conservation Co-benefits from Power Sector Decarbonization

    Science.gov (United States)

    Peng, W.; Wagner, F.; Mauzerall, D. L.; Ramana, M. V.; Zhai, H.; Small, M.; Zhang, X.; Dalin, C.

    2016-12-01

    Decarbonizing the power sector can reduce fossil-based generation and associated air pollution and water use. However, power sector configurations that prioritize air quality benefits can be different from those that maximize water conservation benefits. Despite extensive work to optimize the generation mix under an air pollution or water constraint, little research has examined electricity transmission networks and the choice of which fossil fuel units to displace in order to achieve both environmental objectives simultaneously. When air pollution and water stress occur in different regions, the optimal transmission and displacement decisions still depend on priorities placed on air quality and water conservation benefits even if low-carbon generation planning is fixed. Here we use China as a test case, and develop a new optimization framework to study transmission and displacement decisions and the resulting air quality and water use impacts for six power sector decarbonization scenarios in 2030 ( 50% of national generation is low carbon). We fix low-carbon generation in each scenario (e.g. type, location, quantity) and vary technology choices and deployment patterns across scenarios. The objective is to minimize the total physical costs (transmission costs and coal power generation costs) and the estimated environmental costs. Environmental costs are estimated by multiplying effective air pollutant emissions (EMeff, emissions weighted by population density) and effective water use (Weff, water use weighted by a local water stress index) by their unit economic values, Vem and Vw. We are hence able to examine the effect of varying policy priorities by imposing different combinations of Vem and Vw. In all six scenarios, we find that increasing the priority on air quality co-benefits (higher Vem) reduces air pollution impacts (lower EMeff) at the expense of lower water conservation (higher Weff); and vice versa. Such results can largely be explained by differences

  1. A volume-amending method to improve mass conservation of level set approach for incompressible two-phase flows

    Institute of Scientific and Technical Information of China (English)

    LI XiangYang; WANG YueFa; YU GengZhi; YANG Chao; MAO ZaiSha

    2008-01-01

    A volume-amending method is developed both to keep the level set function as an algebraic distance function and to preserve the bubble mass in a level set approach for incompressible two-phase flows with the significantly deformed free interface. After the traditional reinitialization procedure, a vol-ume-amending method is added for correcting the position of the interface according to mass loss/gain error until the mass error falls in the allowable range designated in advance. The level set approach with this volume-amending method incorporated has been validated by three test cases: the motion of a single axisymmetrical bubble or drop in liquid, the motion of a two-dimensional water drop falling through the air into a water pool, and the interactional motion of two buoyancy-driven three-dimensional deformable bubbles. The computational results with this volume-amending method in-corporated are in good agreement with the reported experimental data and the mass is well preserved in all cases.

  2. A volume-amending method to improve mass conservation of level set approach for incompressible two-phase flows

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A volume-amending method is developed both to keep the level set function as an algebraic distance function and to preserve the bubble mass in a level set approach for incompressible two-phase flows with the significantly deformed free interface. After the traditional reinitialization procedure, a vol-ume-amending method is added for correcting the position of the interface according to mass loss/gain error until the mass error falls in the allowable range designated in advance. The level set approach with this volume-amending method incorporated has been validated by three test cases: the motion of a single axisymmetrical bubble or drop in liquid, the motion of a two-dimensional water drop falling through the air into a water pool, and the interactional motion of two buoyancy-driven three- dimensional deformable bubbles. The computational results with this volume-amending method in-corporated are in good agreement with the reported experimental data and the mass is well preserved in all cases.

  3. Two-phase olive mill waste composting: enhancement of the composting rate and compost quality by grape stalks addition.

    Science.gov (United States)

    Cayuela, Maria Luz; Sánchez-Monedero, Miguel A; Roig, Asunción

    2010-06-01

    Two-phase olive mill waste (TPOMW) is a semisolid sludge generated by the olive oil industry. Its recycling as a soil amendment, either unprocessed or composted, is being promoted as a beneficial agricultural practice in the Mediterranean area. One of the major difficulties when composting TPOMW is the compaction of the material due to its dough-like texture, which leads to an inadequate aeration. For this reason, the addition of bulking agents is particularly important to attain a proper composting process. In this study we followed the evolution of two composting mixtures (A and B) prepared by mixing equal amounts of TPOMW and sheep litter (SL) (in a dry weight basis). In pile B grape stalks (GS) were added (10% dry weight) as bulking agent to study their effect on the development of the composting process and the final compost quality. The incorporation of grape stalks to the composting mixture changed the organic matter (OM) degradation dynamics and notably reduced the total amount of lixiviates. The evolution of several maturation indices (C/N, germination index, water soluble carbon, humification indices, C/N in the leachates) showed a faster and improved composting process when GS were added. Moreover, chemical (NH4+, NO3(-), cation exchange capacity, macro and micronutrients, heavy metals) and physical properties (bulk and real densities, air content, total water holding capacity, porosity) of the final composts were analysed and confirmed the superior quality of the compost where GS were added.

  4. Experimental Study of Energy-Saving Air-Conditioner with Hot Water

    Institute of Scientific and Technical Information of China (English)

    CHEN Jian-bo; CHEN Dan; LU Ying

    2009-01-01

    Energy-saving air-conditioner with hot water is an air source heat pump air-conditioner,which can also supply hot water.The hot water is heated by a double pipe condenser connected with an air-cooled condenser in series in the system.This experiment of the energy-saving air-conditioner was carried out in the enthalpy-dif-ference air-conditioner laboratory.The hot water temperature and the compressor'S discharge and suction pres.sure were recorded in the working condition,where the ambient temperature was at 43℃,35℃,21℃,7℃,and 2℃separately.The results showed that the system operated stably and reliably. This system can supply 240 L hot water at 50℃in the whole year,and its coefficience of performance(COP)is much higher than the conventional air source heat pump system.Its energy conservation WaS proved by comparing the thermal effi.ciency with other sourece water heaters.

  5. Dynamics of the free surface of stratified two-phase flows in channels with rectangular cross-sections

    Energy Technology Data Exchange (ETDEWEB)

    Vallee, Christophe

    2012-08-22

    Stratified two-phase flows were investigated at different test facilities with horizontal test sections in order to provide an experimental database for the development and validation of computational fluid dynamics (CFD) codes. These channels were designed with rectangular cross-sections to enable optimal observation conditions for the application of optical measurement techniques. Consequently, the local flow structure was visualised with a high-speed video camera, delivering data with highresolution in space and time as needed for CFD code validation. Generic investigations were performed at atmospheric pressure and room temperature in two air/water channels made of acrylic glass. Divers preliminary experiments were conducted with various measuring systems in a test section mounted between two separators. The second test facility, the Horizontal Air/Water Channel (HAWAC), is dedicated to co-current flow investigations. The hydraulic jump as the quasi-stationary discontinuous transition between super- and subcritical flow was studied in this closed channel. Moreover, the instable wave growth leading to slug flow was investigated from the test section inlet. For quantitative analysis of the optical measurements, an algorithm was developed to recognise the stratified interface in the camera frames, allowing statistical treatments for comparison with CFD calculation results. The third test apparatus was installed in the pressure chamber of the TOPFLOW test facility in order to be operated at reactor typical conditions under pressure equilibrium with the vessel atmosphere. The test section representing a flat model of the hot leg of the German Konvoi pressurised water reactor (PWR) scaled at 1:3 is equipped with large glass side walls in the region of the elbow and of the steam generator inlet chamber to allow visual observations. The experiments were conducted with air and water at room temperature and maximum pressures of 3 bar as well as with steam and water at

  6. Use Of The Operational Air Quality Monitor (AQM) For In-Flight Water Testing Project

    Science.gov (United States)

    Macatangay, Ariel

    2014-01-01

    A primary requirement for manned spaceflight is Environmental Health which ensures air and water contaminants, acoustic profiles, microbial flora, and radiation exposures within the cabin are maintained to levels needed for crew health and for vehicle system functionality. The reliance on ground analyses of returned samples is a limitation in the current environmental monitoring strategy that will prevent future Exploration missions beyond low-Earth orbit. This proposal attempts to address this shortcoming by advancing in-flight analyses of water and air. Ground analysis of in-flight, air and water samples typically employ vapor-phase analysis by gas chromatography-mass spectrometry (GC-MS) to identify and quantify organic compounds present in the samples. We envision the use of newly-developed direct ionization approaches as the most viable avenue leading towards an integrated analytical platform for the monitoring of water, air, and, potentially bio-samples in the cabin environment. Development of an in-flight instrument capable of analyzing air and water samples would be the logical next step to meeting the environmental monitoring needs of Exploration missions. Currently, the Air Quality Monitor (AQM) on-board ISS provides this specific information for a number of target compounds in the air. However, there is a significant subset of common target compounds between air and water. Naturally, the following question arises, "Can the AQM be used for both air and water quality monitoring?" Previous directorate-level IR&D funding led to the development of a water sample introduction method for mass spectrometry using electrothermal vaporization (ETV). This project will focus on the integration of the ETV with a ground-based AQM. The capabilities of this integrated platform will be evaluated using a subset of toxicologically important compounds.

  7. Determination of Hydrodynamic Parameters on Two--Phase Flow Gas - Liquid in Pipes with Different Inclination Angles Using Image Processing Algorithm

    Science.gov (United States)

    Montoya, Gustavo; Valecillos, María; Romero, Carlos; Gonzáles, Dosinda

    2009-11-01

    In the present research a digital image processing-based automated algorithm was developed in order to determine the phase's height, hold up, and statistical distribution of the drop size in a two-phase system water-air using pipes with 0 , 10 , and 90 of inclination. Digital images were acquired with a high speed camera (up to 4500fps), using an equipment that consist of a system with three acrylic pipes with diameters of 1.905, 3.175, and 4.445 cm. Each pipe is arranged in two sections of 8 m of length. Various flow patterns were visualized for different superficial velocities of water and air. Finally, using the image processing program designed in Matlab/Simulink^, the captured images were processed to establish the parameters previously mentioned. The image processing algorithm is based in the frequency domain analysis of the source pictures, which allows to find the phase as the edge between the water and air, through a Sobel filter that extracts the high frequency components of the image. The drop size was found using the calculation of the Feret diameter. Three flow patterns were observed: Annular, ST, and ST&MI.

  8. Simulation experiments for hot-leg U-bend two-phase flow phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Ishii, M.; Hsu, J.T.; Tucholke, D.; Lambert, G.; Kataoka, I.

    1986-01-01

    In order to study the two-phase natural circulation and flow termination during a small break loss of coolant accident in LWR, simulation experiments have been performed. Based on the two-phase flow scaling criteria developed under this program, an adiabatic hot leg U-bend simulation loop using nitrogen gas and water and a Freon 113 boiling and condensation loop were built. The nitrogen-water system has been used to isolate key hydrodynamic phenomena from heat transfer problems, whereas the Freon loop has been used to study the effect of phase changes and fluid properties. Various tests were carried out to establish the basic mechanism of the flow termination and reestablishment as well as to obtain essential information on scale effects of parameters such as the loop frictional resistance, thermal center, U-bend curvature and inlet geometry. In addition to the above experimental study, a preliminary modeling study has been carried out for two-phase flow in a large vertical pipe at relatively low gas fluxes typical of natural circulation conditions.

  9. Air-Water Exchange of Legacy and Emerging Organic Pollutants across the Great Lakes

    Science.gov (United States)

    Lohmann, R.; Ruge, Z.; Khairy, M.; Muir, D.; Helm, P.

    2014-12-01

    Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) are transported to great water bodies via long-range atmospheric transport and released from the surface water as air concentrations continue to diminish. As the largest fresh water bodies in North America, the Great Lakes have both the potential to accumulate and serve as a secondary source of persistent bioaccumulative toxins. OCP and PCB concentrations were sampled at 30+ sites across Lake Superior, Ontario and Erie in the summer of 2011. Polyethylene passive samplers (PEs) were simultaneously deployed in surface water and near surface atmosphere to determine air-water gaseous exchange of OCPs and PCBs. In Lake Superior, surface water and atmospheric concentrations were dominated by α-HCH (average 250 pg/L and 4.2 pg/m3, respectively), followed by HCB (average 17 pg/L and 89 pg/m3, respectively). Air-water exchange varied greatly between sites and individual OCPs, however α-endosulfan was consistently deposited into the surface water (average 19 pg/m2/day). PCBs in the air and water were characterized by penta- and hexachlorobiphenyls with distribution along the coast correlated with proximity to developed areas. Air-water exchange gradients generally yielded net volatilization of PCBs out of Lake Superior. Gaseous concentrations of hexachlorobenzene, dieldrin and chlordanes were significantly higher (p population data was used to explain variability in the atmospheric concentrations. Results indicated that landuse (urban and/or cropland) greatly explained the variability in the data. Freely dissolved concentrations of OCPs (human health from the consumption of fish. Spatial distributions of freely dissolved OCPs in Lakes Erie and Ontario were influenced by loadings from areas of concern and the water circulation patterns. Air-water exchange calculations indicated that the majority of OCPs were volatilizing from the water; therefore the lower Great Lakes were acting as a secondary source to

  10. SIMULATION OF LOW-CONCENTRATION SEDIMENT-LADEN FLOW BASED ON TWO-PHASE FLOW THEORY

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Low concentration sediment-laden flow is usually involved in water conservancy, environmental protection, navigation and so on. In this article, a mathematical model for low-concentration sediment-laden flow was suggested based on the two-phase flow theory, and a solving scheme for the mathematical model in curvilinear grids was worked out. The observed data in the Zhang River in China was used for the verification of the model, and the calculated results of the water level, velocity and river bed deformation are in agreement with the observed ones.

  11. Simulation Experiments in Electromagnetic Tomography Well Logging in Two-phase flow

    Institute of Scientific and Technical Information of China (English)

    Wu Xiling; Zhao Yanwei

    2006-01-01

    Electromagnetic Computer Tomography (ECT) is a method to probe the interior of an inhomogeneous medium via surface measurement in a non-linear way. Due to the great differences in conductivity and permittivity between oil and water in the well, Electromagnetic Tomography Well Logging (ETWL), a new flow imaging measurement system, is proposed to describe the distribution and movement of oil/water two-phase flow in the well by scanning the detected region and applying a suitable data processing algorithm. The results of the numerical simulation and physical modeling show that the system could provide a clear image of the flow profile.

  12. Inerting characteristics of entrained atomized water on premixed methane-air flame

    Institute of Scientific and Technical Information of China (English)

    Cai Feng; Wang Ping; Zhou Jiebo; Li Chao

    2015-01-01

    A combustion tube experiment platform was designed and used to study the inerting conditions and capacity of entrained atomized water on premixed methane–air flame. The structure of a laminar flame of premixed methane–air gas and the process of interaction between atomized water and flame was recorded, and the rules of combustion velocity, stability and strength rate of laminar flame were experi-mentally studied. The inerting process and mechanism was analyzed, and the characteristics of inerting premixed methane–air gas within explosion limits by atomized water were acquired. The research results show that:for the premixed methane–air gas with a concentration of 7%, the minimum inerting atomized water flux is 20.8 mL/(m2 min);for the premixed methane–air gas with a concentration of 9%, the mini-mum inerting atomized water flux is 32.9 mL/(m2 min);for the premixed methane–air gas with a concen-tration of 11%, the minimum inerting atomized water flux is 44.6 mL/(m2 min). The research results are significant for extinguishing methane flame and inhibiting of methane explosion using atomized water.

  13. Environmental Regulations, Air and Water Pollution, and Infant Mortality in India

    OpenAIRE

    Hanna, Rema N.; Greenstone, Michael

    2011-01-01

    Using the most comprehensive data file ever compiled on air pollution, water pollution, environmental regulations, and infant mortality from a developing country, the paper examines the effectiveness of India’s environmental regulations. The air pollution regulations were effective at reducing ambient concentrations of particulate matter, sulfur dioxide, and nitrogen dioxide. The most successful air pollution regulation is associated with a modest and statistically insignificant decline in ...

  14. A statistical method to get surface level air-temperature from satellite observations of precipitable water

    Digital Repository Service at National Institute of Oceanography (India)

    Pankajakshan, T.; Shikauchi, A.; Sugimori, Y.; Kubota, M.

    Vol. 49, pp. 551 to 558. 1993 A Statistical Method to Get Surface Level Air-Temperature from Satellite Observations of Precipitable Water PANKAJAKSHAN THADATHIL*, AKIRA SHIKAUCHI, YASUHIRO SUGIMORI and MASAHISA KUBOTA School of Marine Science... observations for getting the estimates of heat flux across the air-sea boundary (Miller, 1981; Liu, 1988). Bulk method has widely been used for this purpose and the parameters required are: sea surface temperature, and wind speed, air-temperature and specific...

  15. Performance Prediction of Two-Phase Geothermal Reservoir using Lumped Parameter Model

    Science.gov (United States)

    Nurlaela, F.; Sutopo

    2016-09-01

    Many studies have been conducted to simulate performance of low-temperature geothermal reservoirs using lumped parameter method. Limited work had been done on applying non-isothermal lumped parameter models to higher temperature geothermal reservoirs. In this study, the lumped parameter method was applied to high-temperature two phase geothermal reservoirs. The model couples both energy and mass balance equations thus can predict temperature, pressure and fluid saturation changes in the reservoir as a result of production, reinjection of water, and/or natural recharge. This method was validated using reservoir simulation results of TOUGH2. As the results, the two phase lumped parameter model simulation without recharge shows good matching, however reservoir model with recharge condition show quite good conformity.

  16. Targeted Delivery by Smart Capsules for Controlling Two-phase Flow in Porous Media

    Science.gov (United States)

    Fan, J.; Weitz, D.

    2015-12-01

    Understanding and controlling two-phase flow in porous media are of particular importance to the relevant industry applications, such as enhanced oil recovery, CO2 sequestration, and groundwater remediation. We develop a variety of smart microcapsules that can deliver and release specific substances to the target location in the porous medium, and therefore change the fluid property or medium geometry at certain locations. In this talk, I will present two types of smart capsules for (a) delivering surfactant to the vicinity of oil-water interface and (b) delivering microgels to the high permeability region and therefore blocking the pore space there, respectively. We also show that flooding these two capsules into porous media effectively reduces the trapped oil and improves the homogeneity of the medium, respectively. Besides of its industrial applications, this technique also opens a new window to study the mechanism of two-phase flow in porous media.

  17. Simulation of non-equilibrium two-phase flow in single component fluid systems

    Energy Technology Data Exchange (ETDEWEB)

    Hoyer, Norbert [Scandpower A/S, Kjeller (Norway)

    1996-12-31

    Traditionally, two-phase flow has been modelled by separate correlations for void fraction, pressure drop and flow regimes. A more unified approach, which treats flow regimes as an integral part of the two-fluid model is described in this work. A general, transient simulator for steam-water/inert gas systems has been developed. MONA is based on a full two-fluid, three field, nonequilibrium, nonhomogeneous two-phase flow model. It includes further an extensive heat and mass transfer package. The major contribution for MONA validation comes from the FRIGG loop experiments, covering a wide range of parameters like geometry, flow, subcooling, pressure and heat flux. Both validation against steady state and dynamic experiments has been carried out, the former comprising void fractions, pressure drops as well as natural and forced circulation flow rates while the latter consists of boiling instability analysis. 69 refs., 41 figs., 5 tabs.

  18. Cavitation and two-phase flow characteristics of SRPR (Savannah River Plant Reactor) pump. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1991-07-01

    The possible head degradation of the SRPR pumps may be attributable to two independent phenomena, one due to the inception of cavitation and the other due to the two-phase flow phenomena. The head degradation due to the appearance of cavitation on the pump blade is hardly likely in the conventional pressurized water reactor (PWR) since the coolant circulating line is highly pressurized so that the cavitation is difficult to occur even at LOCA (loss of coolant accident) conditions. On the other hand, the suction pressure of SRPR pump is order-of-magnitude smaller than that of PWR so that the cavitation phenomena, may prevail, should LOCA occur, depending on the extent of LOCA condition. In this study, therefore, both cavitation phenomena and two-phase flow phenomena were investigated for the SRPR pump by using various analytical tools and the numerical results are presented herein.

  19. STUDY OF IDENTIFICATION OF TWO-PHASE FLOW PARAMETERS BY PRESSURE FLUCTUATION ANALYSIS

    Directory of Open Access Journals (Sweden)

    Ondrej Burian

    2016-12-01

    Full Text Available This paper deals with identification of parameters of simple pool boiling in a vertical rectangular channel by analysis of pressure fluctuation. In this work is introduced a small experimental facility about 9 kW power, which was used for simulation of pool boiling phenomena and creation of steam-water volume. Several pressure fluctuations measurements and differential pressure fluctuations measurements at warious were carried out. Main changed parameters were power of heaters and hydraulics resistance of channel internals. Measured pressure data was statistically analysed and compared with goal to find dependencies between parameters of two-phase flow and statistical properties of pressure fluctuation. At the end of this paper are summarized final results and applicability of this method for parameters determination of two phase flow for pool boiling conditions at ambient pressure.

  20. Air Stripping Designs and Reactive Water Purification Processes for the Lunar Surface

    Science.gov (United States)

    Boul, Peter J.; Lange, Kevin; Conger, Bruce; Anderson, Molly

    2010-01-01

    Air stripping designs are considered to reduce the presence of volatile organic compounds in the purified water. Components of the wastewater streams are ranked by Henry's Law Constant and the suitability of air stripping in the purification of wastewater in terms of component removal is evaluated. Distillation processes are modeled in tandem with air stripping to demonstrate the potential effectiveness and utility of these methods in recycling wastewater on the Moon. Scaling factors for distillation and air stripping columns are presented to account for the difference in the lunar gravitation environment. Commercially available distillation and air stripping units which are considered suitable for Exploration Life Support are presented. The advantages to the various designs are summarized with respect to water purity levels, power consumption, and processing rates. An evaluation of reactive distillation and air stripping is presented with regards to the reduction of volatile organic compounds in the contaminated water and air. Among the methods presented, an architecture is presented for the evaluation of the simultaneous oxidation of organics in air and water. These and other designs are presented in light of potential improvements in power consumptions and air and water purities for architectures which include catalytic activity integrated into the water processor. In particular, catalytic oxidation of organics may be useful as a tool to remove contaminants that more traditional distillation and/or air stripping columns may not remove. A review of the current leading edge at the commercial level and at the research frontier in catalytically active materials is presented. Themes and directions from the engineering developments in catalyst design are presented conceptually in light of developments in the nanoscale chemistry of a variety of catalyst materials.