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Sample records for horizontal sub-surface flow

  1. DIVERGENT HORIZONTAL SUB-SURFACE FLOWS WITHIN ACTIVE REGION 11158

    Energy Technology Data Exchange (ETDEWEB)

    Jain, Kiran; Tripathy, S. C.; Hill, F., E-mail: kjain@nso.edu, E-mail: stripathy@nso.edu, E-mail: fhill@nso.edu [National Solar Observatory, 950 N Cherry Avenue, Tucson, AZ 85719 (United States)

    2015-07-20

    We measure the horizontal subsurface flow in a fast emerging active region (AR; NOAA 11158) using the ring-diagram technique and the Helioseismic and Magnetic Imager high spatial resolution Dopplergrams. This AR had a complex magnetic structure and displayed significant changes in morphology during its disk passage. Over a period of six days from 2011 February 11 to 16, the temporal variation in the magnitude of the total velocity is found to follow the trend of magnetic field strength. We further analyze regions of individual magnetic polarity within AR 11158 and find that the horizontal velocity components in these sub-regions have significant variation with time and depth. The leading and trailing polarity regions move faster than the mixed-polarity region. Furthermore, both zonal and meridional components have opposite signs for trailing and leading polarity regions at all depths showing divergent flows within the AR. We also find a sharp decrease in the magnitude of total horizontal velocity in deeper layers around major flares. It is suggested that the re-organization of magnetic fields during flares, combined with the sunspot rotation, decreases the magnitude of horizontal flows or that the flow kinetic energy has been converted into the energy released by flares. After the decline in flare activity and sunspot rotation, the flows tend to follow the pattern of magnetic activity. We also observe less variation in the velocity components near the surface but these tend to increase with depth, further demonstrating that the deeper layers are more affected by the topology of ARs.

  2. Efficiency of a Horizontal Sub-Surface Flow Constructed Wetland Treatment System in an Arid Area

    Directory of Open Access Journals (Sweden)

    Abeer Albalawneh

    2016-02-01

    Full Text Available The main objective of this study was to evaluate the performance and treatment efficiency of the Horizontal Sub-Surface Flow Constructed Wetland treatment system (HSF-CW in an arid climate. Seventeen sub-surface, horizontal-flow HSF-CW units have been operated for approximately three years to improve the quality of partially-treated municipal wastewater. The studied design parameters included two sizes of volcanic tuff media (i.e., fine or coarse, two different bed dimensions (i.e., long and short, and three plantation types (i.e., reed, kenaf, or no vegetation as a control. The effluent Biological Oxygen Demand (BOD5, Chemical Oxygen Demand (COD, Total Suspended Solid (TSS, and phosphorus from all of the treatments were significantly lower as compared to the influent and demonstrated a removal efficiency of 55%, 51%, 67%, and 55%, respectively. There were significant increases in Electrical Conductivity (EC, sulfate, and calcium in the effluent of most HSF-CWs due to evaporative concentration and mineral dissolution from the media. The study suggests that unplanted beds with either fine or coarse media are the most suitable combinations among all of the studied designs based on their treatment efficiency and less water loss in arid conditions.

  3. Statistical Analysis of Nitrogen in the Soil of Constructed Wetland with Horizontal Sub-Surface Flow

    Directory of Open Access Journals (Sweden)

    Jakubaszek Anita

    2014-06-01

    Full Text Available The removal of nitrogen compounds in constructed wetlands depends on various physical, chemical and biomechanical factors as well as on conditions of the environment. The paper presents the results of a statistical analysis of the depositing of nitrogen at HSSF (horizontal subsurface flow construcred wetland. The results of the substrate showed that the highest contents of nitrogen existed in the surface soil layer up to 20 cm of the depth. Nitrogen accumulation decreased in the deposit with depth, and in the direction of the wastewater flow.

  4. UASB followed by Sub-Surface Horizontal Flow Phytodepuration for the Treatment of the Sewage Generated by a Small Rural Community

    Directory of Open Access Journals (Sweden)

    Massimo Raboni

    2014-10-01

    Full Text Available The paper presents the results of an experimental process designed for the treatment of the sewage generated by a rural community located in the north-east of Brazil. The process consists of a preliminary mechanical treatment adopting coarse screens and grit traps, followed by a biological treatment in a UASB reactor and a sub-surface horizontal flow phytodepuration step. The use of a UASB reactor equipped with a top cover, as well as of the phytodepuration process employing a porous medium, showed to present important health advantages. In particular, there were no significant odor emissions and there was no evidence of the proliferation of insects and other disease vectors. The plant achieved the following mean abatement efficiencies: 92.9% for BOD5, 79.2% for COD and 94% for Suspended Solids. With regard to fecal indicators average efficiencies of 98.8% for fecal coliforms and 97.9% for fecal enterococci were achieved. The UASB reactor showed an important role in achieving this result. The research was also aimed at evaluating the optimal operating conditions for the UASB reactor in terms of hydraulic load and organic volumetric loading. The achieved results hence indicated that the process may be highly effective for small rural communities in tropical and sub-tropical areas.

  5. Textural evidence for jamming and dewatering of a sub-surface, fluid-saturated granular flow

    Science.gov (United States)

    Sherry, T. J.; Rowe, C. D.; Kirkpatrick, J. D.; Brodsky, E. E.

    2011-12-01

    Sand injectites are spectacular examples of large-scale granular flows involving migration of hundreds of cubic meters of sand slurry over hundreds of meters to kilometers in the sub-surface. By studying the macro- and microstructural textures of a kilometer-scale sand injectite, we interpret the fluid flow regimes during emplacement and define the timing of formation of specific textures in the injected material. Fluidized sand sourced from the Santa Margarita Fm., was injected upward into the Santa Cruz Mudstone, Santa Cruz County, California. The sand injectite exposed at Yellow Bank Beach records emplacement of both hydrocarbon and aqueous sand slurries. Elongate, angular mudstone clasts were ripped from the wall rock during sand migration, providing evidence for high velocity, turbid flow. However, clast long axis orientations are consistently sub-horizontal suggesting the slurry transitioned to a laminar flow as the flow velocity decreased in the sill-like intrusion. Millimeter to centimeter scale laminations are ubiquitous throughout the sand body and are locally parallel to the mudstone clast long axes. The laminations are distinct in exposure because alternating layers are preferentially cemented with limonite sourced from later groundwater infiltration. Quantitative microstructural analyses show that the laminations are defined by subtle oscillations in grain alignment between limonite and non-limonite stained layers. Grain packing, size and shape distributions do not vary. The presence of limonite in alternating layers results from differential infiltration of groundwater, indicating permeability changes between the layers despite minimal grain scale differences. Convolute dewatering structures deform the laminations. Dolomite-cemented sand, a signature of hydrocarbon saturation, forms irregular bodies that cross-cut the laminations and dewatering structures. Laminations are not formed in the dolomite-cemented sand. The relative viscosity difference

  6. Bubble shape in horizontal and near horizontal intermittent flow

    International Nuclear Information System (INIS)

    Gu, Hanyang; Guo, Liejin

    2015-01-01

    Highlights: • The bubble shapes in intermittent flows are presented experimentally. • The nose-tail inversion phenomenon appears at a low Froude number in downward pipe. • Transition from plug to slug flow occurs when the bubble tail changes from staircase pattern to hydraulic jump. - Abstract: This paper presents an experimental study of the shape of isolated bubbles in horizontal and near horizontal intermittent flows. It is found that the shapes of the nose and body of bubble depend on the Froude number defined by gas/liquid mixture velocity in a pipe, whereas the shape of the back of bubble region depends on both the Froude number and bubble length. The photographic studies show that the transition from plug to slug flow occurs when the back of the bubble changes from staircase pattern to hydraulic jump with the increase of the Froude number and bubble length. The effect of pipe inclination on characteristics of bubble is significant: The bubble is inversely located in a downwardly inclined pipe when the Froude number is low, and the transition from plug flow to slug flow in an upward inclined pipe is more ready to occur compared with that in a downwardly inclined pipe

  7. Flow mapping for ESS horizontal target

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, Y.; Kikura, H.; Taishi, T. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    Flow behaviour for ESS horizontal target is studied experimentally using two dimensional water model. A velocity field of stationary flow in reaction zone has been obtained. Three dimensional effect was also studied as a spanwise flow structure. (author) 3 figs., 3 refs.

  8. Modelling Nitrogen Transformation in Horizontal Subsurface Flow ...

    African Journals Online (AJOL)

    A mathematical model was developed to permit dynamic simulation of nitrogen interaction in a pilot horizontal subsurface flow constructed wetland receiving effluents from primary facultative pond. The system was planted with Phragmites mauritianus, which was provided with root zone depth of 75 cm. The root zone was ...

  9. Mixed convection flow past a horizontal plate

    Directory of Open Access Journals (Sweden)

    Savić Lj.

    2005-01-01

    Full Text Available The mixed convection flow past a horizontal plate being aligned through a small angle of attack to a uniform free stream will be considered in the limit of large Reynolds number and small Richardson number. Even a small angle of inclination of the wake is sufficient for the buoyancy force to accelerate the flow in the wake which causes a velocity overshoot in the wake. Moreover a hydrostatic pressure difference across the wake induces a correction to the potential flow which influences the inclination of the wake. Thus the wake and the correction of the potential flow have to be determined simultaneously. However, it turns out that solutions exist only if the angle of attack is sufficiently large. Solutions are computed numerically and the influence of the buoyancy on the lift coefficient is determined.

  10. Performance assessment and microbial diversity of two pilot scale multi-stage sub-surface flow constructed wetland systems.

    Science.gov (United States)

    Babatunde, A O; Miranda-CasoLuengo, Raul; Imtiaz, Mehreen; Zhao, Y Q; Meijer, Wim G

    2016-08-01

    This study assessed the performance and diversity of microbial communities in multi-stage sub-surface flow constructed wetland systems (CWs). Our aim was to assess the impact of configuration on treatment performance and microbial diversity in the systems. Results indicate that at loading rates up to 100gBOD5/(m(2)·day), similar treatment performances can be achieved using either a 3 or 4 stage configuration. In the case of phosphorus (P), the impact of configuration was less obvious and a minimum of 80% P removal can be expected for loadings up to 10gP/(m(2)·day) based on the performance results obtained within the first 16months of operation. Microbial analysis showed an increased bacterial diversity in stage four compared to the first stage. These results indicate that the design and configuration of multi-stage constructed wetland systems may have an impact on the treatment performance and the composition of the microbial community in the systems, and such knowledge can be used to improve their design and performance. Copyright © 2016. Published by Elsevier B.V.

  11. Investigations on flow reversal in stratified horizontal flow

    International Nuclear Information System (INIS)

    Staebler, T.; Meyer, L.; Schulenberg, T.; Laurien, E.

    2005-01-01

    The phenomena of flow reversal in stratified flows are investigated in a horizontal channel with application to the Emergency Core Cooling System (ECCS) in Pressurized Water Reactors (PWR). In case of a Loss-of-Coolant-Accident (LOCA), coolant can be injected through a secondary pipe within the feeding line of the primary circuit, the so called hot leg, counter-currently to the steam flow. It is essential that the coolant reaches the reactor core to prevent overheating. Due to high temperatures in such accident scenarios, steam is generated in the core, which escapes from the reactor vessel through the hot leg. In case of sufficiently high steam flow rates, only a reduced amount of coolant or even no coolant will be delivered to the reactor core. The WENKA test facility at the Institute for Nuclear and Energy Technologies (IKET) at Forschungszentrum Karlsruhe is capable to investigate the fluid dynamics of two-phase flows in such scenarios. Water and air flow counter-currently in a horizontal channel made of clear acrylic glass to allow full optical access. Flow rates of water and air can be varied independently within a wide range. Once flow reversal sets in, a strong hysteresis effect must be taken into account. This was quantified during the present investigations. Local experimental data are needed to expand appropriate models on flow reversal in horizontal two-phase flow and to include them into numerical codes. Investigations are carried out by means of Particle Image Velocimetry (PIV) to obtain local flow velocities without disturbing the flow. Due to the wavy character of the flow, strong reflections at the interfacial area must be taken into account. Using fluorescent particles and an optical filter allows eliminating the reflections and recording only the signals of the particles. The challenges in conducting local investigations in stratified wavy flows by applying optical measurement techniques are discussed. Results are presented and discussed allowing

  12. Axisymmetric, Ventilated Supercavitation in Unsteady, Horizontal Flow

    Science.gov (United States)

    Kawakami, Ellison; Lee, Seung-Jae; Arndt, Roger

    2012-11-01

    Drag reduction and/or speed augmentation of marine vehicles by means of supercavitation is a topic of great interest. During the initial launch of a supercavitating vehicle, an artificial supercavity is required until the vehicle can reach conditions at which a natural supercavity can be sustained. Previous studies at Saint Anthony Falls Laboratory (SAFL) focused on the behavior of ventilated supercavities in steady horizontal flows. In open waters, vehicles can encounter unsteady flows, especially when traveling under waves. A study has been carried out at SAFL to investigate the effects of unsteady flow on axisymmetric supercavities. An attempt is made to duplicate sea states seen in open waters. In an effort to track cavity dimensions throughout a wave cycle, an automated cavity tracking script has been developed. Using a high speed camera and the proper software, it is possible to synchronize cavity dimensions with pressure measurements taken inside the cavity. Results regarding supercavity shape, ventilation demand, cavitation parameters and closure methods are presented. It was found that flow unsteadiness caused a decrease in the overall length of the supercavity while having only a minimal effect on the maximum diameter. The supercavity volume varied with cavitation number and a possible relationship between the two is being explored. (Supported by ONR)

  13. Evidence for deep sub-surface flow routing in forested upland Wales: implications for contaminant transport and stream flow generation

    Directory of Open Access Journals (Sweden)

    A. H. Haria

    2004-01-01

    Full Text Available Upland streamflow generation has traditionally been modelled as a simple rainfall-runoff mechanism. However, recent hydrochemical studies conducted in upland Wales have highlighted the potentially important role of bedrock groundwater in streamflow generation processes. To investigate these processes, a detailed and novel field study was established in the riparian zone and lower hillslopes of the Hafren catchment at Plynlimon, mid-Wales. Results from this study showed groundwater near the river behaving in a complex and most likely confined manner within depth-specific horizons. Rapid responses to rainfall in all boreholes at the study site indicated rapid recharge pathways further upslope. The different flow pathways and travel times influenced the chemical character of groundwaters with depth. Groundwaters were shown to discharge into the stream from the fractured bedrock. A lateral rapid flow horizon was also identified as a fast flow pathway immediately below the soils. This highlighted a mechanism whereby rising groundwater may pick up chemical constituents from the lower soils and transfer them quickly to the stream channel. Restrictions in this horizon resulted in groundwater upwelling into the soils at some locations indicating soil water to be sourced from both rising groundwater and rainfall. The role of bedrock groundwater in upland streamflow generation is far more complicated than previously considered, particularly with respect to residence times and flow pathways. Hence, water quality models in upland catchments that do not take account of the bedrock geology and the groundwater interactions therein will be seriously flawed. Keywords: bedrock, groundwater, Hafren, hillslope hydrology, Plynlimon, recharge, soil water, streamflow generation

  14. Two-phase flow patterns in horizontal rectangular minichannel

    Directory of Open Access Journals (Sweden)

    Ron’shin Fedor

    2016-01-01

    Full Text Available The two-phase flow in a short horizontal channel of rectangular cross-section of 1 × 19 mm2 has been studied experimentally. Five conventional two-phase flow patterns have been detected (bubble, churn, stratified, annular and jet and transitions between them have been determined. It is shown that a change in the width of the horizontal channels has a substantial effect on the boundaries between the flow regimes.

  15. Removal of organics in constructed wetlands with horizontal sub-surface flow: A review of the field experience

    Czech Academy of Sciences Publication Activity Database

    Vymazal, Jan; Kröpfelová, L.

    2009-01-01

    Roč. 407, č. 13 (2009), s. 3911-3922 ISSN 0048-9697 Institutional research plan: CEZ:AV0Z60870520 Keywords : waste-water-treatment * aquatic plants * loading rate Subject RIV: DA - Hydrology ; Limnology Impact factor: 2.905, year: 2009

  16. Study of gas-water flow in horizontal rectangular channels

    Science.gov (United States)

    Chinnov, E. A.; Ron'shin, F. V.; Kabov, O. A.

    2015-09-01

    The two-phase flow in the narrow short horizontal rectangular channels 1 millimeter in height was studied experimentally. The features of formation of the two-phase flow were studied in detail. It is shown that with an increase in the channel width, the region of the churn and bubble regimes increases, compressing the area of the jet flow. The areas of the annular and stratified flow patterns vary insignificantly.

  17. FLOW DISTRIBUTION IN A SOLAR COLLECTOR PANEL WITH HORIZONTAL FINS

    DEFF Research Database (Denmark)

    Fan, Jianhua; Shah, Louise Jivan; Furbo, Simon

    2005-01-01

    The objective of this work is to theoretically and experimentally investigate the flow and temperature distribution in a solar collector panel with an absorber consisting of horizontal fins. Fluid flow and heat transfer in the collector panel are studied by means of computational fluid dynamics...... (CFD) calculations. Further, experimental investigations of a 12.5 m² solar collector panel with 16 parallel connected horizontal fins are carried out. The flow distribution through the absorber is evaluated by means of temperature measurements on the backside of the absorber tubes. The measured...

  18. 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

  19. Mechanistic multidimensional analysis of horizontal two-phase flows

    International Nuclear Information System (INIS)

    Tselishcheva, Elena A.; Antal, Steven P.; Podowski, Michael Z.

    2010-01-01

    The purpose of this paper is to discuss the results of analysis of two-phase flow in horizontal tubes. Two flow situations have been considered: gas/liquid flow in a long straight pipe, and similar flow conditions in a pipe with 90 deg. elbow. The theoretical approach utilizes a multifield modeling concept. A complete three-dimensional two-phase flow model has been implemented in a state-of-the-art computational multiphase fluid dynamics (CMFD) computer code, NPHASE. The overall model has been tested parametrically. Also, the results of NPHASE simulations have been compared against experimental data for a pipe with 90 deg. elbow.

  20. Slug flow in horizontal pipes with transpiration at the wall

    Science.gov (United States)

    Loureiro, J. B. R.; Silva Freire, A. P.

    2011-12-01

    The present work investigates the behaviour of slug flows in horizontal pipes with a permeable wall. Measurements of pressure drop and of local velocity are given for nine different flow conditions. The liquid phase velocity was measured with laser Doppler anemometry. Single-phase data are compared with the results of other authors. The influence of flow transpiration and of roughness on the features of slug flows is shown to be pronounced. A Shadow Sizer system coupled with Particle Image Velocimetry is used to account for the properties of the slug cell.

  1. Slug flow in horizontal pipes with transpiration at the wall

    Energy Technology Data Exchange (ETDEWEB)

    Loureiro, J B R; Freire, A P Silva, E-mail: jbrloureiro@mecanica.ufrj.br [Mechanical Engineering Program, Federal University of Rio de Janeiro (COPPE/UFRJ), C.P. 68503, 21.941-972, Rio de Janeiro, RJ (Brazil)

    2011-12-22

    The present work investigates the behaviour of slug flows in horizontal pipes with a permeable wall. Measurements of pressure drop and of local velocity are given for nine different flow conditions. The liquid phase velocity was measured with laser Doppler anemometry. Single-phase data are compared with the results of other authors. The influence of flow transpiration and of roughness on the features of slug flows is shown to be pronounced. A Shadow Sizer system coupled with Particle Image Velocimetry is used to account for the properties of the slug cell.

  2. Slug flow in horizontal pipes with transpiration at the wall

    International Nuclear Information System (INIS)

    Loureiro, J B R; Freire, A P Silva

    2011-01-01

    The present work investigates the behaviour of slug flows in horizontal pipes with a permeable wall. Measurements of pressure drop and of local velocity are given for nine different flow conditions. The liquid phase velocity was measured with laser Doppler anemometry. Single-phase data are compared with the results of other authors. The influence of flow transpiration and of roughness on the features of slug flows is shown to be pronounced. A Shadow Sizer system coupled with Particle Image Velocimetry is used to account for the properties of the slug cell.

  3. Nitrogen Transformation and Removal in Horizontal Surface Flow ...

    African Journals Online (AJOL)

    The potential use of Constructed Mangrove Wetlands (CMWs) as a cheaper, effective and appropriate method for Nitrogen removal from domestic sewage of coastal zone in peri-urban cities was investigated from August 2007 to. September, 2008. Field investigations were made on horizontal surface flow constructed ...

  4. Flow Through A Horizontal Porous Channel With A Harmonic ...

    African Journals Online (AJOL)

    In this research work we provide a finite element solution to the problem of the flow through a horizontal channel with a harmonic pressure gradient. Results obtained shows that the velocity and temperature increases with time and that a turning point occurs in the temperature profile due to the viscous dissipation effect.

  5. The model coupling fluid flow in reservoir with flow in horizontal wellbore

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiangping; Jiang, Zhixiang [RIPED-TEXACO Horizontal Well Technology Laboratory (United States)

    1998-12-31

    Three-dimensional pressure distributions of oil flow in a reservoir with horizontal well were derived, and a new formula to calculate pressure drop along the horizontal wellbore was developed based on the principle of conservation of matter and momentum. The formula considers the effect of influx into the horizontal wellbore from the reservoir on pressure drop in the wellbore. A mathematical model to couple fluid flow in the reservoir with flow in the horizontal wellbore is presented. Model results and experimental data showed good correspondence. Results showed the influence of pressure drop on well performance. 13 refs., 2 tabs., 7 figs.

  6. Falling film flow, heat transfer and breakdown on horizontal tubes

    International Nuclear Information System (INIS)

    Rogers, J.T.

    1980-11-01

    Knowledge of falling film flow and heat transfer characteristics on horizontal tubes is required in the assessment of certain CANDU reactor accident sequences for those CANDU reactors which use moderator dump as one of the shut-down mechanisms. In these reactors, subsequent cooling of the calandria tubes is provided by falling films produced by sprays. This report describes studies of falling film flow and heat transfer characteristics on horizontal tubes. Analyses using integral methods are given for laminar and turbulent flow, ignoring and accounting for momentum effects in the film. Preliminary experiments on film flow stability on horizontal tubes are described and various mechanisms of film breakdown are examined. The work described in this report shows that in LOCA with indefinitely delayed ECI in the NPD or Douglas Point (at 70 percent power) reactors, the falling films on the calandria tubes will not be disrupted by any of the mechanisms considered, provided that the pressure tubes do not sag onto the calandria tubes. However, should the pressure tubes sag onto the calandria tubes, film disruption will probably occur

  7. An Experimental Study of Oil / Water Flow in Horizontal Pipes

    Energy Technology Data Exchange (ETDEWEB)

    Elseth, Geir

    2001-07-01

    The purpose of this thesis is to study the behaviour of the simultaneous flow of oil and water in horizontal pipes. In this connection, two test facilities are used. Both facilities have horizontal test sections with inner pipe diameters equal to 2 inches. The largest facility, called the model oil facility, has reservoirs of 1 m{sub 3} of each medium enabling flow rates as high as 30 m{sub 3}/h, which corresponds to mixture velocities as high as 3.35 m/s. The flow rates of oil and water can be varied individually producing different flow patterns according to variations in mixture velocity and input water cut. Two main classes of flows are seen, stratified and dispersed. In this facility, the main focus has been on stratified flows. Pressure drops and local phase fractions are measured for a large number of flow conditions. Among the instruments used are differential pressure transmitters and a traversing gamma densitometer, respectively. The flow patterns that appear are classified in flow pattern maps as functions of either mixture velocity and water cut or superficial velocities. From these experiments a smaller number of stratified flows are selected for studies of velocity and turbulence. A laser Doppler anemometer (LDA) is applied for these measurements in a transparent part of the test section. To be able to produce accurate measurements a partial refractive index matching procedure is used. The other facility, called the matched refractive index facility, has a 0.2 m{sub 3} reservoir enabling mainly dispersed flows. Mixture velocities range from 0.75 m/s to 3 m/s. The fluids in this facility are carefully selected to match the refractive index of the transparent part of the test section. A full refractive index matching procedure is carried out producing excellent optical conditions for velocity and turbulence studies by LDA. In addition, pressure drops and local phase fractions are measured. (author)

  8. Research for rolling effects on flow pattern of gas-water flow in horizontal tubes

    International Nuclear Information System (INIS)

    Luan Feng; Yan Changqi

    2007-01-01

    The flow pattern transition of two-phase flow is caused by the inertial force resulted from rolling and incline of horizontal tubes under rolling state. an experimental study on the flow patterns of gas-water flow was carried out in horizontal tubes under rolling state, which rolling period is 15 second and rolling angle is 10 degrees, and a pattern flow picture is shown. It was found that there are two flow patterns in one rolling period under some gas flux and water flux. (authors)

  9. Horizontal two phase flow pattern identification by neural networks

    International Nuclear Information System (INIS)

    Crivelaro, Kelen Cristina Oliveira; Seleghim Junior, Paulo; Hervieu, Eric

    1999-01-01

    A multiphase fluid can flow according to several flow regimes. The problem associated with multiphase systems are basically related to the behavior of macroscopic parameters, such as pressure drop, thermal exchanges and so on, and their strong correlation to the flow regime. From the industrial applications point of view, the safety and longevity of equipment and systems can only be assured when they work according to the flow regimes for which they were designed to. This implies in the need to diagnose flow regimes in real time. The automatic diagnosis of flow regimes represents an objective of extreme importance, mainly for applications on nuclear and petrochemical industries. In this work, a neural network is used in association to a probe of direct visualization for the identification of a gas-liquid flow horizontal regimes, developed in an experimental circuit. More specifically, the signals produced by the probe are used to compose a qualitative image of the flow, which is promptly sent to the network for the recognition of the regimes. Results are presented for different transitions among the flow regimes, which demonstrate the extremely satisfactory performance of the diagnosis system. (author)

  10. Mass transfer in horizontal flow channels with thermal gradients

    International Nuclear Information System (INIS)

    Bendrich, G.; Shemilt, L.W.

    1997-01-01

    Mass transfer to a wall of a horizontal rectangular channel reactor was investigated by the limiting current technique for Reynolds numbers ranging from 200 to 32000. Overall mass transfer coefficients at various mass transfer surface angles were obtained while the reactor was operated under isothermal and non-isothermal conditions. Dimensionless correlations were developed for isothermal flows from 25 to 55 o C and for non-isothermal flows with applied temperature differences up to 30 o C. In the laminar flow range natural convection dominated, but under turbulent conditions combined natural and forced convection prevailed. Mass transfer was approximately doubled under optimum selection of channel surface rotation, temperature gradient and flow rate. (author)

  11. Stratification of bubbly horizontal flows: modeling and experimental validation

    International Nuclear Information System (INIS)

    Bottin, M.

    2010-01-01

    Hot films and optical probes enabled the acquisition of measurements in bubbly flows at 5, 20 and 40 diameters from the inlet of the vein on the METERO facility which test section is a horizontal circular pipe of 100 mm inner diameter. The distribution of the different phases, the existence of coalescence and sedimentation mechanisms, the influence of the liquid and gas flow rates, the radial and axial evolutions are analyzed thanks to fast camera videos and numerous and varied experimental results (void fraction, bubbles sizes, interfacial area, mean and fluctuating velocities and turbulent kinetic energy of the liquid phase). Some models, based on the idea that the flow reaches an equilibrium state sufficiently far from the inlet of the pipe, were developed to simulate mean interfacial area and turbulent kinetic energy transports in bubbly flows. (author)

  12. Complex networks from experimental horizontal oil–water flows: Community structure detection versus flow pattern discrimination

    International Nuclear Information System (INIS)

    Gao, Zhong-Ke; Fang, Peng-Cheng; Ding, Mei-Shuang; Yang, Dan; Jin, Ning-De

    2015-01-01

    We propose a complex network-based method to distinguish complex patterns arising from experimental horizontal oil–water two-phase flow. We first use the adaptive optimal kernel time–frequency representation (AOK TFR) to characterize flow pattern behaviors from the energy and frequency point of view. Then, we infer two-phase flow complex networks from experimental measurements and detect the community structures associated with flow patterns. The results suggest that the community detection in two-phase flow complex network allows objectively discriminating complex horizontal oil–water flow patterns, especially for the segregated and dispersed flow patterns, a task that existing method based on AOK TFR fails to work. - Highlights: • We combine time–frequency analysis and complex network to identify flow patterns. • We explore the transitional flow behaviors in terms of betweenness centrality. • Our analysis provides a novel way for recognizing complex flow patterns. • Broader applicability of our method is demonstrated and articulated

  13. Experimental measurements of the cavitating flow after horizontal water entry

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Thang Tat; Thai, Nguyen Quang; Phuong, Truong Thi [Institute of Mechanics (IMECH), Vietnam Academy of Science and Technology (VAST), 264—Doi Can, Ba Dinh, Hanoi (Viet Nam); Hai, Duong Ngoc, E-mail: ntthang@imech.vast.vn, E-mail: dnhai@vast.vn, E-mail: nqthai@imech.vast.vn, E-mail: ttphuong@imech.vast.vn [Graduate University of Science and Technology (GUST), VAST, 18—Hoang Quoc Viet, Cau Giay, Hanoi (Viet Nam)

    2017-10-15

    Water-entry cavitating flow is of considerable importance in underwater high-speed applications. That is because of the drag-reduction effect that concerns the presence of a cavity around moving objects. Though the study of the flow has long been carried out, little data are documented in literature so far. Besides, currently, in the case of unsteady flow, experimental measurements of some flow parameters such as the cavity pressure still encounter difficulties. Hence continuing research efforts are of important significance. The objective of this study is to investigate experimentally the unsteady cavitating flow after the horizontal water entry of projectiles. An experimental apparatus has been developed. Qualitative and quantitative optical visualizations of the flow have been carried out by using high-speed videography. Digital image processing has been applied to analyzing the recorded flow images. Based on the known correlations between the ellipsoidal super-cavity’s size and the corresponding cavitation number, the cavity pressure has been measured by utilizing the data of image processing. A comparison between the partial- and super-cavitating flow regimes is reported. The received results can be useful for the design of high-speed underwater projectiles. (paper)

  14. Design and Analysis of Horizontal Axial Flow Motor Shroud

    Science.gov (United States)

    Wang, Shiming; Shen, Yu

    2018-01-01

    The wind turbine diffuser can increase the wind energy utilization coefficient of the wind turbine, and the addition of the shroud to the horizontal axis wind turbine also plays a role of accelerating the flow of the condensate. First, the structure of the shroud was designed and then modeled in gambit. The fluent software was used to establish the mathematical model for simulation. The length of the shroud and the opening angle of the shroud are analyzed to determine the best shape of the shroud. Then compared the efficiency with or without the shroud, through the simulation and the experiment of the water tank, it is confirmed that the horizontal axis of the shroud can improve the hydrodynamic performance.

  15. Subcritical to supercritical flow transition in a horizontal stratified flow

    International Nuclear Information System (INIS)

    Asaka, H.; Kukita, Y.

    1995-01-01

    The conditions for a transition from hydraulically subcritical to supercritical flow in the hot legs of a pressurized water reactor (PWR) were studied using data obtained from a two-phase natural circulation experiment conducted at the ROSA-IV Large Scale Test Facility (LSTF). The LSTF is a 1/48 volumetrically-scaled simulator of a Westinghouse-type PWR. The conditions for the transition were compared with the theory of Gardner. While the model explains the trend in the experimental data, the quantitative agreement was not satisfactory. It was found that the conditions for the transition from the subcritical to supercritical flow were predicted well by introducing energy loss term into the theory. (author)

  16. Local studies in horizontal gas-liquid slug flow

    International Nuclear Information System (INIS)

    Sharma, S.; Lewis, S.; Kojasoy, G.

    1998-01-01

    The local axial velocity profile development in a horizontal air-water slug flow-pattern was experimentally investigated by simultaneously using two hot-film anemometers. One of the probes was exclusively used as phase identifier while the other probe was traversed for local velocity measurements. It was shown that the velocity rapidly develops into asymmetric but nearly fully-developed profiles within the liquid slugs whereas the velocity never develops into quasi-fully-developed profiles within the liquid layer underneath passing gas slugs. Transient nature of velocity at a given location was demonstrated. (author)

  17. Horizontal liquid film-mist two phase flow, (1)

    International Nuclear Information System (INIS)

    Akagawa, Koji; Sakaguchi, Tadashi; Fujii, Terushige; Nakatani, Yoji; Nakaseko, Kosaburo.

    1979-01-01

    The characteristics of liquid film in annular spray flow, the generation of droplets from liquid film and the transport of droplets to a wall are the important matters in the planning and design of nuclear reactor cooling system and the channels of steam generators. The study on the liquid film spray flow is scarce, and its characteristics are not yet elucidated. The purpose of this series of studies is to clarify the characteristics of liquid film, the generation, diffusion and distribution of droplets and pressure loss in the liquid film spray flow composed of the liquid film on the lower wall and spraying gas flow in a rectangular, horizontal channel. In this paper, the concentration distribution and the diffusion coefficient of droplets on a cross section in the region of flow completion are reported. The experimental apparatuses and the experimental method, the flow rate of droplets and the velocity distribution of gas phase, the concentration distribution and the diffusion coefficient of droplets, and the diameter of generated droplets are explained. The equation for the concentration distribution of droplets using dimensionless characteristic value was derived. The mean diffusion coefficient of droplets was constant on a cross section, and the effects of gravity and turbulent diffusion can be evaluated. (Kako, I.)

  18. A droplet entrainment model for horizontal segregated flows

    Energy Technology Data Exchange (ETDEWEB)

    Höhne, Thomas, E-mail: T.Hoehne@hzdr.de [Helmholtz-Zentrum Dresden-Rossendorf (HZDR) – Institute of Fluid Dynamics, P.O. Box 510119, D-01314 Dresden (Germany); Hänsch, Susann [Imperial College, Department of Mechanical Engineering, South Kensington Campus, London SW7 2AZ (United Kingdom)

    2015-05-15

    Highlights: • We further developed the flow morphology detection model AIAD. • An advanced droplet entrainment model was introduced. • The new approach is applied against HAWAC experiments. - Abstract: One limitation in simulating horizontal segregated flows is that there is no treatment of droplet formation mechanisms at wavy surfaces. For self-generating waves and slugs, the interfacial momentum exchange and the turbulence parameters have to be modeled correctly. Furthermore, understanding the mechanism of droplet entrainment for heat and mass transfer processes is of great importance in the chemical and nuclear industry. The development of general computational fluid dynamics models is an essential precondition for the application of CFD codes to the modeling of flow related phenomena. The new formulation for the interfacial drag at the free surface and turbulence parameters within the algebraic interfacial area density model (AIAD) represents one step toward a more physical description of free surface flows including less empiricism. The AIAD approach allows the use of different physical models depending on the local fluid morphology inside a macro-scale multi-fluid framework. A further step of improving the modeling of free interfaces lies within the consideration of droplet entrainment mechanisms. In this paper a new sub-grid entrainment model is proposed, which assumes that due to liquid turbulence the interface gets rough and wavy leading to the formation of droplets. Therefore, the droplet entrainment model requires the consideration of an additional droplet phase, which is described with an own set of balance equations in the spirit of the particle model. Two local key factors determine the rate of droplet entrainment: the liquid turbulent kinetic energy as well as the outward velocity gradient of the liquid relative to the interface motion. The new droplet entrainment approach is included into CFD simulations for attempting to reproduce existing

  19. Method for confirming flow pattern of gas-water flow in horizontal tubes under rolling state

    International Nuclear Information System (INIS)

    Luan Feng; Yan Changqi

    2008-01-01

    An experimental study on the flow patterns of gas-water flow was carried out in horizontal tubes under rolling state. It was found that the pressure drop of two phase flow was with an obvious periodical characteristic. The flow pattern of the gas-water flow was distinguished according to the characteristics of the pressure drop in this paper. It was proved that the characteristics of the pressure drop can distinguish the flow pattern of gas-water flow correctly through comparing with the result of careful observation and high speed digital camera. (authors)

  20. Convection flow study within a horizontal fluid layer under the action of gas flow

    Directory of Open Access Journals (Sweden)

    Kreta Aleksei

    2016-01-01

    Full Text Available Experimental investigation of convective processes within horizontal evaporating liquid layer under shear–stress of gas flow is presented. It is found the structures of the convection, which move in opposite direction relative to each other. First convective structure moves in reverse direction with the flow of gas, and the second convective structure moves towards the gas flow. Convection flow within the liquid layer is registered with help of PIV technique. Average evaporation flow rate of Ethanol liquid layer under Air gas flow is measured. Influence of the gas velocity, at a constant temperature of 20 °C, on the evaporation flow rate has been studied.

  1. Steady particulate flows in a horizontal rotating cylinder

    Science.gov (United States)

    Yamane, K.; Nakagawa, M.; Altobelli, S. A.; Tanaka, T.; Tsuji, Y.

    1998-06-01

    Results of discrete element method (DEM) simulation and magnetic resonance imaging (MRI) experiments are compared for monodisperse granular materials flowing in a half-filled horizontal rotating cylinder. Because opacity is not a problem for MRI, a long cylinder with an aspect ratio ˜7 was used and the flow in a thin transverse slice near the center was studied. The particles were mustard seeds and the ratio of cylinder diameter to particle diameter was approximately 50. The parameters compared were dynamic angle of repose, velocity field in a plane perpendicular to the cylinder axis, and velocity fluctuations at rotation rates up to 30 rpm. The agreement between DEM and MRI was good when the friction coefficient and nonsphericity were adjusted in the simulation for the best fit.

  2. Horizontal Air-Water Flow Analysis with Wire Mesh Sensor

    International Nuclear Information System (INIS)

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

    2012-01-01

    A Wire Mesh Sensor, based on the measurement of the local instantaneous conductivity of the two-phase mixture, has been used to characterize the fluid dynamics of the gas–liquid interface in a horizontal pipe flow. Experiments with a pipe of a nominal diameter of 19.5 mm and total length of 6 m, have been performed with air/water mixtures, at ambient conditions. The flow quality ranges from 0.00016 to 0.22 and the superficial velocities range from 0.1 to 10.5 m/s for air and from 0.02 to 1.7 m/s for water; the flow pattern is stratified, slug/plug and annular. A sensor (WMS200) with an inner diameter of 19.5 mm and a measuring matrix of 16×16 points equally distributed over the cross-section has been chosen for the measurements. From the analysis of the Wire Mesh Sensor digital signals the average and the local void fraction are evaluated and the flow patterns are identified with reference to space, time and flow rate boundary conditions.

  3. Characterization of interfacial waves in horizontal core-annular flow

    Science.gov (United States)

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

    2016-11-01

    In this work, we characterize interfacial waves in horizontal core annular flow (CAF) of fuel-oil and water. Experimental studies on CAF were performed in an acrylic pipe of 15.5mm internal diameter, and the time evolution of the oil-water interface shape was recorded with a high speed camera for a range of different flow-rates of oil (Qo) and water (Qw). The power spectrum of the interface shape shows a range of notable features. First, there is negligible energy in wavenumbers larger than 2 π / a , where a is the thickness of the annulus. Second, for high Qo /Qw , there is no single dominant wavelength, as the flow in the confined annulus does not allow formation of a preferred mode. Third, for lower Qo /Qw , a dominant mode arises at a wavenumber of 2 π / a . We also observe that the power spectrum of the interface shape depends weakly on Qw, and strongly on Qo, perhaps because the net shear rate in the annulus appears to depend weakly on Qw as well. We also attempt to build a general empirical model for CAF by relating the interfacial stress (calculated via the mean pressure gradient) to the flow rate in the annulus, the annular thickness and the core velocity. Authors are thankful to Orica Mining Services (Australia) for the financial support.

  4. Entropy Generation on Nanofluid Flow through a Horizontal Riga Plate

    Directory of Open Access Journals (Sweden)

    Tehseen Abbas

    2016-06-01

    Full Text Available In this article, entropy generation on viscous nanofluid through a horizontal Riga plate has been examined. The present flow problem consists of continuity, linear momentum, thermal energy, and nanoparticle concentration equation which are simplified with the help of Oberbeck-Boussinesq approximation. The resulting highly nonlinear coupled partial differential equations are solved numerically by means of the shooting method (SM. The expression of local Nusselt number and local Sherwood number are also taken into account and discussed with the help of table. The physical influence of all the emerging parameters such as Brownian motion parameter, thermophoresis parameter, Brinkmann number, Richardson number, nanoparticle flux parameter, Lewis number and suction parameter are demonstrated graphically. In particular, we conferred their influence on velocity profile, temperature profile, nanoparticle concentration profile and Entropy profile.

  5. Numerical Investigation of Ice Slurry Flow in a Horizontal Pipe

    Science.gov (United States)

    Rawat, K. S.; Pratihar, A. K.

    2018-02-01

    In the last decade, phase changing material slurry (PCMS) gained much attention as a cooling medium due to its high energy storage capacity and transportability. However the flow of PCM slurry is a complex phenomenon as it affected by various parameters, i.e. fluid properties, velocity, particle size and concentration etc.. In the present work ice is used as a PCM and numerical investigation of heterogeneous slurry flow has been carried out using Eulerian KTGF model in a horizontal pipe. Firstly the present model is validated with existing experiment results available in the literature, and then model is applied to the present problem. Results show that, flow is almost homogeneous for ethanol based ice slurry with particle diameter of 0.1 mm at the velocity of 1 m/s. It is also found that ice particle distribution is more uniform at higher velocity, concentration of ice and ethanol in slurry. Results also show that ice concentration increases on the top of the pipe, and the effect of particle wall collision is more significant at higher particle diameter.

  6. Two-phase flow field simulation of horizontal steam generators

    Energy Technology Data Exchange (ETDEWEB)

    Rabiee, Ataollah; Kamalinia, Amir Hossein; Hadad, Kamal [School of Mechanical Engineering, Shiraz University, Shiraz (Iran, Islamic Republic of)

    2017-02-15

    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.

  7. Two-phase flow through small branches in a horizontal pipe with stratified flow

    International Nuclear Information System (INIS)

    Smoglie, C.

    1985-02-01

    In the field of reactor safety the occurrence of a small break in a horizontal primary coolant pipe is of great importance. This report presents the description and results of experiments designed to determine the mass flow rate and quality through a small break at the bottom, the top or the side of a main pipe with stratified gas-liquid flow. If the interface level is far below (above) the branch, only single-phase gas (liquid) flow enters the branch. For smaller distances the interface is locally deformed because of the pressure decrease due to the fluid acceleration near the branch inlet (Bernoulli effect) and liquid (gas) can be entrained. This report contains photographs illustrating the flow phenomena as well as a general correlation to determine the beginning of entrainment. Results are presented on the branch mass flow rate and quality as a function of a normalized distance between the interface and the branch inlet. A model was developed which enables to predict the branch quality and mass flux. Results from air-water flow through horizontal branches, were extrapolated for steam water flow at high pressure with critical branch mass flux. (orig./HS) [de

  8. Boolean logic analysis for flow regime recognition of gas–liquid horizontal flow

    International Nuclear Information System (INIS)

    Ramskill, Nicholas P; Wang, Mi

    2011-01-01

    In order to develop a flowmeter for the accurate measurement of multiphase flows, it is of the utmost importance to correctly identify the flow regime present to enable the selection of the optimal method for metering. In this study, the horizontal flow of air and water in a pipeline was studied under a multitude of conditions using electrical resistance tomography but the flow regimes that are presented in this paper have been limited to plug and bubble air–water flows. This study proposes a novel method for recognition of the prevalent flow regime using only a fraction of the data, thus rendering the analysis more efficient. By considering the average conductivity of five zones along the central axis of the tomogram, key features can be identified, thus enabling the recognition of the prevalent flow regime. Boolean logic and frequency spectrum analysis has been applied for flow regime recognition. Visualization of the flow using the reconstructed images provides a qualitative comparison between different flow regimes. Application of the Boolean logic scheme enables a quantitative comparison of the flow patterns, thus reducing the subjectivity in the identification of the prevalent flow regime

  9. Multivariate recurrence network analysis for characterizing horizontal oil-water two-phase flow.

    Science.gov (United States)

    Gao, Zhong-Ke; Zhang, Xin-Wang; Jin, Ning-De; Marwan, Norbert; Kurths, Jürgen

    2013-09-01

    Characterizing complex patterns arising from horizontal oil-water two-phase flows is a contemporary and challenging problem of paramount importance. We design a new multisector conductance sensor and systematically carry out horizontal oil-water two-phase flow experiments for measuring multivariate signals of different flow patterns. We then infer multivariate recurrence networks from these experimental data and investigate local cross-network properties for each constructed network. Our results demonstrate that a cross-clustering coefficient from a multivariate recurrence network is very sensitive to transitions among different flow patterns and recovers quantitative insights into the flow behavior underlying horizontal oil-water flows. These properties render multivariate recurrence networks particularly powerful for investigating a horizontal oil-water two-phase flow system and its complex interacting components from a network perspective.

  10. Transition from slug to annular flow in horizontal air-water flow

    International Nuclear Information System (INIS)

    Reismann, J.; John, H.; Seeger, W.

    1981-11-01

    The transition from slug to annular flow in horizontal air-water and steam-water flow was investigated. Test sections of 50; 66.6 and 80 mm ID were used. The system pressure was 0.2 and 0.5 MPa in the air-water experiments and 2.5; 5; 7.5 and 10 MPa in the steam-water experiments. For flow pattern detection local impedance probes were used. This method was compared in a part of the experiments with differential pressure and gamma-beam measurements. The flow regime boundary is shifting strongly to smaller values of the superficial gas velocity with increasing pressure. Correlations from literature fit unsatisfactorily the experimental results. A new correlation is presented. (orig.) [de

  11. Void fraction in horizontal bulk flow boiling at high flow qualities

    International Nuclear Information System (INIS)

    Collado, Fancisco J.; Monne, Carlos; Pascau, Antonio

    2008-01-01

    In this work, a new thermodynamic prediction of the vapor void fraction in bulk flow boiling, which is the core process of many energy conversion systems, is analyzed. The current heat balance is based on the flow quality, which is closely related to the measured void fraction, although some correlation for the vapor-liquid velocity ratio is needed. So here, it is suggested to work with the 'static' or thermodynamic quality, which is directly connected to the void fraction through the densities of the phases. Thus, the relation between heat and the mixture enthalpy (here based on the thermodynamic quality instead of the flow one) should be analyzed in depth. The careful void fraction data taken by Thom during the 'Cambridge project' for horizontal saturated flow boiling with high flow qualities (≤0.8) have been used for this analysis. As main results, first, we have found that the applied heat and the increment of the proposed thermodynamic enthalpy mixture throughout the heated duct do not agree, and for closure, a parameter is needed. Second, it has been checked that this parameter is practically equal to the classic velocity ratio or 'slip' ratio, suggesting that it should be included in a true thermodynamic heat balance. Furthermore, it has been clearly possible to improve the 'Cambridge project' correlations for the 'slip' ratio, here based on inlet pressure and water velocity, and heat flux. The calculated void fractions compare quite well with the measured ones. Finally, the equivalence of the suggested new heat balance with the current one through the 'slip' ratio is addressed. Highlighted is the same new energetic relation for saturated flow boiling that has been recently confirmed by the authors for Knights data, also taken during the 'Cambridge project', which include not only horizontal but also vertical upwards flows with moderate outlet flow quality (≤0.2)

  12. Void fraction in horizontal bulk flow boiling at high flow qualities

    Energy Technology Data Exchange (ETDEWEB)

    Collado, Fancisco J.; Monne, Carlos [Dpto. de Ingenieria Mecanica, Universidad de Zaragoza-CPS, Maria de Luna 3, 50018-Zaragoza (Spain); Pascau, Antonio [Dpto. de Ciencia de los Materiales y Fluidos, Universidad de Zaragoza-CPS, Maria de Luna 3, 50018-Zaragoza (Spain)

    2008-04-15

    In this work, a new thermodynamic prediction of the vapor void fraction in bulk flow boiling, which is the core process of many energy conversion systems, is analyzed. The current heat balance is based on the flow quality, which is closely related to the measured void fraction, although some correlation for the vapor-liquid velocity ratio is needed. So here, it is suggested to work with the 'static' or thermodynamic quality, which is directly connected to the void fraction through the densities of the phases. Thus, the relation between heat and the mixture enthalpy (here based on the thermodynamic quality instead of the flow one) should be analyzed in depth. The careful void fraction data taken by Thom during the 'Cambridge project' for horizontal saturated flow boiling with high flow qualities ({<=}0.8) have been used for this analysis. As main results, first, we have found that the applied heat and the increment of the proposed thermodynamic enthalpy mixture throughout the heated duct do not agree, and for closure, a parameter is needed. Second, it has been checked that this parameter is practically equal to the classic velocity ratio or 'slip' ratio, suggesting that it should be included in a true thermodynamic heat balance. Furthermore, it has been clearly possible to improve the 'Cambridge project' correlations for the 'slip' ratio, here based on inlet pressure and water velocity, and heat flux. The calculated void fractions compare quite well with the measured ones. Finally, the equivalence of the suggested new heat balance with the current one through the 'slip' ratio is addressed. Highlighted is the same new energetic relation for saturated flow boiling that has been recently confirmed by the authors for Knights data, also taken during the 'Cambridge project', which include not only horizontal but also vertical upwards flows with moderate outlet flow quality ({<=}0.2). (author)

  13. Magnitude and sign correlations in conductance fluctuations of horizontal oil water two-phase flow

    International Nuclear Information System (INIS)

    Zhu, L; Jin, N D; Gao, Z K; Zong, Y B; Zhai, L S; Wang, Z Y

    2012-01-01

    In experiment we firstly define five typical horizontal oil-water flow patterns. Then we introduce an approach for analyzing signals by decomposing the original signals increment into magnitude and sign series and exploring their scaling properties. We characterize the nonlinear and linear properties of horizontal oil-water two-phase flow, which relate to magnitude and sign series respectively. We find that the joint distribution of different scaling exponents can effectively identify flow patterns, and the detrended fluctuation analysis (DFA) on magnitude and sign series can represent typical horizontal oil-water two-phase flow dynamics characteristics. The results indicate that the magnitude and sign decomposition method can be a helpful tool for characterizing complex dynamics of horizontal oil-water two-phase flow.

  14. Two-phase flow through small branches in a horizontal pipe with stratified flow

    International Nuclear Information System (INIS)

    Smoglie, C.

    1984-12-01

    This report presents the description and results of experiments designed to determine the mass flow rate and quality through a small break at the bottom, the top or the side of a main pipe with stratified gas-liquid flow. If the interface level is far below (above) the branch, only single-phase gas (liquid) flow enters the branch. For smaller distances the interface is locally deformed because of the pressure decrease due to the fluid acceleration near the branch inlet (Bernoulli effect) and liquid (gas) can be entrained. This report contains photographs illustrating the flow phenomena as well as a general correlation to determine the beginning of entrainment. Results are presented on the branch mass flow rate and quality as a function of a normalized distance between the interface and the branch inlet. A model was developed which enables to predict the branch quality and mass flux. Results from air-water flow through horizontal branches, were extrapolated for steam water flow at high pressure with critical branch mass flux. (orig./HP) [de

  15. Flow structure from a horizontal cylinder coincident with a free surface in shallow water flow

    Directory of Open Access Journals (Sweden)

    Kahraman Ali

    2012-01-01

    Full Text Available Vortex formation from a horizontal cylinder coincident with a free surface of a shallow water flow having a depth of 25.4 [mm] was experimentally investigated using the PIV technique. Instantaneous and time-averaged flow patterns in the wake region of the cylinder were examined for three different cylinder diameter values under the fully developed turbulent boundary layer condition. Reynolds numbers were in the range of 1124£ Re£ 3374 and Froude numbers were in the range of 0.41 £ Fr £ 0.71 based on the cylinder diameter. It was found that a jet-like flow giving rise to increasing the flow entrainment between the core and wake regions depending on the cylinder diameter was formed between the lower surface of the cylinder and bottom surface of the channel. Vorticity intensity, Reynolds stress correlations and the primary recirculating bubble lengths were grown to higher values with increasing the cylinder diameter. On the other hand, in the case of the lowest level of the jet-like flow emanating from the beneath of the smallest cylinder, the variation of flow characteristics were attenuated significantly in a shorter distance. The variation of the reattachment location of the separated flow to the free-surface is a strong function of the cylinder diameter and the Froude number.

  16. Theoretical investigation of flow regime for boiling water two-phase flow in horizontal rectangular narrow channels

    International Nuclear Information System (INIS)

    Zhang Chunwei; Qiu Suizheng; Yan Mingyu; Wang Bulei; Nie Changhua

    2005-01-01

    The flow regime transition criteria for the boiling water two-phase flow in horizontal rectangular narrow channels (1 x 20 mm, 2 x 20 mm) were theoretically explored. The discernible flow patterns were bubble, intermittent slug, churn, annular and steam-water separation flow. By using two-fluid model, equations of conservation of momentum were established for the two-phase flow. New flow-regime criteria were obtained and agreed well with the experiment data. (authors)

  17. Heterogeneous ice slurry flow and concentration distribution in horizontal pipes

    International Nuclear Information System (INIS)

    Wang, Jihong; Zhang, Tengfei; Wang, Shugang

    2013-01-01

    Highlights: • A Mixture CFD model is applied to describe heterogeneous ice slurry flow. • The ice slurry rheological behavior is considered piecewise. • The coupled flow and concentration profiles in heterogeneous slurry flow is acquired. • The current numerical model achieves good balance between precision and universality. -- Abstract: Ice slurry is an energy-intensive solid–liquid mixture fluid which may play an important role in various cooling purposes. Knowing detailed flow information is important from the system design point of view. However, the heterogeneous ice slurry flow makes it difficult to be quantified due to the complex two phase flow characteristic. The present study applies a Mixture computational fluid dynamics (CFD) model based on different rheological behavior to characterize the heterogeneous ice slurry flow. The Mixture CFD model was firstly validated by three different experiments. Then the validated Mixture CFD model was applied to solve the ice slurry isothermal flow by considering the rheological behavior piecewise. Finally, the numerical solutions have displayed the coupled flow information, such as slurry velocity, ice particle concentration and pressure drop distribution. The results show that, the ice slurry flow distribution will appear varying degree of asymmetry under different operating conditions. The rheological behavior will be affected by the asymmetric flow distributions. When mean flow velocity is high, Thomas equation can be appropriate for describing ice slurry viscosity. While with the decreasing of mean flow velocity, the ice slurry behaves Bingham rheology. As compared with experimental pressure drop results, the relative errors of numerical computation are almost within ±15%. The Mixture CFD model is validated to be an effective model for describing heterogeneous ice slurry flow and could supply plentiful flow information

  18. A test section design to simulate horizontal two-phase air-water flow

    International Nuclear Information System (INIS)

    Faccini, Jose Luiz H.; Cesar, Silvia B.G.; Coutinho, Jorge A.; Freitas, Sergio Carlos; Addor, Pedro N.

    2002-01-01

    In this work an air-water two-phase flow horizontal test section assembling at Nuclear Engineering Institute (IEN) is presented. The test section was designed to allow four-phase flow patterns to be simulated: bubble flow, stratified flow, wave flow and slug flow. These flow patterns will be identified by non-conventional ultrasonic techniques which have been developed to meet this particular application. Based on the separated flow and drift-flux models the test section design steps are shown. A description of the test section and its instrumentation and data acquisition system is also provided. (author)

  19. Flooding characteristics of gas-liquid two-phase flow in a horizontal U bend pipe

    International Nuclear Information System (INIS)

    Sakaguchi, T.; Hosokawa, S.; Fujii, Y.

    1995-01-01

    For next-generation nuclear reactors, hybrid safety systems which consist of active and passive safety systems have been planned. Steam generators with horizontal U bend pipelines will be used as one of the passive safety systems. It is required to clarify flow characteristics, especially the onset of flooding, in the horizontal U bend pipelines in order to examine their safety. Flooding in vertical pipes has been studied extensively. However, there is little study on flooding in the horizontal U bend pipelines. It is supposed that the onset of flooding in the horizontal U bend pipelines is different from that in vertical pipes. On the other hand, liquid is generated due to condensation of steam in pipes of the horizontal steam generators at the loss of coolant accident because the steam generators will be used as a condenser of a cooling system of steam from the reactor. It is necessary to simulate this situation by the supply of water at the middle of horizontal pipe. In the present paper, experiments were carried out using a horizontal U bend pipeline with a liquid supply section in the midway of pipeline. The onset of flooding in the horizontal U bend pipeline was measured. Effects of the length of horizontal pipe and the radius of U bend on the onset of flooding were discussed

  20. Flooding characteristics of gas-liquid two-phase flow in a horizontal U bend pipe

    Energy Technology Data Exchange (ETDEWEB)

    Sakaguchi, T.; Hosokawa, S.; Fujii, Y. [Kobe Univ. (Japan)] [and others

    1995-09-01

    For next-generation nuclear reactors, hybrid safety systems which consist of active and passive safety systems have been planned. Steam generators with horizontal U bend pipelines will be used as one of the passive safety systems. It is required to clarify flow characteristics, especially the onset of flooding, in the horizontal U bend pipelines in order to examine their safety. Flooding in vertical pipes has been studied extensively. However, there is little study on flooding in the horizontal U bend pipelines. It is supposed that the onset of flooding in the horizontal U bend pipelines is different from that in vertical pipes. On the other hand, liquid is generated due to condensation of steam in pipes of the horizontal steam generators at the loss of coolant accident because the steam generators will be used as a condenser of a cooling system of steam from the reactor. It is necessary to simulate this situation by the supply of water at the middle of horizontal pipe. In the present paper, experiments were carried out using a horizontal U bend pipeline with a liquid supply section in the midway of pipeline. The onset of flooding in the horizontal U bend pipeline was measured. Effects of the length of horizontal pipe and the radius of U bend on the onset of flooding were discussed.

  1. A study on the instability criterion for the stratified flow in horizontal pipe at cocurrent flow conditions

    Energy Technology Data Exchange (ETDEWEB)

    Sung, Chang Kyung [Korea Electric Power Research Institute, Taejon (Korea, Republic of)

    1997-12-31

    This paper presents a theoretical approach of the instability criterion from stratified to nonstratified flow in horizontal pipe at cocurrent flow conditions. The new theoretical instability criterion for the stratified and nonstratified flow transition in horizontal pipe has been developed by hyperbolic equations in two-phase flow. Critical flow condition criterion and onset of slugging at cocurrent flow condition correspond to zero and imaginary characteristics which occur when the hyperbolicity of a stratified two-phase flow is broken, respectively. Through comparison between results predicted by the present flow is broken, respectively. Through comparison between results predicted by the present theory and the Kukita et al. [1] experimental data of pipes, it is shown that they are in good agreement with data. 4 refs., 2 figs. (Author)

  2. A study on the instability criterion for the stratified flow in horizontal pipe at cocurrent flow conditions

    Energy Technology Data Exchange (ETDEWEB)

    Sung, Chang Kyung [Korea Electric Power Research Institute, Taejon (Korea, Republic of)

    1998-12-31

    This paper presents a theoretical approach of the instability criterion from stratified to nonstratified flow in horizontal pipe at cocurrent flow conditions. The new theoretical instability criterion for the stratified and nonstratified flow transition in horizontal pipe has been developed by hyperbolic equations in two-phase flow. Critical flow condition criterion and onset of slugging at cocurrent flow condition correspond to zero and imaginary characteristics which occur when the hyperbolicity of a stratified two-phase flow is broken, respectively. Through comparison between results predicted by the present flow is broken, respectively. Through comparison between results predicted by the present theory and the Kukita et al. [1] experimental data of pipes, it is shown that they are in good agreement with data. 4 refs., 2 figs. (Author)

  3. Investigation of Two-Phase Flow in Short Horizontal Mini Channel Height of 1 MM

    Directory of Open Access Journals (Sweden)

    Ron’shin Fedor

    2016-01-01

    Full Text Available The experiments with two-phase flow in the short horizontal rectangular minichannel with the height of 1 mm and width of 29 mm have been carried out using water and gas nitrogen. The five two-phase flow patterns have been recognized in the minichannel: churn, stratified, annular, bubble, and jet. These regimes are plotted on a graph and the boundaries between them determine precisely. The height of a horizontal minichannels has a significant role on boundaries between the flow regimes.

  4. An analysis direct-contact condensation in horizontal cocurrent stratified flow of steam and cold water

    International Nuclear Information System (INIS)

    Lee, Suk Ho; Kim, Hho Jung

    1992-01-01

    The physical benchmark problem on the direct-contact condensation under the horizontal cocurrent stratified flow was analyzed using the RELAP5/MOD2 and /MOD3 one-dimensional model. Analysis was performed for the Northwestern experiments, which involved condensing steam/water flow in a rectangular channel. The study showed that the RELAP5 interfacial heat transfer model, under the horizontal stratified flow regime, predicted the condensation rate well though the interfacial heat transfer area was underpredicted. However, some discrepancies in water layer thickness and local heat transfer coefficient with experimental results were found especially when there is a wavy interface, and those were satisfied only within the range. (Author)

  5. Core-annular flow through a horizontal pipe : Hydrodynamic counterbalancing of buoyancy force on core

    NARCIS (Netherlands)

    Ooms, G.; Vuik, C.; Poesio, P.

    2007-01-01

    A theoretical investigation has been made of core-annular flow: the flow of a high-viscosity liquid core surrounded by a low-viscosity liquid annular layer through a horizontal pipe. Special attention is paid to the question of how the buoyancy force on the core, caused by a density difference

  6. Investigation of straitified and countercurrent flows in horizontal piping during a loss-of-coolant accident

    International Nuclear Information System (INIS)

    Bourteele, J.P.

    1980-06-01

    The ECTHOR program consists in a loop having as objective to study the flow regimes in horizontal pipings (stratification, countercurrent flows) in conditions representative of small break transients within commercial PWR. The ECTHOR tests are in process. Experimental results are already available and are presented in this paper: scaling problem, U tube experiments, hot leg experiments, high pressure tests

  7. The root flow of horizontal axis wind turbine blades : Experimental analysis and numerical validation

    NARCIS (Netherlands)

    Akay, B.

    2016-01-01

    Despite a long research history in the field of wind turbine aerodynamics, horizontal axis wind turbine (HAWT) blade's root flow aerodynamics is among the least understood topics. In this thesis work, a detailed investigation of the root flow is performed to gain a better insight into the features

  8. A mechanistic determination of horizontal flow regime bound using void wave celerity

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.W. [Ajou Univ., Suwon (Korea, Republic of)

    1995-09-01

    The two-phase flow regime boundaries in a horizontal channel has been investigated by using the behavior of the second order void wave celerities. The average two-fluid model has been constituted with closure relations for horizontally stratified and bubbly flows. A vapor phase turbulent stress model for a smooth interface geometry has been included. It is found that the second order waves (i.e., eigenvalues) propagate in opposite direction with almost the same speed when the liquid phase is stationary. Using the well-posedness limit of the two-phase system, the dispersed-stratified flow regime boundary has been modeled. Two-phase Froude number has been theoretically found to be a convenient parameter in quantifying the flow regime boundary as a function of the void fraction. It is found that interaction between void wave celerities become stronger as the two-phase Froude number is reduced. This result should be interpreted as that gravity and the relative velocity are key parameters in determining flow regime boundaries in a horizontal flow. The influence of the vapor phase turbulent stress found to stabilize the flow stratification. This study clearly shows that the average two-fluid model is very effective for a mechanistic determination of horizontal flow regimes if appropriate closure relations are developed.

  9. A mechanistic determination of horizontal flow regime bound using void wave celerity

    International Nuclear Information System (INIS)

    Park, J.W.

    1995-01-01

    The two-phase flow regime boundaries in a horizontal channel has been investigated by using the behavior of the second order void wave celerities. The average two-fluid model has been constituted with closure relations for horizontally stratified and bubbly flows. A vapor phase turbulent stress model for a smooth interface geometry has been included. It is found that the second order waves (i.e., eigenvalues) propagate in opposite direction with almost the same speed when the liquid phase is stationary. Using the well-posedness limit of the two-phase system, the dispersed-stratified flow regime boundary has been modeled. Two-phase Froude number has been theoretically found to be a convenient parameter in quantifying the flow regime boundary as a function of the void fraction. It is found that interaction between void wave celerities become stronger as the two-phase Froude number is reduced. This result should be interpreted as that gravity and the relative velocity are key parameters in determining flow regime boundaries in a horizontal flow. The influence of the vapor phase turbulent stress found to stabilize the flow stratification. This study clearly shows that the average two-fluid model is very effective for a mechanistic determination of horizontal flow regimes if appropriate closure relations are developed

  10. Horizontal subsurface flow constructed wetlands for mitigation of ...

    African Journals Online (AJOL)

    The feasibility of using constructed wetlands (CWs) for the mitigation of pesticide runoff has been studied in the last decade. However, a lack of related data was verified when subsurface flow constructed wetlands (SSF CWs) are considered for this purpose. In the present work, SSF CWs were submitted to continuous ...

  11. Application of multiphase flow methods to horizontal underbalanced drilling

    Energy Technology Data Exchange (ETDEWEB)

    Smith, S. P.; Gregory, G. A.; Munro, N.; Muqeem, M.

    1998-12-31

    Ways in which multiphase flow pressure loss calculations can be used in the design and optimization of underbalanced drilling operations are demonstrated. Existing pressure loss calculation methods are evaluated using detailed field measurements for three oil wells and one gas well drilled underbalanced with coiled tubing. 10 refs., 3 tabs., 17 figs.

  12. Anaerobic horizontal flow reactor with polyethylene terephthalate as support material

    Directory of Open Access Journals (Sweden)

    Marcelo Muñoz

    2016-06-01

    Full Text Available A pilot anaerobic reactor was installed to remove the organic load of wastewater from dairy industry. It uses a bacterial inoculum previously acclimated to the substrate. It was disposed horizontally and filled with pieces of polyethylene terephthalate (PET, from plastic bottles. The reactor was operated at room temperature, during 100 days, in three phases: 1 the reactor was stabilized with volumetric organic load from 0.013 to 0.500 kg/day.m³; 2 the hydraulic retention time was of 1 day and the volumetric organic load of 3 kg/day.m³; 3 the volumetric organic load was incremented from 4 to 6.6 kg/day.m³ and the hydraulic retention time was 1 day. Organic material removal efficiencies was of 85%, and approximately 75% were obtained in the second and third phase, respectively. The Y value was 0.15, indicating that 0.15 kg of biomass were generated by kg of QDO supplied to the reactor. Finally, the biomass generated inside the reactor was analyzed, obtaining a value of 18868 mg/L, which is a higher value than those of conventional systems.

  13. Flow distribution in a solar collector panel with horizontally inclined absorber strips

    DEFF Research Database (Denmark)

    Fan, Jianhua; Shah, Louise Jivan; Furbo, Simon

    2007-01-01

    The objective of this work is to theoretically and experimentally investigate the flow and temperature distribution in a solar collector panel with an absorber consisting of horizontally inclined strips. Fluid flow and heat transfer in the collector panel are studied by means of computational fluid...... dynamics (CFD) calculations. Further, experimental investigations of a 12.5 m(2) solar collector panel with 16 parallel connected horizontal fins are carried out. The flow distribution through the absorber is evaluated by means of temperature measurements on the backside of the absorber tubes. The measured...... rate, properties of solar collector fluid, solar collector fluid inlet temperature and collector tilt angle are shown. The flow distribution through the absorber fins is uniform if high flow rates are used. By decreased flow rate and decreased content of glycol in the glycol/water mixture used as solar...

  14. A criterion for the onset of slugging in horizontal stratified air-water countercurrent flow

    International Nuclear Information System (INIS)

    Chun, Moon-Hyun; Lee, Byung-Ryung; Kim, Yang-Seok

    1995-01-01

    This paper presents an experimental and theoretical investigation of wave height and transition criterion from wavy to slug flow in horizontal air-water countercurrent stratified flow conditions. A theoretical formula for the wave height in a stratified wavy flow regime has been developed using the concept of total energy balance over a wave crest to consider the shear stress acting on the interface of two fluids. From the limiting condition of the formula for the wave height, a necessary criterion for transition from a stratified wavy flow to a slug flow has been derived. A series of experiments have been conducted changing the non-dimensional water depth and the flow rates of air in a horizontal pipe and a duct. Comparisons between the measured data and the predictions of the present theory show that the agreement is within ±8%

  15. A criterion for the onset of slugging in horizontal stratified air-water countercurrent flow

    Energy Technology Data Exchange (ETDEWEB)

    Chun, Moon-Hyun; Lee, Byung-Ryung; Kim, Yang-Seok [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)] [and others

    1995-09-01

    This paper presents an experimental and theoretical investigation of wave height and transition criterion from wavy to slug flow in horizontal air-water countercurrent stratified flow conditions. A theoretical formula for the wave height in a stratified wavy flow regime has been developed using the concept of total energy balance over a wave crest to consider the shear stress acting on the interface of two fluids. From the limiting condition of the formula for the wave height, a necessary criterion for transition from a stratified wavy flow to a slug flow has been derived. A series of experiments have been conducted changing the non-dimensional water depth and the flow rates of air in a horizontal pipe and a duct. Comparisons between the measured data and the predictions of the present theory show that the agreement is within {plus_minus}8%.

  16. Fully stratified particle-laden flow in horizontal circular pipe

    Czech Academy of Sciences Publication Activity Database

    Vlasák, Pavel; Kysela, Bohuš; Chára, Zdeněk

    2014-01-01

    Roč. 32, č. 2 (2014), s. 179-185 ISSN 0272-6351. [7th International Conference for Conveying and Handling of Particulate Solids (CHoPS). Friedrichshafen, 10.09.2013-13.09.2012] R&D Projects: GA ČR GAP105/10/1574 Institutional support: RVO:67985874 Keywords : coarse-grained slurry * flow structure * liquid local velocity * particle velocity * PIV Subject RIV: BK - Fluid Dynamics Impact factor: 0.523, year: 2014

  17. Convection Study by PIV Method Within Horizontal Liquid Layer Evaporating Into Inert Gas Flow

    Directory of Open Access Journals (Sweden)

    Kreta Aleksei

    2016-01-01

    Full Text Available The paper is devoted to the experimental study of convection in a horizontal evaporating liquid layer (ethanol of limited size under the action of gas flow (air. The two-dimensional velocity field in the liquid layer is obtained using the PIV method. The existence of a vortex convective flow within a liquid layer directed towards the gas flow has been revealed.

  18. Counter-current flow in a vertical to horizontal tube with obstructions

    Energy Technology Data Exchange (ETDEWEB)

    Tye, P.; Matuszkiewicz, A.; Teyssedou, A. [Institut de Genie Nucleaire, Quebec (Canada)] [and others

    1995-09-01

    This paper presents experimental results on counter-current flow and flooding in an elbow between a vertical and a horizontal run. The experimental technique used allowed not only the flooding limit to be determined, but also the entire partial delivery region to be studied as well. The influence that various size orifices placed in the horizontal run have on both the delivered liquid flow rates and on the flooding limits is also examined. It is observed that both the flooding limits and the delivered liquid flow rates decrease with decreasing orifice size. Further, it is also observed that the mechanisms that govern the partial delivery of the liquid are significantly different when an orifice is present in the horizontal leg as compared to the case when no orifice is present.

  19. Visualization of Two Phase Flow in a Horizontal Flow with Electrical Resistance Tomography based on Extended Kalman Filter

    International Nuclear Information System (INIS)

    Lee, Jeong Seong; Malik, Nauman Muhammad; Khambampati, Anil Kumar; Rashid, Ahmar; Kim, Sin; Kim, Kyung Youn

    2008-01-01

    For the visualization of the phase distribution in two phase flows, the electrical resistance tomography (ERT) technique is introduced. In ERT, the internal resistivity distribution is reconstructed based on the known sets of the injected currents and measured voltages on the surface of the object. The physical relationship between the internal resistivity and the surface voltages is governed by a partial differential equation with appropriate boundary conditions. This paper considers the estimation of the phase distribution with ERT in two phase flow in a horizontal flow using extended Kalman filter. To evaluate the reconstruction performance of the proposed algorithm, the experiments simulated two phase flows in a horizontal flow were carried out. The experiments with two phase flow phantom were done to suggest a practical implication of this research in detecting gas bubble in a feed water pipe of heat transfer systems

  20. Analytical solution of velocity for ammonia-water horizontal falling-film flow

    International Nuclear Information System (INIS)

    Zhang, Qiang; Gao, Yide

    2016-01-01

    Highlights: • We built a new falling-film flow model that analyzed the film flow characteristics. • We have obtained a new formula of film thickness over the horizontal tube. • We derived analysis solution to analyze the effect of inertial force to velocity in the entrance region of liquid film. • It described the characters of the ammonia-waterfalling-film film over the horizontal tube. • It is good for falling-film absorption, generation and evaporation to optimizing the design parameters and further improving the capabilities. - Abstract: A new horizontal tube falling film velocity model was built and calculated to analyze the problem of film flow conditions. This model also analyzed the film thickness distribution in horizontal tube falling film flow and considered the effect of the inertial force on velocity. The film thickness and velocity profile can be obtained based on the principle of linear superposition, a method of separation of variables that introduces the effect of variable inertial force on the velocity profile in the process of falling-film absorption. The film flow condition and the film thickness distribution at different fluid Reynolds numbers (Re) and tube diameters were calculated and compared with the results of the Crank–Nicolson numerical solution under the same conditions. The results show that the film flow condition out of a horizontal tube and that the film thickness increases with the fluid Re. At a specific Re and suitable tube diameter, the horizontal tube reaches a more uniform film. Finally, the analysis results have similar trend with the experimental and numerical predicted data in literature.

  1. FLOW DISTRIBUTION IN A SOLAR COLLECTOR PANEL WITH HORIZONTAL ABSORBER STRIPS

    DEFF Research Database (Denmark)

    Fan, Jianhua; Shah, Louise Jivan; Furbo, Simon

    2007-01-01

    The objective of this work is to theoretically and experimentally investigate the flow and temperature distribution in a solar collector panel with an absorber consisting of horizontal strips. Fluid flow and heat transfer in the collector panel are studied by means of computational fluid dynamics...... (CFD) calculations. Further, experimental investigations of a 12.5 m² solar collector panel with 16 parallel connected horizontal fins are carried out. The flow distribution through the absorber is evaluated by means of temperature measurements on the backside of the absorber tubes. The measured...... collector fluid, and by increased collector tilt and inlet temperature, the flow distribution gets worse resulting in a decreased collector efficiency and an increased risk of boiling in the upper part of the collector panel. Keywords: Solar collector; Flow distribution; Computational Fluid Dynamics (CFD...

  2. Numerical simulation of turbulent buoyant flows in horizontal channels

    International Nuclear Information System (INIS)

    Seiter, C.

    1995-09-01

    A numerical method is presented, to calculate the three-dimensional, time-dependent large scale structure of turbulent buoyant flows. The subject of the study is the Rayleigh-Benard-convection with air (Pr=0.71, Ra=2.5 10 6 , 10 7 ) and sodium (Pr=0.006, Ra=8.4 10 4 , 2.5 10 5 , 10 6 , 10 7 ) and a fluid layer with water and an internal heat source (Pr=7.0, Ra I =1.5 10 10 ) at moderate and high Rayleigh-numbers. The goal of the work is both, the analysis of structures of instantaneous as well as the statistical analysis of spatially and/or time averaged data, to give a contribution to the investigation of the characteristics of turbulent natural convection mainly in fluids with small Prandtl-numbers. The large eddy simulation of natural convection requires the development of appropriate momentum and heat subgrid scale models and the formulation of new boundary conditions. The used energy-length-models in the computer code TURBIT are extended methodically by modification of the characteristic length scales of the sub scale turbulence. The reduction or the increase of the sub scale turbulence correlations, caused by the influence of solid boundaries or the stratification, is considered. In the same way the new boundary conditions for the diffusive terms of the conservation equations are seen to be necessary, when the thermal or in the case of liquid metals the more critical hydrodynamic boundary layer is resolved insufficiently or not at all. The extended and new methods, models and boundary conditions, which enabled the realization of the planned simulations, are presented. (orig.)

  3. Experimental on two sensors combination used in horizontal pipe gas-water two-phase flow

    International Nuclear Information System (INIS)

    Wu, Hao; Dong, Feng

    2014-01-01

    Gas-water two phase flow phenomenon widely exists in production and living and the measurement of it is meaningful. A new type of long-waist cone flow sensor has been designed to measure two-phase mass flow rate. Six rings structure of conductance probe is used to measure volume fraction and axial velocity. The calibration of them have been made. Two sensors have been combined in horizontal pipeline experiment to measure two-phase flow mass flow rate. Several model of gas-water two-phase flow has been discussed. The calculation errors of total mass flow rate measurement is less than 5% based on the revised homogeneous flow model

  4. Simulation of horizontal pipe two-phase slug flows using the two-fluid model

    Energy Technology Data Exchange (ETDEWEB)

    Ortega Malca, Arturo J. [Pontificia Univ. Catolica do Rio de Janeiro, RJ (Brazil). Dept. de Engenharia Mecanica. Nucleo de Simulacao Termohidraulica de Dutos (SIMDUT); Nieckele, Angela O. [Pontificia Univ. Catolica do Rio de Janeiro, RJ (Brazil). Dept. de Engenharia Mecanica

    2005-07-01

    Slug flow occurs in many engineering applications, mainly in the transport of hydrocarbon fluids in pipelines. The intermittency of slug flow causes severe unsteady loading on the pipelines carrying the fluids, which gives rise to design problems. Therefore, it is important to be able to predict the onset and development of slug flow as well as slug characteristics. The present work consists in the simulation of two-phase flow in slug pattern through horizontal pipes using the two-fluid model in its transient and one-dimensional form. The advantage of this model is that the flow field is allowed to develop naturally from a given initial conditions as part of the transient calculation; the slug evolves automatically as a product of the computed flow development. Simulations are then carried out for a large number of flow conditions that lead a slug flow. (author)

  5. Effect of completion geometry and phasing on single-phase liquid flow behaviour in horizontal wells

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, H.; Sarica, C.; Brill, P. [Tulsa Unov., OK (United States)

    1998-12-31

    The effects of completion geometries and the phasing and density of injection openings in horizontal wells was studied. A total of 1,257 tests were conducted for no fluid injections, no main flow at the test section inlet, and with fluid injection for Reynolds numbers ranging from 4,000 to 60,000 and for influx to main flow rate ratios ranging from 1/5 to 1/2000. Results demonstrated the dramatic effects of completion geometry, phasing density, Reynolds number and main flow rate on the pressure behaviour and therefore on the production behaviour of the well. A general friction factor expression for horizontal wells with multiple injection openings was developed based on the conservation of mass and momentum and using a commercial Computational Fluid Dynamics (CFD) computer program to determine the length of the flow developing region in a horizontal well. A field example is presented to show the importance of using the proper friction factor correlation to calculate the pressure drop in a horizontal well. 32 refs., 4 tabs., 20 figs.

  6. ESTIMATION OF THE DECREASING OF 137 CS SEDIMENT IN THE SOIL DUE TO HORIZONTAL FLOWING

    Directory of Open Access Journals (Sweden)

    O. N. Prokof'ev

    2008-01-01

    Full Text Available The purpose of work is to estimate the possible decreasing of the density of  137 Cs sediment in the soil influenced by the horizontal flowing basing on the analysis of on location observations on the density of  137 Cs sediment in the soil after the Chernobyl accident.

  7. Experiment and numerical simulation of bubbly two-phase flow across horizontal and inclined rod bundles

    International Nuclear Information System (INIS)

    Serizawa, A.; Huda, K.; Yamada, Y.; Kataoka, I.

    1997-01-01

    Experimental and numerical analyses were carried out on vertically upward air-water bubbly two-phase flow behavior in both horizontal and inclined rod bundles with either in-line or staggered array. The inclination angle of the rod bundle varied from 0 to 60 with respect to the horizontal. The measured phase distribution indicated non-uniform characteristics, particularly in the direction of the rod axis when the rods were inclined. The mechanisms for this non-uniform phase distribution is supposed to be due to: (1) Bubble segregation phenomenon which depends on the bubble size and shape: (2) bubble entrainment by the large scale secondary flow induced by the pressure gradient in the horizontal direction which crosses the rod bundle; (3) effects of bubble entrapment by vortices generated in the wake behind the rods which travel upward along the rod axis; and (4) effect of bubble entrainment by local flows sliding up along the front surface of the rods. The liquid velocity and turbulence distributions were also measured and discussed. In these speculations, the mechanisms for bubble bouncing at the curved rod surface and turbulence production induced by a bubble were discussed, based on visual observations. Finally, the bubble behaviors in vertically upward bubbly two-phase flow across horizontal rod bundle were analyzed based on a particle tracking method (one-way coupling). The predicted bubble trajectories clearly indicated the bubble entrapment by vortices in the wake region. (orig.)

  8. Unsteady Flow in a Horizontal Double-Sided Symmetric Thin Liquid Films

    Directory of Open Access Journals (Sweden)

    Joseph G. ABDULAHAD

    2017-06-01

    Full Text Available In this paper a mathematical model is constructed to describe a two dimensional incompressible flow in a symmetric horizontal thin liquid film for unsteadies flow. We apply the Navier-Stokes equations with specified boundary conditions and we obtain the equation of the film thickness by using the similarity method in which we can isolate the explicit time dependence and then the shape of the film will depend on one variable only.

  9. Horizontal stratified flow model for the 1-D module of WCOBRA/TRAC-TF2: modeling and validation

    Energy Technology Data Exchange (ETDEWEB)

    Liao, J.; Frepoli, C.; Ohkawa, K., E-mail: liaoj@westinghouse.com [Westinghouse Electric Company LLC, LOCA Integrated Services I, Cranberry Twp, Pennsylvania (United States)

    2011-07-01

    For a two-phase flow in a horizontal pipe, the individual phases may separate by gravity. This horizontal stratification significantly impacts the interfacial drag, interfacial heat transfer and wall drag of the two phase flow. For a PWR small break LOCA, the horizontal stratification in cold legs is a highly important phenomenon during loop seal clearance, boiloff and recovery periods. The low interfacial drag in the stratified flow directly controls the time period for the loop clearance and the level of residual water in the loop seal. Horizontal stratification in hot legs also impacts the natural circulation stage of a small break LOCA. In addition, the offtake phenomenon and cold leg condensation phenomenon are also affected by the occurrence of horizontal stratification in the cold legs. In the 1-D module of the WCOBRA/TRAC-TF2 computer code, a horizontal stratification criterion was developed by combining the Taitel-Dukler model and the Wallis-Dobson model, which approximates the viscous Kelvin-Helmholtz neutral stability boundary. The objective of this paper is to present the horizontal stratification model implemented in the code and its assessment against relevant data. The adequacy of the horizontal stratification transition criterion is confirmed by examining the code-predicted flow regime in a horizontal pipe with the measured data in the flow regime map. The void fractions (or liquid level) for the horizontal stratified flow in cold leg or hot leg are predicted with a reasonable accuracy. (author)

  10. Assessment of horizontal in-tube condensation models using MARS code. Part I: Stratified flow condensation

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Seong-Su [Department of Engineering Project, FNC Technology Co., Ltd., Bldg. 135-308, Seoul National University, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Department of Nuclear Engineering, Seoul National University, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Hong, Soon-Joon, E-mail: sjhong90@fnctech.com [Department of Engineering Project, FNC Technology Co., Ltd., Bldg. 135-308, Seoul National University, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Park, Ju-Yeop; Seul, Kwang-Won [Korea Institute of Nuclear Safety, 19 Kuseong-dong, Yuseong-gu, Daejon (Korea, Republic of); Park, Goon-Cherl [Department of Nuclear Engineering, Seoul National University, Gwanak-gu, Seoul 151-744 (Korea, Republic of)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer This study collected 11 horizontal in-tube condensation models for stratified flow. Black-Right-Pointing-Pointer This study assessed the predictive capability of the models for steam condensation. Black-Right-Pointing-Pointer Purdue-PCCS experiments were simulated using MARS code incorporated with models. Black-Right-Pointing-Pointer Cavallini et al. (2006) model predicts well the data for stratified flow condition. Black-Right-Pointing-Pointer Results of this study can be used to improve condensation model in RELAP5 or MARS. - Abstract: The accurate prediction of the horizontal in-tube condensation heat transfer is a primary concern in the optimum design and safety analysis of horizontal heat exchangers of passive safety systems such as the passive containment cooling system (PCCS), the emergency condenser system (ECS) and the passive auxiliary feed-water system (PAFS). It is essential to analyze and assess the predictive capability of the previous horizontal in-tube condensation models for each flow regime using various experimental data. This study assessed totally 11 condensation models for the stratified flow, one of the main flow regime encountered in the horizontal condenser, with the heat transfer data from the Purdue-PCCS experiment using the multi-dimensional analysis of reactor safety (MARS) code. From the assessments, it was found that the models by Akers and Rosson, Chato, Tandon et al., Sweeney and Chato, and Cavallini et al. (2002) under-predicted the data in the main condensation heat transfer region, on the contrary to this, the models by Rosson and Meyers, Jaster and Kosky, Fujii, Dobson and Chato, and Thome et al. similarly- or over-predicted the data, and especially, Cavallini et al. (2006) model shows good predictive capability for all test conditions. The results of this study can be used importantly to improve the condensation models in thermal hydraulic code, such as RELAP5 or MARS code.

  11. A study of Two-Phase Flow Regime Maps in Vertical and Horizontal Pipes

    International Nuclear Information System (INIS)

    Kim, Kyung Doo; Kang, Doo Hyuk

    2007-10-01

    A safety analysis code to design a pressurized water reactor and to obtain the licences including entire proprietary rights is under development in domestic research and development project. The purpose and scope of this report is to develop the flow regimes related models for inter-phase friction, wall frictions, wall heat transfer, and inter-phase heat and mass transfer in two-phase three-field equations. In order to choose choose the flow regime criteria, we have investigated various exiting best-estimate T/H codes in this chapter 2. They are the RELAP5-3D, TRAC-M, CATHARE, MARS codes. Around 500 references used in these codes have been collected and reviewed. Also we have investigated eleven papers in detail. In chapter 3, based on the selected flow regimes, the flow regime maps for a gas-liquid flow in horizontal and vertical tubes have decided including the mechanisms of flow regime transition regions. Conclusively, the process will be presented for choosing the best flow regime maps which occur in gas-liquid two-phase flow in horizontal and vertical pipes. We will look forward to decide the constitutive relations based upon the flow regime maps that are determined in this works. The constitutive relations will be used for the code under development

  12. Experimental data for the slug two-phase flow characteristics in horizontal pipeline

    Directory of Open Access Journals (Sweden)

    Abdalellah O. Mohmmed

    2018-02-01

    Full Text Available The data presented in this article were the basis for the study reported in the research articles entitled “Statistical assessment of experimental observation on the slug body length and slug translational velocity in a horizontal pipe” (Al-Kayiem et al., 2017 [1] which presents an experimental investigation of the slug velocity and slug body length for air-water tow phase flow in horizontal pipe. Here, in this article, the experimental set-up and the major instruments used for obtaining the computed data were explained in details. This data will be presented in the form of tables and videos.

  13. Interfacial condensation heat transfer for countercurrent steam-water wavy flow in a horizontal circular pipe

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyung Won; Chun, Moon Hyun [Korea Advanced Institute of Science and Technolgy, Taejon (Korea, Republic of); Chu, In Cheol [KAERI, Taejon (Korea, Republic of)

    2000-10-01

    An experimental study of interfacial condensation heat transfer has been performed for countercurrent steam-water wavy flow in a horizontal circular pipe. A total of 105 local interfacial condensation heat transfer coefficients have been obtained for various combinations of test parameters. Two empirical Nusselt number correlations were developed and parametric effects of steam and water flow rates and the degree of water subcooling on the condensation heat transfer were examined. For the wavy interface condition, the local Nusselt number is more strongly sensitive to the steam Reynolds number than water Reynolds number as opposed to the case of smooth interface condition. Comparisons of the present circular pipe data with existing correlations showed that existing correlations developed for rectangular channels are not directly applicable to a horizontal circular pipe flow.

  14. Characterization of the slug flow formation in vertical-to-horizontal channels with obstructions

    International Nuclear Information System (INIS)

    Onder, E.N.

    2004-01-01

    This thesis presents the results of the work carried out to study the formation of slugs under conditions of vertical-to-horizontal counter-current flow with obstructions. A flow instability is the mechanism proposed for the formation of slugs in a co-current flow. However, to the best of author's knowledge no work has been carried out for the formation of slugs in a vertical-to-horizontal counter-current flow with obstructions. Despite the existence of a few studies on counter-current vertical-to-horizontal slug flow with obstructions, it is in particular of great importance in the area of nuclear reactor safety analysis of a CANDU reactor. A test section manufactured of 63.5 mm inner diameter (ID) plexiglass was used for this work. The test section consists of 2022 mm long vertical and 3327 mm long horizontal legs connected by a 90 o PVC elbow. The horizontal leg contains flanges in which an orifice may be installed. These flanges are located at the distance of 1110 mm and 2217 mm from the elbow. The experiments were carried out to study the frequency of the formation of slugs, the slug propagation velocity and the averaged void fraction of slugs. We also carried out experiments for the characterisation of the propagation of waves. This allowed us to obtain the initial conditions required by the present model in order to predict the formation of slugs. In this model, the initial profile of waves was used to start calculations. Therefore, the aim of these experiments was to obtain the initial profile of these waves. The comparison of the experimental data collected at the onset of flooding with that collected at the onset of slugging shows that the results are very close to each other. This reflects the fact that flooding is simultaneously accompanied by the formation of slugs in the horizontal leg. We found that, for a given liquid flow rate, the gas flow rate, necessary to form the slugs as well as to provoke flooding, decreases as the severity of the

  15. Unsteady flow of an incompressible fluid in a horizontal porous medium with suction

    International Nuclear Information System (INIS)

    Bestman, A.R.

    1988-04-01

    A theoretical analysis of two-dimensional unsteady flow in a porous medium bounded by a horizontal wall is presented as a perturbation on a basic flow. It is assumed that the perturbation is occasioned by a sudden suction at the wall. Even for a highly permeable medium the characteristic Reynolds number in porous media flow is usually small and asymptotic solutions are developed by the Laplace transform technique. It is observed that the perturbed shear stress at the wall decays exponentially with time. (author). 5 refs

  16. Numerical simulation of two-phase flow in horizontal interconnected subchannels

    International Nuclear Information System (INIS)

    Shoukri, M.; Tahir, A.; Carver, M.B.

    1983-01-01

    Different subchannel computer codes have been successfully used for the thermal-hydraulic analysis of coolant flow in vertical fuel channels. However, none of these methods is suitable for two-phase flow in horizontal fuel channels, such as those of the CANDU nuclear reactors, due to the lack of appropriate constitutive relationships that can correctly account for the gravity separation effects. This paper describes the incorporation of a transverse vapour drift model which accounts for the combined effect of gravity separation and turbulent diffusion into the existing subchannel computer code SAGA. Although the basic structure of the code remains similar to SAGA III some modifications in both the mathematical formulation and numerical solution have been incorporated. These modifications resulted in significant improvements in the code's ability in modelling horizontal two-phase subchannel flow. The new version of the code was tested and found to be capable of simulating the complex exchange phenomenon between adjacent horizontal subchannels caused by the interaction of turbulent diffusion, pressure gradient as well as gravity induced cross flows. The code predictions were compared with experimental data obtained from two different sources and showed good agreement

  17. Numerical simulation of two-phase flow in horizontal interconnected subchannels

    International Nuclear Information System (INIS)

    Shourki, M.; Carver, M.B.; Tahir, A.

    1985-01-01

    Different subchannel computer codes have been successfully used for the thermal-hydraulic analysis of coolant flow in vertical fuel channels. None of these methods, however, is suitable for two-phase flow in horizontal fuel channels, such as those of the CANDU nuclear reactors, due to the lack of appropriate constitutive relationships that can correctly account for the gravity separation effects. A transverse vapor drift model that accounts for the combined effect of gravity separation and turbulent diffusion has been incorporated into the existing subchannel computer code SAGA. Although the basic structure of the code remains similar to SAGA III, some modifications in both the mathematical formulation and numerical solution have been incorporated. These modifications resulted in significant improvements in the code's ability to model horizontal two-phase subchannel flow. The new version of the code was tested and found to be capable of simulating the complex exchange phenomenon between adjacent horizontal subchannels caused by the interaction of turbulent diffusion, pressure gradient, and gravity-induced cross flows. The code predictions were compared with experimental data obtained from two different sources and showed good agreement

  18. Stereoscopic particle image velocimetry investigations of the mixed convection exchange flow through a horizontal vent

    Science.gov (United States)

    Varrall, Kevin; Pretrel, Hugues; Vaux, Samuel; Vauquelin, Olivier

    2017-10-01

    The exchange flow through a horizontal vent linking two compartments (one above the other) is studied experimentally. This exchange is here governed by both the buoyant natural effect due to the temperature difference of the fluids in both compartments, and the effect of a (forced) mechanical ventilation applied in the lower compartment. Such a configuration leads to uni- or bi-directional flows through the vent. In the experiments, buoyancy is induced in the lower compartment thanks to an electrical resistor. The forced ventilation is applied in exhaust or supply modes and three different values of the vent area. To estimate both velocity fields and flow rates at the vent, measurements are realized at thermal steady state, flush the vent in the upper compartment using stereoscopic particle image velocimetry (SPIV), which is original for this kind of flow. The SPIV measurements allows the area occupied by both upward and downward flows to be determined.

  19. Post-Dryout Heat Transfer to a Refrigerant Flowing in Horizontal Evaporator Tubes

    Science.gov (United States)

    Mori, Hideo; Yoshida, Suguru; Kakimoto, Yasushi; Ohishi, Katsumi; Fukuda, Kenichi

    Studies of the post-dryout heat transfer were made based on the experimental data for HFC-134a flowing in horizontal smooth and spiral1y grooved (micro-fin) tubes and the characteristics of the post-dryout heat transfer were c1arified. The heat transfer coefficient at medium and high mass flow rates in the smooth tube was lower than the single-phase heat transfer coefficient of the superheated vapor flow, of which mass flow rate was given on the assumption that the flow was in a thermodynamic equilibrium. A prediction method of post-dryout heat transfer coefficient was developed to reproduce the measurement satisfactorily for the smooth tube. The post dryout heat transfer in the micro-fin tube can be regarded approximately as a superheated vapor single-phase heat transfer.

  20. Method of measuring horizontal fluid flow in cased off subsurface formations

    International Nuclear Information System (INIS)

    Paap, H.J.; Arnold, D.M.; Scott, H.D.

    1980-01-01

    An improved method is described for determining the flow rate of earth formation liquids moving horizontally past a steel casing in a well borehole, by neutron irradiation and subsequent decay measurements of the 24 Na produced by thermal neutron capture. The system described compensates for spurious gamma radiation such as that from 56 Mn, produced by neutron irradiation of 55 Mn in the steel casing, by taking measurements for at least three separate measured time intervals in an iterative procedure. (U.K.)

  1. Experimental Study of Flow Boiling Heat Transfer in a Horizontal Microfin Tube

    OpenAIRE

    Yu, Jian; Koyama, Shigeru; Momoki, Satoru

    1995-01-01

    An experimental study on flow boiling heat transfer in a horizontal microfin tube is conducted with pure refrigerants HFC134a, HCFC123 and HCFC22 using a water-heated double-tube type test section. The test microfin tube is a copper tube having the following dimensions: 8.37mm mean inside diameter, 0.168mm fin height, 60fin number and 18 degree of helix angle. The local heat transfer coefficients for both counter and parallel flows are measured in a range of heat flux of 1 to 93W/m^2, mass ve...

  2. Interfacial shear stress in stratified flow in a horizontal rectangular duct

    International Nuclear Information System (INIS)

    Lorencez, C.; Kawaji, M.; Murao, Y.

    1995-01-01

    Interfacial shear stress has been experimentally examined for both cocurrent and countercurrent stratified wavy flows in a horizontal interfacial shear stress from the measurements were examined and the results have been compared with existing correlations. Some differences were found in the estimated interfacial shear stress from the measurements were examined and the results have been compared with existing correlations. Some differences were found in the estimated interfacial shear stress values at high gas flow rates which could be attributed to the assumptions and procedures involved in each method. The interfacial waves and secondary motions were also found to have significant effects on the accuracy of Reynolds stress and turbulence kinetic energy extrapolation methods

  3. Effectiveness of horizontal air flow fans supporting natural ventilation in a Mediterranean multi-span greenhouse

    OpenAIRE

    López, Alejandro; Valera, Diego Luis; Molina-Aiz, Francisco Domingo; Peña, Araceli

    2013-01-01

    Natural ventilation is the most important method of climate control in Mediterranean greenhouses. In this study, the microclimate and air flow inside a Mediterranean greenhouse were evaluated by means of sonic anemometry. Experiments were carried out in conditions of moderate wind (≈ 4.0 m s-1), and at low wind speed (≈ 1.8 m s-1) the natural ventilation of the greenhouse was supplemented by two horizontal air flow fans. The greenhouse is equipped with a single roof vent opening t...

  4. Fully developed laminar flow of two immiscible liquids through horizontal pipes: a variational approach

    Energy Technology Data Exchange (ETDEWEB)

    Kurban, Adib Paulo Abdalla [PETROBRAS, Rio de Janeiro (Brazil). Centro de Pesquisas; Bannwart, Antonio Carlos [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Mecanica

    1990-12-31

    The fully developed laminar flow of two immiscible liquids with both different viscosities and densities through a horizontal round pipe is studied. The interface between the fluids as well as their flow fields are determined by the use of a variational principle: the so called viscous dissipation principle: The results foreseen by this paper are in agreement with the physical observation (e.g. Southern and Ballman) that the more viscous fluid is total or partially encapsulated by the less viscous one. (author) 8 refs., 4 figs.

  5. Fully developed laminar flow of two immiscible liquids through horizontal pipes: a variational approach

    Energy Technology Data Exchange (ETDEWEB)

    Kurban, Adib Paulo Abdalla [PETROBRAS, Rio de Janeiro (Brazil). Centro de Pesquisas; Bannwart, Antonio Carlos [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Mecanica

    1991-12-31

    The fully developed laminar flow of two immiscible liquids with both different viscosities and densities through a horizontal round pipe is studied. The interface between the fluids as well as their flow fields are determined by the use of a variational principle: the so called viscous dissipation principle: The results foreseen by this paper are in agreement with the physical observation (e.g. Southern and Ballman) that the more viscous fluid is total or partially encapsulated by the less viscous one. (author) 8 refs., 4 figs.

  6. The horizontally homogeneous model equations of incompressible atmospheric flow in general orthogonal coordinates

    DEFF Research Database (Denmark)

    Jørgensen, Bo Hoffmann

    2003-01-01

    The goal of this brief report is to express the model equations for an incompressible flow which is horizontally homogeneous. It is intended as a computationally inexpensive starting point of a more complete solution for neutral atmospheric flow overcomplex terrain. This idea was set forth...... by Ayotte and Taylor (1995) and in the work of Beljaars et al. (1987). Unlike the previous models, the present work uses general orthogonal coordinates. Strong conservation form of the model equations is employedto allow a robust and consistent numerical procedure. An invariant tensor form of the model...

  7. Interfacial shear stress in stratified flow in a horizontal rectangular duct

    Energy Technology Data Exchange (ETDEWEB)

    Lorencez, C.; Kawaji, M. [Univ. of Toronto (Canada); Murao, Y. [Tokushima Univ. (Japan)] [and others

    1995-09-01

    Interfacial shear stress has been experimentally examined for both cocurrent and countercurrent stratified wavy flows in a horizontal interfacial shear stress from the measurements were examined and the results have been compared with existing correlations. Some differences were found in the estimated interfacial shear stress from the measurements were examined and the results have been compared with existing correlations. Some differences were found in the estimated interfacial shear stress values at high gas flow rates which could be attributed to the assumptions and procedures involved in each method. The interfacial waves and secondary motions were also found to have significant effects on the accuracy of Reynolds stress and turbulence kinetic energy extrapolation methods.

  8. Pattern recognition techniques for horizontal and vertically upward multiphase flow measurement

    Science.gov (United States)

    Arubi, Tesi I. M.; Yeung, Hoi

    2012-03-01

    The oil and gas industry need for high performing and low cost multiphase meters is ever more justified given the rapid depletion of conventional oil reserves that has led oil companies to develop smaller and marginal fields and reservoirs in remote locations and deep offshore, thereby placing great demands for compact and more cost effective solutions of on-line continuous multiphase flow measurement for well testing, production monitoring, production optimisation, process control and automation. The pattern recognition approach for clamp-on multiphase measurement employed in this study provides one means for meeting this need. High speed caesium-137 radioisotope-based densitometers were installed vertically at the top of a 50.8mm and 101.6mm riser as well as horizontally at the riser base in the Cranfield University multiphase flow test facility. A comprehensive experimental campaign comprising flow conditions typical of operating conditions found in the Petroleum Industry was conducted. The application of a single gamma densitometer unit, in conjunction with pattern recognition techniques to determine both the phase volume fractions and velocities to yield the individual phase flow rates of horizontal and vertically upward multiphase flows was investigated. The pattern recognition systems were trained to map the temporal fluctuations in the multiphase mixture density with the individual phase flow rates using statistical features extracted from the gamma counts signals as their inputs. Initial results yielded individual phase flow rate predictions to within ±5% relative error for the two phase airwater flows and ±10% for three phase air-oil-water flows data.

  9. Single-phase flow and flow boiling of water in horizontal rectangular microchannels

    OpenAIRE

    Mirmanto

    2013-01-01

    This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University The current study is part of a long term experimental project devoted to investigating single-phase flow pressure drop and heat transfer, flow boiling pressure drop and heat transfer, flow boiling instability and flow visualization of de-ionized water flow in microchannels. The experimental facility was first designed and constructed by S. Gedupudi (2009) and in the present study; ...

  10. An analytical study on groundwater flow in drainage basins with horizontal wells

    Science.gov (United States)

    Wang, Jun-Zhi; Jiang, Xiao-Wei; Wan, Li; Wang, Xu-Sheng; Li, Hailong

    2014-06-01

    Analytical studies on release/capture zones are often limited to a uniform background groundwater flow. In fact, for basin-scale problems, the undulating water table would lead to the development of hierarchically nested flow systems, which are more complex than a uniform flow. Under the premise that the water table is a replica of undulating topography and hardly influenced by wells, an analytical solution of hydraulic head is derived for a two-dimensional cross section of a drainage basin with horizontal injection/pumping wells. Based on the analytical solution, distributions of hydraulic head, stagnation points and flow systems (including release/capture zones) are explored. The superposition of injection/pumping wells onto the background flow field leads to the development of new internal stagnation points and new flow systems (including release/capture zones). Generally speaking, the existence of n injection/pumping wells would result in up to n new internal stagnation points and up to 2n new flow systems (including release/capture zones). The analytical study presented, which integrates traditional well hydraulics with the theory of regional groundwater flow, is useful in understanding basin-scale groundwater flow influenced by human activities.

  11. Effects of roll waves on annular flow heat transfer at horizontal condenser tube

    International Nuclear Information System (INIS)

    Kondo, Masaya; Nakamura, Hideo; Anoda, Yoshinari; Sakashita, Akihiro

    2002-01-01

    Heat removal characteristic of a horizontal in-tube condensation heat exchanger is under investigation to be used for a passive containment cooling system (PCCS) of a next generation-type BWR. Flow regime observed at the inlet of the condenser tube was annular flow, and the local heat transfer rate was ∼20% larger than the prediction by the Dobson-Chato correlation. Roll waves were found to appear on the liquid film in the annular flow. The measured local condensation heat transfer rate was being closely related to the roll waves frequency. Based on these observations, a model is proposed which predicts the condensation heat transfer coefficient for annular flows around the tube inlet. The proposed model predicts well the influences of pressure, local gas-phase velocity and film thickness. (author)

  12. Reconstruction of a constructed wetland with horizontal subsurface flow after 18 years of operation.

    Science.gov (United States)

    Hudcová, Tereza; Vymazal, Jan; Dunajský, Michal Kriška

    2013-01-01

    The constructed wetland (CW) for 326 PE with horizontal subsurface flow at Kotenčice, Central Bohemia, Czech Republic, was built in 1994. Despite the relatively high efficiency of the CW, the filtration beds suffered from clogging, and therefore it was decided in 2011 to rebuild the whole system. The new treatment system was built as an experimental system consisting of four different combinations of horizontal and vertical beds. The major aim of the design was to determine the best hybrid combination which then could be used in the future for refurbishment of older horizontal flow CWs or for the new systems. The mechanical pretreatment consists of mechanical bar screens, a new Imhoff tank, and the original settling tank which has been converted into the accumulation tank from where the wastewater is pumped into the wetlands. The filters are planted with Phragmites australis, Phalaris arundinacea, Iris pseudacorus, Iris sibirica, Glyceria maxima and Lythrum salicaria in order to evaluate and compare various plant species' effect on the treatment process. The new technology includes a tertiary treatment which consists of a greenhouse with a photo-reactor for the cultivation of algae and hydroponic systems (residual nutrients removal), sludge reed-beds and a composting field.

  13. Lateral Mixing Mechanisms in Vertical and Horizontal Interconnected Subchannel Two-Phase Flows

    International Nuclear Information System (INIS)

    Gencay, Sarman; Teyssedou, Alberto; Tye, Peter

    2002-01-01

    A lateral mixing model based on equal volume exchange between two laterally interconnected subchannels is presented. The following mixing mechanisms are taken into account in this model: (a) diversion cross flow, caused by the lateral pressure difference between adjacent subchannels; (b) turbulent void diffusion, which is governed by the lateral void fraction difference between the subchannels; (c) void drift, responsible for the tendency of the vapor phase to drift toward unobstructed regions; and (d) buoyancy drift, which takes into account the effect of gravity in horizontal flows. Experimental two-phase air-water data obtained using two test sections having different geometries and orientations are used to determine the diffusion coefficients required by the mixing model. Under the absence of diversion crossflow, i.e., negligible lateral pressure difference between the subchannels, it is observed that the diffusion coefficient increases with increasing average void fraction in the subchannels. Moreover, for vertical flows turbulent void diffusion seems to be considerably affected by the geometry of the subchannels. For horizontal flows under nonsymmetric inlet void fraction conditions, even though the interconnected subchannels have the same geometry, different turbulent void diffusion and void drift coefficients are required to satisfy the conditions of hydrodynamic equilibrium. In the present study this condition is achieved by introducing a new void drift coefficient expressed as a correction term applied to the turbulent void drift term

  14. Resolution of thermal striping issue downstream of a horizontal pipe elbow in stratified pipe flow

    International Nuclear Information System (INIS)

    Kuzay, T.M.; Kasza, K.E.

    1985-01-01

    A thermally stratified pipe flow produced by a thermal transient when passing through a horizontal elbow as a result of secondary flow gives rise to large thermal fluctuations on the inner curvature wall of the downstream piping. These fluctuations were measured in a specially instrumented horizontal pipe and elbow system on a test set-up using water in the Mixing Components Technology Facility (MCTF) at Argonne National Laboratory (ANL). This study is part of a larger program which is studying the influence of thermal buoyancy on general reactor component performance. This paper discusses the influence of pipe flow generated thermal oscillations on the thermal stresses induced in the pipe walls. The instrumentation was concentrated around the exit plane of the 90 0 sweep elbow, since prior tests had indicated that the largest thermal fluctuations would occur within about one hydraulic diameter downstream of the elbow exit. The thermocouples were located along the inner curvature of the piping and measured the near surface fluid temperature. The test matrix involved thermal downramps under turbulent flow conditions

  15. Resolution of thermal striping issue downstream of a horizontal pipe elbow in stratified pipe flow. [LMFBR

    Energy Technology Data Exchange (ETDEWEB)

    Kuzay, T.M.; Kasza, K.E.

    1985-01-01

    A thermally stratified pipe flow produced by a thermal transient when passing through a horizontal elbow as a result of secondary flow gives rise to large thermal fluctuations on the inner curvature wall of the downstream piping. These fluctuations were measured in a specially instrumented horizontal pipe and elbow system on a test set-up using water in the Mixing Components Technology Facility (MCTF) at Argonne National Laboratory (ANL). This study is part of a larger program which is studying the influence of thermal buoyancy on general reactor component performance. This paper discusses the influence of pipe flow generated thermal oscillations on the thermal stresses induced in the pipe walls. The instrumentation was concentrated around the exit plane of the 90/sup 0/ sweep elbow, since prior tests had indicated that the largest thermal fluctuations would occur within about one hydraulic diameter downstream of the elbow exit. The thermocouples were located along the inner curvature of the piping and measured the near surface fluid temperature. The test matrix involved thermal downramps under turbulent flow conditions.

  16. Experimental investigation and CFD simulation of horizontal stratified two-phase flow phenomena

    International Nuclear Information System (INIS)

    Vallee, Christophe; Hoehne, Thomas; Prasser, Horst-Michael; Suehnel, Tobias

    2008-01-01

    For the investigation of stratified two-phase flow, two horizontal channels with rectangular cross-section were built at Forschungszentrum Dresden-Rossendorf (FZD). The channels allow the investigation of air/water co-current flows, especially the slug behaviour, at atmospheric pressure and room temperature. The test-sections are made of acrylic glass, so that optical techniques, like high-speed video observation or particle image velocimetry (PIV), can be applied for measurements. The rectangular cross-section was chosen to provide better observation possibilities. Moreover, dynamic pressure measurements were performed and synchronised with the high-speed camera system. CFD post-test simulations of stratified flows were performed using the code ANSYS CFX. The Euler-Euler two fluid model with the free surface option was applied on grids of minimum 4 x 10 5 control volumes. The turbulence was modelled separately for each phase using the k-ω-based shear stress transport (SST) turbulence model. The results compare very well in terms of slug formation, velocity, and breaking. The qualitative agreement between calculation and experiment is encouraging and shows that CFD can be a useful tool in studying horizontal two-phase flow

  17. Experimental investigation and CFD simulation of horizontal stratified two-phase flow phenomena

    International Nuclear Information System (INIS)

    Vallee, Christophe; Hohne, Thomas; Prasser, Horst-Michael; Suhnel, Tobias

    2007-01-01

    For the investigation of stratified two-phase flow, two horizontal channels with rectangular cross-section were built at Forschungszentrum Rossendorf. The channels allow the investigation of air/water co-current flows, especially the slug behaviour, at atmospheric pressure and room temperature. The test-sections are made of acrylic glass, so that optical techniques, like high-speed video observation or particle image velocimetry (PIV), can be applied for measurements. The rectangular cross-section was chosen to provide better observation possibilities. Moreover, dynamic pressure measurements were performed and synchronized with the high-speed camera system. CFD post test simulations of stratified flows were performed using the code ANSYS CFX. The Euler- Euler two fluid model with the free surface option was applied on grids of minimum 4.10 5 control volumes. The turbulence was modelled separately for each phase using the k-ω based shear stress transport (SST) turbulence model. The results compare very well in terms of slug formation, velocity, and breaking. The qualitative agreement between calculation and experiment is encouraging and shows that CFD can be a useful tool in studying horizontal two-phase flow. (authors)

  18. Experimental investigation and CFD simulation of horizontal stratified two-phase flow phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Vallee, Christophe [Forschungszentrum Dresden-Rossendorf e.V., Dresden (Germany)], E-mail: c.vallee@fzd.de; Hoehne, Thomas; Prasser, Horst-Michael; Suehnel, Tobias [Forschungszentrum Dresden-Rossendorf e.V., Dresden (Germany)

    2008-03-15

    For the investigation of stratified two-phase flow, two horizontal channels with rectangular cross-section were built at Forschungszentrum Dresden-Rossendorf (FZD). The channels allow the investigation of air/water co-current flows, especially the slug behaviour, at atmospheric pressure and room temperature. The test-sections are made of acrylic glass, so that optical techniques, like high-speed video observation or particle image velocimetry (PIV), can be applied for measurements. The rectangular cross-section was chosen to provide better observation possibilities. Moreover, dynamic pressure measurements were performed and synchronised with the high-speed camera system. CFD post-test simulations of stratified flows were performed using the code ANSYS CFX. The Euler-Euler two fluid model with the free surface option was applied on grids of minimum 4 x 10{sup 5} control volumes. The turbulence was modelled separately for each phase using the k-{omega}-based shear stress transport (SST) turbulence model. The results compare very well in terms of slug formation, velocity, and breaking. The qualitative agreement between calculation and experiment is encouraging and shows that CFD can be a useful tool in studying horizontal two-phase flow.

  19. Theoretical study of evaporation heat transfer in horizontal microfin tubes: stratified flow model

    Energy Technology Data Exchange (ETDEWEB)

    Honda, H; Wang, Y S [Kyushu Univ., Inst. for Materials Chemistry and Engineering, Kasuga, Fukuoka (Japan)

    2004-08-01

    The stratified flow model of evaporation heat transfer in helically grooved, horizontal microfin tubes has been developed. The profile of stratified liquid was determined by a theoretical model previously developed for condensation in horizontal microfin tubes. For the region above the stratified liquid, the meniscus profile in the groove between adjacent fins was determined by a force balance between the gravity and surface tension forces. The thin film evaporation model was applied to predict heat transfer in the thin film region of the meniscus. Heat transfer through the stratified liquid was estimated by using an empirical correlation proposed by Mori et al. The theoretical predictions of the circumferential average heat transfer coefficient were compared with available experimental data for four tubes and three refrigerants. A good agreement was obtained for the region of Fr{sub 0}<2.5 as long as partial dry out of tube surface did not occur. (Author)

  20. Investigation of Steam Flow Behavior During Horizontal Injection into Vertical Annulus

    International Nuclear Information System (INIS)

    Yoon, Sang H.; Kim, Won J.; Ku, Ja H.; Suh, Kune Y.; Song, Chul H.

    2004-01-01

    Qualification of uncertainty margins for accidents, which are classified as the design basis accidents, requires thermal hydraulic codes and related code models with an enhanced level of sophistication. In a cold leg break accident, the flow in downcomer is multidimensional and the velocity distribution of the steam flow in downcomer serves as a good example. For observation of the flow behavior near the break, experiments are performed to measure the velocity of the steam flow in a vessel scaled down from the APR1400 (Advanced Power Reactor 1400 MWe). In this case, the steam has a quality approaching unity and thus is dealt with as a single-phase gas. The velocity of the steam flow is measured by micro-Pitot tubes arranged horizontally and vertically around the outer shell of the 1/20 scaled-down test vessel OMEGA (Optimized Multidimensional Experiment Geometric Apparatus). A commercial computational fluid dynamics code yields analytic results of multidimensional flow motion in the complex annular passage with flow obstacles. CFX is run with well-defined boundary conditions to obtain velocity profiles of the steam flow in the annular downcomer. Results of CFX shed light on the experimental setup as to fixing the location and angle of the micro-Pitot tubes, and correcting the sensitivity of the micro- Pitot tubes, for instance. This study aims to improve the multidimensional capability of the MARS code, which is based on RELAP5 and COBRA-IV, in predicting the multiphase flow behavior in the reactor downcomer. MARS is currently based on one- and two-dimensional flow analyses, which tends to distort total flow due to misrepresentation of the local phenomena. It is thus necessary to scrutinize the steam flow path and mechanistically model the momentum variation. These experimental and analytical results can locally be applied to developing the models of specific forms and essential phenomena treated in MARS. (authors)

  1. THERMOSS: a thermohydraulic model of flow stagnation in a horizontal fuel channel

    International Nuclear Information System (INIS)

    Gulshani, P.; Caplan, M.Z.; Spinks, N.J.

    1984-01-01

    Following a postulated inlet-side small break in the CANDU reactor, emergency coolant is injected to refull the horizontal fuel channels and remove the decay heat. As part of the accident analysis, the effects of loss of forced circulation during the accident are predicted. A break size exists for which, at the end of pump rundown, the break force balances the natural circulation force and the channel flow is reduced to near zero. The subcooled, stagnant channel condition is referred to as the standing-start condition. Subsequently, the channel coolant boils and stratifies. Eventually the steam flow from the channel heats up the endfitting to the saturation temperature and reaches the vertical feeder. The resulting buoyancy-induced flow then refills the channel. One dimensional, two-fluid conservation equations are solved in closed form to predict the duration of stagnation. In this calculation the channel water level is an important intermediate variable because it determines the amount of steam production

  2. Experimental investigation on the droplet entrainment from interfacial waves in air-water horizontal stratified flow

    International Nuclear Information System (INIS)

    Bae, Byeong Geon; Yun, Byong Jo; Kim, Kyoung Du

    2014-01-01

    It was mainly due to the fact that droplet entrainment affects the Peak Cladding Temperature (PCT) of the nuclear fuel rod in the Postulated accident conditions of NPP. Recently, droplet entrainment in the horizontally arranged primary piping system for the NPP is of interest because it affects directly the steam binding phenomena in the steam generators. Pan and Hanratty correlation is the only applicable one for the droplet entrainment rate model for horizontal flow. Moreover, there are no efforts for the model development on the basis of the droplet entrainment principal and physics phenomena. More recently, Korea Atomic Energy Research Institute (KAERI) proposed a new mechanistic droplet generation model applicable in the horizontal pipe for the SPACE code. However, constitutive relations in this new model require three model coefficients which have not yet been decided. The purpose of present work is determining three model coefficients by visualization experiment. For these model coefficients, the major physical parameters regarding the interfacial disturbance wave should be measured in this experiments. There are the wave slope, liquid fraction, wave hypotenuse length, wave velocity, wave frequency, and wavelength in the major physical parameters. The experiment was conducted at an air water horizontal rectangular channel with the PIV system. In this study, the experimental conditions were stratified-way flow during the droplet generation. Three coefficients were determined based on several data related to the interfacial wave. Additionally, we manufactured the parallel wire conductance probe to measure the fluctuating water level over time, and compared the wave height measured by the parallel wire conductance probe and image processing from images taken by high speed camera. Experimental investigation was performed for droplet entrainment from phase interface wave in an air-water stratified flow. In the experiments, we measured major physical parameters

  3. Design and numerical simulation on an auto-cumulative flowmeter in horizontal oil-water two-phase flow.

    Science.gov (United States)

    Xie, Beibei; Kong, Lingfu; Kong, Deming; Kong, Weihang; Li, Lei; Liu, Xingbin; Chen, Jiliang

    2017-11-01

    In order to accurately measure the flow rate under the low yield horizontal well conditions, an auto-cumulative flowmeter (ACF) was proposed. Using the proposed flowmeter, the oil flow rate in horizontal oil-water two-phase segregated flow can be finely extracted. The computational fluid dynamics software Fluent was used to simulate the fluid of the ACF in oil-water two-phase flow. In order to calibrate the simulation measurement of the ACF, a novel oil flow rate measurement method was further proposed. The models of the ACF were simulated to obtain and calibrate the oil flow rate under different total flow rates and oil cuts. Using the finite-element method, the structure of the seven conductance probes in the ACF was simulated. The response values for the probes of the ACF under the conditions of oil-water segregated flow were obtained. The experiments for oil-water segregated flow under different heights of the oil accumulation in horizontal oil-water two-phase flow were carried out to calibrate the ACF. The validity of the oil flow rate measurement in horizontal oil-water two-phase flow was verified by simulation and experimental results.

  4. Flow Pattern Identification of Horizontal Two-Phase Refrigerant Flow Using Neural Networks

    Science.gov (United States)

    2015-12-31

    classification of liquid–vapor structures into flow patterns is useful for predicting heat transfer rates and, ultimately, system performance. Most flow and...Here, ~x represents the spa- tial variables, x and y, and t is time. This normalization assigns εð~x; tÞ to be zero for only vapor (εg) and one for...tube surface [17,22]. As in stratified wavy flow, interfacial waves were also present in stratified wavy transitional flow. The waves were more fre

  5. Mixed convection between horizontal plates and consequences for chemical vapor deposition flows

    International Nuclear Information System (INIS)

    Chiu, K.C.

    1986-01-01

    To simulate the fluid dynamics of VD systems, mixed convection between horizontal plates (AR = width/height = 10) heated from below was studied by laser Doppler anemometry in a range 1368 < Ra < 8300 and 15 < R3 < 170. The entrance effects were characterized by two lengths: one for the onset of bouyancy-driven instability, and one for the full development of longitudinal convection rolls. Explicit expressions for both entrance lengths are given in terms of Ra and Re. In addition, unsteady longitudinal convection rolls were observed. These are discussed in terms of the admixture of transverse convection rolls and/or contributions from upstream turbulence. For the fully developed region it is shown analytically that the transverse velocities of the longitudinal convection rolls, v and w, are independent of the forced flow and are identical to those of the two-dimensional Rayleigh-Benard convection rolls. These fundamental results serve as a base for the discussion of horizontal CVD flows. The entrance and sidewall effects are found to have pronounced influences on the flow patterns observed in CVD (AR = 2) reactors

  6. Experimental study on two-phase flow in horizontal duct using a visualization technique

    International Nuclear Information System (INIS)

    Oliveira, Livia A.; Tomas, Bruno T.; Cunha Filho, Jurandyr S.; Su, Jian

    2009-01-01

    In this paper an experimental study is performed for visualization of water-air two phase flow, stratified and intermittent, in a 51 mm internal diameter circular section horizontal tube. The study consists in filming a water-air mixture passin by a transparent interval of the tube, using a high speed camera. After that, the obtained images are analysed frame after frame and then, data are extracted of weight of gas-liquid interfaces, length and gas bubbles speeds. Then, these data are verified with experimental and theoretical correlations available in the literature

  7. Mechanistic multidimensional analysis of two-phase flow in horizontal tube with 90 deg elbow

    International Nuclear Information System (INIS)

    Tselishcheva, E.A.; Antal, St.P.; Podowski, M.Z.; Marshall, S.

    2007-01-01

    The development of modeling and simulation capabilities of two-phase flow and heat transfer is very important for the design, operation and safety of nuclear reactors. Whereas a significant progress in this field has been made over the recent years, further advancements are clearly needed for new concepts of advanced (Generation-IV in particular) reactors. Difficulties in analyzing gas/liquid flows are due to the fact that such two-phase mixtures can assume several different flow patterns, each characterized by flow-regime specific interfacial phenomena of mass, momentum and energy transfer. The level of difficulty increases even further in the case of a complex tube geometries and spatial orientations. The purpose of this paper is to discuss the results of the analysis of a two-phase flow in a horizontal pipe with a 90-degree elbow. The overall objective of the present work is the development of a 3-dimensional computational model of a two-phase high-Reynolds number turbulent flow. The overall new model has been encoded in the next-generation Computational Multiphase Fluid Dynamics (CMFD) computer code, NPHASE. The model has been tested parametrically and the results of NPHASE calculations have been compared against experimental data. It has been demonstrated that the proposed model is consistent both physically and numerically, the predictions are in a reasonable agreement with the measurements

  8. EFFECT OF HORIZONTALLY INHOMOGENEOUS HEATING ON FLOW AND MAGNETIC FIELD IN THE CHROMOSPHERE OF THE SUN

    Energy Technology Data Exchange (ETDEWEB)

    Song, P.; Vasyliūnas, V. M., E-mail: paul_song@uml.edu [Space Science Laboratory and Department of Physics, University of Massachusetts Lowell, Lowell, MA 01854 (United States)

    2014-12-01

    The solar chromosphere is heated by damped Alfvén waves propagating upward from the photosphere at a rate that depends on magnetic field strength, producing enhanced heating at low altitudes in the extended weak-field regions (where the additional heating accounts for the radiative losses) between the boundaries of the chromospheric network as well as enhanced heating per particle at higher altitudes in strong magnetic field regions of the network. The resulting inhomogeneous radiation and temperature distribution produces bulk flows, which in turn affect the configuration of the magnetic field. The basic flow pattern is circulation on the spatial scale of a supergranule, with upward flow in the strong-field region; this is a mirror image in the upper chromosphere of photospheric/subphotospheric convection widely associated with the formation of the strong network field. There are significant differences between the neutral and the ionized components of the weakly ionized medium: neutral flow streamlines can form closed cells, whereas plasma is largely constrained to flow along the magnetic field. Stresses associated with this differential flow may explain why the canopy/funnel structures of the network magnetic field have a greater horizontal extent and are relatively more homogeneous at high altitudes than is expected from simple current-free models.

  9. EFFECT OF HORIZONTALLY INHOMOGENEOUS HEATING ON FLOW AND MAGNETIC FIELD IN THE CHROMOSPHERE OF THE SUN

    International Nuclear Information System (INIS)

    Song, P.; Vasyliūnas, V. M.

    2014-01-01

    The solar chromosphere is heated by damped Alfvén waves propagating upward from the photosphere at a rate that depends on magnetic field strength, producing enhanced heating at low altitudes in the extended weak-field regions (where the additional heating accounts for the radiative losses) between the boundaries of the chromospheric network as well as enhanced heating per particle at higher altitudes in strong magnetic field regions of the network. The resulting inhomogeneous radiation and temperature distribution produces bulk flows, which in turn affect the configuration of the magnetic field. The basic flow pattern is circulation on the spatial scale of a supergranule, with upward flow in the strong-field region; this is a mirror image in the upper chromosphere of photospheric/subphotospheric convection widely associated with the formation of the strong network field. There are significant differences between the neutral and the ionized components of the weakly ionized medium: neutral flow streamlines can form closed cells, whereas plasma is largely constrained to flow along the magnetic field. Stresses associated with this differential flow may explain why the canopy/funnel structures of the network magnetic field have a greater horizontal extent and are relatively more homogeneous at high altitudes than is expected from simple current-free models

  10. Numerical analysis of the flow field in a sloshing tank with a horizontal perforated plate

    Science.gov (United States)

    Jin, Heng; Liu, Yong; Li, Huajun; Fu, Qiang

    2017-08-01

    Liquid sloshing is a type of free surface flow inside a partially filled water tank. Sloshing exerts a significant effect on the safety of liquid transport systems; in particular, it may cause large hydrodynamic loads when the frequency of the tank motion is close to the natural frequency of the tank. Perforated plates have recently been used to suppress the violent movement of liquids in a sloshing tank at resonant conditions. In this study, a numerical model based on OpenFOAM (Open Source Field Operation and Manipulation), an open source computed fluid dynamic code, is used to investigate resonant sloshing in a swaying tank with a submerged horizontal perforated plate. The numerical results of the free surface elevations are first verified using experimental data, and then the flow characteristics around the perforated plate and the fluid velocity distribution in the entire tank are examined using numerical examples. The results clearly show differences in sloshing motions under first-order and third-order resonant frequencies. This study provides a better understanding of the energy dissipation mechanism of a horizontal perforated plate in a swaying tank.

  11. Flow behaviour in a CANDU horizontal fuel channel from stagnant subcooled initial conditions

    International Nuclear Information System (INIS)

    Caplan, M.Z.; Gulshani, P.; Holmes, R.W.; Wright, A.C.D.

    1984-01-01

    The flow behaviour in a CANDU primary system with horizontal fuel channels is described following a small inlet header break. With the primary pumps running, emergency coolant injection is in the forward direction so that the channel outlet feeders remain warmer than the inlet thereby promoting forward natural circulation. However, the break force opposes the forward driving force. Should the primary pumps run down after the circuit has refilled, there is a break size for which the natural circulation force is balanced by the break force and channels could, theoretically, stagnate. Result of visualization and of full-size channel tests on channel flow behaviour from an initially stagnant channel condition are discussed. After a channel stagnation, the decay power heats the coolant to saturation. Steam is then formed and the coolant stratifies. The steam expands into the subcooled water in the end fitting in a chugging type of flow regime due to steam condensation. After the end fitting reaches the saturation temperature, steam is able to penetrate into the vertical feeder thereby initiating a large buoyancy induced flow which refills the channel. The duration of stagnation is shown to be sensitive to small asymmetries in the initial conditions. A small initial flow can significantly shorten the occurrence and/or duration of boiling as has been confirmed by reactor experience. (author)

  12. Experimental investigation and CFD validation of Horizontal Air/Water slug flow

    International Nuclear Information System (INIS)

    Vallee, Christophe; Hoehne, Thomas

    2007-01-01

    For the investigation of co-current two-phase flows at atmospheric pressure and room temperature, the Horizontal Air/Water Channel (HAWAC) was built at Forschungszentrum Dresden-Rossendorf (FZD). At the channel inlet, a special device provides adjustable and well-defined inlet boundary conditions and therefore very good CFD validation possibilities. The HAWAC facility is designed for the application of optical measurement techniques, which deliver the high resolution required for CDF validation. Therefore, the 8 m long acrylic glass test-section with rectangular cross-section provides good observation possibilities. High-speed video observation was applied during slug flow. The camera images show the generation of slug flow from the inlet of the test-section. Parallel to the experiments, CFD calculations were carried out. The aim of the numerical simulations is to validate the prediction of slug flow with the existing multiphase flow models built in the commercial code ANSYS CFX. The Euler-Euler two-fluid model with the free surface option was applied to a grid of 600,000 control volumes. The turbulence was modelled separately for each phase using the k-ω based shear stress transport (SST) turbulence model. The results compare well in terms of slug formation, and breaking. The qualitative agreement between calculation and experiment is encouraging, while quantitative comparison show that further model improvement is needed. (author)

  13. Experimental investigation and physical description of stratified flow in horizontal channels

    International Nuclear Information System (INIS)

    Staebler, T.

    2007-05-01

    data which are needed to develop and validate models of horizontal counter-current stratified flows. (orig.)

  14. Reservoir simulation with MUFITS code: Extension for double porosity reservoirs and flows in horizontal wells

    Science.gov (United States)

    Afanasyev, Andrey

    2017-04-01

    Numerical modelling of multiphase flows in porous medium is necessary in many applications concerning subsurface utilization. An incomplete list of those applications includes oil and gas fields exploration, underground carbon dioxide storage and geothermal energy production. The numerical simulations are conducted using complicated computer programs called reservoir simulators. A robust simulator should include a wide range of modelling options covering various exploration techniques, rock and fluid properties, and geological settings. In this work we present a recent development of new options in MUFITS code [1]. The first option concerns modelling of multiphase flows in double-porosity double-permeability reservoirs. We describe internal representation of reservoir models in MUFITS, which are constructed as a 3D graph of grid blocks, pipe segments, interfaces, etc. In case of double porosity reservoir, two linked nodes of the graph correspond to a grid cell. We simulate the 6th SPE comparative problem [2] and a five-spot geothermal production problem to validate the option. The second option concerns modelling of flows in porous medium coupled with flows in horizontal wells that are represented in the 3D graph as a sequence of pipe segments linked with pipe junctions. The well completions link the pipe segments with reservoir. The hydraulics in the wellbore, i.e. the frictional pressure drop, is calculated in accordance with Haaland's formula. We validate the option against the 7th SPE comparative problem [3]. We acknowledge financial support by the Russian Foundation for Basic Research (project No RFBR-15-31-20585). References [1] Afanasyev, A. MUFITS Reservoir Simulation Software (www.mufits.imec.msu.ru). [2] Firoozabadi A. et al. Sixth SPE Comparative Solution Project: Dual-Porosity Simulators // J. Petrol. Tech. 1990. V.42. N.6. P.710-715. [3] Nghiem L., et al. Seventh SPE Comparative Solution Project: Modelling of Horizontal Wells in Reservoir Simulation

  15. Simulation of buoyancy-induced turbulent flow from a hot horizontal jet

    KAUST Repository

    El-Amin, Mohamed

    2014-02-01

    Experimental visualizations and numerical simulations of a horizontal hot water jet entering cold water into a rectangular storage tank are described. Three different temperature differences and their corresponding Reynolds numbers are considered. Both experimental visualization and numerical computations are carried out for the same flow and thermal conditions. The realizable k - ε model is used for modeling the turbulent flow while the buoyancy is modeled using the Boussinesq approximation. Polynomial approximations of the water properties are used to compare with the Boussinesq approximation. Numerical solutions are obtained for unsteady flow while pressure, velocity, temperature and turbulence distributions inside the water tank as well as the Froude number are analyzed. The experimental visualizations are performed at intervals of five seconds for all different cases. The simulated results are compared with the visualized results, and both of them show the stratification phenomena and buoyancy force effects due to temperature difference and density variation. After certain times, depending on the case condition, the flow tends to reach a steady state. © 2014 Publishing House for Journal of Hydrodynamics.

  16. Video imaging measurement of interfacial wave velocity in air-water flow through a horizontal elbow

    Science.gov (United States)

    Al-Wazzan, Amir; Than, Cheok F.; Moghavvemi, Mahmoud; Yew, Chia W.

    2001-10-01

    Two-phase flow in pipelines containing elbows represents a common situation in the oil and gas industries. This study deals with the stratified flow regime between the gas and liquid phase through an elbow. It is of interest to study the change in wave characteristics by measuring the wave velocity and wavelength at the inlet and outlet of the elbow. The experiments were performed under concurrent air-water stratified flow in a horizontal transparent polycarbonate pipe of 0.05m diameter and superficial air and water velocities up to 8.97 and 0.0778 m/s respectively. A non-intrusive video imaging technique was applied to capture the waves. For image analysis, a frame by frame direct overlapping method was used to detect for pulsating flow and a pixel shifting method based on the detection of minimum values in the overlap function was used to determine wave velocity and wavelength. Under superficial gas velocity of less than 4.44 m/s, the results suggest a regular pulsating outflow produced by the elbow. At higher gas velocities, more random pulsation was found and the emergence of localized interfacial waves was detected. Wave velocities measured by this technique were found to produce satisfactory agreement with direct measurements.

  17. Effect of liquid nitrogen flow rate on solidification of stagnant water in a horizontal tube

    International Nuclear Information System (INIS)

    Ibrahim, S.M.

    1995-01-01

    Five experiments are conducted to study the effect of liquid nitrogen flow rate on the solidification of stagnant water inside a horizontal stainless steel tube of inner diameter 19.6 cm and 12 mm thick. This tube simulates the down-comer of the nuclear reactor ET-R R-1. The apparatus design is mentioned more detail description. The results show that for the first experiment where the liquid nitrogen flow rate is 30 1/hr, the progress of solidification of water has stopped at a diameter of 12 cm. By increasing the flow rate from 30 1/hr to 40,50 and 60 1/hr, the time of freezing the water inside the tube is decreased from 86 to 67 and 60 minutes respectively. By increasing the liquid nitrogen flow rate to 70 1/hr, there is no much effect on the time of frozen. In all experiments, where the solidification is happened, the ice block formed inside the tube is subjected to a pressure of 3 at mg least, and is succeed to withstand this pressure without any leak. 7 figs

  18. Two-phase flow and pressure drop in T-junctions with horizontal run and vertical branch

    International Nuclear Information System (INIS)

    Katsaounis, A.

    1987-01-01

    Visual observations of single- and two-phase dividing flow and pressure drop measurements were performed in T-junctions with horizontal run and vertical branch. Both tees used were geometrically similar, in a scale of 1:4. The measurements were performed for plug/slug and stratified flow pattern regime in horizontal tube. Based on the single-phase form-resistance pressure drop correlation of Gardel a corresponded calculation model was developed for the two-phase flow verified by the own measurements. (orig.) [de

  19. Simulation of the distribution of flow and phases in vertical and horizontal bundles using the ASSERT-4 subchannel code

    International Nuclear Information System (INIS)

    Carver, M.B.; Tahir, A.; Kiteley, J.C.; Banas, A.O.; Rowe, D.S.; Midvidy, W.I.

    1990-01-01

    ASSERT-4 is a subchannel code based on the non-equilibrium equations of two-fluid flow. The paper briefly describes the equations and constitutive models used in the code, and reviews a number of validation exercises in which code results were compared to measurements in vertical and horizontal two-phase flows. (orig.)

  20. Transient heat transfer for helium gas flowing over a horizontal cylinder with exponentially increasing heat input

    International Nuclear Information System (INIS)

    Liu, Qiusheng; Fukuda, Katsuya

    2003-01-01

    The transient heat transfer coefficients for forced convection flow of helium gas over a horizontal cylinder were measured under wide experimental conditions. The platinum cylinder with a diameter of 1.0 mm was used as test heater and heated by electric current with an exponentially increasing heat input of Q 0 exp(t/τ). The gas flow velocities ranged from 5 to 35 m/s, the gas temperatures ranged from 25 to 80degC, and the periods of heat generation rate, τ, ranged from 40 ms to 20 s. The surface superheat and heat flux increase exponentially as the heat generation rate increases with the exponential function. It was clarified that the heat transfer coefficient approaches the quasi-steady-state one for the period τ longer than about 1 s, and it becomes higher for the period shorter than around 1 s. The transient heat transfer shows less dependence on the gas flowing velocity when the period becomes very shorter. The gas temperature in this study shows little influence on the heat transfer coefficient. Semi-empirical correlation for quasi-steady-state heat transfer was obtained based on the experimental data. The ratios of transient Nusselt number Nu tr to quasi-steady-state Nusselt number Nu st at various periods, flow velocities, and gas temperatures were obtained. The heat transfer shifts to the quasi-steady-state heat transfer for longer periods and shifts to the transient heat transfer for shorter periods at the same flow velocity. It also approaches the quasi-steady-state one for higher flow velocity at the same period. Empirical correlation for transient heat transfer was also obtained based on the experimental data. (author)

  1. The formation of sporadic E layers by a vortical perturbation excited in a horizontal wind shear flow

    Directory of Open Access Journals (Sweden)

    G. G. Didebulidze

    2008-06-01

    Full Text Available The formation of the mid-latitude sporadic E layers (Es layers by an atmospheric vortical perturbation excited in a horizontal shear flow (horizontal wind with a horizontal linear shear is investigated. A three-dimensional atmospheric vortical perturbation (atmospheric shear waves, whose velocity vector is in the horizontal plane and has a vertical wavenumber kz≠0, can provide a vertical shear of the horizontal wind. The shear waves influence the vertical transport of heavy metallic ions and their convergence into thin and dense horizontal layers. The proposed mechanism takes into account the dynamical influence of the shear wave velocity in the horizontal wind on the vertical drift velocity of the ions. It also can explain the multi-layer structure of Es layers. The pattern of the multi-layer structure depends on the value of the shear-wave vertical wavelength, the ion-neutral collision frequency and the direction of the background horizontal wind. The modelling of formation of sporadic E layers with a single and a double peak is presented. Also, the importance of shear wave coupling with short-period atmospheric gravity waves (AGWs on the variations of sporadic E layer ion density is examined and discussed.

  2. Heat transfer correlations for evaporation of refrigerant mixtures flowing inside horizontal microfin tubes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaoyan [School of Energy Engineering, Xi' an University of Science and Technology, 58 Yanta Street, Xi' an, Shaanxi 710054 (China); School of Energy and Power Engineering, Xi' an Jiaotong University, 28 Xianning Road, Xi' an, Shaanxi 710049 (China); Yuan, Xiuling [School of Energy and Power Engineering, Xi' an Jiaotong University, 28 Xianning Road, Xi' an, Shaanxi 710049 (China)

    2008-11-15

    Based on the experimental results of R417A flowing inside horizontal microfin tubes, the present work deals with the development of prediction methods for evaporation heat transfer of refrigerant mixtures in microfin tube. The microfin model by Thome et al. is modified by adjusting the convective heat transfer term, and the other microfin model is developed by introducing the enhancement factor into the modified-Kattan model. The comparison of the calculations by several microfin models and the experimental results reveals that the new microfin models developed at the present study are in much better agreement with the experimental results with the reducing average deviation by 30-50% than the models by Thome et al. and Cavallini et al., and are recommended for the prediction of evaporation heat transfer coefficients for non-azeotropic refrigerant mixtures inside microfin tubes. (author)

  3. Heat transfer correlations for evaporation of refrigerant mixtures flowing inside horizontal microfin tubes

    Energy Technology Data Exchange (ETDEWEB)

    Xiaoyan, Zhang [School of Energy Engineering, Xi' an University of Science and Technology, 58 Yanta Street, Xi' an, Shaanxi 710054 (China); School of Energy and Power Engineering, Xi' an Jiaotong University, 28 Xianning Road, Xi' an, Shaanxi 710049 (China)], E-mail: gqzxy@sohu.com; Xiuling, Yuan [School of Energy and Power Engineering, Xi' an Jiaotong University, 28 Xianning Road, Xi' an, Shaanxi 710049 (China)

    2008-11-15

    Based on the experimental results of R417A flowing inside horizontal microfin tubes, the present work deals with the development of prediction methods for evaporation heat transfer of refrigerant mixtures in microfin tube. The microfin model by Thome et al. is modified by adjusting the convective heat transfer term, and the other microfin model is developed by introducing the enhancement factor into the modified-Kattan model. The comparison of the calculations by several microfin models and the experimental results reveals that the new microfin models developed at the present study are in much better agreement with the experimental results with the reducing average deviation by 30-50% than the models by Thome et al. and Cavallini et al., and are recommended for the prediction of evaporation heat transfer coefficients for non-azeotropic refrigerant mixtures inside microfin tubes.

  4. Heat transfer correlations for evaporation of refrigerant mixtures flowing inside horizontal microfin tubes

    International Nuclear Information System (INIS)

    Zhang Xiaoyan; Yuan Xiuling

    2008-01-01

    Based on the experimental results of R417A flowing inside horizontal microfin tubes, the present work deals with the development of prediction methods for evaporation heat transfer of refrigerant mixtures in microfin tube. The microfin model by Thome et al. is modified by adjusting the convective heat transfer term, and the other microfin model is developed by introducing the enhancement factor into the modified-Kattan model. The comparison of the calculations by several microfin models and the experimental results reveals that the new microfin models developed at the present study are in much better agreement with the experimental results with the reducing average deviation by 30-50% than the models by Thome et al. and Cavallini et al., and are recommended for the prediction of evaporation heat transfer coefficients for non-azeotropic refrigerant mixtures inside microfin tubes

  5. Water Entry and Exit of Horizontal Cylinder in Free Surface Flow

    International Nuclear Information System (INIS)

    Hafsia, Zouhaier; Maalel, Khlifa; Mnasri, Chokri; Mohamed, Omri

    2009-01-01

    This paper describes two-dimensional numerical simulations of the water entry and exit of horizontal circular cylinder at constant velocity. The deformation of free surface is described by Navier-Stokes (N S) equations of incompressible and viscous fluid with additional transport equation of the volume-of-fluid (VOF). The motion of the cylinder is modeled by the associated momentum source term implemented in the Phoenicis (Parabolic Hyperbolic Or Elliptic Numerical Integration Code Series) code. The domain is discretized by a fixed Cartesian grid using a finite volume method and the cylinder is represented and cut cell method. The simulated results are compared with the numerical results of Lin (2007). This comparison shows good agreement in terms of free surface evolution for water exit and sinking. However, for water entry, the jet flow simulated by Lin is not reproduced. The free surface deformation around the cylinder in downward direction is accurately predicted

  6. The Simulation Study of Horizontal Axis Water Turbine Using Flow Simulation Solidworks Application

    Science.gov (United States)

    Prasetyo, H.; Budiana, EP; Tjahjana, DDDP; Hadi, S.

    2018-02-01

    The design of Horizontal Axis Water Turbine in pico hydro power plants involves many parameters. To simplify that, usually using computer simulation is applied. This research performs simulation process variation on turbine blade number, turbine blade curvature angle, turbine bucket angle and blocking system tilt angle. Those four variations were combined in order to obtain the best design of turbine. The study used Flow Simulation Solidworks application, and obtain data on turbine speed, pressure, force, and torque. However, this research focused on turbine torque value. The best design of turbine was obtained in the turbine with 6 blades, blade curvature angle of 65° and bucket angle of 10°, and blocking system tilt angle of 40°. In the best turbine, the produced torque value was 8.464 Nm.

  7. Mixed convection-radiation interaction in boundary-layer flow over horizontal surfaces

    Science.gov (United States)

    Ibrahim, F. S.; Hady, F. M.

    1990-06-01

    The effect of buoyancy forces and thermal radiation on the steady laminar plane flow over an isothermal horizontal flat plate is investigated within the framework of first-order boundary-layer theory, taking into account the hydrostatic pressure variation normal to the plate. The fluid considered is a gray, absorbing-emitting but nonscattering medium, and the Rosseland approximation is used to describe the radiative heat flux in the energy equation. Both a hot surface facing upward and a cold surface facing downward are considered in the analysis. Numerical results for the local Nusselt number, the local wall shear stress, the local surface heat flux, as well as the velocity and temperature distributions are presented for gases with a Prandtl number of 0.7 for various values of the radiation-conduction parameter, the buoyancy parameter, and the temperature ratio parameter.

  8. Double cascade turbulence and Richardson dispersion in a horizontal fluid flow induced by Faraday waves.

    Science.gov (United States)

    von Kameke, A; Huhn, F; Fernández-García, G; Muñuzuri, A P; Pérez-Muñuzuri, V

    2011-08-12

    We report the experimental observation of Richardson dispersion and a double cascade in a thin horizontal fluid flow induced by Faraday waves. The energy spectra and the mean spectral energy flux obtained from particle image velocimetry data suggest an inverse energy cascade with Kolmogorov type scaling E(k) ∝ k(γ), γ ≈ -5/3 and an E(k) ∝ k(γ), γ ≈ -3 enstrophy cascade. Particle transport is studied analyzing absolute and relative dispersion as well as the finite size Lyapunov exponent (FSLE) via the direct tracking of real particles and numerical advection of virtual particles. Richardson dispersion with ∝ t(3) is observed and is also reflected in the slopes of the FSLE (Λ ∝ ΔR(-2/3)) for virtual and real particles.

  9. Experimental study of mixed convection flow through a horizontal orifice or vent linking two compartments

    International Nuclear Information System (INIS)

    Varrall, Kevin

    2016-01-01

    To answer building issues and fire safety challenges, this thesis deals with the mixed convection flow through a horizontal orifice or vent linking two compartments. The aim is to improve the understanding and the modeling of the exchange of gas through the opening. A small scale experimental study and a theoretical approach are proposed. The study focuses first on the influence of the geometrical ratio L/D of the opening on the flow rate at the vent for free convection regime. Non-intrusive measurements, via the tracking of the interface between two non miscible liquids in an isothermal approach, and thanks to the SPIV in a thermal approach, permit to describe the bidirectional exchange process and to consolidate existing correlations. Experiments for mixed convection regime aim to study the impact of mechanical ventilation (in blowing and extracting modes) on the exchanged flow rates. The comparison between existing correlations and experimental data shows large differences. A modification of the correlation of Cooper is proposed. A theoretical approach from the simplified Navier Stokes equations and with the Boussinesq approximation permits to discuss the construction of existing correlations. From this theory, a more accurate model than those available in the literature is proposed thanks to an adjustment of discharge coefficients from experimental data. (author)

  10. New transient-flow modelling of a multiple-fractured horizontal well

    International Nuclear Information System (INIS)

    Jia, Yong-Lu; Wang, Ben-Cheng; Nie, Ren-Shi; Wang, Dan-Ling

    2014-01-01

    A new transient-flow modelling of a multiple-fractured horizontal well is presented. Compared to conventional modelling, the new modelling considered more practical physical conditions, such as various inclined angles for different fractures, different fracture intervals, different fracture lengths and partially penetrating fractures to formation. A kind of new mathematical method, including a three-dimensional eigenvalue and orthogonal transform, was created to deduce the exact analytical solutions of pressure transients for constant-rate production in real space. In order to consider a wellbore storage coefficient and skin factor, we used a Laplace-transform approach to convert the exact analytical solutions to the solutions in Laplace space. Then the numerical solutions of pressure transients in real space were gained using a Stehfest numerical inversion. Standard type curves were plotted to describe the transient-flow characteristics. Flow regimes were clearly identified from type curves. Furthermore, the differences between the new modelling and the conventional modelling in pressure transients were especially compared and discussed. Finally, an example application to show the accordance of the new modelling with real conditions was implemented. Our new modelling is different from, but more practical than, conventional modelling. (paper)

  11. Simulation of Turbulent Wake at Mixing of Two Confined Horizontal Flows

    Directory of Open Access Journals (Sweden)

    Rok Krpan

    2018-01-01

    Full Text Available The development of a turbulent mixing layer at mixing of two horizontal water streams with slightly different densities is studied by the means of numerical simulation. The mixing of such flows can be modelled as the flow of two components, where the concentration of one component in the mixing region is described as a passive scalar. The velocity field remains common over the entire computational domain, where the density and viscosity difference due to the concentration mainly affects the turbulent fluctuations in the mixing region. The numerical simulations are performed with the open source code OpenFOAM using two different approaches for turbulence modelling, Reynolds Averaged Navier Stokes equations (RANS and Large Eddy Simulation (LES. The simulation results are discussed and compared with the benchmark experiment obtained within the frame of OECD/NEA benchmark test. A good agreement with experimental results is obtained in the case of the single liquid experiment. A high discrepancy between the simulated and the experimental velocity fluctuations in the case of mixing of the flows with the slightly different densities and viscosities triggered a systematic investigation of the modelling approaches that helped us to find out and interpret the main reasons for the disagreement.

  12. Features of two-phase flow patterns in horizontal rectangular microchannels of height 50 μm

    Directory of Open Access Journals (Sweden)

    Ron’shin Fedor

    2016-01-01

    Full Text Available The horizontal microchannel with the height of 50 micrometres and width of 40 mm of a rectangular cross-section has been used to study two-phase flow. The classical patterns of two-phase flow in the channel (bubble, stratified, churn, jet, and annular have been detected. Experimental information allows us to define the characteristics of the regimes and to determine precisely the boundaries between the patterns of the two-phase flows.

  13. Design configurations affecting flow pattern and solids accumulation in horizontal free water and subsurface flow constructed wetlands.

    Science.gov (United States)

    Pedescoll, A; Sidrach-Cardona, R; Sánchez, J C; Carretero, J; Garfi, M; Bécares, E

    2013-03-01

    The aim of this study was to evaluate the effect of different horizontal constructed wetland (CW) design parameters on solids distribution, loss of hydraulic conductivity over time and hydraulic behaviour, in order to assess clogging processes in wetlands. For this purpose, an experimental plant with eight CWs was built at mesocosm scale. Each CW presented a different design characteristic, and the most common CW configurations were all represented: free water surface flow (FWS) with different effluent pipe locations, FWS with floating macrophytes and subsurface flow (SSF), and the presence of plants and specific species (Typha angustifolia and Phragmites australis) was also considered. The loss of the hydraulic conductivity of gravel was greatly influenced by the presence of plants and organic load (representing a loss of 20% and c.a. 10% in planted wetlands and an overloaded system, respectively). Cattail seems to have a greater effect on the development of clogging since its below-ground biomass weighed twice as much as that of common reed. Hydraulic behaviour was greatly influenced by the presence of a gravel matrix and the outlet pipe position. In strict SSF CW, the water was forced to cross the gravel and tended to flow diagonally from the top inlet to the bottom outlet (where the inlet and outlet pipes were located). However, when FWS was considered, water preferentially flowed above the gravel, thus losing half the effective volume of the system. Only the presence of plants seemed to help the water flow partially within the gravel matrix. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Experimental study on two-phase flow in horizontal duct using a visualization technique; Estudo experimental de escoamentos bifasicos em duto horizontal usando uma tecnica de visualizacao

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Livia A.; Tomas, Bruno T.; Cunha Filho, Jurandyr S.; Su, Jian, E-mail: livia.alves.oliveira@gmail.co [Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Faccini, Jose L.H. [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2009-07-01

    In this paper an experimental study is performed for visualization of water-air two phase flow, stratified and intermittent, in a 51 mm internal diameter circular section horizontal tube. The study consists in filming a water-air mixture passin by a transparent interval of the tube, using a high speed camera. After that, the obtained images are analysed frame after frame and then, data are extracted of weight of gas-liquid interfaces, length and gas bubbles speeds. Then, these data are verified with experimental and theoretical correlations available in the literature

  15. The effect of diameter on vertical and horizontal flow boiling crisis in a tube cooled by Freon-12

    International Nuclear Information System (INIS)

    Merilo, M.; Ahmad, S.Y.

    1979-03-01

    The influence of test section orientation and diameter on flow boiling crisis occurring in tubes has been studied experimentally using Freon-12 as a coolant. At low mass flux the critical heat flux (CHF) was lower in horizontal flow than in vertical. As either the liquid or vapour velocity, or both, were increased the vertical and horizontal CHF results converged. Above a mass flux of 4 Mg.m -2 .s -1 the results were essentially identical. The effect of tube diameter on boiling crisis in general depends crucially on the parameters which are maintained constant when the comparison is made. (author)

  16. Two-phase flow in short horizontal rectangular microchannels with a height of 300 μm

    Science.gov (United States)

    Chinnov, E. A.; Ron'shin, F. V.; Kabov, O. A.

    2015-09-01

    The two-phase flow in a narrow short horizontal channel with a rectangular cross section is studied experimentally. The channel has a width of 10, 20, or 30 mm and a height of 300 μm. The specifics of formation of such two-phase flows are investigated. It is demonstrated that the regions of bubble and churn flow regimes grow and constrain the region of jet flow as the channel gets wider. The boundaries of the regions of annular and stratified flow regimes remain almost unaltered.

  17. 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.

  18. 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.

  19. 3-D Numerical Investigation on Oxygen Transfer in a Horizontal Venturi Flow with Two Holes

    Directory of Open Access Journals (Sweden)

    Zegao Yin

    2018-02-01

    Full Text Available In order to investigate the dissolved oxygen increase caused by air suction in a horizontal Venturi flow with two holes, a 3-D computational fluid dynamics model was used to explore the water and bubble mixture flow, coupled with a dissolved oxygen transfer model. A series of experiments were conducted to validate the mathematical model. A relative saturation coefficient correlation was examined factoring in dissolved oxygen concentration at the inlet, water velocity at the inlet, the hole’s diameter, contraction ratio at throat section, and the downstream length of Venturi pipe. It was found that the relative saturation coefficient increases with increasing dissolved oxygen concentration at the inlet and downstream length of Venturi pipe respectively. However, it increases with decreasing water velocity at the inlet and contraction ratio at the throat section to some extent. The hole’s diameter plays a complex role in the relative saturation coefficient. The dimensional analysis method and the least square method were used to deduce a simple formula for the relative saturation coefficient, and this was consistent with related data.

  20. Particle re-entrainment from a powder deposit in an horizontal air flow

    International Nuclear Information System (INIS)

    Alloul, L.; Witschger, O.; Alloul, L.; Renoux, A.; Le Dur, D.; Monnatte, J.

    2000-01-01

    Particle re-entrainment from surfaces to turbulent air flow is an important subject in many different fields like nuclear safety, environmental air pollution, sediment transport by wind, surface contamination in semiconductor operations. Theoretical and experimental studies have been numerous and cover different aspects of the phenomena. Although a number of theoretical works have been devoted for describing the mechanisms of detachment of primary spherical particles form flat smooth surfaces in a turbulent flow, experimental data are still needed in order to comparison. Moreover, the knowledge of the effect of parameters related to the deposit (monolayer, multilayer, cone-like pile), the powder particles (particle-size distribution, adhesive properties), the surface (roughness,...),the airflow (velocity, acceleration, turbulence) or the environment (humidity,...) is still in an elementary stage. The main objective of our work is to contribute to the understanding and quantification of the parameters that govern the particle re-entrainment from a powder deposit in an turbulent horizontal airflow. Therefore, a new experimental facility called BISE (french acronym for wind tunnel for studying particle re-entrainment by airflow) has been designed and built in our laboratory. (authors)

  1. Heat transfer, pressure drop and flow patterns during flow boiling of R407C in a horizontal microfin tube

    Science.gov (United States)

    Rollmann, P.; Spindler, K.; Müller-Steinhagen, H.

    2011-08-01

    The heat transfer, pressure drop and flow patterns during flow boiling of R407C in a horizontal microfin tube have been investigated. The microfin tube is made of copper with a total fin number of 55 and a helix angle of 15°. The fin height is 0.24 mm and the inner tube diameter at fin root is 8.95 mm. The test tube is 1 m long. It is heated electrically. The experiments have been performed at saturation temperatures between -30°C and +10°C. The mass flux was varied between 25 and 300 kg/m2/s, the heat flux from 20,000 W/m2 down to 1,000 W/m2. The vapour quality was kept constant at 0.1, 0.3, 0.5, 0.7 at the inlet and 0.8, 1.0 at the outlet, respectively. The measured heat transfer coefficient is compared with the correlations of Cavallini et al., Shah as well as Zhang et al. Cavallini's correlation contains seven experimental constants. After fitting these constants to our measured values, the correlation achieves good agreement. The measured pressure drop is compared to the correlations of Pierre, Kuo and Wang as well as Müller-Steinhagen and Heck. The best agreement is achieved with the correlation of Kuo and Wang. Almost all values are calculated within an accuracy of ±30%. The flow regimes were observed. It is shown, that changes in the flow regime affect the heat transfer coefficient significantly.

  2. Effectiveness of horizontal air flow fans supporting natural ventilation in a Mediterranean multi-span greenhouse

    Directory of Open Access Journals (Sweden)

    Alejandro López

    2013-08-01

    Full Text Available Natural ventilation is the most important method of climate control in Mediterranean greenhouses. In this study, the microclimate and air flow inside a Mediterranean greenhouse were evaluated by means of sonic anemometry. Experiments were carried out in conditions of moderate wind (≈ 4.0 m s-1, and at low wind speed (≈ 1.8 m s-1 the natural ventilation of the greenhouse was supplemented by two horizontal air flow fans. The greenhouse is equipped with a single roof vent opening to the windward side and two side vents, the windward one being blocked by another greenhouse close to it, while the leeward one is free of obstacles. When no fans are used, air enters through the roof vent and exits through both side vents, thus flowing contrary to the thermal effect which causes hot air to rise and impairing the natural ventilation of the greenhouse. Using fans inside the greenhouse helps the air to circulate and mix, giving rise to a more homogeneous inside temperature and increasing the average value of normalized air velocity by 365 %. These fans also increase the average values of kinetic turbulence energy inside the greenhouse by 550 % compared to conditions of natural ventilation. As the fans are placed 4 m away from the side vents, their effect on the entrance of outside air is insufficient and they do not help to reduce the inside temperature on hot days with little wind. It is therefore recommended to place the fans closer to the side vents to allow an additional increase of the air exchange rate of greenhouses.

  3. Onset of entrainment and degree of dispersion in dual continuous horizontal oil-water flows

    Energy Technology Data Exchange (ETDEWEB)

    Al-Wahaibi, Talal [Department of Petroleum and Chemical Engineering, Sultan Qaboos University, P.O. Box 33, Al-Khoud, P.C. 123 (Oman); Angeli, Panagiota [Department of Chemical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom)

    2009-04-15

    The transition from stratified to dual continuous oil-water flow (where each phase retains its continuity but there is dispersion of one phase into the other) as well as the dispersed phase fractions in the layers of the dual continuous pattern, were studied experimentally. Transition to this pattern from stratified flow occurs when drops of one phase appear into the other (onset of entrainment). The studies were carried out in a 38 mm ID horizontal stainless steel test section using two different inlet geometries, a T- and a Y-junction. The patterns were visualized through a transparent acrylic section located at 7 m from the inlet using a high speed video camera. Phase distribution measurements in a pipe cross section were obtained just before the acrylic section with a local impedance probe and the results were used to calculate the volume fraction of each phase entrained into the other. The onset of entrainment was found to occur at lower superficial water velocities as the oil superficial velocities increased. However, the inlet geometry did not affect significantly the transition line. During dual continuous flow, the dispersion of one phase into the opposite was found to extend further away from the interface with increasing water superficial velocity for a certain oil superficial velocity. An increase in the superficial water velocity increased the entrained fraction of water in oil (E{sub w/o}) but there was no trend with the oil velocity. Similarly, an increase in the superficial oil velocity increased the fraction of oil drops in water (E{sub o/w}) but the water velocity had no clear effect. The entrainment fractions were affected by the inlet geometry, with the T-inlet resulting in higher entrainment than the Y-inlet, perhaps because of the increased mixing induced by the T-inlet. The difference between the two inlets increased as the oil and water velocities increased. (author)

  4. Critical investigations and model development on countercurrent flow of gas and liquid in horizontal and vertical channels

    International Nuclear Information System (INIS)

    Mewes, D.; Beckmann, H.

    1989-01-01

    Countercurrent flow of steam and water occurs in the horizontal and vertical lines of a PWR in case of a LOCA. In order to predict the emergency core cooling behaviour in case of a large or small break LOCA it is important to calculate the volumetric flow rate of water which will get to the reactor core. Theoretical and experimental results of countercurrent flow in horizontal and vertical channels given by publication and reports are critically reviewed for the purpose of a more physical understanding of the flow phenomena. The influence of geometry, pressure and other boundary conditions are emphasized. The existing models which are developed to calculate the onset of flooding are based on experimental results of small test facilities. The applicability of these models to large geometries and high pressures as well as the consideration of condensation and entrainment are investigated. (orig./HP) [de

  5. Vertical Subsurface Flow Mixing and Horizontal Anisotropy in Coarse Fluvial Aquifers: Structural Aspects

    Science.gov (United States)

    Huggenberger, P.; Huber, E.

    2014-12-01

    Detailed descriptions of the subsurface heterogeneities in coarse fluvial aquifer gravel often lack in concepts to distinguish between the essence and the noise of a permeability structure and the ability to extrapolate site specific hydraulic information at the tens to several hundred meters scale. At this scale the heterogeneity strongly influences the anisotropies of the flow field and the mixing processes in groundwater. However, in many hydrogeological models the complexity of natural systems is oversimplified. Understanding the link between the dynamics of the surface processes of braided-river systems and the resulting subsurface sedimentary structures is the key to characterizing the complexity of horizontal and vertical mixing processes in groundwater. From the different depositional elements of coarse braided-river systems, the largest permeability contrasts can be observed in the scour-fills. Other elements (e.g. different types of gravel sheets) show much smaller variabilities and could be considered as a kind of matrix. Field experiments on the river Tagliamento (Northeast Italy) based on morphological observation and ground-penetrating radar (GPR) surveys, as well as outcrop analyses of gravel pit exposures (Switzerland) allowed us to define the shape, sizes, spatial distribution and preservation potential of scour-fills. In vertical sections (e.g. 2D GPR data, vertical outcrop), the spatial density of remnant erosional bounding surfaces of scours is an indicator for the dynamics of the braided-river system (lateral mobility of the active floodplain, rate of sediment net deposition and spatial distribution of the confluence scours). In case of combined low aggradation rate and low lateral mobility the deposits may be dominated by a complex overprinting of scour-fills. The delineation of the erosional bounding surfaces, that are coherent over the survey area, is based on the identification of angular discontinuities of the reflectors. Fence diagrams

  6. Measurements of gravity and gravity-capillary waves in horizontal gas-liquid pipe flow using PIV in both phases

    NARCIS (Netherlands)

    Birvalski, M.; Tummers, M.J.; Henkes, R.A.W.M.

    2016-01-01

    An experimental study was performed in stratified wavy flow of air and water through a horizontal pipe. The velocity fields in both phases were measured simultaneously using PIV and the interfacial shape was resolved using a profile capturing technique. The objective of the study was to

  7. 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)

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

    Science.gov (United States)

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

    2017-08-01

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

  9. Prediction of effective friction factors for single-phase flow in horizontal microfin tubes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, H S; Rose, J W [University of London (United Kingdom). Queen Mary, Department of Engineering

    2004-12-01

    An experimental database, covering a wide range of tube and fin geometric dimensions, Reynolds number and including data for water, R11, and ethylene glycol has been compiled for friction factor for single-phase flow in spirally grooved, horizontal microfin tubes. The tubes (21 in all) had inside diameter at the fin root between 6.46 and 24.13 mm, fin height between 0.13 and 0.47 mm, fin pitch between 0.32 and 1.15 mm, and helix angle between 17 and 45 degrees. The Reynolds number ranged from 2.0x10{sup 3} to 1.63x10{sup 5}. Six earlier friction factor correlations, each based on restricted data sets, have been compared with the database as a whole. None was found to be in good agreement with all of the data. The Jensen and Vlakancic correlation was found to be the best and represents the database within {+-}21%. (author)

  10. High speed ultrasonic system to measure bubbles velocities in a horizontal two-phase flow

    International Nuclear Information System (INIS)

    Cunha Filho, Jurandyr S.; Jian Su; Farias, Marcos S.; Faccini, Jose L.H.; Lamy, Carlos A.

    2009-01-01

    In this work, a non invasive technique consisting of a high speed ultrasonic multitransducer pulse-echo system was developed to characterize gas-liquid two-phase flow parameters that are important in the study of the primary refrigeration circuit of nuclear reactors. The high speed ultrasonic system consists of two transducers (10 MHz/φ 6.35 mm), a generator/multiplexer board, and software that selects and has a data acquisition system of the ultrasonic signals. The resolutions of the system and the pulse time generated from each transducer are, respectively, 10 ns and 1.06 ms. The system initially was used in the local instantaneous measurement of gas-liquid interface in a circular horizontal pipe test section made of a 5 m long stainless steel pipe of 51.2 mm inner diameter, where the elongated bubbles velocity was measured (Taylor bubbles). The results show that the high speed ultrasonic pulse-echo system provides good results for the determination of elongated bubbles velocities. (author)

  11. Wastewater treatment in horizontal subsurface flow constructed wetlands using different media (setup stage

    Directory of Open Access Journals (Sweden)

    Abdel Razik A. Zidan

    2015-04-01

    Full Text Available Wastewater treatment through horizontal subsurface flow (HSSF constructed wetlands (CWs using three different treatment media (gravel, pieces of plastic pipes, and shredded tire rubber chips were investigated in Samaha village, Dakahliya, Egypt. The study focused on the wetland setup stage during the first months of its operation (setup stage. In this stage media porosity, bacterial biofilm, and plant roots growth were in progress and it was prior to the operational steady state stage. Objectives of this paper are to study the change in media porosity of HSSF wetland cells in order to estimate duration of wetland setup stage, and to evaluate the use of different bed media on biological oxygen demand (BOD, chemical oxygen demand (COD and total suspended solids (TSS treatment. The results showed that after 180 days of operation, the wetland cells had reached steady porosity and had started stable treatment. Also performance of plastic media bed in pollutants reduction was better than gravel and rubber beds and gravel media was in advanced than rubber media.

  12. Ibuprofen removal in horizontal subsurface flow constructed wetlands: treatment performance and fungal community dynamics.

    Science.gov (United States)

    Zhang, Dongqing; Luo, Jinxue; Lee, Zarraz May Ping; Gersberg, Richard M; Liu, Yu; Tan, Soon Keat; Ng, Wun Jern

    2016-01-01

    The treatment performance of ibuprofen (IBP)-enriched wastewater by horizontal subsurface flow constructed wetlands planted with cattail (Typha angustifolia) and unplanted control mesocosms was investigated. Removal efficiencies of IBP were significantly (p fungal community in these wetland systems. The overall diversity of the fungal community was reduced under the IBP exposure. Taxonomic analysis revealed that 62.2% of the fungal sequences were affiliated with Basidiomycota, followed by Ascomycota (37.4%) at the phylum level. Uncultured fungus (48.2%), Chaetomium sp. (14.2%), Aspergillus sp. (12.4%), Trichoderma sp. (5.7%), Cladosporium sp. (5.4%), and Emericellopsis sp. (5.2%) were identified as dominant genera. At the genus level, a distinct profile of the fungal community in the IBP-enriched mesocosms was observed as compared to the control beds, and as well specific fungal genera were enhanced in the planted beds, regardless of IBP enrichment. However, despite these differences, the composition of the fungal community (as measured by Bray-Curtis similarity) was mostly unaffected by the significant IBP enrichment. On the other hand, a consistent similarity pattern of fungal community structure in the planted mesocosms suggests that the presence of higher macrophytes in the wetland systems may well help shape the fungal community structure.

  13. Bacterial transformation and biodegradation processes simulation in horizontal subsurface flow constructed wetlands using CWM1-RETRASO.

    Science.gov (United States)

    Llorens, Esther; Saaltink, Maarten W; Poch, Manel; García, Joan

    2011-01-01

    The performance and reliability of the CWM1-RETRASO model for simulating processes in horizontal subsurface flow constructed wetlands (HSSF CWs) and the relative contribution of different microbial reactions to organic matter (COD) removal in a HSSF CW treating urban wastewater were evaluated. Various different approaches with diverse influent configurations were simulated. According to the simulations, anaerobic processes were more widespread in the simulated wetland and contributed to a higher COD removal rate [72-79%] than anoxic [0-1%] and aerobic reactions [20-27%] did. In all the cases tested, the reaction that most contributed to COD removal was methanogenesis [58-73%]. All results provided by the model were in consonance with literature and experimental field observations, suggesting a good performance and reliability of CWM1-RETRASO. According to the good simulation predictions, CWM1-RETRASO is the first mechanistic model able to successfully simulate the processes described by the CWM1 model in HSSF CWs. Copyright © 2010 Elsevier Ltd. All rights reserved.

  14. Influence of chlorothalonil on the removal of organic matter in horizontal subsurface flow constructed wetlands.

    Science.gov (United States)

    Casas-Zapata, Juan C; Ríos, Karina; Florville-Alejandre, Tomás R; Morató, Jordi; Peñuela, Gustavo

    2013-01-01

    This study investigates the effects of chlorothalonil (CLT) on chemical oxygen demand (COD) and dissolved organic carbon (DOC) in pilot-scale horizontal subsurface flow constructed wetlands (HSSFCW) planted with Phragmites australis. Physicochemical parameters of influent and effluent water samples, microbial population counting methods and statistical analysis were used to evaluate the influence of CLT on organic matter removal efficiency. The experiments were conducted on four planted replicate wetlands (HSSFCW-Pa) and one unplanted control wetland (HSSFCW-NPa). The wetlands exhibited high average organic matter removal efficiencies (HSSFCW-Pa: 80.6% DOC, 98.0% COD; HSSFCW-NPa: 93.2% DOC, 98.4% COD). The addition of CLT did not influence organic removal parameters. In all cases CLT concentrations in the effluent occurred in concentrations lower than the detection limit of the analytical method. Microbial population counts from HSSFCW-Pa showed significant correlations among different microbial groups and with different physicochemical variables. The apparent independence of organic matter removal and CLT inputs, along with the CLT depletion observed in effluent samples demonstrated that HSSFCW are a viable technology for the treatment of agricultural effluents contaminated with organo-chloride pesticides like CLT.

  15. Determination and removal of antibiotics in secondary effluent using a horizontal subsurface flow constructed wetland.

    Science.gov (United States)

    Zhang, Chunhui; Ning, Ke; Zhang, Wenwen; Guo, Yuanjie; Chen, Jun; Liang, Chen

    2013-04-01

    Increased attention is currently being directed towards the potential negative effects of antibiotics and other PPCPs discharged into the aquatic environment via municipal WWTP secondary effluents. A number of analytical methods, such as high performance liquid chromatography technologies, including a high performance liquid chromatography-fluorescence method (HPLC-FLD), high performance liquid chromatography-UV detection method (HPLC-UV) and high performance liquid chromatography-mass spectrometry method (HPLC-MS), have been suggested as determination technologies for antibiotic residues in water. In this study, we implement a HPLC-MS/MS combined method to detect and analyze antibiotics in WWTP secondary effluent and apply a horizontal subsurface flow constructed wetland (CW) as an advanced wastewater treatment for removing antibiotics in the WWTP secondary effluent. The results show that there were 2 macrolides, 2 quinolones and 5 sulfas in WWTP secondary effluent among all the 22 antibiotics considered. After the CW advanced treatment, the concentration removal efficiencies and removal loads of 9 antibiotics were 53-100% and 0.004-0.7307 μg m(-2) per day, respectively.

  16. Rivulet flow round a horizontal cylinder subject to a uniform surface shear stress

    KAUST Repository

    Paterson, C.

    2014-09-14

    © 2014 © The Author, 2014. Published by Oxford University Press; all rights reserved. For Permissions, please email: journals.permissions@oup.com. The steady flow of a slowly varying rivulet with prescribed flux in the azimuthal direction round a large stationary horizontal cylinder subject to a prescribed uniform azimuthal surface shear stress is investigated. In particular, we focus on the case where the volume flux is downwards but the shear stress is upwards, for which there is always a solution corresponding to a rivulet flowing down at least part of one side of the cylinder. We consider both a rivulet with constant non-zero contact angle but slowly varying width (that is, de-pinned contact lines) and a rivulet with constant width but slowly varying contact angle (that is, pinned contact lines), and show that they have qualitatively different behaviour. When shear is present, a rivulet with constant non-zero contact angle can never run all the way from the top to the bottom of the cylinder, and so we consider the scenario in which an infinitely wide two-dimensional film of uniform thickness covers part of the upper half of the cylinder and \\'breaks\\' into a single rivulet with constant non-zero contact angle. In contrast, a sufficiently narrow rivulet with constant width can run all the way from the top to the bottom of the cylinder, whereas a wide rivulet can do so only if its contact lines de-pin, and so we consider the scenario in which the contact lines of a wide rivulet de-pin on the lower half of the cylinder.

  17. Mixed convection boundary-layer flow from a horizontal circular cylinder with a constant surface heat flux

    Energy Technology Data Exchange (ETDEWEB)

    Nazar, R.; Amin, N. [Department of Mathematics, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor (Malaysia); Pop, I. [Faculty of Mathematics, University of Cluj, R-3400 Cluj, CP 253 (Romania)

    2004-02-01

    The laminar mixed convection boundary-layer flow of a viscous and incompressible fluid past a horizontal circular cylinder, which is maintained at a constant heat flux and is placed in a stream flowing vertically upward has been theoretically studied in this paper. The solutions for the flow and heat transfer characteristics are evaluated numerically for different values of the mixed convection parameter {lambda} with the Prandtl number Pr = 1 and 7, respectively. It is found, as for the case of a heated or cooled cylinder, considered by Merkin [5], that assisting flow delays separation of the boundary-layer and can, if the assisting flow is strong enough, suppress it completely. The opposing flow, on the other side, brings the separation point nearer to the lower stagnation point and for sufficiently strong opposing flows there will not be a boundary-layer on the cylinder. (orig.)

  18. On the coupled unsaturated–saturated flow process induced by vertical, horizontal, and slant wells in unconfined aquifers

    Directory of Open Access Journals (Sweden)

    X. Liang

    2017-03-01

    established with special consideration of the coupled unsaturated–saturated flow process and the well orientation. Groundwater flow in the saturated zone is described by a three-dimensional governing equation and a linearized three-dimensional Richards' equation in the unsaturated zone. A solution in the Laplace domain is derived by the Laplace–finite-Fourier-transform and the method of separation of variables, and the semi-analytical solutions are obtained using a numerical inverse Laplace method. The solution is verified by a finite-element numerical model. It is found that the effects of the unsaturated zone on the drawdown of a pumping test exist at any angle of inclination of the pumping well, and this impact is more significant in the case of a horizontal well. The effects of the unsaturated zone on the drawdown are independent of the length of the horizontal well screen. The vertical well leads to the largest water volume drained from the unsaturated zone (W during the early pumping time, and the effects of the well orientation on W values become insignificant at the later time. The screen length of the horizontal well does not affect W for the whole pumping period. The proposed solutions are useful for the parameter identification of pumping tests with a general well orientation (vertical, horizontal, and slant in unconfined aquifers affected from above by the unsaturated flow process.

  19. Regional Quasi-Three-Dimensional Unsaturated-Saturated Water Flow Model Based on a Vertical-Horizontal Splitting Concept

    Directory of Open Access Journals (Sweden)

    Yan Zhu

    2016-05-01

    Full Text Available Due to the high nonlinearity of the three-dimensional (3-D unsaturated-saturated water flow equation, using a fully 3-D numerical model is computationally expensive for large scale applications. A new unsaturated-saturated water flow model is developed in this paper based on the vertical/horizontal splitting (VHS concept to split the 3-D unsaturated-saturated Richards’ equation into a two-dimensional (2-D horizontal equation and a one-dimensional (1-D vertical equation. The horizontal plane of average head gradient in the triangular prism element is derived to split the 3-D equation into the 2-D equation. The lateral flow in the horizontal plane of average head gradient represented by the 2-D equation is then calculated by the water balance method. The 1-D vertical equation is discretized by the finite difference method. The two equations are solved simultaneously by coupling them into a unified nonlinear system with a single matrix. Three synthetic cases are used to evaluate the developed model code by comparing the modeling results with those of Hydrus1D, SWMS2D and FEFLOW. We further apply the model to regional-scale modeling to simulate groundwater table fluctuations for assessing the model applicability in complex conditions. The proposed modeling method is found to be accurate with respect to measurements.

  20. An experimental study of gravity-driven countercurrent two-phase flow in horizontal and inclined channels

    International Nuclear Information System (INIS)

    Lillibridge, K.H.; Ghiaasiaan, S.M.; Abdel-Khalik, S.I.

    1994-01-01

    Countercurrent two-phase flow in horizontal and inclined channels, connecting a sealed liquid-filled reservoir to the atmosphere, is experimentally studied. This type of gravity-driven countercurrent two-phase flow can occur during the operation of passive safety coolant injection systems of advanced reactors. It can also occur in the pressurizer surge line of pressurized water reactors during severe accidents when the hot leg becomes voided. Four distinct flow regimes are identified: (a) stratified countercurrent, which mainly occurs when the channel is horizontal; (b) intermittent stratified-slug; (c) oscillating, which occurs when the angle of inclination is ≥30 deg; and (d) annular countercurrent. The characteristics of each regime and their sensitivity to important geometric parameters are examined. The superficial velocities in the stratified countercurrent and oscillating regimes are empirically correlated

  1. Long liquid slugs in stratified gas/liquid flow in horizontal and slightly inclined pipes

    NARCIS (Netherlands)

    Kadri, U.

    2009-01-01

    Long liquid slugs reaching several hundreds pipe diameter may appear when transporting gas and liquid in horizontal and near horizontal pipes. The long slugs cause system vibration and separation difficulties that may lead to operational failures. Identifying and predicting the time and length

  2. Development of an electrical sensor for measurement of void fraction and identification of flow regime in a horizontal pipe

    International Nuclear Information System (INIS)

    Won, Woo Yeon; Lee, Yeon Gun; Lee, Bo An; Ko, Min Seok; Kim, Sin

    2015-01-01

    The electrical signals of the electrical impedance sensor depend on the flow structure as well as the void fraction. For this reason, the electrical responses to a given void fraction differ according to the flow pattern. For reliable void fraction measurement, hence, information on the flow pattern should be given. Based on this idea, a new improved conductance sensor is proposed in this study to measure the void fraction and simultaneously determine the flow pattern of the air-water two-phase mixture in a horizontal pipe. The proposed sensor is composed of a 3-electrode set of adjacent and opposite electrodes. The opposite electrodes measures the void fraction, the adjacent electrode serves to determine the flow patterns. Prior to the real applications of the proposed approach, several numerical calculations based on the FEM are performed to optimize the electrode and insulator sizes in terms of the sensor linearity. The numerical results are assessed in comparison with the data from static experiments. The sensor system is applied for a horizontal flow loop with 40 mm in inner diameter and 5 m in length and its measurement performance for the void fraction is compared with that of a wire-mesh sensor system. In this study, an electrical sensor for measuring the void fraction and identifying flow pattern in horizontal pipes has been designed. For optimization of the sensor, numerical analysis have been performed in order to determine the geometry and verified it through static experiments. Also, the loop experiments were conducted for several flow rate conditions covering stratified and intermittent flow regimes and the experimental results for the void fractions measured by the proposed sensor were compared with those of a wire-mesh sensor. The comparison results are in overall good agreements

  3. Limestone and Zeolite as Alternative Media in Horizontal Subsurface Flow Constructed Wetlands: Laboratory-Scale Studies

    Science.gov (United States)

    Lizama, K.; Jaque, I.; Ayala, J.

    2016-12-01

    Arsenic is well known for its chronic toxicity. Millions of people around the world are currently at risk, drinking water with As concentrations above 10 ppb, the WHO drinking water guideline. Although different treatment options exist, they are often limited by elevated costs and maintenance requirements. Constructed wetlands are a natural water treatment system, capable to remove metals and metalloids -including As- via different physical, chemical and biological processes. The use of alternative supporting media to enhance As removal in subsurface flow wetlands has been recommended, but not sufficiently studied. Limestone and zeolite have been identified as effective supporting media in subsurface flow wetlands aiming As removal. However, there are still key aspects to be addressed, such as the implications of using these media, the speciation in the solid phase, the role of vegetation, etc. This study investigated the performance of limestone and zeolite in three types of experiments: batch, column and as main supporting media in a bench scale horizontal subsurface flow wetland system. Synthetic water resembling a contaminated river in Chile (As concentration=3 mg/L, Fe concentration= 100 mg/L, pH=2) was used in all experiments. In the batch experiments, the As concentration, the mass of media and the contact time were varied. The column system consisted of three limestone columns and three zeolite columns, operated under a hydraulic loading of 20 mm/d. The wetland system consisted of twelve PVC cells: six filled with zeolite and six with limestone. Phragmites australis were planted in three cells of each media type, as control cells. From the batch experiments, maximum As sorption capacities as indicated by Langmuir model were 1.3 mg/g for limestone and 0.17 mg/g for zeolite, at 18 h contact time and 6.3 g/L medium concentration. EDS and XPS analyses revealed that As and Fe were retained in zeolite at the end of the batch experiments. Zeolite and limestone

  4. Developmental assessment of RELAP5/MOD3 code against ROSA-IV/TPTF horizontal two-phase flow experiments

    International Nuclear Information System (INIS)

    Kukita, Yutaka; Asaka, Hideaki; Anoda, Yoshinari; Ishiguro, Misako; Tasaka, Kanji; Mimura, Yuichi; Nemoto, Toshiyuki.

    1990-03-01

    A developmental version of the RELAP5/Mod3 code (as of June 1989) was assessed for accuracy using experimental data taken for high-pressure (7MPa) steam-water two-phase flow in a large-diameter (0.18 m) horizontal-pipe test section of the ROSA-IV Two-Phase Flow Test Facility (TPTF). The agreement between the measured and calculated test section void fractions was much better than that for the previous generation of RELAP5 (MOD2). The improvement was achieved primarily due to the code changes with respect to the flow stratification criterion and interfacial-drag calculation scheme. (author)

  5. An extension of theoretical analysis for the onset of slugging criterion in horizontal stratified air-water countercurrent flow

    International Nuclear Information System (INIS)

    Lee, Byung Ryung

    1997-02-01

    This paper presents an experimental and theoretical investigation of interfacial friction factor, wave height and transition criterion from wavy to slug flow in a long horizontal air-water countercurrent stratified flow condition. A series of experiments have been conducted in adiabatic countercurrent stratified flow with the round pipe and rectangular duct test section to develop the interfacial friction factor and the criterion of onset of slugging in horizontal air-water countercurrent stratified flow. An adiabatic semi-empirical correlation for interfacial friction factor has been developed based on the surface roughness concept. A comparison of the measured data in this study and of other investigators with the predictions of the present correlation shows that the agreement is within ±30% error, and that the present correlation is applicable to a broader range of water flow rate than the correlations of previous investigators. The theories which can calculate the wave height and criteria of onset of slug flow in a stratified wavy flow regime have been developed based on the concept of total energy conservation and also wave theory. This theoretical criteria agree better with the measured data than the other criteria available in the literature, but the criteria range about 92∼107% of the measured data. An empirical formula for the criterion has been also developed and compared with the formula in the literatures. Comparison between the measured data and the predictions of the present theory shows that the agreement is within ±8%

  6. Investigations of post-dryout heat transfer in case of vertical and horizontal pipe flow

    International Nuclear Information System (INIS)

    Schnittger, R.B.

    1982-01-01

    Experimental studies are presented of the heat transfer behaviour of a post dry-out flows in directly heated tubes of 6 m length. The wall temperatures of the tube are measured by thermocouples, which are distributed radially and axially on the outer tube surface. The vapor temperature is determined by a probe at the exit of the tube R 12 is used as a working fluid. Based on the experimental temperature distribution, the influence on pressure, massflow-density, and on specific thermal surface load had been studied. As a result, the heat transfer behaviour is dominated in a broad parameter range by thermal non-equilibrium conditions between the phases. Under these conditions the heat is transfered mainly from the tube wall to the vapor and from the vapor to the droplets. The strong wall temperature decrease observed at higher pressures and specific thermal surface loads after the dryout is not explained by a contact between the droplets and the tube wall, but by the decay of the droplets in the boundary layer of the wall. The non-uniform wall-temperature distribution of the horizontal tube and the lower evaporation rate compared with a vertical tube are explained by a non-uniform vapor temperature - and droplet distribution over the tube cross-section. A model is proposed for the calculation of the wall temperatures, which accounts for all these individual effects. This model can also be applied in the case of water as is demonstrated by a comparison with respective experimental results from the literature. (orig.) [de

  7. Increasing power generation in horizontal axis wind turbines using optimized flow control

    Science.gov (United States)

    Cooney, John A., Jr.

    In order to effectively realize future goals for wind energy, the efficiency of wind turbines must increase beyond existing technology. One direct method for achieving increased efficiency is by improving the individual power generation characteristics of horizontal axis wind turbines. The potential for additional improvement by traditional approaches is diminishing rapidly however. As a result, a research program was undertaken to assess the potential of using distributed flow control to increase power generation. The overall objective was the development of validated aerodynamic simulations and flow control approaches to improve wind turbine power generation characteristics. BEM analysis was conducted for a general set of wind turbine models encompassing last, current, and next generation designs. This analysis indicated that rotor lift control applied in Region II of the turbine power curve would produce a notable increase in annual power generated. This was achieved by optimizing induction factors along the rotor blade for maximum power generation. In order to demonstrate this approach and other advanced concepts, the University of Notre Dame established the Laboratory for Enhanced Wind Energy Design (eWiND). This initiative includes a fully instrumented meteorological tower and two pitch-controlled wind turbines. The wind turbines are representative in their design and operation to larger multi-megawatt turbines, but of a scale that allows rotors to be easily instrumented and replaced to explore new design concepts. Baseline data detailing typical site conditions and turbine operation is presented. To realize optimized performance, lift control systems were designed and evaluated in CFD simulations coupled with shape optimization tools. These were integrated into a systematic design methodology involving BEM simulations, CFD simulations and shape optimization, and selected experimental validation. To refine and illustrate the proposed design methodology, a

  8. Rivulet flow round a horizontal cylinder subject to a uniform surface shear stress

    KAUST Repository

    Paterson, C.; Wilson, S. K.; Duffy, B. R.

    2014-01-01

    large stationary horizontal cylinder subject to a prescribed uniform azimuthal surface shear stress is investigated. In particular, we focus on the case where the volume flux is downwards but the shear stress is upwards, for which there is always a

  9. Effect of Water Cut on Pressure Drop of Oil (D130) -Water Flow in 4″Horizontal Pipe

    Science.gov (United States)

    Basha, Mehaboob; Shaahid, S. M.; Al-Hems, Luai M.

    2018-03-01

    The oil-water flow in pipes is a challenging subject that is rich in physics and practical applications. It is often encountered in many oil and chemical industries. The pressure gradient of two phase flow is still subject of immense research. The present study reports pressure measurements of oil (D130)-water flow in a horizontal 4″ diameter stainless steel pipe at different flow conditions. Experiments were carried out for different water cuts (WC); 0-100%. Inlet oil-water flow rates were varied from 4000 to 8000 barrels-per-day in steps of 2000. It has been found that the frictional pressure drop decreases for WC = 0 - 40 %. With further increase in WC, friction pressure drop increases, this could be due to phase inversion.

  10. An investigation of particle behavior in gas-solid horizontal pipe flow by an extended LDA technique

    Energy Technology Data Exchange (ETDEWEB)

    Yong Lu; Donald H. Glass; William J. Easson [University of Edinburgh, Edinburgh (United Kingdom). Institute for Materials and Processes

    2009-12-15

    An extended Laser Doppler Anemometry (LDA) technique has been developed to measure the distributions of particle velocities and particle number rates over a whole pipe cross-section in a dilute pneumatic conveying system. The first extension concentrates on the transform matrix for predicting the laser beams' cross point in a pipe according to the shift coordinate of the 3D computer-controlled traverse system on which the probes of the LDA system were mounted. The second focuses on the proper LDA sample rate for the measurement of gas-solid pipe flow with polydisperse particles. A suitable LDA sample rate should ensure that enough data is recorded in the measurement interval to precisely calculate the particle mean velocity or other statistical values at every sample point. The present study explores the methodology as well as the fundamentals of measurements, using a laser facility, of the cross-sectional distributions of solid phase. In the horizontal gas-solid pipe flow (glass beads less than 110 {mu}m), the experimental data show that the cross-sectional flow patterns of the solid phase can be classified by annulus-like flow describing the axial particle velocity contours and stratified flow characterising particle number rate distribution over a cross-section. Thus, the cross-sectional flow pattern of the solid phase in a horizontal pipe may be annular or stratified dependent on whether the axial particle velocity or particle number rate is the phenomenon studied. 13 refs., 16 figs., 1 tab.

  11. Analytical Solution for Time-drawdown Response to Constant Pumping from a Homogeneous, Confined Horizontal Aquifer with Unidirectional Flow

    Science.gov (United States)

    Parrish, K. E.; Zhang, J.; Teasdale, E.

    2007-12-01

    An exact analytical solution to the ordinary one-dimensional partial differential equation is derived for transient groundwater flow in a homogeneous, confined, horizontal aquifer using Laplace transformation. The theoretical analysis is based on the assumption that the aquifer is homogeneous and one-dimensional (horizontal); confined between impermeable formations on top and bottom; and of infinite horizontal extent and constant thickness. It is also assumed that there is only a single pumping well penetrating the entire aquifer; flow is everywhere horizontal within the aquifer to the well; the well is pumping with a constant discharge rate; the well diameter is infinitesimally small; and the hydraulic head is uniform throughout the aquifer before pumping. Similar to the Theis solution, this solution is suited to determine transmissivity and storativity for a two- dimensional, vertically confined aquifer, such as a long vertically fractured zone of high permeability within low permeable rocks or a long, high-permeability trench inside a low-permeability porous media. In addition, it can be used to analyze time-drawdown responses to pumping and injection in similar settings. The solution can also be used to approximate the groundwater flow for unconfined conditions if (1) the variation of transmissivity is negligible (groundwater table variation is small in comparison to the saturated thickness); and (2) the unsaturated flow is negligible. The errors associated with the use of the solution to unconfined conditions depend on the accuracies of the above two assumptions. The solution can also be used to assess the impacts of recharge from a seasonal river or irrigation canal on the groundwater system by assuming uniform, time- constant recharge along the river or canal. This paper presents the details for derivation of the analytical solution. The analytical solution is compared to numerical simulation results with example cases. Its accuracy is also assessed and

  12. Investigation of air-water flow in a horizontal pipe with 90 degree bends using wire mesh sensors

    Energy Technology Data Exchange (ETDEWEB)

    Bowden, R.C.; Yang, S.K., E-mail: robert.bowden@cnl.ca, E-mail: sun-kyu.yang@cnl.ca [Canadian Nuclear Laboratories, Chalk River, ON (Canada)

    2015-07-01

    Wire mesh sensors were used to investigate the void fraction distribution along a 9 meter long, 50.8 mm diameter, horizontal test section that contained two 90 degree bends. Deionised water and compressed air were used as the working fluids, with the bubbly flow regime achieved at a superficial liquid velocity of 3.5 m/s and superficial gas velocities that varied between 0.1 and 1.2 m/s. The effects of superficial gas velocity and axial location on the void fraction distribution were investigated. Bubble and slug flow patterns were identified using a probability density function analysis based on a Gaussian mixture model. (author)

  13. Velocity and turbulence measurements of oil-water flow in horizontal and slightly inclined pipes using PIV

    OpenAIRE

    Kumara, W.A.S.; Halvorsen, Britt; Melaaen, Morten Christian

    2009-01-01

    Oil-water flows in horizontal and slightly inclined pipes are investigated using Particle Image Velocimetry (PIV). PIV offers a powerful non-invasive tool to study such flow fields. The experiments are conducted in a 15 m long, 56 mm diameter, inclinable steel pipe using Exxsol D60 oil (viscosity 1.64 mPa s, density 790 kg/m3) and water (viscosity 1.0 mPa s, density 996 kg/m3) as test fluids. The test pipe inclination is changed in the range from 5° upward to 5° downward. The experiments are ...

  14. Three-dimensional coating and rimming flow: a ring of fluid on a rotating horizontal cylinder

    KAUST Repository

    Leslie, G. A.

    2013-01-29

    The steady three-dimensional flow of a thin, slowly varying ring of Newtonian fluid on either the outside or the inside of a uniformly rotating large horizontal cylinder is investigated. Specifically, we study \\'full-ring\\' solutions, corresponding to a ring of continuous, finite and non-zero thickness that extends all of the way around the cylinder. In particular, it is found that there is a critical solution corresponding to either a critical load above which no full-ring solution exists (if the rotation speed is prescribed) or a critical rotation speed below which no full-ring solution exists (if the load is prescribed). We describe the behaviour of the critical solution and, in particular, show that the critical flux, the critical load, the critical semi-width and the critical ring profile are all increasing functions of the rotation speed. In the limit of small rotation speed, the critical flux is small and the critical ring is narrow and thin, leading to a small critical load. In the limit of large rotation speed, the critical flux is large and the critical ring is wide on the upper half of the cylinder and thick on the lower half of the cylinder, leading to a large critical load. We also describe the behaviour of the non-critical full-ring solution and, in particular, show that the semi-width and the ring profile are increasing functions of the load but, in general, non-monotonic functions of the rotation speed. In the limit of large rotation speed, the ring approaches a limiting non-uniform shape, whereas in the limit of small load, the ring is narrow and thin with a uniform parabolic profile. Finally, we show that, while for most values of the rotation speed and the load the azimuthal velocity is in the same direction as the rotation of the cylinder, there is a region of parameter space close to the critical solution for sufficiently small rotation speed in which backflow occurs in a small region on the upward-moving side of the cylinder. © 2013

  15. Biological mechanisms associated with triazophos (TAP) removal by horizontal subsurface flow constructed wetlands (HSFCW)

    International Nuclear Information System (INIS)

    Wu, Juan; Feng, Yuqin; Dai, Yanran; Cui, Naxin; Anderson, Bruce; Cheng, Shuiping

    2016-01-01

    Triazophos (TAP) is a widely used pesticide that is easily accumulated in the environment due to its relatively high stability: this accumulation from agricultural runoff results in potential hazards to aquatic ecosystems. Constructed wetlands are generally considered to be an effective technology for treating TAP polluted surface water. However, knowledge about the biological mechanisms of TAP removal is still lacking. This study investigates the responses of a wetland plant (Canna indica), substrate enzymes and microbial communities in bench-scale horizontal subsurface-flow constructed wetlands (HSCWs) loaded with different TAP concentrations (0, 0.1, 0.5 and 5 mg·L"−"1). The results indicate that TAP stimulated the activities of superoxide dismutase (SOD) and peroxidase (POD) in the roots of C. indica. The highest TAP concentrations significantly inhibited photosynthetic activities, as shown by a reduced effective quantum yield of PS II (Φ_P_S_I_I) and lower electron transport rates (ETR). However, interestingly, the lower TAP loadings exhibited some favorable effects on these two variables, suggesting that C. indica is a suitable species for use in wetlands designed for treatment of low TAP concentrations. Urease and alkaline phosphatase (ALP) in the wetland substrate were activated by TAP. Two-way ANOVA demonstrated that urease activity was influenced by both the TAP concentrations and season, while acidphosphatase (ACP) only responded to seasonal variations. Analysis of high throughput sequencing of 16S rRNA revealed seasonal variations in the microbial community structure of the wetland substrate at the phylum and family levels. In addition, urease activity had a greater correlation with the relative abundance of some functional microbial groups, such as the Bacillaceae family, and the ALP and ACP may be influenced by the plant more than substrate microbial communities. - Highlights: • Physiological responses of the wetland plant to triazophos loads

  16. Optimization of a horizontal-flow biofilm reactor for the removal of methane at low temperatures.

    Science.gov (United States)

    Clifford, E; Kennelly, C; Walsh, R; Gerrity, S; Reilly, E O; Collins, G

    2012-10-01

    Three pilot-scale, horizontal-flow biofilm reactors (HFBRs 1-3) were used to treat methane (CH4)-contaminated air to assess the potential of this technology to manage emissions from agricultural activities, waste and wastewater treatment facilities, and landfills. The study was conducted over two phases (Phase 1, lasting 90 days and Phase 2, lasting 45 days). The reactors were operated at 10 degrees C (typical of ambient air and wastewater temperatures in northern Europe), and were simultaneously dosed with CH4-contaminated air and a synthetic wastewater (SWW). The influent loading rates to the reactors were 8.6 g CH4/m3/hr (4.3 g CH4/m2 TPSA/hr; where TPSA is top plan surface area). Despite the low operating temperatures, an overall average removal of 4.63 g CH4/m3/day was observed during Phase 2. The maximum removal efficiency (RE) for the trial was 88%. Potential (maximum) rates of methane oxidation were measured and indicated that biofilm samples taken from various regions in the HFBRs had mostly equal CH4 removal potential. In situ activity rates were dependent on which part of the reactor samples were obtained. The results indicate the potential of the HFBR, a simple and robust technology, to biologically treat CH4 emissions. The results of this study indicate that the HFBR technology could be effectively applied to the reduction of greenhouse gas emissions from wastewater treatment plants and agricultural facilities at lower temperatures common to northern Europe. This could reduce the carbon footprint of waste treatment and agricultural livestock facilities. Activity tests indicate that methanotrophic communities can be supported at these temperatures. Furthermore, these data can lead to improved reactor design and optimization by allowing conditions to be engineered to allow for improved removal rates, particularly at lower temperatures. The technology is simple to construct and operate, and with some optimization of the liquid phase to improve mass

  17. Three-dimensional coating and rimming flow: a ring of fluid on a rotating horizontal cylinder

    KAUST Repository

    Leslie, G. A.; Wilson, S. K.; Duffy, B. R.

    2013-01-01

    The steady three-dimensional flow of a thin, slowly varying ring of Newtonian fluid on either the outside or the inside of a uniformly rotating large horizontal cylinder is investigated. Specifically, we study 'full-ring' solutions, corresponding to a ring of continuous, finite and non-zero thickness that extends all of the way around the cylinder. In particular, it is found that there is a critical solution corresponding to either a critical load above which no full-ring solution exists (if the rotation speed is prescribed) or a critical rotation speed below which no full-ring solution exists (if the load is prescribed). We describe the behaviour of the critical solution and, in particular, show that the critical flux, the critical load, the critical semi-width and the critical ring profile are all increasing functions of the rotation speed. In the limit of small rotation speed, the critical flux is small and the critical ring is narrow and thin, leading to a small critical load. In the limit of large rotation speed, the critical flux is large and the critical ring is wide on the upper half of the cylinder and thick on the lower half of the cylinder, leading to a large critical load. We also describe the behaviour of the non-critical full-ring solution and, in particular, show that the semi-width and the ring profile are increasing functions of the load but, in general, non-monotonic functions of the rotation speed. In the limit of large rotation speed, the ring approaches a limiting non-uniform shape, whereas in the limit of small load, the ring is narrow and thin with a uniform parabolic profile. Finally, we show that, while for most values of the rotation speed and the load the azimuthal velocity is in the same direction as the rotation of the cylinder, there is a region of parameter space close to the critical solution for sufficiently small rotation speed in which backflow occurs in a small region on the upward-moving side of the cylinder. © 2013 Cambridge

  18. Biological mechanisms associated with triazophos (TAP) removal by horizontal subsurface flow constructed wetlands (HSFCW)

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Juan; Feng, Yuqin; Dai, Yanran; Cui, Naxin [State Key Laboratory of Pollution Control and ResourceReuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China); Anderson, Bruce [Department of Civil Engineering, Queen' s University, Kingston K7L3N6 (Canada); Cheng, Shuiping, E-mail: shpcheng@tongji.edu.cn [State Key Laboratory of Pollution Control and ResourceReuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China)

    2016-05-15

    Triazophos (TAP) is a widely used pesticide that is easily accumulated in the environment due to its relatively high stability: this accumulation from agricultural runoff results in potential hazards to aquatic ecosystems. Constructed wetlands are generally considered to be an effective technology for treating TAP polluted surface water. However, knowledge about the biological mechanisms of TAP removal is still lacking. This study investigates the responses of a wetland plant (Canna indica), substrate enzymes and microbial communities in bench-scale horizontal subsurface-flow constructed wetlands (HSCWs) loaded with different TAP concentrations (0, 0.1, 0.5 and 5 mg·L{sup −1}). The results indicate that TAP stimulated the activities of superoxide dismutase (SOD) and peroxidase (POD) in the roots of C. indica. The highest TAP concentrations significantly inhibited photosynthetic activities, as shown by a reduced effective quantum yield of PS II (Φ{sub PSII}) and lower electron transport rates (ETR). However, interestingly, the lower TAP loadings exhibited some favorable effects on these two variables, suggesting that C. indica is a suitable species for use in wetlands designed for treatment of low TAP concentrations. Urease and alkaline phosphatase (ALP) in the wetland substrate were activated by TAP. Two-way ANOVA demonstrated that urease activity was influenced by both the TAP concentrations and season, while acidphosphatase (ACP) only responded to seasonal variations. Analysis of high throughput sequencing of 16S rRNA revealed seasonal variations in the microbial community structure of the wetland substrate at the phylum and family levels. In addition, urease activity had a greater correlation with the relative abundance of some functional microbial groups, such as the Bacillaceae family, and the ALP and ACP may be influenced by the plant more than substrate microbial communities. - Highlights: • Physiological responses of the wetland plant to triazophos

  19. Characterization of two-phase flow regimes in horizontal tubes using 81mKr tracer experiments.

    Science.gov (United States)

    Oriol, Jean; Leclerc, Jean Pierre; Berne, Philippe; Gousseau, Georges; Jallut, Christian; Tochon, Patrice; Clement, Patrice

    2008-10-01

    The diagnosis of heat exchangers on duty with respect to flow mal-distributions needs the development of non-intrusive inlet-outlet experimental techniques in order to perform an online fault diagnosis. Tracer experiments are an example of such techniques. They can be applied to mono-phase heat exchangers but also to multi-phase ones. In this case, the tracer experiments are more difficult to perform. In order to check for the capabilities of tracer experiments to be used for the flow mal-distribution diagnosis in the case of multi-phase heat exchangers, we present here a preliminary study on the simplest possible system: two-phase flows in a horizontal tube. (81m)Kr is used as gas tracer and properly collimated NaI (TI) crystal scintillators as detectors. The specific shape of the tracer response allows two-phase flow regimes to be characterized. Signal analysis allows the estimation of the gas phase real average velocity and consequently of the liquid phase real average velocity as well as of the volumetric void fraction. These results are compared successfully to those obtained with liquid phase tracer experiments previously presented by Oriol et al. 2007. Characterization of the two-phase flow regimes and liquid dispersion in horizontal and vertical tubes using coloured tracer and no intrusive optical detector. Chem. Eng. Sci. 63(1), 24-34, as well as to those given by correlations from literature.

  20. Characterization of two-phase flow regimes in horizontal tubes using 81mKr tracer experiments

    International Nuclear Information System (INIS)

    Oriol, Jean; Leclerc, Jean Pierre; Berne, Philippe; Gousseau, Georges; Jallut, Christian; Tochon, Patrice; Clement, Patrice

    2008-01-01

    The diagnosis of heat exchangers on duty with respect to flow mal-distributions needs the development of non-intrusive inlet-outlet experimental techniques in order to perform an online fault diagnosis. Tracer experiments are an example of such techniques. They can be applied to mono-phase heat exchangers but also to multi-phase ones. In this case, the tracer experiments are more difficult to perform. In order to check for the capabilities of tracer experiments to be used for the flow mal-distribution diagnosis in the case of multi-phase heat exchangers, we present here a preliminary study on the simplest possible system: two-phase flows in a horizontal tube. 81m Kr is used as gas tracer and properly collimated NaI (TI) crystal scintillators as detectors. The specific shape of the tracer response allows two-phase flow regimes to be characterized. Signal analysis allows the estimation of the gas phase real average velocity and consequently of the liquid phase real average velocity as well as of the volumetric void fraction. These results are compared successfully to those obtained with liquid phase tracer experiments previously presented by Oriol et al. 2007. Characterization of the two-phase flow regimes and liquid dispersion in horizontal and vertical tubes using coloured tracer and no intrusive optical detector. Chem. Eng. Sci. 63(1), 24-34, as well as to those given by correlations from literature

  1. Characterization of two-phase flow regimes in horizontal tubes using {sup 81m}Kr tracer experiments

    Energy Technology Data Exchange (ETDEWEB)

    Oriol, Jean [LPAC, CEA Grenoble, 17, rue des Martyrs, 38054 Grenoble Cedex 9 (France); Leclerc, Jean Pierre [Laboratoire des Sciences du Genie Chimique (LSGC), Nancy-Universite, CNRS, BP 20451, F-54001 Nancy (France)], E-mail: leclerc@ensic.inpl-nancy.fr; Berne, Philippe; Gousseau, Georges [L2T, CEA Grenoble, 17, rue des Martyrs, 38054 Grenoble Cedex 9 (France); Jallut, Christian [Universite de Lyon, Universite Lyon 1, LAGEP, UMR CNRS 5007, ESCPE, 43 Bd du 11 novembre 1918, 69622 Villeurbanne Cedex (France); Tochon, Patrice; Clement, Patrice [GRETh, CEA Grenoble, 17, rue des Martyrs, 38054 Grenoble Cedex 9 (France)

    2008-10-15

    The diagnosis of heat exchangers on duty with respect to flow mal-distributions needs the development of non-intrusive inlet-outlet experimental techniques in order to perform an online fault diagnosis. Tracer experiments are an example of such techniques. They can be applied to mono-phase heat exchangers but also to multi-phase ones. In this case, the tracer experiments are more difficult to perform. In order to check for the capabilities of tracer experiments to be used for the flow mal-distribution diagnosis in the case of multi-phase heat exchangers, we present here a preliminary study on the simplest possible system: two-phase flows in a horizontal tube. {sup 81m}Kr is used as gas tracer and properly collimated NaI (TI) crystal scintillators as detectors. The specific shape of the tracer response allows two-phase flow regimes to be characterized. Signal analysis allows the estimation of the gas phase real average velocity and consequently of the liquid phase real average velocity as well as of the volumetric void fraction. These results are compared successfully to those obtained with liquid phase tracer experiments previously presented by Oriol et al. 2007. Characterization of the two-phase flow regimes and liquid dispersion in horizontal and vertical tubes using coloured tracer and no intrusive optical detector. Chem. Eng. Sci. 63(1), 24-34, as well as to those given by correlations from literature.

  2. Observation and characterization of flow in critical sections of a horizontal pressurized gating system using water models

    Directory of Open Access Journals (Sweden)

    Jaiganesh Venkataramani

    2013-07-01

    Full Text Available This work is concerned with the hydraulics and flow characterization in a pressurized, horizontal gating system with multiple ingates attached to a plate mold, using transparent water models. Runners with two different aspect ratios (w/h = 0.5 and 2 and four different types of ingates (rectangular, convergent, divergent and venturi were examined for their influence on flow behavior. Flow behavior was visualized using a high speed camera capable of capturing images up to 10,000 frames per second. Real time experimentation with a few runner – ingate combinations were carried out to validate the usefulness of water models in predicting the filling behavior. Comparison of the approaches provided useful insights into the filling behavior in critical sections of the flow passages as well as the utility of water models towards understanding of the filling behavior during real time casting.

  3. Two-phase magnetoconvection flow of magnetite (Fe3O4) nanoparticles in a horizontal composite porous annulus

    Science.gov (United States)

    Abbas, Zaheer; Hasnain, Jafar

    A numerical study is performed to examine the two-phase magnetoconvection and heat transfer phenomena of Fe3O4 -kerosene nanofluid flow in a horizontal composite porous annulus with an external magnetic field. The annulus is filled with immiscible fluids flowing between two concentric cylinders. The governing equations of the flow problem are obtained using Darcy-Brinkman model. Heat transfer is analyzed in the presence of viscous and Darcian dissipation terms. The shooting method is used as a tool to solve the obtained non-linear ordinary differential equations for the velocity and temperature profiles. The velocity and temperature distributions are analyzed and discussed under the influence of involved flow parameters with the aid of graphs. It is found that both velocity and temperature of fluid are decreased with ferroparticle volume fraction. In addition to that, it is also presented that the existence of magnetic field decreases the benefit of ferrofluids in heat transfer progression.

  4. Three-phase flow analysis of dense nonaqueous phase liquid infiltration in horizontally layered porous media

    NARCIS (Netherlands)

    Wipfler, E.L.; Dijke, van M.I.J.; Zee, van der S.E.A.T.M.

    2004-01-01

    We considered dense nonaqueous phase liquid (DNAPL) infiltration into a water-unsaturated porous medium that consists of two horizontal layers, of which the top layer has a lower intrinsic permeability than the bottom layer. DNAPL is the intermediate-wetting fluid with respect to the wetting water

  5. Nucleate boiling at the forced flow of binary non-azeotropic mixtures in horizontal tubes

    Directory of Open Access Journals (Sweden)

    Mezentseva N.N.

    2015-01-01

    Full Text Available Analysis of experimental values of heat transfer coefficients obtained through investigation of nucleate boiling of the two-component non-azeotropic mixtures inside the horizontal smooth tubes by various authors is presented. In the zone of nucleate boiling, the experimental data are in good agreement with the calculation dependence.

  6. Visualization of cross-sectional flow structure during condensation of steam in a slightly inclined horizontal tube

    Energy Technology Data Exchange (ETDEWEB)

    Puseya, Andree; Kim, H. [Kyung Hee University, Yongin (Korea, Republic of); Kwon, T. S. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    These flow characteristics called flow patterns still depend on a proper visualization technique in order to identify such local distribution. These proper distributions will have a dependence on the inclination of the tube as well, as it was demonstrated by Lips and Mayer. This work is focused on presenting an experimental investigation to visualize the cross sectional two-phase flow structure for condensation of steam in a horizontal tube and identify the liquid-gas interface using the axial-viewing technique. This innovative technique developed by Hewitt and more recently used in visualization works by Badie, permits the achievement to identify those systems in the area of interest by looking directly into the two-phase flow system during condensation of steam inside a pipe with technology such a high speed camera. An experimental work to visualize and locate the liquid-gas interface for steam condensation in horizontal tubes with slightly inclination was developed on this research The experimental results shows that the axial viewing technique works well with condensation phenomena and can be used for further developments in the field such as determination of liquid film geometry and calculation of void fraction.

  7. The evaluation of validity of the RELAP5/Mod3 flow regime map for horizontal small diameter tubes at low pressure

    Energy Technology Data Exchange (ETDEWEB)

    Agafonova, N. [St. Petersburg State Technical Univ. (Russian Federation); Banati, J. [Lappeenranta Univ. of Technology (Finland)

    1997-12-31

    RELAP5/MOD3 code was developed for Western type power water reactors with vertical steam generators. Thus, this code should be validated also for WWER design with horizontal steam generators. In application for horizontal steam generators the situation with two-phase flow inside small diameter tubes is possible when the first circuit pressure drops in accident below the pressure level in the boiling water. It is known that computer codes have not always modelled correctly the two-phase flow inside horizontal tubes at low pressures (less than 4-6 MPa). It may be the result of erroneous prediction of the flow regime. Correct prediction of the flow regime is especially important for the fully or partly stratified flow in horizontal tubes. The aim of this study is the attempt of verification of the flow regime map, which is used in the RELAP5/MOD3 computer code for two-phase flow in horizontal small diameter tubes. `Small diameter tube` means according RELAP5/MOD3 that the inner diameter of the tube is less (or equal) than 0.018 m. The inner tube diameter in horizontal steam generators is equal 0.013 m. (orig.). 19 refs.

  8. The evaluation of validity of the RELAP5/Mod3 flow regime map for horizontal small diameter tubes at low pressure

    Energy Technology Data Exchange (ETDEWEB)

    Agafonova, N [St. Petersburg State Technical Univ. (Russian Federation); Banati, J [Lappeenranta Univ. of Technology (Finland)

    1998-12-31

    RELAP5/MOD3 code was developed for Western type power water reactors with vertical steam generators. Thus, this code should be validated also for WWER design with horizontal steam generators. In application for horizontal steam generators the situation with two-phase flow inside small diameter tubes is possible when the first circuit pressure drops in accident below the pressure level in the boiling water. It is known that computer codes have not always modelled correctly the two-phase flow inside horizontal tubes at low pressures (less than 4-6 MPa). It may be the result of erroneous prediction of the flow regime. Correct prediction of the flow regime is especially important for the fully or partly stratified flow in horizontal tubes. The aim of this study is the attempt of verification of the flow regime map, which is used in the RELAP5/MOD3 computer code for two-phase flow in horizontal small diameter tubes. `Small diameter tube` means according RELAP5/MOD3 that the inner diameter of the tube is less (or equal) than 0.018 m. The inner tube diameter in horizontal steam generators is equal 0.013 m. (orig.). 19 refs.

  9. Condensation of refrigerants in horizontal, spirally grooved microfin tubes: Numerical analysis of heat transfer in the annular flow regime

    Energy Technology Data Exchange (ETDEWEB)

    Nozu, S; Honda, H

    2000-02-01

    A method is presented for estimating the condensation heat transfer coefficient in a horizontal, spirally grooved microfin tube. Based on the flow observation study performed by the authors, a laminar film condensation model in the annular flow regime is proposed. The model assumes that all the condensate flow occurs through the grooves. The condensate film is segmented into thin and thick film regions. In the thin film region formed on the fin surface, the condensate is assumed to be drained by the combined surface tension and vapor shear forces. In the thick film region formed in the groove, on the other hand, the condensate is assumed to be driven by the vapor shear force. The present and previous local heat transfer data including four fluids (CFC11, HCFC22, HCFC123, and HFCl34a) and three microfin tubes are found to agree with the present predictions to a mean absolute deviation of 15.1%.

  10. Effect of horizontal flow on the cooling of the moderator brick in the advanced gas-cooled reactor

    International Nuclear Information System (INIS)

    Ganesan, P.; He, S.; Hamad, F.; Gotts, J.

    2011-01-01

    The paper reports an investigation of the effect of the horizontal cross flow on the temperature of the moderator brick in UK Advanced Gas-cooled Reactor (AGR) using computational fluid dynamics (CFD) with a conjugate heat transfer model for the solid and fluid. The commercial software package of ANSYS Fluent is used for this purpose. The CFD model comprises the full axial length of one-half of a typical fuel channel (assuming symmetry) and part of neighbouring channels on either side. Two sets of simulations have been carried out, namely, one with cross flow and one without cross flow. The effect of cross flow has subsequently been derived by comparing the results from the two groups of simulations. The study shows that a small cross flow can have a significant effect on the cooling of the graphite brick, causing the peak temperature of the brick to reduce significantly. Two mechanisms are identified to be responsible for this. Firstly, the small cross flow causes a significant redistribution of the main axial downward flow and this leads to an enhancement of heat transfer in some of the small clearances, and an impairment in others although overall, the enhancement is dominant leading to a better cooling. Secondly, the cross flow makes effective use of the small clearances between the key/keyway connections which increases the effective heat transfer area, hence increasing the cooling. Under the conditions of no cross flow, these areas remain largely inactive in heat transfer. The study shows that the cooling of the moderator is significantly enhanced by the cross flow perpendicular to the main cooling flow. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-05-15

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

  12. Groundwater flow to a horizontal or slanted well in an unconfined aquifer

    Science.gov (United States)

    Zhan, Hongbin; Zlotnik, Vitaly A.

    2002-07-01

    New semianalytical solutions for evaluation of the drawdown near horizontal and slanted wells with finite length screens in unconfined aquifers are presented. These fully three-dimensional solutions consider instantaneous drainage or delayed yield and aquifer anisotropy. As a basis, solution for the drawdown created by a point source in a uniform anisotropic unconfined aquifer is derived in Laplace domain. Using superposition, the point source solution is extended to the cases of the horizontal and slanted wells. The previous solutions for vertical wells can be described as a special case of the new solutions. Numerical Laplace inversion allows effective evaluation of the drawdown in real time. Examples illustrate the effects of well geometry and the aquifer parameters on drawdown. Results can be used to generate type curves from observations in piezometers and partially or fully penetrating observation wells. The proposed solutions and software are useful for the parameter identification, design of remediation systems, drainage, and mine dewatering.

  13. Sub-Surface Oil Monitoring Cruise (GU1002, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Objectives were to evaluate ability of acoustic echosounder measurements to detect and localize a sub-surface plume of oil or related hydrocarbons released from the...

  14. One-dimensional three-field model of condensation in horizontal countercurrent flow with supercritical liquid velocity

    International Nuclear Information System (INIS)

    Trewin, Richard R.

    2011-01-01

    Highlights: → CCFL in the hot leg of a PWR with ECC Injection. → Three-Field Model of counter flowing water film and entrained droplets. → Flow of steam can cause a hydraulic jump in the supercritical flow of water. → Condensation of steam on subcooled water increases the required flow for hydraulic jump. → Better agreement with UPTF experimental data than Wallis-type correlation. - Abstract: A one-dimensional three-field model was developed to predict the flow of liquid and vapor that results from countercurrent flow of water injected into the hot leg of a PWR and the oncoming steam flowing from the upper plenum. The model solves the conservation equations for mass, momentum, and energy in a continuous-vapor field, a continuous-liquid field, and a dispersed-liquid (entrained-droplet) field. Single-effect experiments performed in the upper plenum test facility (UPTF) of the former SIEMENS KWU (now AREVA) at Mannheim, Germany, were used to validate the countercurrent flow limitation (CCFL) model in case of emergency core cooling water injection into the hot legs. Subcooled water and saturated steam flowed countercurrent in a horizontal pipe with an inside diameter of 0.75 m. The flow of injected water was varied from 150 kg/s to 400 kg/s, and the flow of steam varied from 13 kg/s to 178 kg/s. The subcooling of the liquid ranged from 0 K to 104 K. The velocity of the water at the injection point was supercritical (greater than the celerity of a gravity wave) for all the experiments. The three-field model was successfully used to predict the experimental data, and the results from the model provide insight into the mechanisms that influence the flows of liquid and vapor during countercurrent flow in a hot leg. When the injected water was saturated and the flow of steam was small, all or most of the injected water flowed to the upper plenum. Because the velocity of the liquid remained supercritical, entrainment of droplets was suppressed. When the injected

  15. An experimental investigation of the interfacial condensation heat transfer in steam/water countercurrent stratified flow in a horizontal pipe

    Energy Technology Data Exchange (ETDEWEB)

    Chu, In Cheol; Yu, Seon Oh; Chun, Moon Hyun [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of); Kim, Byong Sup; Kim, Yang Seok; Kim, In Hwan; Lee, Sang Won [Korea Electric Power Research Institute, Taejon (Korea, Republic of)

    1998-12-31

    An interfacial condensation heat transfer phenomenon in a steam/water countercurrent stratified flow in a nearly horizontal pipe has been experimentally investigated. The present study has been focused on the measurement of the temperature and velocity distributions within the water layer. In particular, the water layer thickness used in the present work is large enough so that the turbulent mixing is limited and the thermal stratification is established. As a result, the thermal resistance of the water layer to the condensation heat transfer is increased significantly. An empirical correlation of the interfacial condensation heat transfer has been developed. The present correlation agrees with the data within {+-} 15%. 5 refs., 6 figs. (Author)

  16. Pattern transitions of oil-water two-phase flow with low water content in rectangular horizontal pipes probed by terahertz spectrum.

    Science.gov (United States)

    Feng, Xin; Wu, Shi-Xiang; Zhao, Kun; Wang, Wei; Zhan, Hong-Lei; Jiang, Chen; Xiao, Li-Zhi; Chen, Shao-Hua

    2015-11-30

    The flow-pattern transition has been a challenging problem in two-phase flow system. We propose the terahertz time-domain spectroscopy (THz-TDS) to investigate the behavior underlying oil-water flow in rectangular horizontal pipes. The low water content (0.03-2.3%) in oil-water flow can be measured accurately and reliably from the relationship between THz peak amplitude and water volume fraction. In addition, we obtain the flow pattern transition boundaries in terms of flow rates. The critical flow rate Qc of the flow pattern transitions decreases from 0.32 m3 h to 0.18 m3 h when the corresponding water content increases from 0.03% to 2.3%. These properties render THz-TDS particularly powerful technology for investigating a horizontal oil-water two-phase flow system.

  17. Measurement of hydrogeologic parameters of Indian volcanic rocks by sub-surface hydronuclear techniques

    International Nuclear Information System (INIS)

    Bardhan, M.

    1977-01-01

    Sub-surface hydronuclear techniques namely neutron-neutron, gamma-gamma and tracer dilution logging and single and double well tracer methods were adopted to investigate the hitherto inadequately studied hydrophysical properties of the Deccan lava flows which constitute the principal Indian volcanic suit of rocks. The hydrogeologic parameters measured in the field pertain to hydrostratigraphy, hydrostorage properties and geohydraulic characteristics of these layered hard formations. Results of the studies are presented and discussed briefly. (author)

  18. Experimental Study on Flow Boiling of Carbon Dioxide in a Horizontal Microfin Tube

    Science.gov (United States)

    Kuwahara, Ken; Ikeda, Soshi; Koyama, Shigeru

    This paper deals with the experimental study on flow boiling heat transfer of carbon dioxide in a micro-fin tube. The geometrical parameters of micro-fin tube used in this study are 6.07 mm in outer diameter, 5.24 mm in average inner diameter, 0.256 mm in fin height, 20.4 in helix angle, 52 in number of grooves and 2.35 in area expansion ratio. Flow patterns and heat transfer coefficients were measured at 3-5 MPa in pressure, 300-540 kg/(m2s) in mass velocity and -5 to 15 °C in CO2 temperature. Flow patterns of wavy flow, slug flow and annular flow were observed. The measured heat transfer coefficients of micro-fin tube were 10-40 kW/(m2K). Heat transfer coefficients were strongly influenced by pressure.

  19. Structural elements of collapses in shallow water flows with horizontally nonuniform density

    Energy Technology Data Exchange (ETDEWEB)

    Goncharov, V. P., E-mail: v.goncharov@rambler.ru [Russian Academy of Sciences, Obukhov Institute of Atmospheric Physics (Russian Federation); Pavlov, V. I., E-mail: Vadim.Pavlov@univ-lille1.fr [Universite de Lille 1, UFR de Mathematiques Pures et Appliquees-LML UMR 8107 (France)

    2013-10-15

    The mechanisms and structural elements of instability whose evolution results in the occurrence of the collapse are studied in the scope of the rotating shallow water model with a horizontally nonuniform density. The diagram stability based on the integral collapse criterion is suggested to explain system behavior in the space of constants of motion. Analysis of the instability shows that two collapse scenarios are possible. One scenario implies anisotropic collapse during which the contact area of a collapsing drop-like fragment with the bottom contracts into a rotating segment. The other implies isotropic contraction of the area into a point.

  20. A Comprehensive Prediction Model of Hydraulic Extended-Reach Limit Considering the Allowable Range of Drilling Fluid Flow Rate in Horizontal Drilling.

    Science.gov (United States)

    Li, Xin; Gao, Deli; Chen, Xuyue

    2017-06-08

    Hydraulic extended-reach limit (HERL) model of horizontal extended-reach well (ERW) can predict the maximum measured depth (MMD) of the horizontal ERW. The HERL refers to the well's MMD when drilling fluid cannot be normally circulated by drilling pump. Previous model analyzed the following two constraint conditions, drilling pump rated pressure and rated power. However, effects of the allowable range of drilling fluid flow rate (Q min  ≤ Q ≤ Q max ) were not considered. In this study, three cases of HERL model are proposed according to the relationship between allowable range of drilling fluid flow rate and rated flow rate of drilling pump (Q r ). A horizontal ERW is analyzed to predict its HERL, especially its horizontal-section limit (L h ). Results show that when Q min  ≤ Q r  ≤ Q max (Case I), L h depends both on horizontal-section limit based on rated pump pressure (L h1 ) and horizontal-section limit based on rated pump power (L h2 ); when Q min  drilling fluid flow rate, while L h2 keeps decreasing as the drilling fluid flow rate increases. The comprehensive model provides a more accurate prediction on HERL.

  1. Flow condensation pressure drop characteristics of R410A-oil mixture inside small diameter horizontal microfin tubes

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Xiangchao; Ding, Guoliang; Hu, Haitao; Zhu, Yu [Institute of Refrigeration and Cryogenics, Shanghai Jiaotong University, Shanghai 200240 (China); Gao, Yifeng [International Copper Association Shanghai Office, Shanghai 200020 (China); Deng, Bin [Institute of Heat Transfer Technology, Golden Dragon Precise Copper Tube Group Inc., Shanghai 200135 (China)

    2010-11-15

    Flow condensation pressure drop characteristics of R410A-oil mixture inside small diameter (5.0 mm and 4.0 mm O.D.) horizontal microfin tubes were investigated experimentally covering nominal oil concentrations from 0% to 5%. The research results indicate that, comparing with the frictional pressure drop of pure R410A, the frictional pressure drop of R410A-oil mixture may decrease by maximum of 18% when the vapor quality is lower than 0.6, and increase by maximum of 13% when the vapor quality is higher than 0.6. A new frictional pressure drop correlation for R410A-oil mixture flow condensation inside microfin tubes is developed based on the refrigerant-oil mixture properties, and can agree with 94% of the experimental data within a deviation of -30% to +30%. (author)

  2. Measurements of local liquid velocity and interfacial parameters of air-water bubbly flows in a horizontal tube

    International Nuclear Information System (INIS)

    Yang Jian; Zhang Mingyuan; Zhang Chaojie; Su Yuliang

    2002-01-01

    Distribution of local kinematic parameters of air-water bubbly flows in a horizontal tube with an ID of 35 mm was investigated. The local liquid velocity was measured with a cylindrical hot film probe, and local void fraction, bubble frequency and bubble velocity were measured with a double-sensor probe. It was found that the axial liquid velocity has a same profile as that of single liquid phase flow in the lower part of the tube, and it suffers a sudden reduction in the upper part of the tube. With increasing airflow rate, the liquid velocity would increase in the lower part of the tube, and further decrease at the upper part of the tube, respectively. Most bubbles are congested at the upper part of the tube, and the void fraction and bubble frequencies have similar profile and both are asymmetrical with the tube axis with their maximum values located near the upper tube wall

  3. Experimental investigation on isothermal stratified flow mixing in a horizontal T-junction

    Energy Technology Data Exchange (ETDEWEB)

    Isaev, Alexander; Kulenovic, Rudi; Laurien, Eckart [Stuttgart Univ. (Germany). Inst. fuer Kernenergetik und Energiesysteme (IKE)

    2016-10-15

    Turbulent and stratified flows can lead to thermal fatigue in piping systems of nuclear power plants (NPP). Such flows can be investigated in the University of Stuttgart Fluid-Structure-Interaction (FSI) facility with a T-Junction at thermal conditions with temperature differences of up to 255 K and at pressures of maximum 75 bars.

  4. Deformation and rupture of a horizontal liquid layer by thermal and solutal Marangoni flows

    Energy Technology Data Exchange (ETDEWEB)

    Viviani, Antonio [Seconda Universita di Napoli (SUN), Dipartimento di Ingegneria Aerospaziale e Meccanica (DIAM), via Roma 29, 81031 Aversa (Italy); Zuev, Andrew [Institute of Continuous Media Mechanics, UB Russian Academy of Sciences, Academic Korolev Street 1, 614013 Perm (Russian Federation)

    2008-11-15

    The evolution of strong surface deformation of a thin viscous fluid layer on a horizontal solid wettable substrate was studied experimentally. Layer deformation is caused by the concentration gradient of surface tension generated by a drop of soluble surfactant placed on the free layer surface. The conditions leading to the layer rupture and drying of the bottom section under the spreading drop were studied. The dependence of the dry spot radius on time, horizontal dimension and thickness of the layer, volume of the introduced droplet and fluids properties, were obtained for various fluid pairs. It was found that the critical initial thickness of the layer, at which its deformation reaches the layer bottom, is practically insensitive to the quantity of the applied surfactant and is defined by the difference in surface tension between the drop and the layer. Comparison of the data with the results of the study of the thermocapillary rupture of a cylindrical layer heated at the center and cooled along the periphery showed good agreement between the dependences of the critical layer thickness on the thermal and the solutal surface tension difference. (author)

  5. Modelling and control of growing slugs in horizontal multiphase pipe flows

    Directory of Open Access Journals (Sweden)

    Steinar M. Elgsæter

    2006-07-01

    Full Text Available In this paper, the use of active control to restrict the length of growing slugs in horizontal pipelines is investigated. Specifically, the paper attempts to determine if such control can be attained with realistic measurements and actuators. Simulations in OLGA2000 show that a feedback controller can use measurements or estimates of slug length to control the growth of a slug in a horizontal pipeline by partially closing inlet or outlet chokes. A control-volume approach is used to develop a low-order model of inlet choke-slug growth dynamics based on mass- and impulse balances. The resulting model is a system of nonlinear differential-algebraic equations, which is suitable for observer-design. The tuned model is found to be in good agreement with experiments and OLGA2000-simulations. Linearizations of the model are found to be observable around realistic trajectories when rates and pressures at the inlet and outlet are measured. An extended Luenberger-observer is shown to give good estimates of slug length and -position in simulations even under model uncertainty.

  6. Evaluation of correlations of flow boiling heat transfer of R22 in horizontal channels.

    Science.gov (United States)

    Zhou, Zhanru; Fang, Xiande; Li, Dingkun

    2013-01-01

    The calculation of two-phase flow boiling heat transfer of R22 in channels is required in a variety of applications, such as chemical process cooling systems, refrigeration, and air conditioning. A number of correlations for flow boiling heat transfer in channels have been proposed. This work evaluates the existing correlations for flow boiling heat transfer coefficient with 1669 experimental data points of flow boiling heat transfer of R22 collected from 18 published papers. The top two correlations for R22 are those of Liu and Winterton (1991) and Fang (2013), with the mean absolute deviation of 32.7% and 32.8%, respectively. More studies should be carried out to develop better ones. Effects of channel dimension and vapor quality on heat transfer are analyzed, and the results provide valuable information for further research in the correlation of two-phase flow boiling heat transfer of R22 in channels.

  7. Ebullition, Plant-Mediated Transport, and Subsurface Horizontal Water Flow Dominate Methane Transport in an Arctic Sphagnum Bog

    Science.gov (United States)

    Wehr, R. A.; McCalley, C. K.; Logan, T. A.; Chanton, J.; Crill, P. M.; Rich, V. I.; Saleska, S. R.

    2017-12-01

    Emission of the greenhouse gas methane from wetlands is of prime concern in the prediction of climate change - especially emission associated with thawing permafrost, which may drive a positive feedback loop of emission and warming. In addition to the biochemistry of methane production and consumption, wetland methane emission depends critically on the transport mechanisms by which methane moves through and out of the ecosystem. We therefore developed a model of methane biochemistry and transport for a sphagnum bog representing an intermediate permafrost thaw stage in Stordalen Mire, Sweden. In order to simultaneously reproduce measured profiles of both the concentrations and isotopic compositions of both methane and carbon dioxide in the peat pore water (Fig. 1) - as well as the surface methane emission - it was necessary for the model to include ebullition, plant-mediated transport via aerenchyma, and subsurface horizontal water flow. Diffusion of gas through the pore water was relatively unimportant. As a result, 90% of the produced methane escaped the wetland rather than being consumed by methanotrophic organisms in the near-surface pore water. Our model provides a comprehensive picture of methane emission from this bog site by quantifying the vertical profiles of: acetoclastic methanogenesis, hydrogenotrophic methanogenesis, methane oxidation, aerobic respiration, ebullition, plant-mediated transport, subsurface horizontal water flow, and diffusion.

  8. Characterisation of two-phase horizontal flow regime transition by the application of time-frequency analysis methods

    International Nuclear Information System (INIS)

    Seleghim, Paulo

    1996-01-01

    This work concerns the development of a methodology which objective is to characterize and diagnose two-phase flow regime transitions. The approach is based on the fundamental assumption that a transition flow is less stationary than a flow with an established regime. In a first time, the efforts focused on: 1) the design and construction of an experimental loop, allowing to reproduce the main horizontal two-phase flow patterns, in a stable and controlled way, 2) the design and construction of an electrical impedance probe, providing an imaged information of the spatial phase distribution in the pipe, the systematic study of the joint time-frequency and time-scale analysis methods, which permitted to define an adequate parameter quantifying the un-stationary degree. In a second time, in order to verify the fundamental assumption, a series of experiments were conducted, which objective was to demonstrate the correlation between un-stationary and regime transition. The un-stationary degree was quantified by calculating the Gabor's transform time-frequency covariance of the impedance probe signals. Furthermore, the phenomenology of each transition was characterized by the joint moments and entropy. The results clearly show that the regime transitions are correlated with local-time frequency covariance peaks, which demonstrates that these regime transitions are characterized by a loss of stationarity. Consequently, the time-frequency covariance constitutes an objective two-phase flow regime transition indicator. (author) [fr

  9. Enhancement of melting heat transfer of ice slurries by an injection flow in a rectangular cross sectional horizontal duct

    International Nuclear Information System (INIS)

    Fujii, Kota; Yamada, Masahiko

    2013-01-01

    Ice slurries are now commonly used as cold thermal storage materials, and have the potential to be applied to other engineering fields such as quenching metals to control properties, emergency cooling systems, and preservation of food and biomaterials at low temperatures. Although ice slurries have been widely utilized because of their high thermal storage densities, previous studies have revealed that the latent heat of ice particles is not completely released on melting because of insufficient contact between the ice particles and a heated surface. In this study, an injection flow that was bifurcated from the main flow of an ice slurry was employed to promote melting heat transfer of ice particles on a horizontal heated surface. The effects of injection angle and injection flow rate on local heat transfer coefficients and heat transfer coefficient ratios were determined experimentally. The results show that from two to three times higher heat transfer coefficients can be obtained by using large injection flow rates and injection angles. However, low injection angles improved the utilization rate of the latent heat of ice near the injection point by approximately a factor of two compared to that without injection. -- Highlights: • Melting of ice slurries were enhanced by the injection under constant total flow rate. • Contribution of ice particles and their latent heat to heat transfer was investigated. • Effect of velocity ratio of injection to that of main flow was examined. • Effect of the angle of injection flow to the main flow was also examined. • Appropriate conditions for the use of latent heat of ice and heat transfer did not coincide

  10. Experimental determination and modelling of interface area concentration in horizontal stratified flow

    International Nuclear Information System (INIS)

    Junqua-Moullet, Alexandra

    2003-01-01

    This research thesis concerns the modelling and experimentation of biphasic liquid/gas flows (water/air) while using the two-fluid model, a six-equation model. The author first addresses the modelling of interfacial magnitudes for a known topology (problem of two-fluid model closure, closure relationships for some variables, equation for a given configuration). She reports the development of an equation system for interfacial magnitudes. The next parts deal with experiments and report the study of stratified flows in the THALC experiment, and more particularly the study of the interfacial area concentration and of the liquid velocities in such flows. Results are discussed, as well as their consistency

  11. Flow visualization study of two-phase flow in the horizontal annulus of the fuel-channel outlet end-fitting of a CANDU reactor

    International Nuclear Information System (INIS)

    Supa-Amornkul, S.; Steward, F.R.; Lister, D.H.

    2005-01-01

    In CANDU-6 reactors, the pressurized hightemperature coolant flows through 380 fuel channels passing horizontally through the core. In 1996, higher than expected rates of wall thinning of the outlet feeders were ascribed to flow-accelerated corrosion (FAC). Such corrosion is strongly influenced by the hydrodynamics of the coolant. Results of preliminary flow visualization and modelling studies have suggested that flow conditions in the end-fitting annulus upstream of the outlet feeder may influence the pattern of FAC. For a full-scale flow visualization, an acrylic test section was built to simulate the cylindrical end-fitting with its annulus flow path. The tests were performed with water and air at atmospheric pressure and room temperature. The phase distribution along the length of the annulus was recorded with a digital video recorder. Size, concentration and velocity of the air bubbles at particular locations were studied with a high-speed digital still camera and a high-speed digital video camera. Phase distributions and variations in bubble size with velocity were determined. Significant effects on the flow patterns of spacer buttons in the annulus were observed. A commercial computational fluid dynamics (CFD) code-Fluent 6.1-was used to model the results. (authors)

  12. The effects of a flow obstacle on liquid film flowing concurrently with air in a horizontal rectangular duct

    International Nuclear Information System (INIS)

    Fukano, Tohru; Tominaga, Akira; Morikawa, Kengo.

    1986-01-01

    The aspect of a liquid film flowing near a flat plate type obstacle was observed, and the liquid film thickness and the entrainment were measured under a wide range of gas and liquid flow rates. The results are summarized as follows: (1) The configurations of film flows near the obstacle are classified according to whether (a) the liquid film climbs over the obstacle or not, (b) the air flows under the obstacle or not, or (c) the liquid film swells or sinks just upstream or downstream of the obstacle. (2) The lower the liquid flow rate, the larger the effect of the obstacle on the film thickness. (3) The generation of entrainment is regulated by the obstacle when the air volumetric flux is high and by the disturbance wave when it is low. (author)

  13. Simulation of buoyancy-induced turbulent flow from a hot horizontal jet

    KAUST Repository

    El-Amin, Mohamed; Sun, Shuyu; Salama, Amgad

    2014-01-01

    force effects due to temperature difference and density variation. After certain times, depending on the case condition, the flow tends to reach a steady state. © 2014 Publishing House for Journal of Hydrodynamics.

  14. Demineralized water flow cancelling experiments with ice plug into high diameter horizontal tube (300 nominal diameter)

    International Nuclear Information System (INIS)

    Gyongyosi, T.; Valeca, S.; Corbescu, B.; Puiu, D.; Panaitescu, V. N.

    2015-01-01

    The isolation with ice plug of a high diameter horizontal pipeline section is a specific technique for repairs activities/ replacements of components owning to thermo-hydraulic installations working with liquid agents. The application of such technique don.t assumes stopping of the entire system. The ice plugging inside of the pipeline assumes using of a special device and of an own specific technology for application. The paper contains a brief description of the experimental technological facilities used, followed by setting off the main moments in evolution of two experimental tests carried out on the test section with 300 mm nominal diameter for demineralized water and, finally, by a brief results analysis and some conclusions. The paper is dedicated to the specialists working in the research and technological engineering. (authors)

  15. Plugging of drinking water flow into horizontal high diameter pipeline with artificial ice plug

    International Nuclear Information System (INIS)

    Gyongyosi, T.; Valeca, S.; Panaitescu, V. N.; Prisecaru, I.

    2013-01-01

    Local isolation of a pipeline section, placed horizontally into a loop of drinking water supply network, can be made with an ice plug resulting after controlled process inside of pipeline without stopping the consumer supply. The technique is applying in order to perform repairs or items replacement, without closing the drinking water supply network at the same time decreasing the fluid loss resulted after discharge of the affected loop. In facts, the technique is simple one and assumes to apply a special device sized for each case using a freezing liquid agent injected continuously. The paper contains a constructive description of the experimental technological facilities and of the experimental model for ice plugging device used. The test, the first results get and some conclusion are following. The paper is dedicated to the specialists working in the research and technological engineering. (authors)

  16. Modeling the scooping phenomenon for the heat transfer in liquid–gas horizontal slug flows

    International Nuclear Information System (INIS)

    Bassani, Carlos L.; Pereira, Fernando H.G.; Barbuto, Fausto A.A.; Morales, Rigoberto E.M.

    2016-01-01

    Highlights: • A low computational tool for heat transfer prediction on slug flows is presented. • The scooping phenomenon is modeled on a stationary approach. • The scooping phenomenon improved in 8% the heat transfer results. - Abstract: The heat transfer between the deep sea waters and the oil and gas mixtures flowing through production lines is a common situation in the petroleum industry. The optimum prediction of the liquid–gas flow parameters along those lines, when the intermittent flow pattern known as slug flow is dominant, has extreme importance in facilities' design. The mixture temperature drop caused by the colder sea waters, which can be regarded as an infinite medium with constant temperature, directly affects physical properties of the fluids such as the viscosity and specific mass. Gas expansion may also occur due to pressure and temperature gradients, thus changing the flow hydrodynamics. Finally, the temperature gradient affects the thermodynamic equilibrium between the phases, favoring wax deposition and thus increasing pressure drops or even blocking the production line. With those issues in mind, the present work proposes a stationary model to predict the mixture temperature distribution and the two-phase flow heat transfer coefficient based on the mass, momentum and energy conservation equations applied to different unit cell regions. The main contribution of the present work is the modeling of the thermal scooping phenomenon, i.e., the heat transfer between two adjacent unit cells due to the mass flux known as scooping. The model was implemented as a structured Fortran95 code with an upwind difference scheme. The results were compared to experimental data and presented good agreement. The analysis showed that the inclusion of the scooping phenomenon into the model resulted in an averaged 8% improvement in the temperature gradient calculation and heat transfer coefficient prediction for the flowing mixture.

  17. Flow structure of coarse-grained slurry in a horizontal pipe

    Czech Academy of Sciences Publication Activity Database

    Vlasák, Pavel; Kysela, Bohuš; Chára, Zdeněk

    2012-01-01

    Roč. 60, č. 2 (2012), s. 115-124 ISSN 0042-790X R&D Projects: GA ČR GAP105/10/1574 Institutional research plan: CEZ:AV0Z20600510 Keywords : coarse-grained slurry * turbulent flow * pressure drop * velocity distribution * flow structure * concentration effect Subject RIV: BK - Fluid Dynamics Impact factor: 0.653, year: 2012

  18. Estimation of gas wall shear stress in horizontal stratified gas-liquid pipe flow

    International Nuclear Information System (INIS)

    Newton, C.H.; Behnia, M.

    1996-01-01

    Two-phase pipe flows occur in many industrial applications, such as condensers and evaporators, chemical processing equipment, nuclear reactors, and oil pipelines. A variety of basic mechanistic flow models for predicting the pressure gradient and liquid loading characteristics of these types of flows to assist in design calculations has emerged over the past two decades, especially for the stratified and slug flow regimes. These models generally rely on a number of basic assumptions and empirical closure equations. Possibly the most notable of these relates to the evaluation of interfacial shear stresses. However, one of the most important yet least discussed assumptions used in most of these models is that the phase wall shear stresses can be accurately estimated from correlations developed for single-phase pipe flows. The object of this article is to present measurements of gas wall shear up to locations in close proximity to the gas-liquid interface for a variety of interface conditions in developed flow, and to determine the effects of the interface on average gas wall friction factors. In this context the interface may be smooth, rippled or wavy

  19. Experimental investigation on TBAB clathrate hydrate slurry flows in a horizontal tube: Forced convective heat transfer behaviors

    Energy Technology Data Exchange (ETDEWEB)

    Wenji, Song [Guangzhou Institute of Energy Conversion, CAS, No. 2 Nengyuan Road, Tianhe District, Guangzhou 510640 (China); Key Laboratory of Renewable Energy and Gas Hydrate, CAS, No. 2 Nengyuan Road, Tianhe District, Guangzhou 510640 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Rui, Xiao; Chong, Huang; Shihui, He; Kaijun, Dong; Ziping, Feng [Guangzhou Institute of Energy Conversion, CAS, No. 2 Nengyuan Road, Tianhe District, Guangzhou 510640 (China); Key Laboratory of Renewable Energy and Gas Hydrate, CAS, No. 2 Nengyuan Road, Tianhe District, Guangzhou 510640 (China)

    2009-11-15

    Tetra-n-butyl-ammonium bromide (TBAB) clathrate hydrate slurry (CHS) is one kind of secondary refrigerants, which is promising to be applied into air-conditioning or latent-heat transportation systems as a thermal storage or cold carrying medium for energy saving. It is a solid-liquid two phase mixture which is easy to produce and has high latent heat and good fluidity. In this paper, the heat transfer characteristics of TBAB slurry were investigated in a horizontal stainless steel tube under different solid mass fractions and flow velocities with constant heat flux. One velocity region of weakened heat transfer was found. Moreover, TBAB CHS was treated as a kind of Bingham fluids, and the influences of the solid particles, flow velocity and types of flow on the forced convective heat transfer coefficients of TBAB CHS were investigated. At last, criterial correlations of Nusselt number for laminar and turbulent flows in the form of power function were summarized, and the error with experimental results was within {+-}20%. (author)

  20. Stratified flow instability and slug formation leading to condensation-induced water hammer in a horizontal refrigerant pipe

    International Nuclear Information System (INIS)

    Samuel Martin, C.

    2005-01-01

    Full text of publication follows: An experimental apparatus was designed for the purpose of investigating the phenomenon of condensation-induced water hammer in an ammonia refrigeration system. Water hammer was initiated by introducing warm ammonia gas over static subcooled ammonia liquid placed in a horizontal 146.3 mm diameter carbon steel pipe 6.0 m in length. By means of fast response piezoelectric pressure transducers and a high speed data acquisition system rapid dynamic pressures were recorded whenever a shock event occurred. Moreover, by means of top-mounted diaphragm pressure transducers the speed of liquid slugs propagating along the pipe was determined. The occurrence of condensation induced water hammer depended upon three major variables; namely, (1) initial liquid depth, (2) liquid temperature, and (3) mass flow rate of warm gas. For given liquid depth and temperature, once the warm gas threshold conditions were exceeded shocks occurred with greater magnitude as the mass flow rate of gas input was increased. With adequate subcooling condensation-induced water hammer occurred for initial liquid depths ranging from 25% to 95% of internal pipe diameter. The threshold mass flow rate of warm gas necessary to initiate water hammer was greater as the initial liquid depth was lowered. Based upon experimental results obtained from four pressure transducers located on the top of the test pipe conditions corresponding to bridging were ascertained. For various initial liquid depths the onset of instability from stratified flow to bridging was correlated with the Taitel-Dukler instability criterion. (author)

  1. Experimental investigation of droplet separation in a horizontal counter-current air/water stratified flow

    International Nuclear Information System (INIS)

    Gabriel, Stephan Gerhard

    2015-01-01

    A stratified counter-current two-phase gas/liquid flow can occur in various technical systems. In the past investigations have mainly been motivated by the possible occurrence of these flows in accident scenarios of nuclear light water-reactors and in numerous applications in process engineering. However, the precise forecast of flow parameters, is still challenging, for instance due to their strong dependency on the geometric boundary conditions. A new approach which uses CFD methods (Computational Fluid Dynamics) promises a better understanding of the flow phenomena and simultaneously a higher scalability of the findings. RANS methods (Reynolds Averaged Navier Stokes) are preferred in order to compute industrial processes and geometries. A very deep understanding of the flow behavior and equation systems based on real physics are necessary preconditions to develop the equation system for a reliable RANS approach with predictive power. Therefore, local highly resolved, experimental data is needed in order to provide and validate the required turbulence and phase interaction models. The central objective of this work is to provide the data needed for the code development for these unsteady, turbulent and three-dimensional flows. Experiments were carried out at the WENKA facility (Water Entrainment Channel Karlsruhe) at the Karlsruhe Institute of Technology (KIT). The work consists of a detailed description of the test-facility including a new bended channel, the measurement techniques and the experimental results. The characterization of the new channel was done by flow maps. A high-speed imaging study gives an impression of the occurring flow regimes, and different flow phenomena like droplet separation. The velocity distributions as well as various turbulence values were investigated by particle image velocimetry (PIV). In the liquid phase fluorescent tracer-particles were used to suppress optical reflections from the phase surface (fluorescent PIV, FPIV

  2. Theoretical and experimental studies on transient heat transfer for forced convection flow of helium gas over a horizontal cylinder

    International Nuclear Information System (INIS)

    Liu Qiusheng; Katsuya Fukuda; Zhang Zheng

    2005-01-01

    Forced convection transient heat transfer for helium gas at various periods of exponential increase of heat input to a horizontal cylinder (heater) was theoretically and experimentally studied. In the theoretical study, transient heat transfer was numerically solved based on a turbulent flow model. It was clarified that the surface superheat and heat flux increase exponentially as the heat generation rate increases with the exponential function. The temperature distribution near the cylinder becomes larger as the surface temperature increases. The values of numerical solution for surface temperature and heat flux agree well with the experimental data for the cylinder diameter of 1 mm. However, the heat flux shows difference from the experimental values for the cylinder diameters of 0.7 mm and 2.0 mm. In the experimental studies, the authors measured heat flux, surface temperature, and transient heat transfer coefficients for forced convection flow of helium gas over horizontal cylinders under wide experimental conditions. The platinum cylinders with diameters of 1.0 mm, 0.7 mm, and 2.0 mm were used as test heaters and heated by electric current with an exponential increase of Q 0exp (t/τ) . The gas flow velocities ranged from 2 to 10 m/s, the gas temperatures ranged from 303 to 353 K, and the periods ranged from 50 ms to 20 s. It was clarified that the heat transfer coefficient approaches the quasi-steady-state one for the period τ longer than about 1 s, and it becomes higher for the period shorter than around 1 s. The transient heat transfer shows less dependence on the gas flowing velocity when the period becomes very shorter. The heat transfer shifts to the quasi-steady-state heat transfer for longer periods and shifts to the transient heat transfer for shorter periods at the same flow velocity. It also approaches the quasi-steady-state one for higher flow velocity at the same period. The transient heat transfer coefficients show significant dependence on

  3. Electromagnetic holographic sensitivity field of two-phase flow in horizontal wells

    Science.gov (United States)

    Zhang, Kuo; Wu, Xi-Ling; Yan, Jing-Fu; Cai, Jia-Tie

    2017-03-01

    Electromagnetic holographic data are characterized by two modes, suggesting that image reconstruction requires a dual-mode sensitivity field as well. We analyze an electromagnetic holographic field based on tomography theory and Radon inverse transform to derive the expression of the electromagnetic holographic sensitivity field (EMHSF). Then, we apply the EMHSF calculated by using finite-element methods to flow simulations and holographic imaging. The results suggest that the EMHSF based on the partial derivative of radius of the complex electric potential φ is closely linked to the Radon inverse transform and encompasses the sensitivities of the amplitude and phase data. The flow images obtained with inversion using EMHSF better agree with the actual flow patterns. The EMHSF overcomes the limitations of traditional single-mode sensitivity fields.

  4. Numerical analysis of interfacial growth and deformation in horizontal stratified two-phase flow by lattice Boltzmann method

    International Nuclear Information System (INIS)

    Ebihara, Ken-ichi

    2005-03-01

    paper, first, the validity and the usefulness of the lattice-gas model and the lattice Boltzmann method for the numerical analysis of two-phase flow are examined by applying the two-phase fluid model of these methods to the phenomena of the falling droplet and the rising bubble. Next, on the basis of the examination of its numerical results, the horizontal stratified two-phase flow, which is the fundamental and important flow and often observed in a practical situation, is simulated by use of the HCZ model that is the two-phase fluid model of the lattice Boltzmann method proposed by He, Chen, and Zhang. The HCZ model can simulate Rayleigh-Taylor instability which shows complex interfacial phenomena. It is verified that the simulated interfacial growth is subject to the Kelvin-Helmholtz instability theory and can reproduce the curve concerning the interfacial growth of the theoretical flow regime map proposed by Taitel and Dukler (T-D map). Furthermore, it is found that the interfacial growth in the channel with the narrow width needs more superficial flow velocity than that given by the T-D map. In the simulation of the droplet generation in the horizontal stratified two-phase flow, it is verified that the HCZ model can also reproduce the experimental correlation proposed by Ishii and Grolmes within the range of the distribution of experimental data. According to the results of this report, it is found that the HCZ model of the lattice Boltzmann method can simulate complex interfacial phenomena in the horizontal stratified two-phase flow and reproduce the theoretical flow regime map and the experimental correlation. Considering the application of this model to more practical two-phase flow, it is also seen that this model has some problems which have to be solved, such as practical density difference, thermal influence and so on. (author)

  5. ASSERT-PV simulations of two-phase flow in horizontal and vertical subchannels

    International Nuclear Information System (INIS)

    Park, J.-W.; Chae, K.M.; Choi, H.

    1999-01-01

    This is a part of the effort to assess the ASSERT-PV code which is supposedly capable of quantifying the effect of small flow boundary changes in the fuel channel of CANDU reactors. Two independently performed subchannel experiments are simulated by the ASSERT-PV code. The result includes the pressure and the void fraction distributions in each subchannel. It is found that the ASSERT-PV predicts both experimental data quite well by selecting the void diffusion constant properly for the adiabatic two-phase flows. (author)

  6. Cuttings-liquid frictional pressure loss model for horizontal narrow annular flow with rotating drillpipe

    International Nuclear Information System (INIS)

    Ofei, T N; Irawan, S; Pao, W

    2015-01-01

    During oil and gas drilling operations, frictional pressure loss is experienced as the drilling fluid transports the drilled cuttings from the bottom-hole, through the annulus, to the surface. Estimation of these pressure losses is critical when designing the drilling hydraulic program. Two-phase frictional pressure loss in the annulus is very difficult to predict, and even more complex when there is drillpipe rotation. Accurate prediction will ensure that the correct equivalent circulating density (ECD) is applied in the wellbore to prevent formation fracture, especially in formations with narrow window between the pore pressure and fracture gradient. Few researchers have attempted to propose cuttings-liquid frictional pressure loss models, nevertheless, these models fail when they are applied to narrow wellbores such as in casing- while-drilling and slimhole applications. This study proposes improved cuttings-liquid frictional pressure loss models for narrow horizontal annuli with drillpipe rotation using Dimensional Analysis. Both Newtonian and non-Newtonian fluids were considered. The proposed model constants were fitted by generated data from a full-scale simulation study using ANSYS-CFX. The models showed improvement over existing cuttings-liquid pressure loss correlations in literature. (paper)

  7. Experimental and numerical investigations on the direct contact condensation phenomenon in horizontal flow channels and its implications in nuclear safety

    Energy Technology Data Exchange (ETDEWEB)

    Ceuca, Sabin Cristian [Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) gGmbH, Garching (Germany); Laurinavicius, Darius [Lithuanian Energy Institute, Kaunas (Lithuania)

    2016-11-15

    The complex direct contact condensation phenomenon is investigated in horizontal flow channels both experimentally and numerically with special emphasis on its implications on safety assessment studies. Under certain conditions direct contact condensation can act as the driving force for the water hammer phenomenon with potentially local devastating results, thus posing a threat to the integrity of the affected NPP components. New experimental results of in-depth analysis of the direct contact condensation phenomena obtained in Kaunas at the Lithuanian Energy Institute will be presented. The German system code ATHLET employing for the calculation of the heat transfer coefficient a mechanistic model accounting for two different eddy length scales, combined with the interfacial area transport equation will be assessed against condensation induced water hammer experimental data from the integral thermal-hydraulic experimental facility PMK-2, located at the KFKI Atomic Energy Research Institute in Budapest Hungary.

  8. A study on the unsteady flow of two immiscible micropolar and Newtonian fluids through a horizontal channel: A numerical approach

    Science.gov (United States)

    Devakar, M.; Raje, Ankush

    2018-05-01

    The unsteady flow of two immiscible micropolar and Newtonian fluids through a horizontal channel is considered. In addition to the classical no-slip and hyper-stick conditions at the boundary, it is assumed that the fluid velocities and shear stresses are continuous across the fluid-fluid interface. Three cases for the applied pressure gradient are considered to study the problem: one with constant pressure gradient and the other two cases with time-dependent pressure gradients, viz. periodic and decaying pressure gradient. The Crank-Nicolson approach has been used to obtain numerical solutions for fluid velocity and microrotation for diverse sets of fluid parameters. The nature of fluid velocities and microrotation with various values of pressure gradient, Reynolds number, ratio of viscosities, micropolarity parameter and time is illustrated through graphs. It has been observed that micropolarity parameter and ratio of viscosities reduce the fluid velocities.

  9. Heat transfer characteristics for evaporation of R417A flowing inside horizontal smooth and internally grooved tubes

    Energy Technology Data Exchange (ETDEWEB)

    Xiaoyan, Zhang [School of Energy and Power Engineering, Xi' an Jiaotong University, 28 Xianning Road, Xi' an, Shaanxi 710049 (China); School of Energy Engineering, Xi' an University of Science and Technology, 58 Yanta Street, Xi' an, Shaanxi 710054 (China)], E-mail: gqzxy@sohu.com; Xingqun, Zhang; Yunguang, Chen; Xiuling, Yuan [School of Energy and Power Engineering, Xi' an Jiaotong University, 28 Xianning Road, Xi' an, Shaanxi 710049 (China)

    2008-06-15

    The experimental study on evaporation heat transfer of R417A (R125/R134a/R600) flowing inside horizontal smooth and two internally grooved tubes with different geometrical parameters was conducted with the mass flow rate range from 176 to 344 kg m{sup -2} s{sup -1}, heat flux from 11 to 32 kW m{sup -2}, evaporation temperature from 0 to 5.5 deg. C and vapor quality from 0.2 to 1. Based on the experimental results, the mechanism and role of the mass flow rate, heat flux, vapor quality and enhanced surface influencing the evaporation heat transfer coefficients were analyzed and discussed. In comparison to R22, the evaporation heat transfer coefficients for R417A were lower and much lower in the internally grooved tubes than in the smooth tube. The present experimental results are also compared with the existing correlations, and the modified Kattan model is found to be in much better agreement with the experimental results than the Kattan model. The Koyama and Wellsandt microfin models all tend to over predict the evaporation heat transfer coefficients rather strongly for R417A inside internally grooved tubes.

  10. Heat transfer characteristics for evaporation of R417A flowing inside horizontal smooth and internally grooved tubes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaoyan [School of Energy and Power Engineering, Xi' an Jiaotong University, 28 Xianning Road, Xi' an, Shaanxi 710049 (China); School of Energy Engineering, Xi' an University of Science and Technology, 58 Yanta Street, Xi' an, Shaanxi 710054 (China); Zhang, Xingqun; Chen, Yunguang; Yuan, Xiuling [School of Energy and Power Engineering, Xi' an Jiaotong University, 28 Xianning Road, Xi' an, Shaanxi 710049 (China)

    2008-06-15

    The experimental study on evaporation heat transfer of R417A (R125/R134a/R600) flowing inside horizontal smooth and two internally grooved tubes with different geometrical parameters was conducted with the mass flow rate range from 176 to 344 kg m{sup -2} s{sup -1}, heat flux from 11 to 32 kW m{sup -2}, evaporation temperature from 0 to 5.5{sup o}C and vapor quality from 0.2 to 1. Based on the experimental results, the mechanism and role of the mass flow rate, heat flux, vapor quality and enhanced surface influencing the evaporation heat transfer coefficients were analyzed and discussed. In comparison to R22, the evaporation heat transfer coefficients for R417A were lower and much lower in the internally grooved tubes than in the smooth tube. The present experimental results are also compared with the existing correlations, and the modified Kattan model is found to be in much better agreement with the experimental results than the Kattan model. The Koyama and Wellsandt microfin models all tend to over predict the evaporation heat transfer coefficients rather strongly for R417A inside internally grooved tubes. (author)

  11. Heat transfer characteristics for evaporation of R417A flowing inside horizontal smooth and internally grooved tubes

    International Nuclear Information System (INIS)

    Zhang Xiaoyan; Zhang Xingqun; Chen Yunguang; Yuan Xiuling

    2008-01-01

    The experimental study on evaporation heat transfer of R417A (R125/R134a/R600) flowing inside horizontal smooth and two internally grooved tubes with different geometrical parameters was conducted with the mass flow rate range from 176 to 344 kg m -2 s -1 , heat flux from 11 to 32 kW m -2 , evaporation temperature from 0 to 5.5 deg. C and vapor quality from 0.2 to 1. Based on the experimental results, the mechanism and role of the mass flow rate, heat flux, vapor quality and enhanced surface influencing the evaporation heat transfer coefficients were analyzed and discussed. In comparison to R22, the evaporation heat transfer coefficients for R417A were lower and much lower in the internally grooved tubes than in the smooth tube. The present experimental results are also compared with the existing correlations, and the modified Kattan model is found to be in much better agreement with the experimental results than the Kattan model. The Koyama and Wellsandt microfin models all tend to over predict the evaporation heat transfer coefficients rather strongly for R417A inside internally grooved tubes

  12. Image processing analysis on the air-water slug two-phase flow in a horizontal pipe

    Science.gov (United States)

    Dinaryanto, Okto; Widyatama, Arif; Majid, Akmal Irfan; Deendarlianto, Indarto

    2016-06-01

    Slug flow is a part of intermittent flow which is avoided in industrial application because of its irregularity and high pressure fluctuation. Those characteristics cause some problems such as internal corrosion and the damage of the pipeline construction. In order to understand the slug characteristics, some of the measurement techniques can be applied such as wire-mesh sensors, CECM, and high speed camera. The present study was aimed to determine slug characteristics by using image processing techniques. Experiment has been carried out in 26 mm i.d. acrylic horizontal pipe with 9 m long. Air-water flow was recorded 5 m from the air-water mixer using high speed video camera. Each of image sequence was processed using MATLAB. There are some steps including image complement, background subtraction, and image filtering that used in this algorithm to produce binary images. Special treatments also were applied to reduce the disturbance effect of dispersed bubble around the bubble. Furthermore, binary images were used to describe bubble contour and calculate slug parameter such as gas slug length, gas slug velocity, and slug frequency. As a result the effect of superficial gas velocity and superficial liquid velocity on the fundamental parameters can be understood. After comparing the results to the previous experimental results, the image processing techniques is a useful and potential technique to explain the slug characteristics.

  13. Numerical analysis of water hammer induced by injection of subcooled water into steam flow in a horizontal pipe

    International Nuclear Information System (INIS)

    Minato, Akihiko; Nagoyoshi, Takuji; Nakamura, Akira; Fujii, Yuzo; Aya, Izuo; Yamane, Kenji

    2004-01-01

    Subcooled water injection into steam flow in piping systems may generate a water column containing a large steam slug. The steam slug collapses due to rapid condensation and interfaces on both sides collides with each other. Water hammer takes place and sharp pressure pulse propagates through the pipe. The purpose of this study is to show capability of the present numerical simulation method for predictions of pressure transient and loads on a piping system following steam slug collapse. A three-dimensional computer code for transient gas-liquid two-phase flow was applied to simulate an experiment of steam-condensation-induced water hammer with a horizontal polycarbonate pipe. The code was based on the extended two-fluid model, which treated interface motion using the VOF (Volume of Fluid) technique. The Godunov scheme of highly compressible single-phase flow was modified for application to the Riemann problem solution of gas-liquid mixture. Analysis of local steam slug collapse resulted in comparable peak pressure and pulse width of pressure transients with the observation. The calculation of pressure pulse propagation and impact load on piping system showed the quasi-steady pressure load was imposed especially on elbow at 1/10 of water hammer peak pressure. (author)

  14. Simulation of two-phase flow in horizontal fracture networks with numerical manifold method

    Science.gov (United States)

    Ma, G. W.; Wang, H. D.; Fan, L. F.; Wang, B.

    2017-10-01

    The paper presents simulation of two-phase flow in discrete fracture networks with numerical manifold method (NMM). Each phase of fluids is considered to be confined within the assumed discrete interfaces in the present method. The homogeneous model is modified to approach the mixed fluids. A new mathematical cover formation for fracture intersection is proposed to satisfy the mass conservation. NMM simulations of two-phase flow in a single fracture, intersection, and fracture network are illustrated graphically and validated by the analytical method or the finite element method. Results show that the motion status of discrete interface significantly depends on the ratio of mobility of two fluids rather than the value of the mobility. The variation of fluid velocity in each fracture segment and the driven fluid content are also influenced by the ratio of mobility. The advantages of NMM in the simulation of two-phase flow in a fracture network are demonstrated in the present study, which can be further developed for practical engineering applications.

  15. Theoretical study on bubble formation and flow condensation in downflow channel with horizontal gas injection

    Science.gov (United States)

    Zhu, Kang; Li, Yanzhong; Wang, Jiaojiao; Ma, Yuan; Wang, Lei; Xie, Fushou

    2018-05-01

    Bubble formation and condensation in liquid pipes occur widely in industrial systems such as cryogenic propellant feeding system. In this paper, an integrated theoretical model is established to give a comprehensive description of the bubble formation, motion and condensation process. The model is validated by numerical simulations and bubble condensation experiments from references, and good agreements are achieved. The bubble departure diameter at the orifice and the flow condensation length in the liquid channel are predicted by the model, and effects of various influencing parameters on bubble behaviors are analyzed. Prediction results indicate that the orifice diameter, the gas feeding rate, and the liquid velocity are the primary influence factors on the bubble departure diameter. The interfacial heat transfer as well as the bubble departure diameter has a direct impact on the bubble flow condensation length, which increases by 2.5 times over a system pressure range of 0.1 0.4 MPa, and decreases by 85% over a liquid subcooling range of 5 30 K. This work could be beneficial to the prediction of bubble formation and flow condensation processes and the design of cryogenic transfer pipes.

  16. Wavelet analysis of interfacial waves in cocurrent two-phase flow in horizontal duct

    International Nuclear Information System (INIS)

    Kondo, Masaya; Kukita, Yutaka

    1996-07-01

    Wavelet analysis was applied to spatially-growing interfacial waves in a cocurrent gas/liquid two-phase flow. The wave growth plays a key role in the transition from stratified-wavy to slug flow, which is an important phenomena in many engineering applications. Of particular interest to the present study was the quick growth or decay of particular waves which were observed in experiments together with the general growth of waves with distance in the flow direction. Among the several wavelet functions tested in the present study, the Morlet wavelet and the Gabor function were found to have spectral and spatial resolutions suitable to the analysis of interfacial wave data taken by the authors. The analysis revealed that 1) the spectral components composing the interfacial waves are propagating at different phase velocities which agree to the theoretical velocities of deep-water waves, 2) the group velocity of the waves also agrees to the deep-water theory, and 3) the quick growth and decay of particular waves occur as a result of the superposition of spectral components with different phase velocities. (author)

  17. Detailed analysis of the blade root flow of a horizontal axis wind turbine

    Directory of Open Access Journals (Sweden)

    I. Herráez

    2016-07-01

    Full Text Available The root flow of wind turbine blades is subjected to complex physical mechanisms that influence significantly the rotor aerodynamic performance. Spanwise flows, the Himmelskamp effect, and the formation of the root vortex are examples of interrelated aerodynamic phenomena that take place in the blade root region. In this study we address those phenomena by means of particle image velocimetry (PIV measurements and Reynolds-averaged Navier–Stokes (RANS simulations. The numerical results obtained in this study are in very good agreement with the experiments and unveil the details of the intricate root flow. The Himmelskamp effect is shown to delay the stall onset and to enhance the lift force coefficient Cl even at moderate angles of attack. This improvement in the aerodynamic performance occurs in spite of the negative influence of the mentioned effect on the suction peak of the involved blade sections. The results also show that the vortex emanating from the spanwise position of maximum chord length rotates in the opposite direction to the root vortex, which affects the wake evolution. Furthermore, the aerodynamic losses in the root region are demonstrated to take place much more gradually than at the tip.

  18. Testing Augmented Reality Systems for Spotting Sub-Surface Impurities

    DEFF Research Database (Denmark)

    Hald, Kasper; Rehm, Matthias; Moeslund, Thomas B.

    2018-01-01

    This paper describes setup and procedure for testing augmented reality systems for showing sub-surface positions of foreign elements in an opaque mass. The goal is it test four types of setup in terms of user accuracy and speed, the four setups being a head-mounted see-through display, an arm...

  19. Extrusion and erosion of bentonite buffer material in a flow-through, horizontal, artificial fracture system

    International Nuclear Information System (INIS)

    Schatz, Timothy; Kanerva, Noora; Martikainen, Jari

    2012-01-01

    Document available in extended abstract form only. One scenario of interest for the long-term safety assessment of a spent nuclear fuel repository involves the loss of bentonite buffer material through contact with dilute groundwater at a transmissive fracture interface [SKB 2011, Posiva 2012]. In order to simulate the potential extrusion/erosion behaviour of bentonite buffer material in such an environment, a series of small-scale, flow-through, artificial fracture experiments were performed in which swelling clay material could extrude/erode into a well defined, system (see Figure 1). The fracture dimensions were 24 cm (length) x 24 cm (width) x 1 mm (aperture) and the compacted sample dimensions were 2 cm (height) x 2 cm (diameter). Extrusion/erosion effects were analysed against solution chemistry (salt concentration and composition), material composition (sodium montmorillonite and admixtures with calcium montmorillonite), and flow velocity. No erosion was observed for sodium montmorillonite against solution compositions from 10 to 0.5 g/L NaCl. Comparatively, most reports in the literature indicate that a concentration of 0.5 g/L NaCl (8.6 mM) is below, in some cases well below, the (experimentally observed) critical coagulation concentration (CCC) for the colloidal sodium montmorillonite/sodium chloride system [Garcia-Garcia et al. 2007]. It was also the case that no erosion was observed for 50/50 calcium/sodium montmorillonite against 0.5 g/L NaCl. Overall, the results of the flow-through, artificial fracture tests, indicate stability to erosion down to a dilute concentration range between 8 to 4 mM NaCl for both sodium and 50/50 calcium/sodium montmorillonite. These limits compare favorably to the erosion stability limits observed by Birgersson et al. [2009] in the case of the latter material but less so for the former. A number of tests were conducted for which measurable erosion was observed. The calculated mass loss rates for these tests, expressed in

  20. New flow boiling heat transfer model for hydrocarbons evaporating inside horizontal tubes

    International Nuclear Information System (INIS)

    Chen, G. F.; Gong, M. Q.; Wu, J. F.; Zou, X.; Wang, S.

    2014-01-01

    Hydrocarbons have high thermodynamic performances, belong to the group of natural refrigerants, and they are the main components in mixture Joule-Thomson low temperature refrigerators (MJTR). New evaluations of nucleate boiling contribution and nucleate boiling suppression factor in flow boiling heat transfer have been proposed for hydrocarbons. A forced convection heat transfer enhancement factor correlation incorporating liquid velocity has also been proposed. In addition, the comparisons of the new model and other classic models were made to evaluate its accuracy in heat transfer prediction

  1. Evolution of long wave disturbances in horizontal gas-liquid flows

    International Nuclear Information System (INIS)

    Kuru, W.C.; Montalbano, E.D.; Brennecke, J.F.; McCready, M.J.

    1993-01-01

    Coherent nonlinear interactions between linearly stable, long wavelength modes and modes that are near the peak of the growth rate are observed in experiments. These open-quotes side-bandclose quotes interactions are suggested as the mechanism for initiation of long wavelength modes that are otherwise predicted to be stable from linear stability theory. Quadratic interaction theory is used to provide insight into when long wavelength modes will appear and how their frequency will be selected. The present work differs from previous side band analyses in that a low frequency mode is retained as a dominant mode (consistent with observations). Because of its relevance to continued growth of long wavelength disturbances and possibly slug formation and owing to its importance in modeling flow regime transitions, a discussion of the validity of the one-dimensional macroscopic equations and the boundary-layer equations as models of long wavelength disturbances for the two-layer stability problem is given in the context of laminar flow of a fluid over a solid wavy surface

  2. Unsteady Bioconvection Squeezing Flow in a Horizontal Channel with Chemical Reaction and Magnetic Field Effects

    Directory of Open Access Journals (Sweden)

    Qingkai Zhao

    2017-01-01

    Full Text Available The time-dependent mixed bioconvection flow of an electrically conducting fluid between two infinite parallel plates in the presence of a magnetic field and a first-order chemical reaction is investigated. The fully coupled nonlinear systems describing the total mass, momentum, thermal energy, mass diffusion, and microorganisms equations are reduced to a set of ordinary differential equations via a set of new similarity transformations. The detailed analysis illustrating the influences of various physical parameters such as the magnetic, squeezing, and chemical reaction parameters and the Schmidt and Prandtl numbers on the distributions of temperature and microorganisms as well as the skin friction and the Nusselt number is presented. The conclusion is drawn that the flow field, temperature, and chemical reaction profiles are significantly influenced by magnetic parameter, heat generation/absorption parameter, and chemical parameter. Some examples of potential applications of such bioconvection could be found in pharmaceutical industry, microfluidic devices, microbial enhanced oil recovery, modeling oil, and gas-bearing sedimentary basins.

  3. Preferential Concentration Of Solid Particles In Turbulent Horizontal Circular Pipe Flow

    Science.gov (United States)

    Kim, Jaehee; Yang, Kyung-Soo

    2017-11-01

    In particle-laden turbulent pipe flow, turbophoresis can lead to a preferential concentration of particles near the wall. To investigate this phenomenon, one-way coupled Direct Numerical Simulation (DNS) has been performed. Fully-developed turbulent pipe flow of the carrier fluid (air) is at Reτ = 200 based on the pipe radius and the mean friction velocity, whereas the Stokes numbers of the particles (solid) are St+ = 0.1 , 1 , 10 based on the mean friction velocity and the kinematic viscosity of the fluid. The computational domain for particle simulation is extended along the axial direction by duplicating the domain of the fluid simulation. By doing so, particle statistics in the spatially developing region as well as in the fully-developed region can be obtained. Accumulation of particles has been noticed at St+ = 1 and 10 mostly in the viscous sublayer, more intensive in the latter case. Compared with other authors' previous results, our results suggest that drag force on the particles should be computed by using an empirical correlation and a higher-order interpolation scheme even in a low-Re regime in order to improve the accuracy of particle simulation. This work was supported by the National Research Foundation of Korea (NRF) Grant funded by the Korea government (MSIP) (No. 2015R1A2A2A01002981).

  4. Effect of Variable Viscosity on Vortex Instability of Non-Darcy Mixed Convection Boundary Layer Flow Adjacent to a Nonisothermal Horizontal Surface in a Porous Medium

    Directory of Open Access Journals (Sweden)

    A. M. Elaiw

    2012-01-01

    Full Text Available We study the effect of variable viscosity on the flow and vortex instability for non-Darcy mixed convection boundary layer flow on a nonisothermal horizontal plat surface in a saturated porous medium. The variation of viscosity is expressed as an exponential function of temperature. The analysis of the disturbance flow is based on linear stability theory. The base flow equations and the resulting eigenvalue problem are solved using finite difference schemes. It is found that the variable viscosity effect enhances the heat transfer rate and destabilizes the flow for liquid heating, while the opposite trend is true for gas heating.

  5. Condensation heat transfer coefficient in horizontal stratified cocurrent flow of steam and cold water

    International Nuclear Information System (INIS)

    Kim, Kap; Kim, Hho Jung

    1986-01-01

    Some studies on direct-contact condensation in cocurrent stratified flow of steam and subcooled water were reviewed. Several approaches have been performed to develop the condensation heat transfer coefficient relationship. The local Nusselt number is correlated in terms of the local water Reynolds and Prandtl numbers as well as the steam Froude number. In addition, a turbulence-centered model, developed principally for gas absorption in several geometries, is modified by using calculated interfacial parameters for the turbulent velocity and length scales. These approaches result in a fairly good agreement with the data, whereas, the turbulence-centered model is here recommended since it is based on the turbulent properties which may be closely related to the condensation phenomena. (Author)

  6. Treatment of fishpond water by recirculating horizontal and vertical flow constructed wetlands in the tropics

    DEFF Research Database (Denmark)

    Konnerup, Dennis; Trang, Ngo Thuy Diem; Brix, Hans

    2011-01-01

    quantities of phytoplankton algae were removed in the CWs but abundance of toxic algae such as Microcystis was low. It is concluded that particularly vertical flow CWs have great potential for treatment of fishpond water in recirculating aquaculture systems in the tropics as the discharge of polluted water......Common practice of aquaculture in Vietnam and other countries in South East Asia involves frequent discharge of polluted water into rivers which results in eutrophication and degradation of receiving water bodies. There is therefore a need to develop improved aquaculture systems which have a more...... efficient use of water and less environmental impact. The aim of this study was to assess the suitability of using constructed wetlands (CWs) for the treatment of fishpond water in a recirculating aquaculture system in the Mekong Delta of Vietnam. Water from a fishpond stocked with Nile tilapia (Oreochromis...

  7. Optimization of Operation Parameters for Helical Flow Cleanout with Supercritical CO2 in Horizontal Wells Using Back-Propagation Artificial Neural Network.

    Science.gov (United States)

    Song, Xianzhi; Peng, Chi; Li, Gensheng; He, Zhenguo; Wang, Haizhu

    2016-01-01

    Sand production and blockage are common during the drilling and production of horizontal oil and gas wells as a result of formation breakdown. The use of high-pressure rotating jets and annular helical flow is an effective way to enhance horizontal wellbore cleanout. In this paper, we propose the idea of using supercritical CO2 (SC-CO2) as washing fluid in water-sensitive formation. SC-CO2 is manifested to be effective in preventing formation damage and enhancing production rate as drilling fluid, which justifies tis potential in wellbore cleanout. In order to investigate the effectiveness of SC-CO2 helical flow cleanout, we perform the numerical study on the annular flow field, which significantly affects sand cleanout efficiency, of SC-CO2 jets in horizontal wellbore. Based on the field data, the geometry model and mathematical models were built. Then a numerical simulation of the annular helical flow field by SC-CO2 jets was accomplished. The influences of several key parameters were investigated, and SC-CO2 jets were compared to conventional water jets. The results show that flow rate, ambient temperature, jet temperature, and nozzle assemblies play the most important roles on wellbore flow field. Once the difference between ambient temperatures and jet temperatures is kept constant, the wellbore velocity distributions will not change. With increasing lateral nozzle size or decreasing rear/forward nozzle size, suspending ability of SC-CO2 flow improves obviously. A back-propagation artificial neural network (BP-ANN) was successfully employed to match the operation parameters and SC-CO2 flow velocities. A comprehensive model was achieved to optimize the operation parameters according to two strategies: cost-saving strategy and local optimal strategy. This paper can help to understand the distinct characteristics of SC-CO2 flow. And it is the first time that the BP-ANN is introduced to analyze the flow field during wellbore cleanout in horizontal wells.

  8. Large-eddy simulation analysis of turbulent flow over a two-blade horizontal wind turbine rotor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae Young [Dept. of Mechanical Engineering, Carnegie Mellon University, Pittsburgh (United States); You, Dong Hyun [Dept. of Mechanical Engineering, Pohang University of Science and Technology, Pohang (Korea, Republic of)

    2016-11-15

    Unsteady turbulent flow characteristics over a two-blade horizontal wind turbine rotor is analyzed using a large-eddy simulation technique. The wind turbine rotor corresponds to the configuration of the U.S. National Renewable Energy Laboratory (NREL) phase VI campaign. The filtered incompressible Navier-Stokes equations in a non-inertial reference frame fixed at the centroid of the rotor, are solved with centrifugal and Coriolis forces using an unstructured-grid finite-volume method. A systematic analysis of effects of grid resolution, computational domain size, and time-step size on simulation results, is carried out. Simulation results such as the surface pressure coefficient, thrust coefficient, torque coefficient, and normal and tangential force coefficients are found to agree favorably with experimental data. The simulation showed that pressure fluctuations, which produce broadband flow-induced noise and vibration of the blades, are especially significant in the mid-chord area of the suction side at around 70 to 95 percent spanwise locations. Large-scale vortices are found to be generated at the blade tip and the location connecting the blade with an airfoil cross section and the circular hub rod. These vortices propagate downstream with helical motions and are found to persist far downstream from the rotor.

  9. Natural convective flows in a horizontal channel provided with heating isothermal blocks: Effect of the inter blocks spacing

    International Nuclear Information System (INIS)

    Bakkas, M.; Hasnaoui, M.; Amahmid, A.

    2010-01-01

    A numerical study of laminar steady natural convection induced in a two dimensional horizontal channel provided with rectangular heating blocks, periodically mounted on its lower wall, is carried out. The blocks' surface temperature, T H ' , is maintained constant and the former are connected with adiabatic surfaces. The upper wall of the channel is maintained cold at a temperature T C ' H ' . Fluid flow, temperature fields and heat transfer rates are presented for different combinations of the governing parameters which are the Rayleigh number (10 2 ≤Ra≤2x10 6 ), the blocks' spacing (1/4≤C=l ' /H ' ≤1), the blocks' height (1/8≤B=h ' /H ' ≤1/2) and the relative width of the blocks (A=(L ' -l ' )/H ' =1/2). The results obtained in the case of air (Pr = 0.72) show that the flow structure and the heat transfer are significantly influenced by the control parameters. It is found that there are situations where the increase of the blocks' spacing leads to a reduction of heat transfer.

  10. Effect of physico-chemical pretreatment on the removal efficiency of horizontal subsurface-flow constructed wetlands

    Energy Technology Data Exchange (ETDEWEB)

    Caselles-Osorio, Aracelly [Environmental Engineering Division, Hydraulics, Coastal and Environmental Engineering Department, Technical University of Catalonia, c/Jordi Girona 1-3, Modul D-1, 08034 Barcelona (Spain); Department of Biology, Atlantic University, Km 7 Higway Old Colombia Port, Barranquilla (Colombia); Garcia, Joan [Environmental Engineering Division, Hydraulics, Coastal and Environmental Engineering Department, Technical University of Catalonia, c/Jordi Girona 1-3, Modul D-1, 08034 Barcelona (Spain)]. E-mail: joan.garcia@upc.edu

    2007-03-15

    In this study, we tested the effect of a physico-chemical pretreatment on contaminant removal efficiency in two experimental horizontal subsurface-flow constructed wetlands (SSF CWs). One SSF CW was fed with settled urban wastewater, whereas the other with the same wastewater after it had undergone a physico-chemical pretreatment. The SSF CWs were operated with three different hydraulic retention times. During the experiments the effluent concentrations of COD, ammonia N and sulfate were very similar, and, therefore, the physico-chemical pretreatment did not improve the quality of the effluents. COD removal efficiency (as percentage or mass surface removal rate) was slightly greater in the SSF CW fed with pretreated wastewater. Ammonia N removal efficiency was, in general, similar in both SSF CWs and very high (80-90%). At the end of the experiments it was observed that in the SSF CW fed with settled wastewater the hydraulic conductivity decreased by a 20%. - A physico-chemical pretreatment may help to reduce the risk of clogging of subsurface-flow constructed wetlands.

  11. Effect of physico-chemical pretreatment on the removal efficiency of horizontal subsurface-flow constructed wetlands

    International Nuclear Information System (INIS)

    Caselles-Osorio, Aracelly; Garcia, Joan

    2007-01-01

    In this study, we tested the effect of a physico-chemical pretreatment on contaminant removal efficiency in two experimental horizontal subsurface-flow constructed wetlands (SSF CWs). One SSF CW was fed with settled urban wastewater, whereas the other with the same wastewater after it had undergone a physico-chemical pretreatment. The SSF CWs were operated with three different hydraulic retention times. During the experiments the effluent concentrations of COD, ammonia N and sulfate were very similar, and, therefore, the physico-chemical pretreatment did not improve the quality of the effluents. COD removal efficiency (as percentage or mass surface removal rate) was slightly greater in the SSF CW fed with pretreated wastewater. Ammonia N removal efficiency was, in general, similar in both SSF CWs and very high (80-90%). At the end of the experiments it was observed that in the SSF CW fed with settled wastewater the hydraulic conductivity decreased by a 20%. - A physico-chemical pretreatment may help to reduce the risk of clogging of subsurface-flow constructed wetlands

  12. Lie Group Solution for Free Convective Flow of a Nanofluid Past a Chemically Reacting Horizontal Plate in a Porous Media

    Directory of Open Access Journals (Sweden)

    M. M. Rashidi

    2014-01-01

    Full Text Available The optimal homotopy analysis method (OHAM is employed to investigate the steady laminar incompressible free convective flow of a nanofluid past a chemically reacting upward facing horizontal plate in a porous medium taking into account heat generation/absorption and the thermal slip boundary condition. Using similarity transformations developed by Lie group analysis, the continuity, momentum, energy, and nanoparticle volume fraction equations are transformed into a set of coupled similarity equations. The OHAM solutions are obtained and verified by numerical results using a Runge-Kutta-Fehlberg fourth-fifth order method. The effect of the emerging flow controlling parameters on the dimensionless velocity, temperature, and nanoparticle volume fraction have been presented graphically and discussed. Good agreement is found between analytical and numerical results of the present paper with published results. This close agreement supports our analysis and the accuracy of the numerical computations. This paper also includes a representative set of numerical results for reduced Nusselt and Sherwood numbers in a table for various values of the parameters. It is concluded that the reduced Nusselt number increases with the Lewis number and reaction parameter whist it decreases with the order of the chemical reaction, thermal slip, and generation parameters.

  13. Treatment of landfill leachate using an aerated, horizontal subsurface-flow constructed wetland.

    Science.gov (United States)

    Nivala, J; Hoos, M B; Cross, C; Wallace, S; Parkin, G

    2007-07-15

    A pilot-scale subsurface-flow constructed wetland was installed at the Jones County Municipal Landfill, near Anamosa, Iowa, in August 1999 to demonstrate the use of constructed wetlands as a viable low-cost treatment option for leachate generated at small landfills. The system was equipped with a patented wetland aeration process to aid in removal of organic matter and ammonia nitrogen. The high iron content of the leachate caused the aeration system to cease 2 years into operation. Upon the installation of a pretreatment chamber for iron removal and a new aeration system, treatment efficiencies dramatically improved. Seasonal performance with and without aeration is reported for 5-day biochemical oxygen demand (BOD(5)), chemical oxygen demand (COD), ammonia nitrogen (NH(4)-N), and nitrate nitrogen (NO(3)-N). Since winter air temperatures in Iowa can be very cold, a layer of mulch insulation was installed on top of the wetland bed to keep the system from freezing. When the insulation layer was properly maintained (either through sufficient litterfall or replenishing the mulch layer), the wetland sustained air temperatures of as low as -26 degrees C without freezing problems.

  14. A horizontal plug-flow baffled bioelectrocatalyzed reactor for the reductive decolorization of Alizarin Yellow R.

    Science.gov (United States)

    Sun, Qian; Li, Zhiling; Wang, Youzhao; Cui, Dan; Liang, Bin; Thangavel, Sangeetha; Chung, Jong Shik; Wang, Aijie

    2015-11-01

    An application-oriented membrane-free, continuous plug-flow baffled bioelectrocatalyzed reactor (PFB-BER), was designed and testified for the decolorization of Alizarin Yellow R. Decolorization efficiency (DE) with an external power source of 0.5 V was higher than without electrolysis, i.e. 93.4% versus 73.6% (HRT of 24 h). Product formation efficiencies of p-phenylenediamine and 5-aminosalicylic acid were above 95% and 50%, respectively. When HRT decreased to 8 h and 4 h, DE reduced to 69.9% and 44.9%, respectively. An additional electrode assembly improved DE to 96.4% (HRT of 8 h) and 80% (HRT of 4 h), while energy consumption (HRT of 4 h) was lower than that of HRT of 12 h with single electrode assembly under comparable DE. The PFB-BER with higher removal capacity, lower internal resistance and energy consumption provides a new solution to treat the high loading azo dye-containing wastewaters. Copyright © 2015. Published by Elsevier Ltd.

  15. Wire-mesh sensor, ultrasound and high-speed videometry applied for the characterization of horizontal gas-liquid slug flow

    Science.gov (United States)

    Ofuchi, C. Y.; Morales, R. E. M.; Arruda, L. V. R.; Neves, F., Jr.; Dorini, L.; do Amaral, C. E. F.; da Silva, M. J.

    2012-03-01

    Gas-liquid flows occur in a broad range of industrial applications, for instance in chemical, petrochemical and nuclear industries. Correct understating of flow behavior is crucial for safe and optimized operation of equipments and processes. Thus, measurement of gas-liquid flow plays an important role. Many techniques have been proposed and applied to analyze two-phase flows so far. In this experimental research, data from a wire-mesh sensor, an ultrasound technique and high-speed camera are used to study two-phase slug flows in horizontal pipes. The experiments were performed in an experimental two-phase flow loop which comprises a horizontal acrylic pipe of 26 mm internal diameter and 9 m length. Water and air were used to produce the two-phase flow and their flow rates are separately controlled to produce different flow conditions. As a parameter of choice, translational velocity of air bubbles was determined by each of the techniques and comparatively evaluated along with a mechanistic flow model. Results obtained show good agreement among all techniques. The visualization of flow obtained by the different techniques is also presented.

  16. The effect of heat generation on mixed convection flow in nano fluids over a horizontal circular cylinder

    Science.gov (United States)

    Juliyanto, Bagus; Widodo, Basuki; Imron, Chairul

    2018-04-01

    The purpose of this research is to study the effect of heat generation on mixed convection flow on Nano fluids over a horizontal circular cylinder of a heated in two dimension form. A stream of fluids are steady and incompressible, a stream flowing vertically upwards for circular cylinder and the boundary layer at the stagnation point. Three different types of nanoparticles considered are Cu, Al2O3, and TiO2. Mixed convection flow in Nano fluids on the surface of a circular cylinder will cause the boundary layer. The governing boundary layer equations are transformed into a non-dimensional form, and then the non-dimensional forms are transformed into a similar boundary equations by using stream function. Furthermore, an implicit finite-difference scheme known as the Keller-box method is applied to solve numerically the resulting similar boundary layer equations. The result of the research by varying the non-dimensional parameters are mixed convection, Prandtl number, nanoparticle volume fraction, heat generation, and radius of a cylinder are as follows. First, the velocity profile increase and temperature profile decrease when mixed convection parameter increase. Second, the velocity and temperature profiles decrease when Prandtl number parameter increase. Third, the velocity profile with the variation of nanoparticle volume fraction (χ) is increased when the value of χ is 0,1 ≤ χ ≤ 0,15 and the velocity profile decreases when the value of χ is 0,19 ≤ χ ≤ 0,5 while the temperature profile is increasing when the value of χ is 0,1 ≤ χ ≤ 0,5. Fourth, the velocity and temperature profiles increase when heat generation and the radius of the cylinder increase. The last, Cu, Al 2 O 3, and TiO 2 nanoparticles produce the same velocity and temperature profiles, but the three types of nanoparticles are different at the velocity and temperature values.

  17. Experimental investigation of the two-phase flow in a short horizontal microchannel with the height of 50 μm and width of 20 mm

    Directory of Open Access Journals (Sweden)

    Ronshin Fedor

    2017-01-01

    Full Text Available The two-phase flow has been studied experimentally in a short horizontal microchannel with the height of 50 μm and width of 20 mm. The following regimes of two-phase flows have been registered: jet, bubble, stratified, annular, and churn. The regime map of two-phase flow has been plotted. This map has been compared with the regime map plotted for the channels of larger cross-section; it is shown that the height and width of a rectangular channel has a significant effect on the boundaries between flow regimes.

  18. Sub-surface defect detection using transient thermography

    International Nuclear Information System (INIS)

    Mohd Zaki Umar; Huda Abdullah; Abdul Razak Hamzah; Wan Saffiey Wan Abdullah; Ibrahim Ahmad; Vavilov, Vladimir

    2009-04-01

    An experimental research had been carried out to study the potential of transient thermography in detecting sub-surface defect of non-metal material. In this research, eight pieces of bakelite material were used as samples. Each samples had a sub-surface defect in the circular shape with different diameters and depths. Experiment was conducted using one-sided Pulsed Thermal technique. Heating of samples were done using 30 k Watt adjustable quartz lamp while infra red (IR) images of samples were recorded using THV 550 IR camera. These IR images were then analysed with thermo fit TM Pro software to obtain the Maximum Absolute Differential Temperature Signal value, ΔT max and the time of its appearance, τ max (ΔT). Result showed that all defects were able to be detected even for the smallest and deepest defect (diameter = 5 mm and depth = 4 mm). However the highest value of Differential Temperature Signal (ΔT max ), were obtained at defect with the largest diameter, 20 mm and at the shallowest depth, 1 mm. As a conclusion, the sensitivity of the pulsed thermography technique to detect sub-surface defects of bakelite material is proportionately related with the size of defect diameter if the defect area at the same depth. On the contrary, the sensitivity of the pulsed thermography technique inversely related with the depth of defect if the defects have similar diameter size. (author)

  19. 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

    International Nuclear Information System (INIS)

    Nakamura, Hideo

    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

  20. R404A condensing under forced flow conditions inside smooth, microfin and cross-hatched horizontal tubes

    Energy Technology Data Exchange (ETDEWEB)

    Infante Ferreira, C A; Nan, X [Delft University of Technology (Netherlands). Laboratory for Refrigeration and Indoor Climate Control; Newell, T A; Chato, J C [University of Illinois, Urbana, IL (United States). Dept. of Mechanical and Industrial Engineering

    2003-06-01

    Two-phase heat transfer coefficient characteristics of R404A condensing under forced flow conditions inside smooth, microfin and cross-hatched horizontal tubes are experimentally investigated. Experimental parameters include a lubricating polyol ester oil concentration varied from 0 to 4%. The test runs were done at average inlet saturated condensing temperatures of 40{sup o}C. The inlet vapor was kept at saturation (quality = 1.0). The mass fluxes were between 200 and 600 kg/m{sup 2}s, and the heat fluxes were selected to obtain a quality of 0.0 at the outlet of the test section, varying from 5 to 45 kW/m{sup 2}. The heat transfer enhancement factor varied between 1.8 and 2.4 for both microfin and cross-hatched tubes. The larger values applied for larger mass fluxes for the cross-hatched tube and smaller mass fluxes for the microfin tube. Enhancement factors increased as oil concentration increased up to oil concentrations of 2%. For higher oil concentrations the enhancement decreased especially at high mass fluxes, the cross-hatched tube being less sensitive to oil contamination. Pressure drop in the test section increased by approximately 25% as the oil concentration increased from 0 to 4%. The results from the experiments are compared with those calculated from correlations reported in the literature. Moreover, modified correlations for the condensation heat transfer coefficient are proposed for practical applications. (author)

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

    CERN Document Server

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

    2011-01-01

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

  2. High-resolution digital movies of emerging flux and horizontal flows in active regions on the sun

    Science.gov (United States)

    Topka, K.; Ferguson, S.; Frank, Z.; Tarbell, T.; Title, A.

    1988-01-01

    High-resolution observations of active regions in many wavelength bands obtained at the Vacuum Tower Telescope of NSO/Sunspot (Sacramento Peak) are presented. The SOUP tunable filter, HRSO 1024 x 1024 CCD camera, and a sunspot tracker for image stabilization were used. Subarrays of 512 x 512 pixels were processed digitally and recorded on videodisk in movie format. The movies with 0.5 to 1 arcsecond resolution of the following simultaneous observations were shown: green continuum, longitudinal magnetogram, Doppler velocity, Fe I 5576 A line center, H alpha wings, and H alpha line center. The best set of movies show a 90 x 90 arcsecond field-of-view of an active region at S29, W11. When viewed at speeds of a few thousand times real-time, the photospheric movies clearly show the active region fields being distorted by a remarkable combination of systematic flows and small eruptions of new flux. Flux emergence is most easily discovered in line center movies: an elongated dark feature appears first, followed soon after by bright points at one or both ends. A brief, strong upflow is seen when the dark feature first appears; downflow in the bright points persists much longer. The magnetic flux appears to increase gradually over this extended period. Some of the flux emergence events were studied in detail, with measurements of horizontal and vertical velocities and magnetic flux versus time within one footpoint of the loop.

  3. RANS study of unsteady flow around a profile blade : application to stall of horizontal axis wind turbine

    Energy Technology Data Exchange (ETDEWEB)

    Belkheir, N. [Khemis Miliana Univ., Ain Defla (Algeria); Dizene, R. [Univ. des Sciences et de la Technologie Houari Boumediene, Algiers (Algeria). Laboratoire de Mecanique Avancee; Khelladi, S.; Massouh, F.; Dobrev, I. [Arts et Metiers Paris Tech., Paris (France)

    2010-07-01

    The shape of an airfoil is designed to achieve the best aerodynamic performance. An aerofoil section undergoes dynamic stall when subjected to any form of unsteady angle of pitch. The study of a horizontal-axis wind turbine (HAWT) under wind operating conditions is complex because it is subject to instantaneous speed and wind direction variation. When turbine blades are driven into a dynamic stall, the lift coefficient drops suddenly resulting in a degradation in aerodynamic performance. This study presented steady and unsteady wind load predictions over an oscillating S809 airfoil tested in a subsonic wind tunnel. A model of sinusoidal pitch oscillations was used. The values for the angles of attack in steady state ranged from -20 to +40 degrees. The model considered 3 frequencies and 2 amplitudes. The two-dimensional numerical model simulated the instantaneous change of wind direction with respect to the turbine blade. Results were compared with data measurements of S809 aerofoil. Reasonable deviations were obtained between the predicted and experimental results for pitch oscillations. The URANS approach was used to predict the stall while the software FLUENT was used for the numerical solution. It was concluded that the behaviour of the unsteady flow in the wind farm must be considered in order to obtain an accurate estimate of the wind turbine aerodynamic load. 12 refs., 5 figs.

  4. Effect of multilayer substrate configuration in horizontal subsurface flow constructed wetlands: assessment of treatment performance, biofilm development, and solids accumulation.

    Science.gov (United States)

    Ding, Yanli; Lyu, Tao; Bai, Shaoyuan; Li, Zhenling; Ding, Haijing; You, Shaohong; Xie, Qinglin

    2018-01-01

    This study investigates the influence of multilayer substrate configuration in horizontal subsurface flow constructed wetlands (HSCWs) on their treatment performance, biofilm development, and solids accumulation. Three pilot-scale HSCWs were built to treat campus sewage and have been operational for 3 years. The HSCWs included monolayer (CW1), three-layer (CW3), and six-layer (CW6) substrate configurations with hydraulic conductivity of the substrate increasing from the surface to bottom in the multilayer CWs. It was demonstrated the pollutant removal performance after a 3-year operation improved in the multilayer HSCWs (49-80%) compared to the monolayer HSCW (29-41%). Simultaneously, the multilayer HSCWs exhibited significant features that prevented clogging compared to the monolayer configuration. The amount of accumulated solids was notably higher in the monolayer CW compared to multilayer CWs. Further, multilayer HSCWs could delay clogging by providing higher biofilm development for organics removal and consequently, lesser solids accumulations. Principal component analysis strongly supported the visualization of the performance patterns in the present study and showed that multilayer substrate configuration, season, and sampling locations significantly influenced biofilm growth and solids accumulation. Finally, the present study provided important information to support the improved multilayer configured HSCW implication in the future.

  5. Hydrogen sulfide oxidation in novel Horizontal-Flow Biofilm Reactors dominated by an Acidithiobacillus and a Thiobacillus species.

    Science.gov (United States)

    Gerrity, S; Kennelly, C; Clifford, E; Collins, G

    2016-09-01

    Hydrogen Sulfide (H2S) is an odourous, highly toxic gas commonly encountered in various commercial and municipal sectors. Three novel, laboratory-scale, Horizontal-Flow Biofilm Reactors (HFBRs) were tested for the removal of H2S gas from air streams over a 178-day trial at 10°C. Removal rates of up to 15.1 g [H2S] m(-3) h(-1) were achieved, demonstrating the HFBRs as a feasible technology for the treatment of H2S-contaminated airstreams at low temperatures. Bio-oxidation of H2S in the reactors led to the production of H(+) and sulfate (SO(2-)4) ions, resulting in the acidification of the liquid phase. Reduced removal efficiency was observed at loading rates of 15.1 g [H2S] m(-3) h(-1). NaHCO3 addition to the liquid nutrient feed (synthetic wastewater (SWW)) resulted in improved H2S removal. Bacterial diversity, which was investigated by sequencing and fingerprinting 16S rRNA genes, was low, likely due to the harsh conditions prevailing in the systems. The HFBRs were dominated by two species from the genus Acidithiobacillus and Thiobacillus. Nonetheless, there were significant differences in microbial community structure between distinct HFBR zones due to the influence of alkalinity, pH and SO4 concentrations. Despite the low temperature, this study indicates HFBRs have an excellent potential to biologically treat H2S-contaminated airstreams.

  6. High-resolution digital movies of emerging flux and horizontal flows in active regions on the sun

    International Nuclear Information System (INIS)

    Topka, K.; Ferguson, S.; Frank, Z.; Tarbell, T.; Title, A.

    1988-01-01

    High-resolution observations of active regions in many wavelength bands obtained at the Vacuum Tower Telescope of NSO/Sunspot (Sacramento Peak) are presented. The SOUP tunable filter, HRSO 1024 x 1024 CCD camera, and a sunspot tracker for image stabilization were used. Subarrays of 512 x 512 pixels were processed digitally and recorded on videodisk in movie format. The movies with 0.5 to 1 arcsecond resolution of the following simultaneous observations were shown: green continuum, longitudinal magnetogram, Doppler velocity, Fe I 5576 A line center, H alpha wings, and H alpha line center. The best set of movies show a 90 x 90 arcsecond field-of-view of an active region at S29, W11. When viewed at speeds of a few thousand times real-time, the photospheric movies clearly show the active region fields being distorted by a remarkable combination of systematic flows and small eruptions of new flux. Flux emergence is most easily discovered in line center movies: an elongated dark feature appears first, followed soon after by bright points at one or both ends. A brief, strong upflow is seen when the dark feature first appears; downflow in the bright points persists much longer. The magnetic flux appears to increase gradually over this extended period. Some of the flux emergence events were studied in detail, with measurements of horizontal and vertical velocities and magnetic flux versus time within one footpoint of the loop

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-11-15

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

  8. Phytoextraction, phytotransformation and rhizodegradation of ibuprofen associated with Typha angustifolia in a horizontal subsurface flow constructed wetland.

    Science.gov (United States)

    Li, Yifei; Zhang, Jiefeng; Zhu, Guibing; Liu, Yu; Wu, Bing; Ng, Wun Jern; Appan, Adhityan; Tan, Soon Keat

    2016-10-01

    Widespread occurrence of trace pharmaceutical residues in aquatic environments is of great concerns due to the potential chronic toxicity of certain pharmaceuticals including ibuprofen on aquatic organisms even at environmental levels. In this study, the phytoextraction, phytotransformation and rhizodegradation of ibuprofen associated with Typha angustifolia were investigated in a horizontal subsurface flow constructed wetland system. The experimental wetland system consisted of a planted bed with Typha angustifolia and an unplanted bed (control) to treat ibuprofen-loaded wastewater (∼107.2 μg L(-1)). Over a period of 342 days, ibuprofen was accumulated in leaf sheath and lamina tissues at a mean concentration of 160.7 ng g(-1), indicating the occurrence of the phytoextraction of ibuprofen. Root-uptake ibuprofen was partially transformed to ibuprofen carboxylic acid, 2-hydroxy ibuprofen and 1-hydroxy ibuprofen which were found to be 1374.9, 235.6 and 301.5 ng g(-1) in the sheath, respectively, while they were 1051.1, 693.6 and 178.7 ng g(-1) in the lamina. The findings from pyrosequencing analysis of the rhizosphere bacteria suggest that the Dechloromonas sp., the Clostridium sp. (e.g. Clostridium saccharobutylicum), the order Sphingobacteriales, and the Cytophaga sp. in the order Cytophagales were most probably responsible for the rhizodegradation of ibuprofen. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. High-resolution digital movies of emerging flux and horizontal flows in active regions on the sun

    Science.gov (United States)

    Topka, K.; Ferguson, S.; Frank, Z.; Tarbell, T.; Title, A.

    1988-11-01

    High-resolution observations of active regions in many wavelength bands obtained at the Vacuum Tower Telescope of NSO/Sunspot (Sacramento Peak) are presented. The SOUP tunable filter, HRSO 1024 x 1024 CCD camera, and a sunspot tracker for image stabilization were used. Subarrays of 512 x 512 pixels were processed digitally and recorded on videodisk in movie format. The movies with 0.5 to 1 arcsecond resolution of the following simultaneous observations were shown: green continuum, longitudinal magnetogram, Doppler velocity, Fe I 5576 A line center, H alpha wings, and H alpha line center. The best set of movies show a 90 x 90 arcsecond field-of-view of an active region at S29, W11. When viewed at speeds of a few thousand times real-time, the photospheric movies clearly show the active region fields being distorted by a remarkable combination of systematic flows and small eruptions of new flux. Flux emergence is most easily discovered in line center movies: an elongated dark feature appears first, followed soon after by bright points at one or both ends. A brief, strong upflow is seen when the dark feature first appears; downflow in the bright points persists much longer. The magnetic flux appears to increase gradually over this extended period. Some of the flux emergence events were studied in detail, with measurements of horizontal and vertical velocities and magnetic flux versus time within one footpoint of the loop.

  10. Flow visualization study of two phase flow in a single bend outlet feeder pipe and horizontal annulus of outlet end-fitting of a CANDU reactor

    International Nuclear Information System (INIS)

    Supa-Amornkul, S.; Lister, D.H.; Steward, F.R.

    2005-01-01

    'Full text:' In CANDU-6 reactors, the pressurized high-temperature coolant flows through 380 fuel channels passing horizontally through the core. Each end of a fuel channel has a stainless steel annular end-fitting connected to a carbon steel feeder pipe. The outlet coolant, which is at 310 o C with up to 0.30 steam voidage, turns through 90 o as it passes from flow in the annular end-fitting to pipe flow in the feeder via a Grayloc connector. Since 1996, several CANDU stations have reported excessive corrosion of their outlet feeder pipes; especially between the first metre, which consisted of single or double bends. Early studies related the attack to the hydrodynamics of the coolant and verified that it was a type of flow accelerated corrosion. In order to understand the hydrodynamics of the coolant in the outlet feeders by flow-visualization, a full-scale transparent test section simulating the geometry and orientation of an outlet feeder bend with its upstream annular end-fitting were fabricated. The feeder consisted of a 54 mm inside diameter acrylic pipe with a 73 o bend, connecting to an acrylic simulation of a Grayloc flanged fitting and annular end-fitting. The annular end-fitting consisted of an inner pipe, 110 mm outer diameter, and an outer pipe, 150 mm inner diameter, both 190.7 cm long in length. The tests were performed with water and air at atmospheric pressure and room temperature. The maximum water volumetric flow rate was 19 L/s and the volume fraction of air varied from 0.05 to 0.56. The phase distributions within the feeder pipe and along the length of the annulus were investigated with a digital video recorder. Size, concentration and velocity of the air bubbles at particular locations were studied with a high-speed digital still camera and a high-speed digital video camera. Phase distributions and variations in bubble size with velocity were determined. Particular attention was paid to the flow pattern at the inside of the bend, where a CFD

  11. Flow visualization study of two phase flow in a single bend outlet feeder pipe and horizontal annulus of outlet end-fitting of a CANDU reactor

    Energy Technology Data Exchange (ETDEWEB)

    Supa-Amornkul, S.; Lister, D.H.; Steward, F.R. [Univ. of New Brunswick, Fredericton, New Brunswick (Canada)]. E-mail: h796e@unb.ca; dlister@unb.ca; fsteward@unb.ca

    2005-07-01

    'Full text:' In CANDU-6 reactors, the pressurized high-temperature coolant flows through 380 fuel channels passing horizontally through the core. Each end of a fuel channel has a stainless steel annular end-fitting connected to a carbon steel feeder pipe. The outlet coolant, which is at 310{sup o}C with up to 0.30 steam voidage, turns through 90{sup o} as it passes from flow in the annular end-fitting to pipe flow in the feeder via a Grayloc connector. Since 1996, several CANDU stations have reported excessive corrosion of their outlet feeder pipes; especially between the first metre, which consisted of single or double bends. Early studies related the attack to the hydrodynamics of the coolant and verified that it was a type of flow accelerated corrosion. In order to understand the hydrodynamics of the coolant in the outlet feeders by flow-visualization, a full-scale transparent test section simulating the geometry and orientation of an outlet feeder bend with its upstream annular end-fitting were fabricated. The feeder consisted of a 54 mm inside diameter acrylic pipe with a 73{sup o} bend, connecting to an acrylic simulation of a Grayloc flanged fitting and annular end-fitting. The annular end-fitting consisted of an inner pipe, 110 mm outer diameter, and an outer pipe, 150 mm inner diameter, both 190.7 cm long in length. The tests were performed with water and air at atmospheric pressure and room temperature. The maximum water volumetric flow rate was 19 L/s and the volume fraction of air varied from 0.05 to 0.56. The phase distributions within the feeder pipe and along the length of the annulus were investigated with a digital video recorder. Size, concentration and velocity of the air bubbles at particular locations were studied with a high-speed digital still camera and a high-speed digital video camera. Phase distributions and variations in bubble size with velocity were determined. Particular attention was paid to the flow pattern at the inside

  12. The Self-Potential Anomaly Produced by a Subsurface Flow at the Contact of Two Horizontal Layers and Its Quantitative Interpretation

    OpenAIRE

    Skianis, Georgios Aim.

    2012-01-01

    In the present paper the problem of a polarized cylinder with a small cross-section, which is located at the contact of two horizontal layers with different resistivities, is studied. Such a polarization geometry simulates the self-potential (SP) field produced by a horizontal flow at the contact between the two layers. First, the expression of the self potential at the space domain is derived, applying the image technique. Then, the expression for the Fourier transform of the SP anomaly is f...

  13. A comparative pressure analysis of air flow between horizontal and V-Tail of UAV MALE of NACA0012H with speed variation

    Directory of Open Access Journals (Sweden)

    Riza Rahmat

    2018-01-01

    Full Text Available NACA0012H is an airfoil type that could be used for Unmanned Aerial Vehicle Medium Altitude Long Endurance. This experiment was used to analyze stress in the surface of Tail of UAV MALE that was caused by air flow. The experiment was conducted using Computational Fluid Dynamics Software. Two designs of tail, horizontal and V-tail, were considered to simulate pressure occurred on the surface of leading edge, chamber and trailing edge. The simulation was developed varying the speed of the UAV MALE. The results showed that pressure occurred on the surface of horizontal tail higher than pressure on the V-tail.

  14. Thermohydraulics of a horizontal diphasic flow of superfluid helium; Thermo-hydraulique d'un ecoulement horizontal d'helium superfluide diphasique

    Energy Technology Data Exchange (ETDEWEB)

    Perraud, S

    2007-12-15

    This study aims at characterizing helium two phase flows, and to identify the dependence of their characteristics on various thermo-hydraulic parameters: vapour velocity, liquid height, vapour density, specificities of superfluidity. Both the engineer and the physicist's points of view are taken into consideration: the first one in terms of optimization of a particular cooling scheme based on a two-phase flow, and these second one in terms of more fundamental atomization-related questions. It has been shown that for velocities around 3 to 4 m/s, the liquid phase that was initially stratified undergoes an atomization through the presence of a drop haze carried by the vapor phase.This happens for superfluid helium as well as for normal helium without main differences on atomization.

  15. Magnetohydrodynamics effect on three-dimensional viscous incompressible flow between two horizontal parallel porous plates and heat transfer with periodic injection/suction

    Directory of Open Access Journals (Sweden)

    R. C. Chaudhary

    2004-11-01

    Full Text Available We investigate the hydromagnetic effect on viscous incompressible flow between two horizontal parallel porous flat plates with transverse sinusoidal injection of the fluid at the stationary plate and its corresponding removal by periodic suction through the plate in uniform motion. The flow becomes three dimensional due to this injection/suction velocity. Approximate solutions are obtained for the flow field, the pressure, the skin-friction, the temperature field, and the rate of heat transfer. The dependence of solution on M (Hartmann number and λ (injection/suction is investigated by the graphs and tables.

  16. Analytical framework for borehole heat exchanger (BHE) simulation influenced by horizontal groundwater flow and complex top boundary conditions

    Science.gov (United States)

    Rivera, Jaime; Blum, Philipp; Bayer, Peter

    2015-04-01

    Borehole heat exchangers (BHE) are the most widely used technologies for tapping low-enthalpy energy resources in the shallow subsurface. Analysis of these systems requires a proper simulation of the relevant processes controlling the transfer of heat between the BHE and the ground. Among the available simulation approaches, analytical methods are broadly accepted, especially when low computational costs and comprehensive analyses are demanded. Moreover, these methods constitute the benchmark solutions to evaluate the performance of more complex numerical models. Within the spectrum of existing (semi-)analytical models, those based on the superposition of problem-specific Green's functions are particularly appealing. Green's functions can be derived, for instance, for nodal or line sources with constant or transient strengths. In the same manner, functional forms can be obtained for scenarios with complex top boundary conditions whose temperature may vary in space and time. Other relevant processes, such as advective heat transport, mechanical dispersion and heat transfer through the unsaturated zone could be incorporated as well. A keystone of the methodology is that individual solutions can be added up invoking the superposition principle. This leads to a flexible and robust framework for studying the interaction of multiple processes on thermal plumes of BHEs. In this contribution, we present a new analytical framework and its verification via comparison with a numerical model. It simulates a BHE as a line source, and it integrates both horizontal groundwater flow and the effect of top boundary effects due to variable land use. All these effects may be implemented as spatially and temporally variable. For validation, the analytical framework is successfully applied to study cases where highly resolved temperature data is available.

  17. Feasibility of correlation mapping optical coherence tomography (cmOCT) for anti-spoof sub-surface fingerprinting.

    Science.gov (United States)

    Zam, Azhar; Dsouza, Roshan; Subhash, Hrebesh M; O'Connell, Marie-Louise; Enfield, Joey; Larin, Kirill; Leahy, Martin J

    2013-09-01

    We propose the use of correlation mapping optical coherence tomography (cmOCT) to deliver additional biometrics associated with the finger that could complement existing fingerprint technology for law enforcement applications. The current study extends the existing fingerprint paradigm by measuring additional biometrics associated with sub-surface finger tissue such as sub-surface fingerprints, sweat glands, and the pattern of the capillary bed to yield a user-friendly cost effective and anti-spoof multi-mode biometric solution associated with the finger. To our knowledge no other method has been able to capture sub-surface fingerprint, papillary pattern and horizontal vessel pattern in a single scan or to show the correspondence between these patterns in live adult human fingertip. Unlike many current technologies this approach incorporates 'liveness' testing by default. The ultimate output is a biometric module which is difficult to defeat and complements fingerprint scanners that currently are used in border control and law enforcement applications. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Optimization of Operation Parameters for Helical Flow Cleanout with Supercritical CO2 in Horizontal Wells Using Back-Propagation Artificial Neural Network.

    Directory of Open Access Journals (Sweden)

    Xianzhi Song

    Full Text Available Sand production and blockage are common during the drilling and production of horizontal oil and gas wells as a result of formation breakdown. The use of high-pressure rotating jets and annular helical flow is an effective way to enhance horizontal wellbore cleanout. In this paper, we propose the idea of using supercritical CO2 (SC-CO2 as washing fluid in water-sensitive formation. SC-CO2 is manifested to be effective in preventing formation damage and enhancing production rate as drilling fluid, which justifies tis potential in wellbore cleanout. In order to investigate the effectiveness of SC-CO2 helical flow cleanout, we perform the numerical study on the annular flow field, which significantly affects sand cleanout efficiency, of SC-CO2 jets in horizontal wellbore. Based on the field data, the geometry model and mathematical models were built. Then a numerical simulation of the annular helical flow field by SC-CO2 jets was accomplished. The influences of several key parameters were investigated, and SC-CO2 jets were compared to conventional water jets. The results show that flow rate, ambient temperature, jet temperature, and nozzle assemblies play the most important roles on wellbore flow field. Once the difference between ambient temperatures and jet temperatures is kept constant, the wellbore velocity distributions will not change. With increasing lateral nozzle size or decreasing rear/forward nozzle size, suspending ability of SC-CO2 flow improves obviously. A back-propagation artificial neural network (BP-ANN was successfully employed to match the operation parameters and SC-CO2 flow velocities. A comprehensive model was achieved to optimize the operation parameters according to two strategies: cost-saving strategy and local optimal strategy. This paper can help to understand the distinct characteristics of SC-CO2 flow. And it is the first time that the BP-ANN is introduced to analyze the flow field during wellbore cleanout in

  19. Assessing the efficiency of an unplanted horizontal flow constructed wetland to reduce some emerging organic micropollutants. Preliminary results

    Science.gov (United States)

    Tapias, Josefina C.; Vila, Marta; Himi, Mahjoub; Salvadó, Victoria; Casas, Albert; Hidalgo, Manuela

    2017-04-01

    The presence of emerging organic contaminants (EOC) such as pharmaceutical and personal care products, pesticides or antiseptics in wastewater is an increasing concern worldwide due to their potential toxicological effects for humans and other living organisms. Because of their low concentration and persistence their removal using conventional treatment technologies is often incomplete and for this reason there is a growing interest for assessing the efficiency of alternative wastewater treatment technologies such as constructed wetlands (CWs). CWs are engineered systems for wastewater treatment plant (WWTP) designed to take advantage of many of the same processes that occur in natural wetlands, but within a more controlled environment. CWs are a cost-effective alternative to conventional wastewater treatment plants especially in the context of small communities with less than 2000 people equivalent. Our study has been conducted at the Verdú WWTP (Lleida, Catalonia, NE Spain). This system has a primary treatment consisting on three septic tanks in parallel with a volume of 50 m3 and three chambers each one. The primary effluent is distributed to four parallel horizontal subsurface flow (HSSF) CWs. Originally the system was planted with common reed (Phragmites australis), but currently after twelve years of service the system show evidences of clogging and then gravel bed was replaced and plants removed. After the HSSF CWs, there are two wastewater stabilization ponds (WSPs) followed by two smaller polishing horizontal HSSF CWs. Excellent overall treatment performance was exhibited on the elimination of conventional water quality parameters (93-98% average removal efficiency for TSS, COD, BOD5 and NTK), and its final effluent proved to comply with existing Spanish guidelines. Sampling has been conducted along two years at different seasons and examined EOC substances included analgesic and anti-inflammatory drugs (ibuprofen, diclofenac, and naproxene

  20. An investigation of the constitutive relations for intersubchannel transfer mechanisms in horizontal flows as applied in the ASSERT-4 subchannel code

    International Nuclear Information System (INIS)

    Tye, P.; Teyssedou, A.; Tapucu, A.

    1994-01-01

    In this paper, the influence that the constitutive relations used to represent some of the intersubchannel transfer mechanisms has on the predictions of the ASSERT-4 subchannel code for horizontal flows is examined. In particular the choices made in the representation of the gravity driven phase separation phenomena are analyzed. This is done by comparing the predictions of the ASSERT subchannel code with experimental data on void fraction and mass flow rate, obtained for two horizontal interconnected subchannels. ASSERT uses a drift flux model which allows the two phases to have different velocities. In particular ASSERT contains models for the buoyancy effects which cause phase separation between adjacent subchannels in horizontal flows. This feature, which is of great importance in the subchannel analysis of CANDU reactors, is implemented in the constitutive relationship for the relative velocity. In order to isolate different intersubchannel transfer mechanisms, three different subchannel orientations are analyzed. These are the two subchannels at the same elevation, the high void subchannel below the low void subchannel, and the high void subchannel above the low void subchannel. It is observed that for all three subchannel orientations ASSERT does a reasonably good job of predicting the experimental trends. However, certain modifications to the representation of the gravitational phase separation effects which seem to improve the overall predictions are suggested. ((orig.))

  1. Prediction of evaporation heat transfer coefficient based on gas-liquid two-phase annular flow regime in horizontal microfin tubes

    International Nuclear Information System (INIS)

    Wang Yueshe; Wang Yanling; Wang, G.-X.; Honda, Hiroshi

    2009-01-01

    A physical model of gas-liquid two-phase annular flow regime is presented for predicting the enhanced evaporation heat transfer characteristics in horizontal microfin tubes. The model is based on the equivalence of a periodical distortion of the disturbance wave in the substrate layer. Corresponding to the stratified flow model proposed previously by authors, the dimensionless quantity Fr 0 = G/[gd e ρ v (ρ l - ρ v )] 0.5 may be used as a measure for determining the applicability of the present theoretical model, which was used to restrict the transition boundary between the stratified-wavy flow and the annular/intermittent flows. Comparison of the prediction of the circumferential average heat transfer coefficient with available experimental data for four tubes and three refrigerants reveals that a good agreement is obtained or the trend is better than that of the previously developed stratified flow model for Fr 0 > 4.0 as long as the partial dry out of tube does not occur. Obviously, the developed annular model is applicable and reliable for evaporation in horizontal microfin tubes under the case of high heat flux and high mass flux.

  2. Prediction of evaporation heat transfer coefficient based on gas-liquid two-phase annular flow regime in horizontal microfin tubes

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yueshe, E-mail: wangys@mail.xjtu.edu.cn [State Key Laboratory of Multiphase Flow in Power Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Yanling, Wang [State Key Laboratory of Multiphase Flow in Power Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Wang, G -X [Mechanical Engineering Department, The University of Akron, Akron, OH 44325-3903 (United States); Honda, Hiroshi [Kyushu University, 337 Kasuya-machi, Kasuya-gun, Kukuoka 811-2307 (Japan)

    2009-10-15

    A physical model of gas-liquid two-phase annular flow regime is presented for predicting the enhanced evaporation heat transfer characteristics in horizontal microfin tubes. The model is based on the equivalence of a periodical distortion of the disturbance wave in the substrate layer. Corresponding to the stratified flow model proposed previously by authors, the dimensionless quantity Fr{sub 0} = G/[gd{sub e}{rho}{sub v}({rho}{sub l} - {rho}{sub v})]{sup 0.5} may be used as a measure for determining the applicability of the present theoretical model, which was used to restrict the transition boundary between the stratified-wavy flow and the annular/intermittent flows. Comparison of the prediction of the circumferential average heat transfer coefficient with available experimental data for four tubes and three refrigerants reveals that a good agreement is obtained or the trend is better than that of the previously developed stratified flow model for Fr{sub 0} > 4.0 as long as the partial dry out of tube does not occur. Obviously, the developed annular model is applicable and reliable for evaporation in horizontal microfin tubes under the case of high heat flux and high mass flux.

  3. Simulation of a multistage fractured horizontal well in a water-bearing tight fractured gas reservoir under non-Darcy flow

    Science.gov (United States)

    Zhang, Rui-Han; Zhang, Lie-Hui; Wang, Rui-He; Zhao, Yu-Long; Huang, Rui

    2018-06-01

    Reservoir development for unconventional resources such as tight gas reservoirs is in increasing demand due to the rapid decline of production in conventional reserves. Compared with conventional reservoirs, fluid flow in water-bearing tight gas reservoirs is subject to more nonlinear multiphase flow and gas slippage in nano/micro matrix pores because of the strong collisions between rock and gas molecules. Economic gas production from tight gas reservoirs depends on extensive application of water-based hydraulic fracturing of horizontal wells, associated with non-Darcy flow at a high flow rate, geomechanical stress sensitivity of un-propped natural fractures, complex flow geometry and multiscale heterogeneity. How to efficiently and accurately predict the production performance of a multistage fractured horizontal well (MFHW) is challenging. In this paper, a novel multicontinuum, multimechanism, two-phase simulator is established based on unstructured meshes and the control volume finite element method to analyze the production performance of MFHWs. The multiple interacting continua model and discrete fracture model are coupled to integrate the unstimulated fractured reservoir, induced fracture networks (stimulated reservoir volumes, SRVs) and irregular discrete hydraulic fractures. Several simulations and sensitivity analyses are performed with the developed simulator for determining the key factors affecting the production performance of MFHWs. Two widely applied fracturing models, classic hydraulic fracturing which generates long double-wing fractures and the volumetric fracturing aimed at creating large SRVs, are compared to identify which of them can make better use of tight gas reserves.

  4. Treatment of high-strength wastewater in tropical constructed wetlands planted with Sesbania sesban: Horizontal subsurface flow versus vertical downflow

    DEFF Research Database (Denmark)

    Dan, Truong Hoang; Quang, Le Nhat; Chiem, Nguyen Huu

    2011-01-01

    Treatment of various types of wastewaters is an urgent problem in densely populated areas of many tropical countries. We studied the potential of using Sesbania sesban, an N2-fixing shrub, in constructed wetland systems for the treatment of high-strength wastewater. A replicated horizontal subsur...

  5. Assessment of fluid-to-fluid modelling of critical heat flux in horizontal 37-element bundle flows

    International Nuclear Information System (INIS)

    Yang, S.K.

    2006-01-01

    Fluid-to-fluid modelling laws of critical heat flux (CHF) available in the literature were reviewed. The applicability of the fluid-to-fluid modelling laws was assessed using available data ranging from low to high mass fluxes in horizontal 37-element bundles simulating a CANDU fuel string. Correlations consisting of dimensionless similarity groups were derived using modelling fluid data (Freon-12) to predict water CHF data in horizontal 37-element bundles with uniform and non-uniform axial-heat flux distribution (AFD). The results showed that at mass fluxes higher than ∼4,000 kg/m 2 s (water equivalent value), the vertical fluid-to-fluid modelling laws of Ahmad (1973) and Katto (1979) predict water CHF in horizontal 37-element bundles with non-uniform AFD with average errors of 1.4% and 3.0% and RMS errors of 5.9% and 6.1%, respectively. The Francois and Berthoud (2003) fluid-to-fluid modelling law predicts CHF in non-uniformly heated 37-element bundles in the horizontal orientation with an average error of 0.6% and an RMS error of 10.4% over the available range of 2,000 to 6,200 kg/m 2 s. (author)

  6. MHD convective flow through porous medium in a horizontal channel with insulated and impermeable bottom wall in the presence of viscous dissipation and Joule heating

    Directory of Open Access Journals (Sweden)

    K.V.S. Raju

    2014-06-01

    Full Text Available This paper deals with a steady MHD forced convective flow of a viscous fluid of finite depth in a saturated porous medium over a fixed horizontal channel with thermally insulated and impermeable bottom wall in the presence of viscous dissipation and joule heating. The governing equations are solved in the closed form and the exact solutions are obtained for velocity and temperature distributions when the temperatures on the fixed bottom and on the free surface are prescribed. The expressions for flow rate, mean velocity, temperature, mean temperature, mean mixed temperature in the flow region and the Nusselt number on the free surface have been obtained. The cases of large and small values of porosity coefficients have been obtained as limiting cases. Further, the cases of small depth (shallow fluid and large depth (deep fluid are also discussed. The results are presented and discussed with the help of graphs.

  7. Defining the Post-Machined Sub-surface in Austenitic Stainless Steels

    Science.gov (United States)

    Srinivasan, N.; Sunil Kumar, B.; Kain, V.; Birbilis, N.; Joshi, S. S.; Sivaprasad, P. V.; Chai, G.; Durgaprasad, A.; Bhattacharya, S.; Samajdar, I.

    2018-06-01

    Austenitic stainless steels grades, with differences in chemistry, stacking fault energy, and thermal conductivity, were subjected to vertical milling. Anodic potentiodynamic polarization was able to differentiate (with machining speed/strain rate) between different post-machined sub-surfaces in SS 316L and Alloy A (a Cu containing austenitic stainless steel: Sanicroe 28™), but not in SS 304L. However, such differences (in the post-machined sub-surfaces) were revealed in surface roughness, sub-surface residual stresses and misorientations, and in the relative presence of sub-surface Cr2O3 films. It was shown, quantitatively, that higher machining speed reduced surface roughness and also reduced the effective depths of the affected sub-surface layers. A qualitative explanation on the sub-surface microstructural developments was provided based on the temperature-dependent thermal conductivity values. The results herein represent a mechanistic understanding to rationalize the corrosion performance of widely adopted engineering alloys.

  8. Defining the Post-Machined Sub-surface in Austenitic Stainless Steels

    Science.gov (United States)

    Srinivasan, N.; Sunil Kumar, B.; Kain, V.; Birbilis, N.; Joshi, S. S.; Sivaprasad, P. V.; Chai, G.; Durgaprasad, A.; Bhattacharya, S.; Samajdar, I.

    2018-04-01

    Austenitic stainless steels grades, with differences in chemistry, stacking fault energy, and thermal conductivity, were subjected to vertical milling. Anodic potentiodynamic polarization was able to differentiate (with machining speed/strain rate) between different post-machined sub-surfaces in SS 316L and Alloy A (a Cu containing austenitic stainless steel: Sanicroe 28™), but not in SS 304L. However, such differences (in the post-machined sub-surfaces) were revealed in surface roughness, sub-surface residual stresses and misorientations, and in the relative presence of sub-surface Cr2O3 films. It was shown, quantitatively, that higher machining speed reduced surface roughness and also reduced the effective depths of the affected sub-surface layers. A qualitative explanation on the sub-surface microstructural developments was provided based on the temperature-dependent thermal conductivity values. The results herein represent a mechanistic understanding to rationalize the corrosion performance of widely adopted engineering alloys.

  9. The Self-Potential Anomaly Produced by a Subsurface Flow at the Contact of Two Horizontal Layers and Its Quantitative Interpretation

    Directory of Open Access Journals (Sweden)

    Georgios Aim. Skianis

    2012-01-01

    Full Text Available In the present paper the problem of a polarized cylinder with a small cross-section, which is located at the contact of two horizontal layers with different resistivities, is studied. Such a polarization geometry simulates the self-potential (SP field produced by a horizontal flow at the contact between the two layers. First, the expression of the self potential at the space domain is derived, applying the image technique. Then, the expression for the Fourier transform of the SP anomaly is found and the behavior of the amplitude spectrum is studied. Based on this study, a direct interpretation method at the spatial frequency domain is proposed, in order to calculate the depth of the flow and the reflection coefficient of the stratified medium. Experimentation with a synthetic model shows that the method works well (small deviations between true and calculated values. When the SP curve contains noise, deviations between calculated and true depths are smaller than those between calculated and true reflection coefficients. The proposed method, which is also applied on SP data from a geothermal system (Mauri et al., 2010, may be useful in detecting underground water or heat flows.

  10. Horizontal Accelerator

    Data.gov (United States)

    Federal Laboratory Consortium — The Horizontal Accelerator (HA) Facility is a versatile research tool available for use on projects requiring simulation of the crash environment. The HA Facility is...

  11. A comparative pressure analysis of air flow between horizontal and V-Tail of UAV MALE of NACA0012H with speed variation

    OpenAIRE

    Riza Rahmat; Kurniawan Dicky; Wicaksono Arif Budi

    2018-01-01

    NACA0012H is an airfoil type that could be used for Unmanned Aerial Vehicle Medium Altitude Long Endurance. This experiment was used to analyze stress in the surface of Tail of UAV MALE that was caused by air flow. The experiment was conducted using Computational Fluid Dynamics Software. Two designs of tail, horizontal and V-tail, were considered to simulate pressure occurred on the surface of leading edge, chamber and trailing edge. The simulation was developed varying the speed of the UAV M...

  12. Using Differential Transform Method and Padé Approximant for Solving MHD Flow in a Laminar Liquid Film from a Horizontal Stretching Surface

    Directory of Open Access Journals (Sweden)

    Mohammad Mehdi Rashidi

    2010-01-01

    Full Text Available The purpose of this study is to approximate the stream function and temperature distribution of the MHD flow in a laminar liquid film from a horizontal stretching surface. In this paper DTM-Padé method was used which is a combination of differential transform method (DTM and Padé approximant. The DTM solutions are only valid for small values of independent variables. Comparison between the solutions obtained by the DTM and the DTM-Padé with numerical solution (fourth-order Runge–Kutta revealed that the DTM-Padé method is an excellent method for solving MHD boundary-layer equations.

  13. Profile of the horizontal wind variance near the ground in near neutral flow – K-theory and the transport of the turbulent kinetic energy

    Directory of Open Access Journals (Sweden)

    S. Yahaya

    2009-05-01

    Full Text Available This paper deals with the characteristics of the atmospheric turbulent flow in the vicinity of the ground, and particularly with the profile of the horizontal wind variance. The study is based on experimental measurements performed with fast cup anemometers located near the ground at 5 different levels (from 0.25 to 4 m and sampled at 1 Hz. The experiment was carried over two agricultural plots with various tillage treatments in a fallow semiarid area (Central Aragon, Spain. The results of this study reveal that near the ground surface and under moderate wind, the horizontal wind variance logarithmically increases with height, in direct relationship with the friction velocity and the roughness length scale. A theoretical development has allowed us to link this behaviour to the modeling of the turbulent kinetic energy (TKE transport through the eddy diffusivity. Thus, the study proposes a formulation of the similarity universal function of the horizontal wind variance. Besides, the formulation offers a new method for the determination of the friction velocity and the roughness length scale and can be used for the evaluation of the TKE transport rate.

  14. Attempts to isolate a horizontal high diameter (300 mm nominal diameter) pipeline with an ice plug at minimum water flow and without water flow

    International Nuclear Information System (INIS)

    Corbescu, B.; Gyongyosi, T.; Puiu, D.; Panaitescu, V. N.

    2016-01-01

    The ice plug isolation technique used for high diameter horizontal pipes is used for repair and maintenance activities on hydraulic installations that use liquid working agents. These techniques do not require shutting down the entire plant. The ice plug development inside the pipe requires using custom specialized equipment for each individual application. This paper briefly describes the experimental technological facilities used for conducting the experiments and highlights the important aspects in an experiment conducted on a horizontal NPS 12 testing section running demineralized water followed by the result analysis and conclusions. The paper is dedicated to specialists working in research and technological engineering. (authors)

  15. Non-invasive classification of gas–liquid two-phase horizontal flow regimes using an ultrasonic Doppler sensor and a neural network

    International Nuclear Information System (INIS)

    Abbagoni, Baba Musa; Yeung, Hoi

    2016-01-01

    The identification of flow pattern is a key issue in multiphase flow which is encountered in the petrochemical industry. It is difficult to identify the gas–liquid flow regimes objectively with the gas–liquid two-phase flow. This paper presents the feasibility of a clamp-on instrument for an objective flow regime classification of two-phase flow using an ultrasonic Doppler sensor and an artificial neural network, which records and processes the ultrasonic signals reflected from the two-phase flow. Experimental data is obtained on a horizontal test rig with a total pipe length of 21 m and 5.08 cm internal diameter carrying air-water two-phase flow under slug, elongated bubble, stratified-wavy and, stratified flow regimes. Multilayer perceptron neural networks (MLPNNs) are used to develop the classification model. The classifier requires features as an input which is representative of the signals. Ultrasound signal features are extracted by applying both power spectral density (PSD) and discrete wavelet transform (DWT) methods to the flow signals. A classification scheme of ‘1-of-C coding method for classification’ was adopted to classify features extracted into one of four flow regime categories. To improve the performance of the flow regime classifier network, a second level neural network was incorporated by using the output of a first level networks feature as an input feature. The addition of the two network models provided a combined neural network model which has achieved a higher accuracy than single neural network models. Classification accuracies are evaluated in the form of both the PSD and DWT features. The success rates of the two models are: (1) using PSD features, the classifier missed 3 datasets out of 24 test datasets of the classification and scored 87.5% accuracy; (2) with the DWT features, the network misclassified only one data point and it was able to classify the flow patterns up to 95.8% accuracy. This approach has demonstrated the

  16. Non-invasive classification of gas-liquid two-phase horizontal flow regimes using an ultrasonic Doppler sensor and a neural network

    Science.gov (United States)

    Musa Abbagoni, Baba; Yeung, Hoi

    2016-08-01

    The identification of flow pattern is a key issue in multiphase flow which is encountered in the petrochemical industry. It is difficult to identify the gas-liquid flow regimes objectively with the gas-liquid two-phase flow. This paper presents the feasibility of a clamp-on instrument for an objective flow regime classification of two-phase flow using an ultrasonic Doppler sensor and an artificial neural network, which records and processes the ultrasonic signals reflected from the two-phase flow. Experimental data is obtained on a horizontal test rig with a total pipe length of 21 m and 5.08 cm internal diameter carrying air-water two-phase flow under slug, elongated bubble, stratified-wavy and, stratified flow regimes. Multilayer perceptron neural networks (MLPNNs) are used to develop the classification model. The classifier requires features as an input which is representative of the signals. Ultrasound signal features are extracted by applying both power spectral density (PSD) and discrete wavelet transform (DWT) methods to the flow signals. A classification scheme of ‘1-of-C coding method for classification’ was adopted to classify features extracted into one of four flow regime categories. To improve the performance of the flow regime classifier network, a second level neural network was incorporated by using the output of a first level networks feature as an input feature. The addition of the two network models provided a combined neural network model which has achieved a higher accuracy than single neural network models. Classification accuracies are evaluated in the form of both the PSD and DWT features. The success rates of the two models are: (1) using PSD features, the classifier missed 3 datasets out of 24 test datasets of the classification and scored 87.5% accuracy; (2) with the DWT features, the network misclassified only one data point and it was able to classify the flow patterns up to 95.8% accuracy. This approach has demonstrated the

  17. Flow transport and mixing induced by horizontal jets impinging on a vertical wall of the multi-compartment PANDA facility

    International Nuclear Information System (INIS)

    Paladino, Domenico; Zboray, Robert; Andreani, Michele; Dreier, Joerg

    2010-01-01

    In the frame of the OECD/NEA SETH project an experimental campaign has been carried out in the PANDA facility to investigate gas transport and mixing induced by a plume or a jet in the large-scale multi-compartment PANDA facility. The paper summarizes the results of the horizontal jet test series consisting of eight tests. Horizontal jets impinging on a vertical wall of one of the cylindrical PANDA containment vessels have been generated by changing various parameters, such as: type of injected fluid (steam or a mixture of steam and helium), fluid injection velocity, elevation (with respect to the containment vessel) of the injection exit, initial fluid composition in the vessels, and location of the vent line. The initial jet Froude number has been varied between 17 and 36 and in one of the test condensation occurred. The paper shows the effect of these parameters variation on the test evolution with respect to jet impingement location in the vertical curved wall and variation of impingement location as a function of buoyancy variation. Fluid mixing and stratification, characteristics of gas transport between the compartment and the effect of condensation on the overall phenomena evolution are analyzed in the paper.

  18. Two-phase heat transfer and pressure drop of LNG during saturated flow boiling in a horizontal tube

    Science.gov (United States)

    Chen, Dongsheng; Shi, Yumei

    2013-12-01

    Two-phase heat transfer and pressure drop of LNG (liquefied natural gas) have been measured in a horizontal smooth tube with an inner diameter of 8 mm. The experiments were conducted at inlet pressures from 0.3 to 0.7 MPa with a heat flux of 8-36 kW m-2, and mass flux of 49.2-201.8 kg m-2 s-1. The effect of vapor quality, inlet pressure, heat flux and mass flux on the heat transfer characteristic are discussed. The comparisons of the experimental data with the predicted value by existing correlations are analyzed. Zou et al. (2010) correlation shows the best accuracy with 24.1% RMS deviation among them. Moreover four frictional pressure drop methods are also chosen to compare with the experimental database.

  19. Near-Horizontal, Two-Phase Flow Patterns of Nitrogen and Hydrogen at Low Mass Heat and Flux Supplement

    Science.gov (United States)

    VanDresar, Neil T.; Siegwarth, James D.

    2001-01-01

    This CD is a companion to NASA/TP-2001-210380. It contains digitized movies of particular flow patterns observed in experimental work. The movies have been provided in QuickTime format, encoded at 320w x 240h pixels, 15 fps, using the Sorenson Video Codec for compression.

  20. Partida de um reator anaeróbio horizontal para tratamento de efluentes do processamento dos frutos do cafeeiro Start-up of an anaerobic horizontal-flow reactor for treating wastewater from a coffee fruits processing

    Directory of Open Access Journals (Sweden)

    Alisson C. Borges

    2009-01-01

    Full Text Available O presente estudo teve o objetivo de avaliar a partida e a adaptação de um reator anaeróbio horizontal de leito fixo (RAHLF no tratamento de águas residuárias do processamento primário dos frutos do cafeeiro (ARC. O reator foi construído com tubos de PVC de 0,2 m de diâmetro e 3,2 m de comprimento. O sistema foi preenchido com cubos de espuma de poliuretano para imobilização de biomassa ativa. O reator apresentou volume total de 0,1 m³ e volume útil equivalente a 0,04 m³. Em média, houve remoção de 49% da matéria orgânica, com o reator trabalhando sob carga orgânica volumétrica média de 2,66 kg m-3 d-1, medida como DQO. A suplementação de alcalinidade, somada à inoculação prévia de biomassa, proporcionou partida estável do RAHLF, confirmada pelo consumo de ácidos voláteis e adaptação da microbiota ao resíduo. O sistema apresentou resistência às variações de vazão e de carga orgânica observadas, e os teores de fenol e potássio monitorados não causaram inibição da atividade biológica no RAHLF. O maior controle sobre as variações de carga é fator importante na continuidade dos estudos.This study aimed to evaluate the start-up and the adaptation of an anaerobic horizontal-flow immobilized biomass (HAIB reactor in order to treat wastewater from a primary processing of coffee fruits. The reactor was built with PVC tubes of 0.2 m in diameter and 3.2 m in length. The system was filled with cubes of polyurethane foam for immobilization of active biomass. The reactor presented a total capacity of 0.1 m³ and reaction volume equal to 0.04 m³. 49% of organic matter. Removal efficiency was observed, with medium organic volumetric loads equal to 2.66 kg m-3 d-1 (as chemical oxygen demand. The supplementary addition of alkalinity and the previous biomass inoculation provided a stable start-up of the reactor, as confirmed by the reduction of volatile acids and an adaptation of the present microbiology community

  1. Free convection boundary layer flow past a horizontal flat plate embedded in porous medium filled by nano-fluid containing gyro-tactic microorganisms

    Energy Technology Data Exchange (ETDEWEB)

    Aziz, A. [Department of Mechanical Engineering, School of Engineering and Applied Science, Gonzaga University, Spokane, WA 99258 (United States); Khan, W.A. [Department of Engineering Sciences, National University of Sciences and Technology, Karachi 75350 (Pakistan); Pop, I. [Department of Applied Mathematics, Babes-Bolyai University, Cluj-Napoca (Romania)

    2012-06-15

    The steady boundary layer free convection flow past a horizontal flat plate embedded in a porous medium filled by a water-based nano-fluid containing gyro-tactic microorganisms is investigated. The Oberbeck-Boussinesq approximation is assumed in the analysis. The effects of bio-convection parameters on the dimensionless velocity, temperature, nano-particle concentration and density of motile microorganisms as well as on the local Nusselt, Sherwood and motile microorganism numbers are investigated and presented graphically. In the absence of bio-convection, the results are compared with the existing data in the open literature and found to be in good agreement. The bio-convection parameters strongly influence the heat, mass, and motile microorganism transport rates. (authors)

  2. Influence of oil on flow condensation heat transfer of R410A inside 4.18 mm and 1.6 mm inner diameter horizontal smooth tubes

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Xiangchao; Ding, Guoliang; Hu, Haitao; Zhu, Yu.; Peng, Hao [Institute of Refrigeration and Cryogenics, Shanghai Jiaotong University, Shanghai 200240 (China); Gao, Yifeng [International Copper Association Shanghai Office, Shanghai 200020 (China); Deng, Bin [Institute of Heat Transfer Technology, Golden Dragon Precise Copper Tube Group Inc., Shanghai 200135 (China)

    2010-01-15

    The influence of oil on condensation heat transfer of R410A inside 4.18 mm and 1.6 mm inner diameter horizontal smooth tubes is investigated experimentally. The experimental condensing temperature is 40 C, and nominal oil concentration range is from 0% to 5%. The test results indicate that the presence of oil deteriorates the heat transfer, and the deterioration effect becomes obvious with the increase of oil concentration. At oil concentration of 5%, the heat transfer coefficient decreases by maximum 24.9% and 28.5% for 4.18 mm and 1.6 mm tubes, respectively. A new correlation for heat transfer coefficients of R410A-oil mixture flow condensation inside smooth tubes is proposed, which agrees with all the experimental data within a deviation of -30% {proportional_to} +20%. (author)

  3. Review and investigations of oscillatory flow behaviour of a horizontal ceiling opening for nuclear containment and fire safety analysis

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, P.K.; Singh, R.K.; Ghosh, A.K. [Bhabha Atomic Research Centre, Trombay, Mumbai (India). Reactor Safety Div.

    2011-05-15

    In the thermal hydraulics codes developed for fire safety analysis and for containment thermal hydraulic analysis, junctions in the multi-compartment geometries is often modeled as uni-directional junctions. However, ceiling junctions are known to depict unstable/oscillatory bi-directional flow behavior. Detailed investigations have been carried out to understand the unstable flow behaviour of a junction by analyzing an earlier reported experiment and its subsequent two dimensional numerical RANS based study of fire in an enclosure. The authors attempt more realistic and desired three dimensional and inherently transient large eddy simulations using a computer code Fire Dynamics Simulator (FDS). The paper presents the details of the analysis, the results obtained and further studies required to be conducted so that the findings can be applied to the fire/containment thermal hydraulics analysis codes successfully. (orig.)

  4. Nitrogen Removal in a Horizontal Subsurface Flow Constructed Wetland Estimated Using the First-Order Kinetic Model

    Directory of Open Access Journals (Sweden)

    Lijuan Cui

    2016-11-01

    Full Text Available We monitored the water quality and hydrological conditions of a horizontal subsurface constructed wetland (HSSF-CW in Beijing, China, for two years. We simulated the area-based constant and the temperature coefficient with the first-order kinetic model. We examined the relationships between the nitrogen (N removal rate, N load, seasonal variations in the N removal rate, and environmental factors—such as the area-based constant, temperature, and dissolved oxygen (DO. The effluent ammonia (NH4+-N and nitrate (NO3−-N concentrations were significantly lower than the influent concentrations (p < 0.01, n = 38. The NO3−-N load was significantly correlated with the removal rate (R2 = 0.96, p < 0.01, but the NH4+-N load was not correlated with the removal rate (R2 = 0.02, p > 0.01. The area-based constants of NO3−-N and NH4+-N at 20 °C were 27 ± 26 (mean ± SD and 14 ± 10 m∙year−1, respectively. The temperature coefficients for NO3−-N and NH4+-N were estimated at 1.004 and 0.960, respectively. The area-based constants for NO3−-N and NH4+-N were not correlated with temperature (p > 0.01. The NO3−-N area-based constant was correlated with the corresponding load (R2 = 0.96, p < 0.01. The NH4+-N area rate was correlated with DO (R2 = 0.69, p < 0.01, suggesting that the factors that influenced the N removal rate in this wetland met Liebig’s law of the minimum.

  5. Hydrogen production from a rectangular horizontal filter press Divergent Electrode-Flow-Through (DEFT™) alkaline electrolysis stack

    Science.gov (United States)

    Gillespie, M. I.; Kriek, R. J.

    2017-12-01

    A membraneless Divergent Electrode-Flow-Through (DEFT™) alkaline electrolyser, for unlocking profitable hydrogen production by combining a simplistic, inexpensive, modular and durable design, capable of overcoming existing technology current density thresholds, is ideal for decentralised renewable hydrogen production, with the only requirement of electrolytic flow to facilitate high purity product gas separation. Scale-up of the technology was performed, representing a deviation from the original tested stack design, incorporating elongated electrodes housed in a filter press assembly. The pilot plant operating parameters were limited to a low flow velocity range (0.03 m s-1 -0.04 m s-1) with an electrode gap of 2.5 mm. Performance of this pilot plant demonstrated repeatability to results previously obtained. Mesh electrodes with geometric area of 344.32 cm2 were used for plant performance testing. A NiO anode and Ni cathode combination developed optimal performance yielding 508 mA cm-2 at 2 VDC in contrast to a Ni anode and cathode combination providing 467 mA cm-2 at 2.26 VDC at 0.04 m s-1, 30% KOH and 80 °C. An IrO2/RuO2/TiO2 anode and Pt cathode combination underwent catalyst deactivation. Owing to the nature of the gas/liquid separation system, gas qualities were inadequate compared to results achieved previously. Future improvements will provide qualities similar to results achieved before.

  6. Laying-up of sterile instruments in the operating theatre: equal or superior protection by using a horizontal unidirectional air flow system.

    Science.gov (United States)

    Traversari, A A L; Goedhart, C A; Dusseldorp, E; Bode, A; Keuning, F; Pelk, M S J; Vos, M C

    2013-10-01

    A system for the preparation of sterilized instruments with unidirectional horizontal air flow (UDHF) has several advantages over a unidirectional down flow system (UDDF). The advantages are based on the installation of the system being more flexible and easier to use, no cooling of the air flow being necessary and less air being needed for circulation, resulting in reduced energy use. The objective of this study was to determine whether a system with UDHF performs equal or superior to a system with UDDF in terms of prevention of contamination of the air (the presence of particles and micro-organisms) during the laying-up process. The degree of protection (DP) offered by two UDHF system variants and two UDDF system variants was determined for several static set-ups and a dynamic simulation of the process. In addition to determining the level of protection for several categories of particle size, colony-forming units (CFU) were also measured during process simulations. When maximum protection (no particles present) is considered, the UDHF systems performed significantly better than the UDDF systems for particles ≥2.5μm. When particles were present, there was no significant difference between systems for particles ≥0.3 and ≥0.5μm. However, the performance of the UDHF system was superior to that of the UDDF system (DP) for particles ≥1.0μm representing the bacteria-carrying particles. During the process measurements, no CFU were found with the UDDF system in 64% of the measurements, compared with 90% for the UDHF system (P = 0.012). The UDHF system offers equal or superior protection to the UDDF system against contamination of the clean area within which the laying up takes place. Despite our finding that the differences did not always reach statistical significance (due to low background concentrations), there is a clear trend, from the small-sized particles (≥1.0μm) up to the largest sizes considered, including bacteria-carrying particles, that

  7. Heat transfer and flow pattern during two-phase flow boiling of R-134a in horizontal smooth and microfin tubes

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Minghuei; Lin, Tsunkuo; Tseng, Chyuanchyi [National Sun Yat Sen Univ., Taiwan (China). Dept. of Mechanical Engineering

    2002-09-01

    Flow pattern and heat transfer during evaporation in a 10.7 mm diameter smooth tube and a micro-fin tube are presented. The tubes were tested in the ranges of mass flux between 163 and 408 kg m{sup -2}s{sup -1} and heat flux between 2200 and 56 000 W m{sup -2}. The evaporation temperature was 6{sup o}C. Flow maps for both the tubes are plotted in the coordinates of mass flux and vapor quality. The relations of flow pattern and local heat transfer coefficient are discussed. The heat transfer coefficients for intermittent and annular flows in both the smooth tube and the micro-fin tube are shown to agree well with Gungor and Winterton's correlation with modified constants. (author)

  8. Experimental study on heat transfer enhancement of laminar ferrofluid flow in horizontal tube partially filled porous media under fixed parallel magnet bars

    Energy Technology Data Exchange (ETDEWEB)

    Sheikhnejad, Yahya; Hosseini, Reza, E-mail: hoseinir@aut.ac.ir; Saffar Avval, Majid

    2017-02-15

    In this study, steady state laminar ferroconvection through circular horizontal tube partially filled with porous media under constant heat flux is experimentally investigated. Transverse magnetic fields were applied on ferrofluid flow by two fixed parallel magnet bar positioned on a certain distance from beginning of the test section. The results show promising notable enhancement in heat transfer as a consequence of partially filled porous media and magnetic field, up to 2.2 and 1.4 fold enhancement were observed in heat transfer coefficient respectively. It was found that presence of both porous media and magnetic field simultaneously can highly improve heat transfer up to 2.4 fold. Porous media of course plays a major role in this configuration. Virtually, application of Magnetic field and porous media also insert higher pressure loss along the pipe which again porous media contribution is higher that magnetic field. - Highlights: • Porous media can improve the coefficient of heat transfer up to 2.2 fold. • Both porous media and Nano particles have undesired pressure drop effect. • Application of both porous media and magnetic field in ferrofluid flow will result in significant enhancement in heat transfer up to 2.4 fold. • Magnet bar effect is mainly restricted to approximately one fourth of the test section. • Diluted Ferrofluids 2%, results in over 1.4 fold enhancement in heat transfer coefficient.

  9. Comparison of simple, small, full-scale sewage treatment systems in Brazil: UASB-maturation ponds-coarse filter; UASB-horizontal subsurface-flow wetland; vertical-flow wetland (first stage of French system).

    Science.gov (United States)

    von Sperling, M

    2015-01-01

    This paper presents a comparison between three simple sewage treatment lines involving natural processes: (a) upflow anaerobic sludge blanket (UASB) reactor-three maturation ponds in series-coarse rock filter; (b) UASB reactor-horizontal subsurface-flow constructed wetland; and (c) vertical-flow constructed wetlands treating raw sewage (first stage of the French system). The evaluation was based on several years of practical experience with three small full-scale plants receiving the same influent wastewater (population equivalents of 220, 60 and 100 inhabitants) in the city of Belo Horizonte, Brazil. The comparison included interpretation of concentrations and removal efficiencies based on monitoring data (organic matter, solids, nitrogen, phosphorus, coliforms and helminth eggs), together with an evaluation of practical aspects, such as land and volume requirements, sludge production and handling, plant management, clogging and others. Based on an integrated evaluation of all aspects involved, it is worth emphasizing that each system has its own specificities, and no generalization can be made on the best option. The overall conclusion is that the three lines are suitable for sewage treatment in small communities in warm-climate regions.

  10. Nitrogen removal and its relationship with the nitrogen-cycle genes and microorganisms in the horizontal subsurface flow constructed wetlands with different design parameters.

    Science.gov (United States)

    Chen, Jun; Ying, Guang-Guo; Liu, You-Sheng; Wei, Xiao-Dong; Liu, Shuang-Shuang; He, Liang-Ying; Yang, Yong-Qiang; Chen, Fan-Rong

    2017-07-03

    This study aims to investigate nitrogen removal and its relationship with the nitrogen-cycle genes and microorganisms in the horizontal subsurface flow constructed wetlands (CWs) with different design parameters. Twelve mesocosm-scale CWs with four substrates and three hydraulic loading rates were set up in the outdoor. The result showed the CWs with zeolite as substrate and HLR of 20 cm/d were selected as the best choice for the TN and NH 3 -N removal. It was found that the single-stage mesocosm-scale CWs were incapable to achieve high removals of TN and NH 3 -N due to inefficient nitrification process in the systems. This was demonstrated by the lower abundance of the nitrification genes (AOA and AOB) than the denitrification genes (nirK and nirS), and the less diverse nitrification microorganisms than the denitrification microorganisms in the CWs. The results also show that microorganism community structure including nitrogen-cycle microorganisms in the constructed wetland systems was affected by the design parameters especially the substrate type. These findings show that nitrification is a limiting factor for the nitrogen removal by CWs.

  11. The Effect of Deflector Angle in Savonius Water Turbine with Horizontal Axis on the Power Output of Water Flow in Pipe

    Science.gov (United States)

    Prasetyo, Ari; Kristiawan, Budi; Danardono, Dominicus; Hadi, Syamsul

    2018-03-01

    Savonius turbine is one type of turbines with simple design and low manufacture. However, this turbine has a relatively low efficiency. This condition can be solved by installing fluid deflectors in the system’s circuit. The deflector is used to direct the focus of the water flow, thus increasing the torque working moment. In this study, a single stage horizontal axis Savonius water turbine was installed on a 3 inch diameter pipeline. This experiment aims to obtain optimal deflector angle design on each water discharge level. The deflector performance is analyzed through power output, TSR, and power coefficient generated by the turbine. The deflector angles tested are without deflector, 20°, 30°, 40°, and 50° with a deflector ratio of 50%. The experimental results at 10.67x10-3m3/s discharge show that turbine equipped with 30° deflector has the most optimal performance of 18.04 Watt power output, TSR of 1.12 and power coefficient 0.127. While with the same discharge, turbine without deflector produces only 9.77 Watt power output, TSR of 0.93, and power coefficient of 0.09. Thus, it can be concluded that the deflector increases power output equal to 85%.

  12. 47nm alumina–water nanofluid flow within boundary layer formed on upper horizontal surface of paraboloid of revolution in the presence of quartic autocatalysis chemical reaction

    Directory of Open Access Journals (Sweden)

    Isaac Lare Animasaun

    2016-09-01

    Full Text Available In this article, a modified version of buoyancy-induced model is considered to investigate the flow of 47nm alumina–water nanofluid along an upper surface of horizontal paraboloid of revolution in the presence of nonlinear thermal radiation, Lorentz force and quartic autocatalysis kind of homogeneous heterogeneous chemical reaction. The case of unequal diffusion coefficients of reactant A (bulk fluid and B (high concentration of catalyst at the surface in the presence of bioconvection is considered. Governing equation suitable to unravel the thermophoresis which takes place within the boundary layer is presented. Since chemical reactant B is of higher concentration at the surface more than the concept described as cubic autocatalytic, the suitable schemes are herein described as isothermal quartic autocatalytic reaction and first order reaction. The viscosity and thermal conductivity are assumed to vary with volume fraction (ϕ and suitable models for the case 0%⩽ϕ⩽0.8% are adopted. The transformed governing equations are solved numerically using Runge–Kutta fourth order along with shooting technique (RK4SM. Good agreement is obtained between the solutions of RK4SM and MATLAB bvp5c for a limiting case. The influence of some pertinent parameters on velocity, temperature, diffusion of motile microorganism, concentration of bulk fluid and catalyst is illustrated graphically and discussed.

  13. Liquid film characterization in horizontal, annular, two-phase, gas-liquid flow using time-resolved laser-induced fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Farias, P.S.C.; Martins, F.J.W.A.; Azevedo, L.F.A. [PUC-Rio, Department of Mechanical Engineering, Rio de Janeiro (Brazil); Sampaio, L.E.B. [LMTA/PGMEC, UFF, Department of Mechanical Engineering, Laboratory of Theoretical and Applied Mechanics, Rio de Janeiro (Brazil); Serfaty, R. [Petrobras R and D Center, Rio de Janeiro (Brazil)

    2012-03-15

    A non-intrusive optical technique was developed to provide time-resolved longitudinal and cross-sectional images of the liquid film in horizontal annular pipe flow of air and water, revealing the interfacial wave behavior. Quantitative information on the liquid film dynamics was extracted from the time-resolved images. The planar laser-induced fluorescence technique was utilized to allow for optical separation of the light emitted by the film from that scattered by the air-water interface. The visualization test section was fabricated from a tube presenting nearly the same refractive index as water, which allowed the visualization of the liquid film at regions very close to the pipe wall. Longitudinal images of the liquid film were captured using a high-frame-rate digital video camera synchronized with a high-repetition-rate laser. An image processing algorithm was developed to automatically detect the position of the air-water interface in each image frame. The thickness of the liquid film was measured at two axial stations in each processed image frame, providing time history records of the film thickness at two different positions. Wave frequency information was obtained by analyzing the time-dependent signals of film thickness for each of the two axial positions recorded. Wave velocities were measured by cross-correlating the amplitude signals from the two axial positions. For the film cross-section observations, two high-speed digital video cameras were used in a stereoscopic arrangement. Comparisons with results from different techniques available in literature indicate that the technique developed presents equivalent accuracy in measuring the liquid film properties. Time-resolved images of longitudinal and cross-section views of the film were recorded, which constitute valuable information provided by the technique implemented. (orig.)

  14. Thermal healing of the sub-surface damage layer in sapphire

    International Nuclear Information System (INIS)

    Pinkas, Malki; Lotem, Haim; Golan, Yuval; Einav, Yeheskel; Golan, Roxana; Chakotay, Elad; Haim, Avivit; Sinai, Ela; Vaknin, Moshe; Hershkovitz, Yasmin; Horowitz, Atara

    2010-01-01

    The sub-surface damage layer formed by mechanical polishing of sapphire is known to reduce the mechanical strength of the processed sapphire and to degrade the performance of sapphire based components. Thermal annealing is one of the methods to eliminate the sub-surface damage layer. This study focuses on the mechanism of thermal healing by studying its effect on surface topography of a- and c-plane surfaces, on the residual stresses in surface layers and on the thickness of the sub-surface damage layer. An atomically flat surface was developed on thermally annealed c-plane surfaces while a faceted roof-top topography was formed on a-plane surfaces. The annealing resulted in an improved crystallographic perfection close to the sample surface as was indicated by a noticeable decrease in X-ray rocking curve peak width. Etching experiments and surface roughness measurements using white light interferometry with sub-nanometer resolution on specimens annealed to different extents indicate that the sub-surface damage layer of the optically polished sapphire is less than 3 μm thick and it is totally healed after thermal treatment at 1450 deg. C for 72 h.

  15. Condensation of refrigerants in horizontal microfin tubes. Numerical analysis of heat transfer for annular flow regime; Reibai no microfin tsuki suihei kannai gyoshuku. Kanjoryu ryoiki ni okeru netsudentatsu no suchi kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Nozu, S [Okayama Prefectural University, Okayama (Japan); Honda, H [Kyushu University, Fukuoka (Japan). Institute of Advanced Material Study

    1998-07-25

    A method for predicting the local heat transfer coefficient is presented for film condensation of vapor in a spirally grooved horizontal microfin-tube. Based on the flow observation study performed by the present authors, film flow model between fins in the annular flow regime is proposed. For the fin surface, laminar condensate film controlled by the combined effects of vapor shear and surface tension forces is analyzed. While, in the groove, thick condensate film driven by the vapor shear force is taken into consideration. A parameter which accounts for the transition from annular- to stratified flow regimes is also derived. The present and previous local heat transfer data for fluorocarbon refrigerants in the annular flow regime are found by the present numerical analysis to have a mean absolute deviation of 15.1 percent. 12 refs., 10 figs., 2 tabs.

  16. Understanding wetland sub-surface hydrology using geologic and isotopic signatures

    Directory of Open Access Journals (Sweden)

    P. Sahu

    2009-07-01

    Full Text Available This paper attempts to utilize hydrogeology and isotope composition of groundwater to understand the present hydrological processes prevalent in a freshwater wetland, source of wetland groundwater, surface water/groundwater interaction and mixing of groundwater of various depth zones in the aquifer. This study considers East Calcutta Wetlands (ECW – a freshwater peri-urban inland wetland ecosystem located at the lower part of the deltaic alluvial plain of South Bengal Basin and east of Kolkata city. This wetland is well known over the world for its resource recovery systems, developed by local people through ages, using wastewater of the city. Geological investigations reveal that the sub-surface geology is completely blanketed by the Quaternary sediments comprising a succession of silty clay, sand of various grades and sand mixed with occasional gravels and thin intercalations of silty clay. At few places the top silty clay layer is absent due to scouring action of past channels. In these areas sand is present throughout the geological column and the areas are vulnerable to groundwater pollution. Groundwater mainly flows from east to west and is being over-extracted to the tune of 65×103 m3/day. δ18O and δD values of shallow and deep groundwater are similar indicating resemblance in hydrostratigraphy and climate of the recharge areas. Groundwater originates mainly from monsoonal rain with some evaporation prior to or during infiltration and partly from bottom of ponds, canals and infiltration of groundwater withdrawn for irrigation. Relatively high tritium content of the shallow groundwater indicates local recharge, while the deep groundwater with very low tritium is recharged mainly from distant areas. At places the deep aquifer has relatively high tritium, indicating mixing of groundwater of shallow and deep aquifers. Metals such as copper, lead, arsenic, cadmium, aluminium, nickel and chromium are also

  17. Understanding wetland sub-surface hydrology using geologic and isotopic signatures

    Science.gov (United States)

    Sikdar, P. K.; Sahu, P.

    2009-07-01

    This paper attempts to utilize hydrogeology and isotope composition of groundwater to understand the present hydrological processes prevalent in a freshwater wetland, source of wetland groundwater, surface water/groundwater interaction and mixing of groundwater of various depth zones in the aquifer. This study considers East Calcutta Wetlands (ECW) - a freshwater peri-urban inland wetland ecosystem located at the lower part of the deltaic alluvial plain of South Bengal Basin and east of Kolkata city. This wetland is well known over the world for its resource recovery systems, developed by local people through ages, using wastewater of the city. Geological investigations reveal that the sub-surface geology is completely blanketed by the Quaternary sediments comprising a succession of silty clay, sand of various grades and sand mixed with occasional gravels and thin intercalations of silty clay. At few places the top silty clay layer is absent due to scouring action of past channels. In these areas sand is present throughout the geological column and the areas are vulnerable to groundwater pollution. Groundwater mainly flows from east to west and is being over-extracted to the tune of 65×103 m3/day. δ18O and δD values of shallow and deep groundwater are similar indicating resemblance in hydrostratigraphy and climate of the recharge areas. Groundwater originates mainly from monsoonal rain with some evaporation prior to or during infiltration and partly from bottom of ponds, canals and infiltration of groundwater withdrawn for irrigation. Relatively high tritium content of the shallow groundwater indicates local recharge, while the deep groundwater with very low tritium is recharged mainly from distant areas. At places the deep aquifer has relatively high tritium, indicating mixing of groundwater of shallow and deep aquifers. Metals such as copper, lead, arsenic, cadmium, aluminium, nickel and chromium are also present in groundwater of various depths. Therefore

  18. Quantitative sub-surface and non-contact imaging using scanning microwave microscopy

    International Nuclear Information System (INIS)

    Gramse, Georg; Kasper, Manuel; Hinterdorfer, Peter; Brinciotti, Enrico; Rankl, Christian; Kienberger, Ferry; Lucibello, Andrea; Marcelli, Romolo; Patil, Samadhan B.; Giridharagopal, Rajiv

    2015-01-01

    The capability of scanning microwave microscopy for calibrated sub-surface and non-contact capacitance imaging of silicon (Si) samples is quantitatively studied at broadband frequencies ranging from 1 to 20 GHz. Calibrated capacitance images of flat Si test samples with varying dopant density (10 15 –10 19 atoms cm −3 ) and covered with dielectric thin films of SiO 2 (100–400 nm thickness) are measured to demonstrate the sensitivity of scanning microwave microscopy (SMM) for sub-surface imaging. Using standard SMM imaging conditions the dopant areas could still be sensed under a 400 nm thick oxide layer. Non-contact SMM imaging in lift-mode and constant height mode is quantitatively demonstrated on a 50 nm thick SiO 2 test pad. The differences between non-contact and contact mode capacitances are studied with respect to the main parameters influencing the imaging contrast, namely the probe tip diameter and the tip–sample distance. Finite element modelling was used to further analyse the influence of the tip radius and the tip–sample distance on the SMM sensitivity. The understanding of how the two key parameters determine the SMM sensitivity and quantitative capacitances represents an important step towards its routine application for non-contact and sub-surface imaging. (paper)

  19. Non-invasive classification of gas–liquid two-phase horizontal flow regimes using an ultrasonic Doppler sensor and a neural network

    OpenAIRE

    Abbagoni, Baba Musa; Yeung, Hoi

    2016-01-01

    The identification of flow pattern is a key issue in multiphase flow which is encountered in the petrochemical industry. It is difficult to identify the gas–liquid flow regimes objectively with the gas–liquid two-phase flow. This paper presents the feasibility of a clamp-on instrument for an objective flow regime classification of two-phase flow using an ultrasonic Doppler sensor and an artificial neural network, which records and processes the ultrasonic signals reflected from the two-phase ...

  20. Numerical exploration of a non-Newtonian Carreau fluid flow driven by catalytic surface reactions on an upper horizontal surface of a paraboloid of revolution, buoyancy and stretching at the free stream

    Directory of Open Access Journals (Sweden)

    I.L. Animasaun

    2017-12-01

    Full Text Available Geometrically, the upper pointed surface of an aircraft and bonnet of a car are examples of upper horizontal surfaces of a paraboloid of revolution (uhspr. The motion of these objects strongly depends on the boundary layer that is formed within the immediate space on it. However, each of these surfaces is neither a horizontal/vertical nor cone/wedge and neither a cone nor a wedge. This article presents the motion of 2-dimensional Blasius flow of Carreau fluid on the surface of such object. The case in which the reaction between the Carreau fluid and catalyst at the surface produces significant temperature differences which consequently set up buoyancy-driven flows within the boundary layer is investigated. Single first-order Arrhenius kinetics is adopted to model the reaction on the surface of the catalyst situated on uhspr which initiates the free convection. Suitable similarity variables are applied to non-dimensionalized, parameterized and reduce the governing partial differential equations to a coupled ordinary differential equations (BVP. The BVP is solved numerically using the shooting technique. Temperature distribution in the flow of viscoelastic Carreau fluid is greater than that of a Newtonian fluid. Local heat transfer rate decreases faster when the Carreau fluid is characterized as shear-thinning. Maximum concentration is guaranteed at a small value of power-law index n and large value of thickness parameter. Keywords: Viscoelastic-Carreau fluid, Catalitic surface, Paraboloid of revolution, Numerical method, Uhspr, Boundary layer analysis

  1. Reconstruction of sub-surface archaeological remains from magnetic data using neural computing.

    Science.gov (United States)

    Bescoby, D. J.; Cawley, G. C.; Chroston, P. N.

    2003-04-01

    The remains of a former Roman colonial settlement, once part of the classical city of Butrint in southern Albania have been the subject of a high resolution magnetic survey using a caesium-vapour magnetometer. The survey revealed the surviving remains of an extensive planned settlement and a number of outlying buildings, today buried beneath over 0.5 m of alluvial deposits. The aim of the current research is to derive a sub-surface model from the magnetic survey measurements, allowing an enhanced archaeological interpretation of the data. Neural computing techniques are used to perform the non-linear mapping between magnetic data and corresponding sub-surface model parameters. The adoption of neural computing paradigms potentially holds several advantages over other modelling techniques, allowing fast solutions for complex data, while having a high tolerance to noise. A multi-layer perceptron network with a feed-forward architecture is trained to estimate the shape and burial depth of wall foundations using a series of representative models as training data. Parameters used to forward model the training data sets are derived from a number of trial trench excavations targeted over features identified by the magnetic survey. The training of the network was optimized by first applying it to synthetic test data of known source parameters. Pre-processing of the network input data, including the use of a rotationally invariant transform, enhanced network performance and the efficiency of the training data. The approach provides good results when applied to real magnetic data, accurately predicting the depths and layout of wall foundations within the former settlement, verified by subsequent excavation. The resulting sub-surface model is derived from the averaged outputs of a ‘committee’ of five networks, trained with individualized training sets. Fuzzy logic inference has also been used to combine individual network outputs through correlation with data from a second

  2. On the development of a new methodology in sub-surface parameterisation on the calibration of groundwater models

    Science.gov (United States)

    Klaas, D. K. S. Y.; Imteaz, M. A.; Sudiayem, I.; Klaas, E. M. E.; Klaas, E. C. M.

    2017-10-01

    In groundwater modelling, robust parameterisation of sub-surface parameters is crucial towards obtaining an agreeable model performance. Pilot point is an alternative in parameterisation step to correctly configure the distribution of parameters into a model. However, the methodology given by the current studies are considered less practical to be applied on real catchment conditions. In this study, a practical approach of using geometric features of pilot point and distribution of hydraulic gradient over the catchment area is proposed to efficiently configure pilot point distribution in the calibration step of a groundwater model. A development of new pilot point distribution, Head Zonation-based (HZB) technique, which is based on the hydraulic gradient distribution of groundwater flow, is presented. Seven models of seven zone ratios (1, 5, 10, 15, 20, 25 and 30) using HZB technique were constructed on an eogenetic karst catchment in Rote Island, Indonesia and their performances were assessed. This study also concludes some insights into the trade-off between restricting and maximising the number of pilot points and offers a new methodology for selecting pilot point properties and distribution method in the development of a physically-based groundwater model.

  3. Productivity and injectivity of horizontal wells

    Energy Technology Data Exchange (ETDEWEB)

    Aziz, Khalid

    2000-03-06

    One of the key issues addressed was pressure drop in long horizontal wells and its influence on well performance. Very little information is available in the literature on flow in pipes with influx through pipe walls. Virtually all of this work has been in small diameter pipes and with single-phase flow. In order to address this problem new experimental data on flow in horizontal and near horizontal wells have been obtained. Experiments were conducted at an industrial facility on typical 6 1/8 ID, 100 feet long horizontal well model. The new data along with available information in the literature have been used to develop new correlations and mechanistic models. Thus it is now possible to predict, within reasonable accuracy, the effect of influx through the well on pressure drop in the well.

  4. Atmospheric horizontal divergence and diffusion

    International Nuclear Information System (INIS)

    Castans, M.

    1981-01-01

    The action of horizontal divergence on diffusion near the ground is established through.a very simple flow model. The shape of the well-known Pasquill-Gifford-Turner curves, that apparently take account in some way of divergence, is justified. The possibility of explaining the discre--pancies between the conventional straight line model and experimental results, mainly under low-wind-speed satable conditions, is considered. Some hints for further research are made. (auth.)

  5. Influence of Si wafer thinning processes on (sub)surface defects

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Fumihiro, E-mail: fumihiro.inoue@imec.be [Imec, Kapeldreef 75, 3001 Leuven (Belgium); Jourdain, Anne; Peng, Lan; Phommahaxay, Alain; De Vos, Joeri; Rebibis, Kenneth June; Miller, Andy; Sleeckx, Erik; Beyne, Eric [Imec, Kapeldreef 75, 3001 Leuven (Belgium); Uedono, Akira [Division of Applied Physics, Faculty of Pure and Applied Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan)

    2017-05-15

    Highlights: • Mono-vacancy free Si-thinning can be accomplished by combining several thinning techniques. • The grinding damage needs to be removed prior to dry etching, otherwise vacancies remain in the Si at a depth around 0.5 to 2 μm after Si wafer thickness below 5 μm. • The surface of grinding + CMP + dry etching is equivalent mono vacancy level as that of grinding + CMP. - Abstract: Wafer-to-wafer three-dimensional (3D) integration with minimal Si thickness can produce interacting multiple devices with significantly scaled vertical interconnections. Realizing such a thin 3D structure, however, depends critically on the surface and subsurface of the remaining backside Si after the thinning processes. The Si (sub)surface after mechanical grinding has already been characterized fruitfully for a range of few dozen of μm. Here, we expand the characterization of Si (sub)surface to 5 μm thickness after thinning process on dielectric bonded wafers. The subsurface defects and damage layer were investigated after grinding, chemical mechanical polishing (CMP), wet etching and plasma dry etching. The (sub)surface defects were characterized using transmission microscopy, atomic force microscopy, and positron annihilation spectroscopy. Although grinding provides the fastest removal rate of Si, the surface roughness was not compatible with subsequent processing. Furthermore, mechanical damage such as dislocations and amorphous Si cannot be reduced regardless of Si thickness and thin wafer handling systems. The CMP after grinding showed excellent performance to remove this grinding damage, even though the removal amount is 1 μm. For the case of Si thinning towards 5 μm using grinding and CMP, the (sub)surface is atomic scale of roughness without vacancy. For the case of grinding + dry etch, vacancy defects were detected in subsurface around 0.5–2 μm. The finished surface after wet etch remains in the nm scale in the strain region. By inserting a CMP step in

  6. Surface and sub-surface thermal oxidation of thin ruthenium films

    Energy Technology Data Exchange (ETDEWEB)

    Coloma Ribera, R.; Kruijs, R. W. E. van de; Yakshin, A. E.; Bijkerk, F. [MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands); Kokke, S.; Zoethout, E. [FOM Dutch Institute for Fundamental Energy Research (DIFFER), P.O. Box 1207, 3430 BE Nieuwegein (Netherlands)

    2014-09-29

    A mixed 2D (film) and 3D (nano-column) growth of ruthenium oxide has been experimentally observed for thermally oxidized polycrystalline ruthenium thin films. Furthermore, in situ x-ray reflectivity upon annealing allowed the detection of 2D film growth as two separate layers consisting of low density and high density oxides. Nano-columns grow at the surface of the low density oxide layer, with the growth rate being limited by diffusion of ruthenium through the formed oxide film. Simultaneously, with the growth of the columns, sub-surface high density oxide continues to grow limited by diffusion of oxygen or ruthenium through the oxide film.

  7. Sub-surface Fatigue Crack Growth at Alumina Inclusions in AISI 52100 Roller Bearings

    DEFF Research Database (Denmark)

    Cerullo, Michele

    2014-01-01

    Sub-surface fatigue crack growth at non metallic inclusions is studied in AISI 52100 bearing steel under typical rolling contact loads. A first 2D plane strain finite element analysis is carried out to compute the stress history in the innner race at a characteristic depth, where the Dang Van...... damage factor is highest. Subsequently the stress history is imposed as boundary conditions in a periodic unit cell model, where an alumina inclusion is embedded in a AISI 52100 matrix. Cracks are assumed to grow radially from the inclusion under cyclic loading. The growth is predicted by means...

  8. Near-Horizontal, Two-Phase Flow Patterns of Nitrogen and Hydrogen at Low Mass Heat and Flux (on CD-ROM)

    Science.gov (United States)

    VanDresar, N. T.; Siegwarth, J. D.

    2001-01-01

    One reason for NASA's interest in cryogenic two-phase flow with low mass and heat flux is the need to design spacecraft heat exchangers used for vaporizing cryogenic propellants. The CD-ROM provides digitized movies of particular flow patterns observed in experimental work. The movies have been provided in (QuickTime9Trademark) format, encoded at 320w x 240h pixels, 15 fps, using the Sorenson(Trademark) Video Codec for compression. Experiments were conducted to obtain data on the two-phase (liquid and vapor) flow behavior of cryogenic nitrogen and hydrogen under low mass and heat flux conditions. Tests were performed in normal gravity with a 1.5 degree up flow configuration. View ports in the apparatus permitted visual observation of the two-phase flow patterns. Computer codes to predict flow patterns were developed from theoretical/empirical models reported in the literature. Predictions from the computer codes were compared with experimental flow pattern observations. Results are presented employing the traditional two-dimensional flow pattern map format using the liquid and gas superficial velocities as coordinates. In general, the agreement between the experimental results and the analytical predictive methods is reasonably good. Small regions of the flow pattern maps are identified where the models are deficient as a result of neglecting phase change phenomena. Certain regions of the maps were beyond the range of the experiments and could not be completely validated. Areas that could benefit from further work include modeling of the transition from separated flow, collection of additional data in the bubble and annular flow regimes, and collection of experimental data at other inclination angles, tube diameters and high heat flux.

  9. Leaching of 14-Carbofuran into sub-surface water in vegetable agroecosystem

    International Nuclear Information System (INIS)

    Nashriyah Mat; Misman Sumin; Maizatul Akmam Mohd Nasir; Kubiak, R.

    2000-01-01

    An experimental setup was constructed to investigate leaching of 14C C arbofuran into sub-surface water through Bungor series sandy loam soil. The indoor lysimeter was constructed using homogenous and packed disturbed soil column. The outdoor lysimeter was constructed using undisturbed soil column. In the field, leachate production was influenced by rainfall intensity but tracer transport was independent of water transport to a certain degree. A high rainfall intensity at 39 DAA has not enhanced tracer leaching into sub-surface water in vegetable agroecosystem whereas a lower rainfall intensity at 21 DAA has enhanced its leaching. Indoor lysimeter behaved incoherently and showed non-parallel relationship between applied water and also volume of leachate produced with tracer transport. In both types of lysimeter, tracer transport and carbofuran transport generally correlated. Carbofuran and tracer were leached at a lower magnitude in outdoor lysimeter compared to the indoor lysimeter. The maximum total radioactivities leached were 1.1% and 0.4% of applied radio activities from indoor lysimeter and outdoor lysimeter at 35 and 21 DAA respectively. The maximum total carbofuran equivalent leached were 193.9 μg/L and 39.3 μg/L at 35 DAA and 21 DAA from indoor lysimeter and outdoor lysimeter respectively. (author)

  10. Process induced sub-surface damage in mechanically ground silicon wafers

    International Nuclear Information System (INIS)

    Yang Yu; De Munck, Koen; Teixeira, Ricardo Cotrin; Swinnen, Bart; De Wolf, Ingrid; Verlinden, Bert

    2008-01-01

    Micro-Raman spectroscopy, scanning electron microcopy, atomic force microscopy and preferential etching were used to characterize the sub-surface damage induced by the rough and fine grinding steps used to make ultra-thin silicon wafers. The roughly and ultra-finely ground silicon wafers were examined on both the machined (1 0 0) planes and the cross-sectional (1 1 0) planes. They reveal similar multi-layer damage structures, consisting of amorphous, plastically deformed and elastically stressed layers. However, the thickness of each layer in the roughly ground sample is much higher than its counterpart layers in the ultra-finely ground sample. The residual stress after rough and ultra-fine grinding is in the range of several hundreds MPa and 30 MPa, respectively. In each case, the top amorphous layer is believed to be the result of sequential phase transformations (Si-I to Si-II to amorphous Si). These phase transformations correspond to a ductile grinding mechanism, which is dominating in ultra-fine grinding. On the other hand, in rough grinding, a mixed mechanism of ductile and brittle grinding causes multi-layer damage and sub-surface cracks

  11. Effective Detection of Sub-Surface Archeological Features from Laser Scanning Point Clouds and Imagery Data

    Science.gov (United States)

    Fryskowska, A.; Kedzierski, M.; Walczykowski, P.; Wierzbicki, D.; Delis, P.; Lada, A.

    2017-08-01

    The archaeological heritage is non-renewable, and any invasive research or other actions leading to the intervention of mechanical or chemical into the ground lead to the destruction of the archaeological site in whole or in part. For this reason, modern archeology is looking for alternative methods of non-destructive and non-invasive methods of new objects identification. The concept of aerial archeology is relation between the presence of the archaeological site in the particular localization, and the phenomena that in the same place can be observed on the terrain surface form airborne platform. One of the most appreciated, moreover, extremely precise, methods of such measurements is airborne laser scanning. In research airborne laser scanning point cloud with a density of 5 points/sq. m was used. Additionally unmanned aerial vehicle imagery data was acquired. Test area is located in central Europe. The preliminary verification of potentially microstructures localization was the creation of digital terrain and surface models. These models gave an information about the differences in elevation, as well as regular shapes and sizes that can be related to the former settlement/sub-surface feature. The paper presents the results of the detection of potentially sub-surface microstructure fields in the forestry area.

  12. EFFECTIVE DETECTION OF SUB-SURFACE ARCHEOLOGICAL FEATURES FROM LASER SCANNING POINT CLOUDS AND IMAGERY DATA

    Directory of Open Access Journals (Sweden)

    A. Fryskowska

    2017-08-01

    Full Text Available The archaeological heritage is non-renewable, and any invasive research or other actions leading to the intervention of mechanical or chemical into the ground lead to the destruction of the archaeological site in whole or in part. For this reason, modern archeology is looking for alternative methods of non-destructive and non-invasive methods of new objects identification. The concept of aerial archeology is relation between the presence of the archaeological site in the particular localization, and the phenomena that in the same place can be observed on the terrain surface form airborne platform. One of the most appreciated, moreover, extremely precise, methods of such measurements is airborne laser scanning. In research airborne laser scanning point cloud with a density of 5 points/sq. m was used. Additionally unmanned aerial vehicle imagery data was acquired. Test area is located in central Europe. The preliminary verification of potentially microstructures localization was the creation of digital terrain and surface models. These models gave an information about the differences in elevation, as well as regular shapes and sizes that can be related to the former settlement/sub-surface feature. The paper presents the results of the detection of potentially sub-surface microstructure fields in the forestry area.

  13. Sorption of pathogens during sub-surface drip irrigation with wastewater

    Science.gov (United States)

    Levi, Laillach; Gillerman Gillerman, Leonid; Kalavrouziotis, Ioannis; Oron, Gideon

    2017-04-01

    Water scarcity continues to be one of the major threats to human survival in many regions worldwide, such as Africa, the Mediterranean Basin, the State of California in the US. Due to a mixture of factors such as population growth, reduction in water resources availability and higher demand for high quality waters in these regions these countries face water shortage issues that stem from overuse, extensive extraction of groundwater, and frequent drought events. In addition, there are increases in environmental and health awareness that have led to intensive efforts in the treatment and reuse of nonconventional water sources, mainly wastewater and greywater. One approach to water shortages issues is to use wastewater as means to close the gap between supply and demand. However, the need to treat wastewater and to disinfect it forces additional economic burden on the users, primarily for agricultural irrigation. A possible solution might be to use the soil as a sorbent for the contained pathogens. Under sub-surface drip irrigation, not allowing the wastewater to reach the soil surface, the pathogens will remain in the soil. It was as well shown in field experiments that the opening size of roots will not allow pathogens to penetrate into the plants. Additional advantages such as water saving, protection of the pipe systems and others are also important. Field experiments in commercial fields just emphasize the main advantages of sub-surface drip irrigation.

  14. An improved algorithm of image processing technique for film thickness measurement in a horizontal stratified gas-liquid two-phase flow

    Energy Technology Data Exchange (ETDEWEB)

    Kuntoro, Hadiyan Yusuf, E-mail: hadiyan.y.kuntoro@mail.ugm.ac.id; Majid, Akmal Irfan; Deendarlianto, E-mail: deendarlianto@ugm.ac.id [Center for Energy Studies, Gadjah Mada University, Sekip K-1A Kampus UGM, Yogyakarta 55281 (Indonesia); Department of Mechanical and Industrial Engineering, Faculty of Engineering, Gadjah Mada University, Jalan Grafika 2, Yogyakarta 55281 (Indonesia); Hudaya, Akhmad Zidni; Dinaryanto, Okto [Department of Mechanical and Industrial Engineering, Faculty of Engineering, Gadjah Mada University, Jalan Grafika 2, Yogyakarta 55281 (Indonesia)

    2016-06-03

    Due to the importance of the two-phase flow researches for the industrial safety analysis, many researchers developed various methods and techniques to study the two-phase flow phenomena on the industrial cases, such as in the chemical, petroleum and nuclear industries cases. One of the developing methods and techniques is image processing technique. This technique is widely used in the two-phase flow researches due to the non-intrusive capability to process a lot of visualization data which are contain many complexities. Moreover, this technique allows to capture direct-visual information data of the flow which are difficult to be captured by other methods and techniques. The main objective of this paper is to present an improved algorithm of image processing technique from the preceding algorithm for the stratified flow cases. The present algorithm can measure the film thickness (h{sub L}) of stratified flow as well as the geometrical properties of the interfacial waves with lower processing time and random-access memory (RAM) usage than the preceding algorithm. Also, the measurement results are aimed to develop a high quality database of stratified flow which is scanty. In the present work, the measurement results had a satisfactory agreement with the previous works.

  15. Heavy oil, water and air three-phase flow patterns in horizontal pipes; Padroes de escoamento trifasico de oleo pesado, agua e ar em tubulacoes horizontais

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-07-01

    A significant extent of the Brazilian oil reserves consists of heavy oil, and its importance and economic value have been increasing in the last years. However, these oils, besides their elevated densities (API degree lower than 20), have viscosities higher than 100 mPa.s, which make it more difficult their transportation in pipelines. A solution for this problem is the injection of water in the pipe, which causes a reduction of the friction factor and, consequently, of the energy expend for a given oil flow rate. The two-phase flow of heavy oil and water has been the object of a number of recent studies, and concepts such as the core-flow technology can be useful for heavy oil transportation. But in production operations, gas is also present, initially dissolved in the oil phase then leaving the solution to form a free gas phase if the pressure drops below the bubble point pressure, the study of three-phase flow of heavy oil, water and gas is in order. The present paper presents the experimental work developed to evaluate the effect that this third phase causes on the heavy oil-water two-phase flow pattern. Initially two-phase flow of heavy and gas-water was studied to establish the flow rate ranges that cover the main patterns already known. The superficial velocities used varied from 0,04 to 0,5 m/s for water, 0,01 to 22 m/s for gas and 0,02 to 1,2 m/s for oil. After that, three-phase flow patterns were visually determined through a 2,84 cm i.d. plexiglas tube using a high-speed camera. Nine three-phase flow patterns were identified which are presented visually and described. These flow-patterns are also presented in flow maps where the effect of the gas phase can be observed. Water was the continuous phase for all flow patterns observed, ensuring a low pressure drop along the pipe. (author)

  16. Pressure gradient of a two-region solid-liquid flow in horizontal wells; Gradiente de presion de un flujo bifasico solido-liquido de dos regiones en pozos horizontales

    Energy Technology Data Exchange (ETDEWEB)

    Salazar Mendoza, R.; Garcia Gutierrez, A. [Centro Nacional de Investigacion y Desarrollo Tecnologico (CENIDET), Cuernavaca, Morelos (Mexico); Espinosa Paredes, G. [Universidad Autonoma Metropolitana-Iztapalapa, Mexico, D.F. (Mexico)

    2005-12-01

    A theoretical analysis is presented for the problem of cutting transport in a two-region, slurry-flow system in horizontal pipes, with a stationary bed of drill cuttings as a porous medium (w-region) below a two-phase dispersed flow (n-region). Volume averaging was applied to derive a rigorous mathematical model where each variable is precisely defined. The model includes volume-averaged transport equations for both the two-phase dispersed flow and the porous-medium regions, and terms from a macroscopic forces balance. The solution of the two-region model allowed evaluation of the behavior of the pressure gradient as a function of velocity, total volume fraction of cuttings, and the relationship between the height of the stationary bed and pipe diameter. It is based on a backward, finite-difference explicit scheme. The simulated physical system is a pipe diameter. It is based on a backward, finite-difference explicit scheme. The simulated physical system is a pipe of 4.135 m in horizontal length and 0.0508 m in diameter. A one dimensional, mesh-centered grid is used, consisting of 10 nodes. The numerical results were compared with experimental data on slurry flows and a good agreement was found. [Spanish] Se presenta un analisis teorico del problema de transporte de recortes de perforacion en pozos horizontales. Se estudia el flujo bifasico solido-liquido en dos regiones donde la region inferior es un lecho estacionario de recortes, considerado como medio poroso, mientras que la region superior es un flujo bifasico disperso solido-liquido. Se aplica el metodo de promediado en volumen para derivar de manera matematicamente rigurosa el modelo de dos regiones. El modelo incluye las ecuaciones de transporte promediadas en volumen para cada region y terminos que resultan de un balance de fuerzas macroscopico. La solucion del modelo permite evaluar el comportamiento del gradiente de presion como funcion de la velocidad, la fraccion de volumen de recortes total y la

  17. Two-phase flow regimes in a horizontal microchannel with the height of 50 μm and width of 10 mm

    Science.gov (United States)

    Fina, V. P.; Ronshin, F. V.

    2017-11-01

    Two-phase flows of distilled deionized nanofiltered water and nitrogen gas in a microchannel with a height of 50 μm and a width of 10 mm have been investigated experimentally. The schlieren method has been used to determine main features of the two-phase flow in the microchannel. This method allows detecting the liquid film on the lower and upper walls of the microchannel as well as droplets of various shapes and sizes or vertical liquid bridges. Two-phase flow regimes have been observed, and their boundaries precisely determined using post-processing of the recordings. The following flow regimes have been distinguished: bubble, churn, jet, stratified and annular. Comparison of regime maps for channels of different widths has been carried out, and this parameter showed to have a significant impact on the boundaries between the regimes in microchannels of a height of less than 100 μm.

  18. Almost horizontal turbulence

    International Nuclear Information System (INIS)

    Kolmogorov, A N

    2004-01-01

    The paper is published without modifications. Kolmogorov's manuscript was apparently prepared during his participation in one of expeditions of the ship 'D. Mendeleev' to the Atlantic Ocean (1969) or in a circumnavigation of the world (1971) organized by the Institute for Oceanology led at the time by A.S. Monin. As Kolmogorov himself wrote, the choice of the topic was stimulated by observations concerning '...meanders with horizontal sizes of hundreds of kilometers on a flow involving a layer of hundreds of meters, with subsequent disintegration of these meanders into vortices gradually decreasing in size to several kilometers'. In modern terminology, the paper is devoted to the problem of intensive mixing in pycnoclines, that is, thin layers of stratified fluid, caused by internal waves whose frequencies are less than the Brent-Vaeisaelae frequency. Here I would like to note two circumstances. The first is the scientific insight characteristic for Kolmogorov; this very approach was later reflected in numerous publications (see, for instance, the monograph by V.S. Modevich, V.I. Nikulin, and A.G. Stetsenko 'Dynamics of internal mixing in a stratified medium', Institute for Hydromechanics, Academy of Sciences of Ukraine, Naukova Dumka, Kiev 1988). The second, the more significant in my opinion, is the genuine intellectual curiosity and breadth of thought of this great thinker, who studied not only the most abstract mathematical constructions but also got his head out of the clouds with great interest to solve concrete applied problems

  19. The Development of a Sub-Surface Monitoring System for Organic Contamination in Soils and Groundwater

    Directory of Open Access Journals (Sweden)

    Sharon L. Huntley

    2002-01-01

    Full Text Available A major problem when dealing with environmental contamination is the early detection and subsequent surveillance of the contamination. This paper describes the potential of sub-surface sensor technology for the early detection of organic contaminants in contaminated soils, sediments, and landfill sites. Rugged, low-power hydrocarbon sensors have been developed, along with a data-logging system, for the early detection of phase hydrocarbons in soil. Through laboratory-based evaluation, the ability of this system to monitor organic contamination in water-based systems is being evaluated. When used in conjunction with specific immunoassays, this can provide a sensitive and low-cost solution for long-term monitoring and analysis, applicable to a wide range of field applications.

  20. Direct investigation of (sub-) surface preparation artifacts in GaAs based materials by FIB sectioning

    Energy Technology Data Exchange (ETDEWEB)

    Belz, Jürgen; Beyer, Andreas; Torunski, Torsten; Stolz, Wolfgang; Volz, Kerstin

    2016-04-15

    The introduction of preparation artifacts is almost inevitable when producing samples for (scanning) transmission electron microscopy ((S)TEM). These artifacts can be divided in extrinsic artifacts like damage processes and intrinsic artifacts caused by the deviations from the volume strain state in thin elastically strained material systems. The reduction and estimation of those effects is of great importance for the quantitative analysis of (S)TEM images. Thus, optimized ion beam preparation conditions are investigated for high quality samples. Therefore, the surface topology is investigated directly with atomic force microscopy (AFM) on the actual TEM samples. Additionally, the sectioning of those samples by a focused ion beam (FIB) is used to investigate the damage depth profile directly in the TEM. The AFM measurements show good quantitative agreement of sample height modulation due to strain relaxation to finite elements simulations. Strong indications of (sub-) surface damage by ion beams are observed. Their influence on high angle annular dark field (HAADF) imaging is estimated with focus on thickness determination by absolute intensity methods. Data consolidation of AFM and TEM measurements reveals a 3.5 nm surface amorphization, negligible surface roughness on the scale of angstroms and a sub-surface damage profile in the range of up to 8.0 nm in crystalline gallium arsenide (GaAs) and GaAs-based ternary alloys. A correction scheme for thickness evaluation of absolute HAADF intensities is proposed and applied for GaAs based materials. - Highlights: • The damage by Ar-ion milling during TEM sample preparation is investigated directly. • After FIB sectioning damage and deep disorder of c-GaAs is seen in cross-section. • The influence of such disorder on conventional ADF measurements is estimated. • A correction for HAADF measurements is proposed with focus on thickness estimations.

  1. Sub-surface defects detection of by using active thermography and advanced image edge detection

    International Nuclear Information System (INIS)

    Tse, Peter W.; Wang, Gaochao

    2017-01-01

    Active or pulsed thermography is a popular non-destructive testing (NDT) tool for inspecting the integrity and anomaly of industrial equipment. One of the recent research trends in using active thermography is to automate the process in detecting hidden defects. As of today, human effort has still been using to adjust the temperature intensity of the thermo camera in order to visually observe the difference in cooling rates caused by a normal target as compared to that by a sub-surface crack exists inside the target. To avoid the tedious human-visual inspection and minimize human induced error, this paper reports the design of an automatic method that is capable of detecting subsurface defects. The method used the technique of active thermography, edge detection in machine vision and smart algorithm. An infrared thermo-camera was used to capture a series of temporal pictures after slightly heating up the inspected target by flash lamps. Then the Canny edge detector was employed to automatically extract the defect related images from the captured pictures. The captured temporal pictures were preprocessed by a packet of Canny edge detector and then a smart algorithm was used to reconstruct the whole sequences of image signals. During the processes, noise and irrelevant backgrounds exist in the pictures were removed. Consequently, the contrast of the edges of defective areas had been highlighted. The designed automatic method was verified by real pipe specimens that contains sub-surface cracks. After applying such smart method, the edges of cracks can be revealed visually without the need of using manual adjustment on the setting of thermo-camera. With the help of this automatic method, the tedious process in manually adjusting the colour contract and the pixel intensity in order to reveal defects can be avoided. (paper)

  2. Mobile depth profiling and sub-surface imaging techniques for historical paintings—A review

    International Nuclear Information System (INIS)

    Alfeld, Matthias; Broekaert, José A.C.

    2013-01-01

    Hidden, sub-surface paint layers and features contain valuable information for the art-historical investigation of a painting's past and for its conservation for coming generations. The number of techniques available for the study of these features has been considerably extended in the last decades and established techniques have been refined. This review focuses on mobile non-destructive subsurface imaging and depth profiling techniques, which allow for the in-situ investigation of easel paintings, i.e. paintings on a portable support. Among the techniques discussed are: X-ray radiography and infrared reflectography, which are long established methods and are in use for several decades. Their capabilities of element/species specific imaging have been extended by the introduction of energy/wavelength resolved measurements. Scanning macro-X-ray fluorescence analysis made it for the first time possible to acquire elemental distribution images in-situ and optical coherence tomography allows for the non-destructive study the surface paint layers in virtual cross-sections. These techniques and their variants are presented next to other techniques, such as Terahertz imaging, Nuclear Magnetic Resonance depth profiling and established techniques for non destructive testing (thermography, ultrasonic imaging and laser based interference methods) applied in the conservation of historical paintings. Next to selected case studies the capabilities and limitations of the techniques are discussed. - Highlights: • All mobile sub-surface and depth-profiling techniques for paintings are reviewed. • The number of techniques available has increased considerably in the last years. • X-ray radiography and infrared reflectography are still the most used techniques. • Scanning macro-XRF and optical coherence tomography begin to establish. • Industrial non destructive testing techniques support the preservation of paintings

  3. Mobile depth profiling and sub-surface imaging techniques for historical paintings—A review

    Energy Technology Data Exchange (ETDEWEB)

    Alfeld, Matthias, E-mail: matthias.alfeld@desy.de [University of Hamburg, Department of Chemistry, Martin-Luther-King Platz 6, D-20146 Hamburg (Germany); University of Antwerp, Department of Chemistry, Groenenbrogerlaan 171, B-2020 Antwerp (Belgium); Broekaert, José A.C., E-mail: jose.broekaert@chemie.uni-hamburg.de [University of Hamburg, Department of Chemistry, Martin-Luther-King Platz 6, D-20146 Hamburg (Germany)

    2013-10-01

    Hidden, sub-surface paint layers and features contain valuable information for the art-historical investigation of a painting's past and for its conservation for coming generations. The number of techniques available for the study of these features has been considerably extended in the last decades and established techniques have been refined. This review focuses on mobile non-destructive subsurface imaging and depth profiling techniques, which allow for the in-situ investigation of easel paintings, i.e. paintings on a portable support. Among the techniques discussed are: X-ray radiography and infrared reflectography, which are long established methods and are in use for several decades. Their capabilities of element/species specific imaging have been extended by the introduction of energy/wavelength resolved measurements. Scanning macro-X-ray fluorescence analysis made it for the first time possible to acquire elemental distribution images in-situ and optical coherence tomography allows for the non-destructive study the surface paint layers in virtual cross-sections. These techniques and their variants are presented next to other techniques, such as Terahertz imaging, Nuclear Magnetic Resonance depth profiling and established techniques for non destructive testing (thermography, ultrasonic imaging and laser based interference methods) applied in the conservation of historical paintings. Next to selected case studies the capabilities and limitations of the techniques are discussed. - Highlights: • All mobile sub-surface and depth-profiling techniques for paintings are reviewed. • The number of techniques available has increased considerably in the last years. • X-ray radiography and infrared reflectography are still the most used techniques. • Scanning macro-XRF and optical coherence tomography begin to establish. • Industrial non destructive testing techniques support the preservation of paintings.

  4. Data report: the wake of a horizontal-axis wind turbine model, measurements in uniform approach flow and in a simulated atmospheric boundary layer

    NARCIS (Netherlands)

    Talmon, A.M.

    1985-01-01

    Wake effects will cause power loss when wínd turbínes are grouped in so called wind turbine parks. Wind tunnel measurements of the wake of a wind turbíne model are conducted in order to refine calculatíons of wake effects. Wake effects caused by tower and nacelle are studied in uniform flow. Wake

  5. Entrainment and deposition studies in two-phase cross flow: comparison between air-water and steam-water in a square horizontal duct. Technical report (final)

    International Nuclear Information System (INIS)

    Berryman, R.J.; Ralph, J.C.; Wade, C.D.

    1981-03-01

    Air-water simulation studies of two phase steam water flow relevant to the upper plenum of a PWR during reflood situations have recently been undertaken at Harwell for the US Nuclear Regulatory Commission. In order to give confidence that the simulation fluids were capable of modelling the important features of the actual system, a relatively basic comparison experiment has been carried out. Water entrainment and deposition tests have been carried out on a pair of 2.5 cm diameter vertical rods mounted in a cross flow of steam or air in a 10.2 cm x 10.2 cm tunnel. The air and steam systems exhibited similar characteristics to one another. A 'critical' film flowrate was identified for the rods which, once reached, either by injection through the sinters or by entrainment from the main two phase stream, was not exceeded with further water addition. The 'critical' film flowrate decreased with increase of cross flow velocity and was lower for air than steam at the same velocity. The results from the air and steam tests were found to be reasonably well correlated on the basis of the cross flow momentum flux of the air or steam

  6. Vertical and horizontal subsidiarity

    Directory of Open Access Journals (Sweden)

    Ivan V. Daniluk

    2016-02-01

    Full Text Available This article makes an attempt to analyze the principle of subsidiarity in its two main manifestations, namely vertical and horizontal, to outline the principles of relations between the state and regions within the vertical subsidiarity, and features a collaboration of the government and civil society within the horizontal subsidiarity. Scientists identify two types, or two levels of the subsidiarity principle: vertical subsidiarity and horizontal subsidiarity. First, vertical subsidiarity (or territorial concerning relations between the state and other levels of subnational government, such as regions and local authorities; second, horizontal subsidiarity (or functional concerns the relationship between state and citizen (and civil society. Vertical subsidiarity expressed in the context of the distribution of administrative responsibilities to the appropriate higher level lower levels relative to the state structure, ie giving more powers to local government. However, state intervention has subsidiary-lower action against local authorities in cases of insolvency last cope on their own, ie higher organisms intervene only if the duties are less authority is insufficient to achieve the goals. Horizontal subsidiarity is within the relationship between power and freedom, and is based on the assumption that the concern for the common good and the needs of common interest community, able to solve community members (as individuals and citizens’ associations and role of government, in accordance horizontal subsidiarity comes to attracting features subsidiarity assistance, programming, coordination and possibly control.

  7. Effects of interspecific competition on the growth of macrophytes and nutrient removal in constructed wetlands: A comparative assessment of free water surface and horizontal subsurface flow systems.

    Science.gov (United States)

    Zheng, Yucong; Wang, Xiaochang; Dzakpasu, Mawuli; Zhao, Yaqian; Ngo, Huu Hao; Guo, Wenshan; Ge, Yuan; Xiong, Jiaqing

    2016-05-01

    The outcome of competition between adjoining interspecific colonies of Phragmites and Typha in two large field pilot-scale free water surface (FWS) and subsurface flow (SSF) CWs is evaluated. According to findings, the effect of interspecific competition was notable for Phragmites australis, whereby it showed the highest growth performance in both FWS and SSF wetland. In a mixed-culture, P. australis demonstrates superiority in terms of competitive interactions for space between plants. Furthermore, the interspecific competition among planted species seemed to cause different ecological responses of plant species in the two CWs. For example, while relatively high density and shoot height determined the high aboveground dry weight of P. australis in the FWS wetland, this association was not evident in the SSF. Additionally, while plants nutrients uptake accounts for a higher proportion of the nitrogen removal in FWS, that in the SSF accounts for a higher proportion of the phosphorous removal. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Domestic Wastewater Depuration Using a Horizontal Subsurface Flow Constructed Wetland and Theoretical Surface Optimization: A Case Study under Dry Mediterranean Climate

    Directory of Open Access Journals (Sweden)

    Pedro Andreo-Martínez

    2016-10-01

    Full Text Available The wastewater generated by isolated houses without access to public sewers can cause environmental problems, like the contamination of aquifers with nitrates and phosphates, as occurs in southeastern Spain. The effectiveness of a previously built horizontal subsurface flow constructed wetland (HF-CW was studied over two years as a possible solution. This HF-CW measured 27 m2; it was planted with Phragmites australis(Cav. Trin. Ex Steuds sp. Altissima and the parameters studied were those required by European Union (EU legislation and adopted by Spain. Average abatement efficiency rates, for the first and the second year of study, were: biochemical oxygen demand over five days (BOD5 (96.4%, 92.0%, chemical oxygen demand (COD (84.6%, 77.7%, total suspended solids(TSS (94.8%,89.9%,total nitrogen(TN(79.5%,66.0%,ammonium nitrogen(NH4+-N(98.8%, 86.6% and total phosphorous (TP (83.7%, 82.8%. Average abatement efficiency for nitrate nitrogen (NO3−-N (−1280.5%, −961.1% and nitrite nitrogen (NO2−-N (−5.8%, −40.0% were negative because its content in influent wastewater was very low and they appear mainly from influent NH4+-N, as a result of purification processes carried out in the HF-CW bed. The abatement rates make the system suitable to produce discharges into the environment in accordance with Spanish law. It is noteworthy that the HF-CW patch suffered an episode of bed drying during the summer of 2013, whereby the causes were related to system oversizing and high evapotranspiration in the area. As a consequence, the decrease in the abatement of water pollutants during the second year can be attributed to the creation of preferential water flow paths and short circuits through the constructed wetland (CW bed. As a result of the oversizing of the CW, a theoretical resizing based on BOD5, TSS, TN or TP is proposed. The calculated values for the redesign were: 5.22 m2 considering DBO5, 0.18 m2 considering TSS, 10.14 m2 considering

  9. The decompression of basaltic magma into a sub-surface repository

    NARCIS (Netherlands)

    Bokhove, Onno; Woods, A.W.

    2002-01-01

    We examine the ascent of volatile-rich basaltic magma through a vertical dike that intersects a horizontal tunnel of comparable cross-sectional area to the dike and located 300 $m$ below the surface and initially filled with air at atmospheric pressure. This process is a simplified representation of

  10. Nitrogen isotope ratios in surface and sub-surface soil horizons

    International Nuclear Information System (INIS)

    Rennie, D.A.; Paul, E.A.

    1975-01-01

    Nitrogen isotope analysis of surface soils and soil-derived nitrate for selected chernozemic and luvisolic soils showed mean delta 15 N values of 11.7 and 11.3, respectively. Isotope enrichment of the total N reached a maximum in the lower B horizon. Sub-soil parent material samples from the one deep profile included in the study indicated a delta 15 N value (NO 3 -N) of 1/3 that of the Ap horizon, at a depth of 180 cm. The delta 15 N of sub-surface soil horizons containing residual fertilizer N were low (-2.2) compared to the surface horizon (9.9). The data reported from this preliminary survey suggest that the natural variations in 15 N abundance between different soils and horizons of the same soil reflect the cumulative effects of soil genesis and soil management. More detailed knowledge and understanding of biological and other processes which control N isotope concentrations in these soils must be obtained before the data reported can be interpreted. (author)

  11. A size selective porous silicon grating-coupled Bloch surface and sub-surface wave biosensor.

    Science.gov (United States)

    Rodriguez, Gilberto A; Ryckman, Judson D; Jiao, Yang; Weiss, Sharon M

    2014-03-15

    A porous silicon (PSi) grating-coupled Bloch surface and sub-surface wave (BSW/BSSW) biosensor is demonstrated to size selectively detect the presence of both large and small molecules. The BSW is used to sense large immobilized analytes at the surface of the structure while the BSSW that is confined inside but near the top of the structure is used to sensitively detect small molecules. Functionality of the BSW and BSSW modes is theoretically described by dispersion relations, field confinements, and simulated refractive index shifts within the structure. The theoretical results are experimentally verified by detecting two different small chemical molecules and one large 40 base DNA oligonucleotide. The PSi-BSW/BSSW structure is benchmarked against current porous silicon technology and is shown to have a 6-fold higher sensitivity in detecting large molecules and a 33% improvement in detecting small molecules. This is the first report of a grating-coupled BSW biosensor and the first report of a BSSW propagating mode. © 2013 Published by Elsevier B.V.

  12. Surface complexation models for uranium adsorption in the sub-surface environment

    International Nuclear Information System (INIS)

    Payne, T.E.

    2007-01-01

    Adsorption experiments with soil component minerals under a range of conditions are being used to develop models of uranium(VI) uptake in the sub-surface environment. The results show that adsorption of U on iron oxides and clay minerals is influenced by chemical factors including the pH, partial pressure of CO 2 , and the presence of ligands such as phosphate. Surface complexation models (SCMs) can be used to simulate U adsorption on these minerals. The SCMs are based on plausible mechanistic assumptions and describe the experimental data more adequately than Kd values or sorption isotherms. It is conceptually possible to simulate U sorption data on complex natural samples by combining SCMs for individual component minerals. This approach was used to develop a SCM for U adsorption to mineral assemblages from Koongarra (Australia), and produced a reasonable description of U uptake. In order to assess the applicability of experimental data to the field situation, in-situ measurements of U distributions between solid and liquid phases were undertaken at the Koongarra U deposit. This field partitioning data showed a satisfactory agreement with laboratory sorption data obtained under comparable conditions. (author)

  13. Salinity maxima associated with some sub-surface water masses in the upper layers of the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Varadachari, V.V.R.; Murty, C.S.; Reddy, C.V.G.

    The distribution of some sub-surface water masses in the western bay of Bengal during the south-west monsoon period is presented. Based on the salinity maxima and sigma t values the existence of waters of Persian Gulf and Red Sea origin could...

  14. Characteristics of Buoyancy Driven Natural Ventilation through Horizontal Openings

    DEFF Research Database (Denmark)

    Li, Zhigang

    through horizontal openings. Two cases of full-scale measurements of buoyancy driven natural ventilation through horizontal openings are performed: one horizontal opening and one horizontal opening combined with one vertical opening. For the case of one horizontal opening, the measurements are made....... Computational fluid dynamics (CFD) are used to study these two air flow cases. The air flow rate and air flow pattern are predicted and compared with the full-scale measurements. The measurement data are used to compare two CFD models: standard k- ε model and large eddy simulation (LES) model. The cases...... transient, unstable and complex, and the air flow rates oscillate with time. Correlations between the Froude number Fr and the opening ratio L/D are obtained, which is reasonable agreement with Epstein's formula derived from brine-water measurements, but the obtained Fr values show considerable deviations...

  15. ESTUDIO COMPARATIVO DE LA REMOCIÓN DE MATERIA ORGÁNICA EN HUMEDALES CONSTRUIDOS DE FLUJO HORIZONTAL SUBSUPERFICIAL USANDO TRES ESPECIES DE MACRÓFITAS ESTUDO COMPARATIVO DA REMOÇÃO DE MATÉRIA ORGÂNICA EM BANHADOS CONSTRUÍDOS DE FLUXO HORIZONTAL SUBSUPERFICIAL USANDO TRES ESPÉCIES DE MACRÓFITAS COMPARATIVE STUDY OF THE ORGANIC MATTER REMOVAL IN HORIZONTAL SUBSURFACE FLOW CONSTRUCTED WETLANDS USING THREE SPECIES OF MACROPHYTES

    Directory of Open Access Journals (Sweden)

    JORGE IGNACIO MONTOYA

    2010-12-01

    present time like a promising technology in reducing the pollution by waste waters; this study investigated the organic matter removal with synthetic waste water, in terms of chemical oxygen demand (COD, biological oxygen demand (BOD5 and in situ measurements of pH, oxygen and temperature every 15 days, during three months, in six horizontal subsurface-flow constructed wetland systems, in pilot scale, seeded with three different macrophytes: Canna limbata, Heliconia psittacorum and Phragmites sp; the average removals of COD were of 97,31 % and 95,94 % for Canna limbata; 94,49 % and 93,50 % for Heliconia psittacorum; 97,39 % and 97,13 % for Phragmites sp. In BOD they were of 100 % and 99,36 % for Canna limbata; 99,09 % and 97,49 % for Heliconia psittacorum; 100 % and 99,45 % for Phragmites sp. We conclude that there are significant differences in DQO removal between different plants (P < 0,05; in BOD5 removal significant differences between the different plants do not exist statistically (P < 0,05. This study demonstrates the option to reduce the polution from organic matter using constructed wetlands.

  16. Size-induced axial band structure and directional flow of a ternary-size granular material in a 3-D horizontal rotating drum

    Science.gov (United States)

    Yang, Shiliang; Sun, Yuhao; Ma, Honghe; Chew, Jia Wei

    2018-05-01

    Differences in the material property of the granular material induce segregation which inevitably influences both natural and industrial processes. To understand the dynamical segregation behavior, the band structure, and also the spatial redistribution of particles induced by the size differences of the particles, a ternary-size granular mixture in a three-dimensional rotating drum operating in the rolling flow regime is numerically simulated using the discrete element method. The results demonstrate that (i) the axial bands of the medium particles are spatially sandwiched in between those of the large and small ones; (ii) the total mass in the active and passive regions is a global parameter independent of segregation; (iii) nearly one-third of all the particles are in the active region, with the small particles having the highest mass fraction; (iv) the axial bands initially appear near the end wall, then become wider and purer in the particular species with time as more axial bands form toward the axial center; and (v) the medium particle type exhibits segregation later and has the narrowest axial bandwidth and least purity in the bands. Compared to the binary-size system, the presence of the medium particle type slightly increases the total mass in the active region, leads to larger mass fractions of the small and large particle types in the active region, and enhances the axial segregation in the system. The results obtained in the current work provide valuable insights regarding size segregation, and band structure and formation in the rotating drum with polydisperse particles.

  17. Potential of electrical resistivity tomography and muon density imaging to study spatio-temporal variations in the sub-surface

    Science.gov (United States)

    Lesparre, Nolwenn; Cabrera, Justo; Courbet, Christelle

    2015-04-01

    affecting density and electrical resistivity physical parameters. We show with data sets acquired before and after an important rainfall event how muon density and electrical resistivity imaging may complementary characterize variations of the medium properties. The development of such innovative experiments for hydrogeophysical studies presents then the ability to supply new information on fluid dynamics in the sub-surface.

  18. The study of sub-surface damage distributions during grinding process on different abrasion materials

    Science.gov (United States)

    Kuo, Ching-Hsiang; Huang, Chien-Yao; Yu, Zong-Ru; Shu, Shyu-Cheng; Chang, Keng-Shou; Hsu, Wei-Yao

    2017-10-01

    The grinding process is the primary technology for curvature generation (CG) on glass optics. The higher material removal rate (MRR) leads to deeper sub-surface damage (SSD) on lens surface. The SSD must be removed by following lapping and polishing processes to ensure the lens quality. However, these are not an easy and an efficient process to remove the SSD from ground surface directly for aspheric surfaces with tens or hundreds microns departure from bestfit- sphere (BFS). An efficient fabrication procedure for large aspheric departure on glass materials must be considered. We propose 3-step fabrication procedures for aspheric surface with larger departure. 1st step is to generate a specific aspheric surface with depth less than 10 μm of SSD residual. 2nd step is to remove SSD and keep the aspheric form by using Zeeko polisher with higher MRR pad. Final step is to figure and finish the aspheric surface by using QED MRF machine. In this study, we focus on the 1st step to investigate the residual depth of SSD after grinding process on different abrasion materials. The materials of tested part are fused silica, S-NPH2, and S-PHM52. The cross grinding would be configured and depth of SSD/surface roughness would be evaluated in this study. The characteristic of SSD could be observed after etching by confocal microscope. The experimental results show the depth of SSD below 31.1 μm with #400 grinding wheel. And the near 10 μm depth of SSD would be achieved with #1,000 grinding wheel. It means the aspherization polishing on large parts with large departure from best fit sphere would be replaced. The fabrication of large aspheric part would be efficient.

  19. Horizontal violence in Nursing

    Directory of Open Access Journals (Sweden)

    Tsimoulaki Evangelia

    2017-01-01

    Full Text Available One’s effort to clarify the definition of horizontal labour violence is of great importance, due to the variety of definitions that are mentioned in the worldwide scientific literature. Furthermore, the reference of multiple forms of such violence herein the nurse professional group is challenging, as well. Another fact of great importance is that, any form of professional violence (horizontal violence, horizontal mobbing in the work place environment can be possibly escalated and include even physical abuse (Bullying, besides the psychological and emotional impact for the victim. The definitions of Horizontal violence, Mobbing and Bullying, include a repeated negative behaviour emanating from at least one “predator” towards at least one “victim”, with work status differences and the existence or lack of physical abuse (Bullying. Horizontal violence is a hostile, aggressive and harmful behaviour which is either overt or concealed and is pointed from an individual to another individual of the same working rank and causes intense emotional pain at the victim. The manifestations vary from humiliating tasks assignment or the victim’s efforts undermining to clearly aggressive behaviors (criticism, intimidation, sarcasm etc.. The reason behind this phenomenon is multifactorial extended not only towards the working environment but also to the personal characteristics of the “predator” as well as the possible “victim”. The researchers emphasize the high incidence of the phenomenon, as well as the cost that is induced by the violent behaviors to both the health professionals and the hospital. Finally, they point out the paradox of the presence of violence inside a system that is designed to promote health.

  20. Bacterial diversity and community structure of a sub-surface aquifer exposed to realistic low herbicide concentrations

    DEFF Research Database (Denmark)

    Lipthay, Julia R. de; Johnsen, Kaare; Albrechtsen, H.-J.

    2004-01-01

    contaminants. We examined the effect of in situ exposure to realistic low concentrations of herbicides on the microbial diversity and community structure of sub-surface sediments from a shallow aquifer near Vejen (Denmark). Three different community analyses were performed: colony morphology typing, sole...... community analyses. In contrast, no significant effect was found on the bacterial diversity, except for the culturable fraction where a significantly increased richness and Shannon index was found in the herbicide acclimated sediments. The results of this study show that in situ exposure of sub-surface...... aquifers to realistic low concentrations of herbicides may alter the overall structure of a natural bacterial community, although significant effects on the genetic diversity and carbon substrate usage cannot be detected. The observed impact was probably due to indirect effects. In future investigations...

  1. Horizontal bridges in polar dielectric liquids

    Science.gov (United States)

    Woisetschläger, Jakob; Wexler, Adam D.; Holler, Gert; Eisenhut, Mathias; Gatterer, Karl; Fuchs, Elmar C.

    2012-01-01

    When a high-voltage direct-current is applied to two beakers filled with polar liquid dielectrica like water or methanol, a horizontal bridge forms between the two beakers. By repeating a version of Pellat's experiment, it is shown that a horizontal bridge is stable by the action of electrohydrodynamic pressure. Thus, the static and dynamic properties of the phenomenon called a `floating water bridge' can be explained by the gradient of Maxwell pressure, replenishing the liquid within the bridge against any drainage mechanism. It is also shown that a number of liquids can form stable and long horizontal bridges. The stability of such a connection, and the asymmetry in mass flow through such bridges caused by the formation of ion clouds in the vicinity of the electrodes, is also discussed by two further experiments.

  2. Horizontal bridges in polar dielectric liquids

    Energy Technology Data Exchange (ETDEWEB)

    Woisetschlaeger, Jakob [Graz University of Technology, Experimental Turbomachinery Research and Optical Measurement Group, Institute for Thermal Turbomachinery and Machine Dynamics, Graz (Austria); Wexler, Adam D.; Fuchs, Elmar C. [Wetsus, Center of Excellence for Sustainable Water Technology, Leeuwarden (Netherlands); Holler, Gert [Graz University of Technology, Institute of Electrical Measurement and Measurement Signal Processing, Graz (Austria); Eisenhut, Mathias [Graz University of Technology, Institute of Analytical Chemistry and Food Chemistry, Graz (Austria); Gatterer, Karl [Graz University of Technology, Institute of Physical and Theoretical Chemistry, Graz (Austria)

    2012-01-15

    When a high-voltage direct-current is applied to two beakers filled with polar liquid dielectrica like water or methanol, a horizontal bridge forms between the two beakers. By repeating a version of Pellat's experiment, it is shown that a horizontal bridge is stable by the action of electrohydrodynamic pressure. Thus, the static and dynamic properties of the phenomenon called a 'floating water bridge' can be explained by the gradient of Maxwell pressure, replenishing the liquid within the bridge against any drainage mechanism. It is also shown that a number of liquids can form stable and long horizontal bridges. The stability of such a connection, and the asymmetry in mass flow through such bridges caused by the formation of ion clouds in the vicinity of the electrodes, is also discussed by two further experiments. (orig.)

  3. Sheared bioconvection in a horizontal tube

    Science.gov (United States)

    Croze, O. A.; Ashraf, E. E.; Bees, M. A.

    2010-12-01

    The recent interest in using microorganisms for biofuels is motivation enough to study bioconvection and cell dispersion in tubes subject to imposed flow. To optimize light and nutrient uptake, many microorganisms swim in directions biased by environmental cues (e.g. phototaxis in algae and chemotaxis in bacteria). Such taxes inevitably lead to accumulations of cells, which, as many microorganisms have a density different to the fluid, can induce hydrodynamic instabilites. The large-scale fluid flow and spectacular patterns that arise are termed bioconvection. However, the extent to which bioconvection is affected or suppressed by an imposed fluid flow and how bioconvection influences the mean flow profile and cell transport are open questions. This experimental study is the first to address these issues by quantifying the patterns due to suspensions of the gravitactic and gyrotactic green biflagellate alga Chlamydomonas in horizontal tubes subject to an imposed flow. With no flow, the dependence of the dominant pattern wavelength at pattern onset on cell concentration is established for three different tube diameters. For small imposed flows, the vertical plumes of cells are observed merely to bow in the direction of flow. For sufficiently high flow rates, the plumes progressively fragment into piecewise linear diagonal plumes, unexpectedly inclined at constant angles and translating at fixed speeds. The pattern wavelength generally grows with flow rate, with transitions at critical rates that depend on concentration. Even at high imposed flow rates, bioconvection is not wholly suppressed and perturbs the flow field.

  4. Bioremediation of arsenic (As from mine effluent by a horizontal flow constructed wetland: A case study in largest borax reserve area in over the world, Kırka, Eskişehir

    Directory of Open Access Journals (Sweden)

    Onur Can Türker

    2016-12-01

    Full Text Available In this study, a horizontal flow constructed wetland (HFCW planted with Typha angustifolia, was tested to bioremediation potential for arsenic from mine effluent under the natural climatic conditions in largest boron mine reserve area over the world, Kırka (Eskişehir. Briefly, the objective of the present experiment was to investigate arsenic bioremediation capability of wetland system and asses the phytoremediation efficiency of T. angustifolia, selected as a donor plant in this study, with different initial arsenic concentrations. Our results indicated that HFCW has capability to decreased arsenic in mine effluent from 49 µg L-1 to 21.8 µg L-1 in a period of 84 days, suggesting that HFCW could be a reasonable bio-filter option to control arsenic pollution directly from mining effluent in largest borax reserve over the world. Furthermore, we found that arsenic concentration in outflow samples was stably below 10 µg L-1 (drinking water safety limit with an inflow range from 42.3 to 42.1 arsenic µg L-1 during the first 28 days. Our results also indicated that belowground parts of T.angustifolia accumulate more arsenic from mine effluent compared to aboveground parts during experiment period. Therefore, we suggested that belowground parts of the plants in HFCW play an important role for arsenic bioremediation from mine effluent which origin of Kırka Borax reserve area. In this respect, bioconcentration factor (BCF for the plants which grown in HFCW was found higher than those of control group. Moreover, results of the present experiment also showed that relatively high level of arsenic retained in the filtration media of HFCW during the experiment period, indicating that filtration media which was used in HFCW has potential to filter arsenic from mine effluent. Consequently, the scientific insight of the present study is to present an innovative, cost effective, and easy operating method for arsenic remediation from mine effluent.

  5. Horizontal wells in subsurface remediation

    International Nuclear Information System (INIS)

    Losonsky, G.; Beljin, M.S.

    1992-01-01

    This paper reports on horizontal wells which offer an effective alternative to vertical wells in various environmental remediation technologies. Hydrogeological advantages of horizontal wells over vertical wells include a larger zone of influence, greater screen length, higher specific capacity and lower groundwater screen entrance velocity. Because of these advantages, horizontal wells can reduce treatment time and costs of groundwater recovery (pump-and-treat), in situ groundwater aeration (sparging) and soil gas extraction (vacuum extraction). Horizontal wells are also more effective than vertical wells in landfill leachate collection (under-drains), bioremediation, and horizontal grout injection

  6. Sub-surface microstructure of single and polycrystalline tungsten after high flux plasma exposure studied by TEM

    Energy Technology Data Exchange (ETDEWEB)

    Dubinko, A., E-mail: adubinko@sckcen.be [Institute for Nuclear Material Sciences, SCK-CEN, 2400 Mol (Belgium); Department of Applied Physics, Ghent University, 9000 Ghent (Belgium); Terentyev, D. [Institute for Nuclear Material Sciences, SCK-CEN, 2400 Mol (Belgium); Bakaeva, A. [Institute for Nuclear Material Sciences, SCK-CEN, 2400 Mol (Belgium); Department of Applied Physics, Ghent University, 9000 Ghent (Belgium); Hernández-Mayoral, M. [Division of Materials, CIEMAT, 28040 Madrid (Spain); De Temmerman, G. [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St Paul-lez-Durance Cedex (France); Buzi, L. [Forschungszentrum Julich, Inst. Energie & Klimaforsch Plasmaphys, D-52425 Julich (Germany); Noterdaeme, J.-M. [Department of Applied Physics, Ghent University, 9000 Ghent (Belgium); Unterberg, B. [Forschungszentrum Julich, Inst. Energie & Klimaforsch Plasmaphys, D-52425 Julich (Germany)

    2017-01-30

    Highlights: • Plasma exposure induces dislocation-dominated microstructure as indicated by TEM. • Plasma exposure increases surface dislocation density by an order of magnitude in the polycrystalline tungsten. • Intensive dislocation-grain boundary interaction observed in polycrystalline tungsten. • Dislocation loops are observed in both polycrystalline and single crystal tungsten. - Abstract: We have performed high flux plasma exposure of tungsten and subsequent microstructural characterization using transmission electron microscopy (TEM) techniques. The aim was to reveal the nanometric features in the sub-surface region as well as to compare the microstructural evolution in tungsten single crystal and ITER-relevant specification. In both types of samples, TEM examination revealed the formation of a dense dislocation network and dislocation tangles. The estimated dislocation density in the sub-surface region was of the order of 10{sup 14} m{sup −2} and it gradually decreased with a depth position of the examined sample. Besides individual dislocation lines, networks and tangles, the interstitial dislocation loops have been observed in all examined samples only after the exposure. Contrary to that, examination of the pristine single crystal W and backside of the plasma-exposed samples did not reveal the presence of dislocation loops and tangles. This clearly proves that high flux plasma exposure induces severe plastic deformation in the sub-surface region irrespective of the presence of initial dislocations and sub-grains, and the formation of dislocation tangles, networks and interstitial loops is a co-product of thermal stress and intensive plasma particles uptake.

  7. Measurement of gas-liquid two-phase flow around horizontal tube bundle using SF6-water. Simulating high-pressure high-temperature gas-liquid two-phase flow of PWR/SG secondary coolant side at normal pressure

    International Nuclear Information System (INIS)

    Ishikawa, Atsushi; Imai, Ryoj; Tanaka, Takahiro

    2014-01-01

    In order to improve prediction accuracy of analysis code used for design and development of industrial products, technology had been developed to create and evaluate constitutive equation incorporated in analysis code. The experimental facility for PWR/SG U tubes part was manufactured to measure local void fraction and gas-liquid interfacial velocity with forming gas-liquid upward two-phase flow simulating high-pressure high-temperature secondary coolant (water-steam) rising vertically around horizontal tube bundle. The experimental facility could reproduce flow field having gas-liquid density ratio equivalent to real system with no heating using SF6 (Sulfur Hexafluoride) gas at normal temperature and pressure less than 1 MPa, because gas-liquid density ratio, surface tension and gas-liquid viscosity ratio were important parameters to determine state of gas-liquid two-phase flow and gas-liquid density ratio was most influential. Void fraction was measured by two different methods of bi-optical probe and conductivity type probe. Test results of gas-liquid interfacial velocity vs. apparent velocity were in good agreement with existing empirical equation within 10% error, which could confirm integrity of experimental facility and appropriateness of measuring method so as to set up original constitutive equation in the future. (T. Tanaka)

  8. Nitrate and nitrite contamination of sub-surface water in some areas of North West Frontier Province (N.W.F.P.) Pakistan

    International Nuclear Information System (INIS)

    Khan, M.; Khawaja, M.A.; Imdadullah

    1998-01-01

    Over the past few years, nitrate and nitrite contamination of sub-surface water samples from Peshawar, Charsada, Mardan and Nowshera districts of NWFP has been studied. In all the areas under study, nitrate concentration of sub-surface water was found to be below WHO approved limit of 45 mg/l. Whereas city area after 1987 showed a decreasing level of nitrate contamination of sub-surface water, it appeared to be on the increase in water samples from the outskirts of Peshawar-Charsada road. No uniform increasing or decreasing patterns of nitrate contamination were observed for water samples from cantonment, University and Hayatabad, areas of Mardan, Charsada and Nowshera under study. The nitrate contamination of sub-surface water appeared to be due to both the agricultural activities as well as human and animal wastes. A few sub-surface water samples from Peshawar city, Mardan and Nowshera areas indicated high concentration of nitrite, which is alarming in view of the earlier reports showing absence of nitrite in water samples from these areas. However, since 1993, nitrite presence has not been detected in sub-surface water samples from all the areas under present investigation. (author)

  9. Study of 'inadvertent human intrusion or rare natural event scenarios' for sub-surface disposal of radioactive waste

    International Nuclear Information System (INIS)

    Nakatani, Takayoshi; Ishitoya, Kimihide; Funabashi, Hideyuki; Sugaya, Toshikatsu; Sone, Tomoyuki; Shimada, Hidemitsu; Nakai, Kunihiro

    2010-03-01

    Japan Atomic Energy Agency (JAEA) is making preparations for the sub-surface disposal of radioactive wastes, in an integrated fashion according to the properties of the waste material regardless of the generators or waste sources. In this study, 'Inadvertent Human Intrusion or Rare Natural Event Scenarios' of 'Three Types scenarios' was considered according to the standard of the Atomic Energy Society of Japan (AESJ) on the sub-surface disposal system that was based on 'Basic Policy for Safety Regulation Concerning Land Disposal of Low-Level Radioactive Waste (Interim Report)' by Nuclear Safety Commission of Japan (NSC). Selection of the assessed scenarios, development of the assessment tool and preliminary exposure dose assessment for general public were conducted. Among the assessed scenarios, the exposure dose of 'well water drinking scenario' was the highest under the very conservative assessment condition. This scenario assumed that the groundwater in Excavation Disturbed Zone (EDZ) was directly used as drinking water without any dilution. Although this was very conservative condition and the result exceeded 10 mSv/y, it stayed under the upper limit of standard dose value for 'Inadvertent Human Intrusion or Rare Natural Event Scenarios' (10 - 100 mSv/y). (author)

  10. The Development of 3d Sub-Surface Mapping Scheme and its Application to Martian Lobate Debris Aprons

    Science.gov (United States)

    Baik, H.; Kim, J.

    2017-07-01

    The Shallow Subsurface Radar (SHARAD), a sounding radar equipped on the Mars Reconnaissance Orbiter (MRO), has produced highly valuable information about the Martian subsurface. In particular, the complicated substructures of Mars such as polar deposit, pedestal crater and the other geomorphic features involving possible subsurface ice body has been successfully investigated by SHARAD. In this study, we established a 3D subsurface mapping strategy employing the multiple SHARAD profiles. A number of interpretation components of SHARAD signals were integrated into a subsurface mapping scheme using radargram information and topographic data, then applied over a few mid latitude Lobate Debris Aprons (LDAs). From the identified subsurface layers of LDA, and the GIS data base incorporating the other interpretation outcomes, we are expecting to trace the origin of LDAs. Also, the subsurface mapping scheme developed in this study will be further applied to other interesting Martian geological features such as inter crater structures, aeolian deposits and fluvial sediments. To achieve higher precision sub-surface mapping, the clutter simulation employing the high resolution topographic data and the upgraded clustering algorithms assuming multiple sub-surface layers will be also developed.

  11. A horizontal well analysis from a view of its productivity

    Directory of Open Access Journals (Sweden)

    Lucia Sciranková

    2006-10-01

    Full Text Available The 1990s may become known in the oil field as the decade of the horizontal well. Horizontal wells can increase the production rate and the ultimate recovery, and can reduce the number of platforms on wells required to develop a reservoir.An empirical equation to calculate the inflow performance of two-phase flow for a vertical and a horizontal well in regime of dissolved gas presented by Vogel in 1968. His equation was based on the results of reservoir simulation. The created model whore result (output is the ratio of the productivity of a horizontal well to the productivity of a vertical well for a given area expressed by anumber of vertical wells the replaced by one horizontal well. The model is applied for a concrete ideological model.

  12. A review on critical heat flux in horizontal tubes

    International Nuclear Information System (INIS)

    Baburajan, P.K.; Gaikwad, Avinash; Prabhu, S.V.

    2015-01-01

    Coolant channels of PHWR during accident similar to loss of coolant accident (LOCA) may experience different flow transients with low pressure and low flow conditions. In the advanced PHWRs it is desired to have small amount of positive quality at the exit of the coolant channel to increase the thermal efficiency. Investigation on pressure drop and heat transfer coefficient under subcooled boiling condition is important in the design and operation of the PHWRs. Understanding of thermal hydraulic phenomena associated with horizontal flow is also important in the safety and accident management in these reactors. A detailed experimental investigation on the important thermal hydraulic phenomena of horizontal tubes under low pressure and low flow conditions is carried out. The phenomena covered in this work are measurement of diabatic single phase and subcooled boiling pressure drop and local heat transfer coefficients, steady state CHF, effect of upstream flow restrictions on flow transients and CHF, CHF under oscillatory flow and flow decreasing transients. A detailed literature review is carried out on CHF in horizontal channels to take stock of the works being carried out along with current state of the art and to justify the motivation for the experimental study. This paper presents the review of available literature on horizontal CHF with the results of the experimental work. (author)

  13. Seismic sensitivity to sub-surface solar activity from 18 yr of GOLF/SoHO observations

    Science.gov (United States)

    Salabert, D.; García, R. A.; Turck-Chièze, S.

    2015-06-01

    Solar activity has significantly changed over the last two Schwabe cycles. After a long and deep minimum at the end of Cycle 23, the weaker activity of Cycle 24 contrasts with the previous cycles. In this work, the response of the solar acoustic oscillations to solar activity is used in order to provide insights into the structural and magnetic changes in the sub-surface layers of the Sun during this on-going unusual period of low activity. We analyze 18 yr of continuous observations of the solar acoustic oscillations collected by the Sun-as-a-star GOLF instrument on board the SoHO spacecraft. From the fitted mode frequencies, the temporal variability of the frequency shifts of the radial, dipolar, and quadrupolar modes are studied for different frequency ranges that are sensitive to different layers in the solar sub-surface interior. The low-frequency modes show nearly unchanged frequency shifts between Cycles 23 and 24, with a time evolving signature of the quasi-biennial oscillation, which is particularly visible for the quadrupole component revealing the presence of a complex magnetic structure. The modes at higher frequencies show frequency shifts that are 30% smaller during Cycle 24, which is in agreement with the decrease observed in the surface activity between Cycles 23 and 24. The analysis of 18 yr of GOLF oscillations indicates that the structural and magnetic changes responsible for the frequency shifts remained comparable between Cycle 23 and Cycle 24 in the deeper sub-surface layers below 1400 km as revealed by the low-frequency modes. The frequency shifts of the higher-frequency modes, sensitive to shallower regions, show that Cycle 24 is magnetically weaker in the upper layers of Sun. Appendices are available in electronic form at http://www.aanda.orgThe following 68 GOLF frequency tables are available and Table A.1 is also available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc

  14. Characteristic Value Method of Well Test Analysis for Horizontal Gas Well

    Directory of Open Access Journals (Sweden)

    Xiao-Ping Li

    2014-01-01

    Full Text Available This paper presents a study of characteristic value method of well test analysis for horizontal gas well. Owing to the complicated seepage flow mechanism in horizontal gas well and the difficulty in the analysis of transient pressure test data, this paper establishes the mathematical models of well test analysis for horizontal gas well with different inner and outer boundary conditions. On the basis of obtaining the solutions of the mathematical models, several type curves are plotted with Stehfest inversion algorithm. For gas reservoir with closed outer boundary in vertical direction and infinite outer boundary in horizontal direction, while considering the effect of wellbore storage and skin effect, the pseudopressure behavior of the horizontal gas well can manifest four characteristic periods: pure wellbore storage period, early vertical radial flow period, early linear flow period, and late horizontal pseudoradial flow period. For gas reservoir with closed outer boundary both in vertical and horizontal directions, the pseudopressure behavior of the horizontal gas well adds the pseudosteady state flow period which appears after the boundary response. For gas reservoir with closed outer boundary in vertical direction and constant pressure outer boundary in horizontal direction, the pseudopressure behavior of the horizontal gas well adds the steady state flow period which appears after the boundary response. According to the characteristic lines which are manifested by pseudopressure derivative curve of each flow period, formulas are developed to obtain horizontal permeability, vertical permeability, skin factor, reservoir pressure, and pore volume of the gas reservoir, and thus the characteristic value method of well test analysis for horizontal gas well is established. Finally, the example study verifies that the new method is reliable. Characteristic value method of well test analysis for horizontal gas well makes the well test analysis

  15. Condensation Analysis of Steam/Air Mixtures in Horizontal Tubes

    International Nuclear Information System (INIS)

    Lee, Kwon Yeong; Bae, Sung Won; Kim, Moo Hwan

    2008-01-01

    Perhaps the most common flow configuration in which a convective condensation occurs is a flow in a horizontal circular tube. This configuration is encountered in air-conditioning and refrigeration condensers as well as condensers in Rankine power cycles. Although a convective condensation is also sometimes contrived to occur in a co-current vertical downward flow, a horizontal flow is often preferred because the flow can be repeatedly passed through the heat exchanger core in a serpentine fashion without trapping liquid or vapor in the return bends. Many researchers have investigated a in-tube condensation for horizontal heat exchangers. However, almost all of them obtained tube section-averaged data without a noncondensable gas. Recently, Wu and Vierow have experimentally studied the condensation of steam in a horizontal heat exchanger with air present. In order to measure the condenser tube inner surface temperatures and to calculate the local heat fluxes, they developed an innovative thermocouple design that allowed for nonintrusive measurements. Here we developed a theoretical model using the heat and mass analogy to analyze a steam condensation with a noncondensable gas in horizontal tubes

  16. Selectively placing many fractures in openhole horizontal wells improves production

    Energy Technology Data Exchange (ETDEWEB)

    Love, T. G.; McCarty, R. A. [Chevron USA Inc (United States); Suraatmadja, J. B.; Chambers, R. W.; Grundmann, S. R.

    1998-12-31

    Result of a simulation of an openhole horizontal well that was treated with hydrajet fracturing, a new fracturing process wherein fractures are placed at different locations in a horizontal well without using sectional isolation techniques, are discussed. The process uses high-pressure jetting to concentrate fracturing energy at a precise fracture location, and data is obtained by means of surface and downhole pressure recorders, flow recorders, and tracers. This technique was used in a substantially depleted horizontal well in New Mexico with good results. The new process is reported to be expensive to implement which prevents widespread application at the present time. 7 refs., 9 figs.

  17. Remediation of a contaminated thin aquifer by horizontal wells

    Energy Technology Data Exchange (ETDEWEB)

    Breh, W.; Suttheimer, J.; Hoetzl, H. [Univ. of Karlsruhe (Germany); Frank, K. [GEO-Service GmbH, Rheinmuenster (Germany)

    1997-12-31

    At an industrial site in Bruchsal (Germany) a huge trichloroethene contamination was found. After common remedial actions proved to be widely ineffective, new investigations led to a highly contaminated thin aquifer above the main aquifer. The investigation and the beginning of the remediation of the thin aquifer by two horizontal wells is described in this paper. Special attention was given to the dependence between precipitation and the flow direction in the thin aquifer and to hydraulic connections between the thin and the main aquifer. Also a short introduction into a new remedial technique by horizontal wells and first results of the test phase of the horizontal wells are given.

  18. Genome sequencing reveals the potential of an indigenous arsenotrophic bacterium; Achromobacter sp. KAs 3-5 for sub-surface arsenic mobilization and strategies for bioremediation

    Directory of Open Access Journals (Sweden)

    Balaram Mohapatra

    2017-12-01

    desired traits through horizontal gene transfer events. The ability of the organism to metabolize mono-poly aromatics like benzene, toluene, naphthalene, anthracene, etc. (by catechol, homogentisate pathways coupled to As reduction (through arsHBC, arsC, ACR3 found to be well validated by genomic observations. X-ray absorption fine structure (XANES also enabled us to decipher detailed Fe-based reductive As release process from sediment and its interaction. The obtained genome data provide us with a better understanding of sub-surface mechanisms of hydrocarbon (organic matter driven As release, which may contribute to the future design of rational strategies for bioremediation of As/other heavy metal contaminated environments.

  19. A new approach to define surface/sub-surface transition in gravel beds

    Science.gov (United States)

    Haynes, Heather; Ockelford, Anne-Marie; Vignaga, Elisa; Holmes, William

    2012-12-01

    The vertical structure of river beds varies temporally and spatially in response to hydraulic regime, sediment mobility, grain size distribution and faunal interaction. Implicit are changes to the active layer depth and bed porosity, both critical in describing processes such as armour layer development, surface-subsurface exchange processes and siltation/ sealing. Whilst measurements of the bed surface are increasingly informed by quantitative and spatial measurement techniques (e.g., laser displacement scanning), material opacity has precluded the full 3D bed structure analysis required to accurately define the surface-subsurface transition. To overcome this problem, this paper provides magnetic resonance imaging (MRI) data of vertical bed porosity profiles. Uniform and bimodal (σ g = 2.1) sand-gravel beds are considered following restructuring under sub-threshold flow durations of 60 and 960 minutes. MRI data are compared to traditional 2.5D laser displacement scans and six robust definitions of the surface-subsurface transition are provided; these form the focus of discussion.

  20. Micrograph evidence of meniscus solidification and sub-surface microstructure evolution in continuous-cast ultralow-carbon steels

    International Nuclear Information System (INIS)

    Sengupta, J.; Shin, H.-J.; Thomas, B.G.; Kim, S.-H.

    2006-01-01

    Hooks and other sub-surface features in continuous-cast ultralow-carbon steel samples were examined using optical microscopy, electron backscattering diffraction, energy dispersive X-ray spectroscopy, and electron probe microanalysis techniques. Special etching reagents revealed dendrites growing from both sides of the line of hook origin. This line was found to represent the frozen meniscus and persisted into the final microstructure, as revealed by grain orientation measurements. A broken hook tip was observed in one micrograph, which explains the characteristic truncated shape of most hooks. Mold powder was found entrapped along the frozen meniscus. These results provide evidence of both solidification and subsequent overflow of the liquid steel meniscus. Thus, the instantaneous meniscus shape governs the shape and microstructure of the final hook, and the extent of the liquid steel overflow determines the shape of oscillation marks. This mechanism has important implications for the entrapment of inclusions and other surface defects

  1. Desert water harvesting to benefit wildlife: a simple, cheap, and durable sub-surface water harvester for remote locations.

    Science.gov (United States)

    Rice, William E

    2004-12-01

    A sub-surface desert water harvester was constructed in the sagebrush steppe habitat of south-central Idaho, U.S.A. The desert water harvester utilizes a buried micro-catchment and three buried storage tanks to augment water for wildlife during the dry season. In this region, mean annual precipitation (MAP) ranges between about 150-250 mm (6"-10"), 70% of which falls during the cold season, November to May. Mid-summer through early autumn, June through October, is the dry portion of the year. During this period, the sub-surface water harvester provides supplemental water for wildlife for 30-90 days, depending upon the precipitation that year. The desert water harvester is constructed with commonly available, "over the counter" materials. The micro-catchment is made of a square-shaped, 20 mL. "PERMALON" polyethylene pond liner (approximately 22.9 m x 22.9 m = 523 m2) buried at a depth of about 60 cm. A PVC pipe connects the harvester with two storage tanks and a drinking trough. The total capacity of the water harvester is about 4777 L (1262 U.S. gallons) which includes three underground storage tanks, a trough and pipes. The drinking trough is refined with an access ramp for birds and small animals. The technology is simple, cheap, and durable and can be adapted to other uses, e.g. drip irrigation, short-term water for small livestock, poultry farming etc. The desert water harvester can be used to concentrate and collect water from precipitation and run-off in semi-arid and arid regions. Water harvested in such a relatively small area will not impact the ground water table but it should help to grow small areas of crops or vegetables to aid villagers in self-sufficiency.

  2. Using GNSS-R techniques to investigate the near sub-surface of Mars with the Deep Space Network

    Science.gov (United States)

    Elliott, H. M.; Bell, D. J.; Jin, C.; Decrossas, E.; Asmar, S.; Lazio, J.; Preston, R. A.; Ruf, C. S.; Renno, N. O.

    2017-12-01

    Global Navigation Satellite Systems Reflectometry (GNSS-R) has shown that passive measurements using separate active sources can infer the soil moisture, snow pack depth and other quantities of scientific interest. Here, we expand upon this method and propose that a passive measurement of the sub-surface dielectric profile of Mars can be made by using multipath interference between reflections off the surface and subsurface dielectric discontinuities. This measurement has the ability to reveal changes in the soil water content, the depth of a layer of sand, thickness of a layer of ice, and even identify centimeter-scale layering which may indicate the presence of a sedimentary bed. We have created a numerical ray tracing model to understand the potential of using multipath interference techniques to investigate the sub-surface dielectric properties and structure of Mars. We have further verified this model using layered beds of sand and concrete in laboratory experiments and then used the model to extrapolate how this technique may be applied to future Mars missions. We will present new results demonstrating how to characterize a multipath interference patterns as a function of frequency and/or incidence angle to measure the thickness of a dielectric layer of sand or ice. Our results demonstrate that dielectric discontinuities in the subsurface can be measured using this passive sensing technique and it could be used to effectively measure the thickness of a dielectric layer in the proximity of a landed spacecraft. In the case of an orbiter, we believe this technique would be effective at measuring the seasonal thickness of CO2 ice in the Polar Regions. This is exciting because our method can produce similar results to traditional ground penetrating radars without the need to have an active radar transmitter in-situ. Therefore, it is possible that future telecommunications systems can serve as both a radio and a scientific instrument when used in conjunction with

  3. Liquid Hydrogen Propellant Tank Sub-Surface Pressurization with Gaseous Helium

    Science.gov (United States)

    Stephens, J. R.; Cartagena, W.

    2015-01-01

    A series of tests were conducted to evaluate the performance of a propellant tank pressurization system with the pressurant diffuser intentionally submerged beneath the surface of the liquid. Propellant tanks and pressurization systems are typically designed with the diffuser positioned to apply pressurant gas directly into the tank ullage space when the liquid propellant is settled. Space vehicles, and potentially propellant depots, may need to conduct tank pressurization operations in micro-gravity environments where the exact location of the liquid relative to the diffuser is not well understood. If the diffuser is positioned to supply pressurant gas directly to the tank ullage space when the propellant is settled, then it may become partially or completely submerged when the liquid becomes unsettled in a microgravity environment. In such case, the pressurization system performance will be adversely affected requiring additional pressurant mass and longer pressurization times. This series of tests compares and evaluates pressurization system performance using the conventional method of supplying pressurant gas directly to the propellant tank ullage, and then supplying pressurant gas beneath the liquid surface. The pressurization tests were conducted on the Engineering Development Unit (EDU) located at Test Stand 300 at NASA Marshall Space Flight Center (MSFC). EDU is a ground based Cryogenic Fluid Management (CFM) test article supported by Glenn Research Center (GRC) and MSFC. A 150 ft3 propellant tank was filled with liquid hydrogen (LH2). The pressurization system used regulated ambient helium (GHe) as a pressurant, a variable position valve to maintain flow rate, and two identical independent pressurant diffusers. The ullage diffuser was located in the forward end of the tank and was completely exposed to the tank ullage. The submerged diffuser was located in the aft end of the tank and was completely submerged when the tank liquid level was 10% or greater

  4. Horizontal drilling under Lake Erie

    Energy Technology Data Exchange (ETDEWEB)

    Meller, R.

    2001-07-01

    Drilling oil wells under Lake Erie calls for horizontal drilling wells to be drilled from shore out into the pay-zone under the lake. The nature and characteristics of horizontal wells as compared to vertical wells are explored. Considerations that have to be taken into account in drilling horizontal wells are explained (the degree of curvature, drilling fluid quality, geosteering in the pay-zone, steering instrumentation, measurements while drilling (MWD), logging while drilling (LWD)). The concept and reasons for extended reach wells are outlined, along with characteristic features of multilateral wells.

  5. Horizontal, floating, plastic hose oil skimmer

    Energy Technology Data Exchange (ETDEWEB)

    1978-04-01

    A horizontal, floating, plastic hose oil skimmer operates at -20/sup 0/ to +100/sup 0/C as a moving belt driven by a motor at 0.7 kw at 1400 rpm to pick up oil by adhesion from a surface such as that of used cooling water or cutting oil for subsequent stripping and collection by gravity flow. Two models provide collection rates of 10-45 l./hr for diesel oil, 35-115 l./hr for hydraulic oil, and 170-455 l./hr for gear oils and heavy heating oils.

  6. Natural convection in horizontal fluid layers

    International Nuclear Information System (INIS)

    Suo-Antilla, A.J.

    1977-02-01

    The experimental work includes developing and using a thermal convection cell to obtain measurements of the heat flux and turbulent core temperature of a horizontal layer of fluid heated internally and subject to both stabilizing and destabilizing temperature differences. The ranges of Rayleigh numbers tested were 10 7 equal to or less than R/sub I/ equal to or less than 10 13 and -10 10 equal to or less than R/sub E/ equal to or less than 10 10 . Power integral methods were found to be adequate for interpolating and extrapolating the data. The theoretical work consists of the derivation, solution and use of the mean field equations for study of thermally driven convection in horizontal layers of infinite extent. The equations were derived by a separation of variables technique where the horizontal directions were described by periodic structures and the vertical being some function of z. The derivation resulted in a coupled set of momentum and energy equations. The equations were simplified by using the infinite Prandtl number limit and neglecting direct intermodal interaction. Solutions to these equations are used to predict the existence of multi-wavenumber flows at all supercritical Rayleigh numbers. Subsequent inspection of existing experimental photographs of convecting fluids confirms their existence. The onset of time dependence is found to coincide with the onset of the second convective mode. Each mode is found to consist of two wavenumbers and typically the velocity and temperature fields of the right modal branch are found to be out of phase

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Flame spread along thermally thick horizontal rods

    Science.gov (United States)

    Higuera, F. J.

    2002-06-01

    An analysis is carried out of the spread of a flame along a horizontal solid fuel rod, for which a weak aiding natural convection flow is established in the underside of the rod by the action of the axial gradient of the pressure variation that gravity generates in the warm gas surrounding the flame. The spread rate is determined in the limit of infinitely fast kinetics, taking into account the effect of radiative losses from the solid surface. The effect of a small inclination of the rod is discussed, pointing out a continuous transition between upward and downward flame spread. Flame spread along flat-bottomed solid cylinders, for which the gradient of the hydrostatically generated pressure drives the flow both along and across the direction of flame propagation, is also analysed.

  12. Microplastics in Arctic polar waters: the first reported values of particles in surface and sub-surface samples

    Science.gov (United States)

    Lusher, Amy L.; Tirelli, Valentina; O’Connor, Ian; Officer, Rick

    2015-01-01

    Plastic, as a form of marine litter, is found in varying quantities and sizes around the globe from surface waters to deep-sea sediments. Identifying patterns of microplastic distribution will benefit an understanding of the scale of their potential effect on the environment and organisms. As sea ice extent is reducing in the Arctic, heightened shipping and fishing activity may increase marine pollution in the area. Microplastics may enter the region following ocean transport and local input, although baseline contamination measurements are still required. Here we present the first study of microplastics in Arctic waters, south and southwest of Svalbard, Norway. Microplastics were found in surface (top 16 cm) and sub-surface (6 m depth) samples using two independent techniques. Origins and pathways bringing microplastic to the Arctic remain unclear. Particle composition (95% fibres) suggests they may either result from the breakdown of larger items (transported over large distances by prevailing currents, or derived from local vessel activity), or input in sewage and wastewater from coastal areas. Concurrent observations of high zooplankton abundance suggest a high probability for marine biota to encounter microplastics and a potential for trophic interactions. Further research is required to understand the effects of microplastic-biota interaction within this productive environment. PMID:26446348

  13. Impact of post-infiltration soil aeration at different growth stages of sub-surface trickle-irrigated tomato plants

    Science.gov (United States)

    Li, Yuan; Jia, Zong-xia; Niu, Wen-Quan; Wang, Jing-wei

    2016-07-01

    Sensitivity to low rhizosphere soil aeration may change over time and therefore plant response may also depend on different growth stages of a crop. This study quantified effects of soil aeration during 5 different periods, on growth and yield of trickle-irrigated potted single tomato plants. Irrigation levels were 0.6 to 0.7 (low level) or 0.7 to 0.8 (high level) of total water holding capacity of the pots. Soil was aerated by injecting 2.5 l of air into each pot through the drip tubing immediately after irrigation. Fresh fruit yield, above ground plant dry weight, plant height, and leaf area index response to these treatments were measured. For all these 4 response variables, means of post-infiltration aeration between 58 to 85 days after sowing were 13.4, 43.5, 13.7, and 37.7% higher than those for the non-aerated pots, respectively. The results indicated that: post-infiltration soil aeration can positively impact the yield and growth of sub-surface trickle-irrigated potted tomato plants; positive effects on plant growth can be obtained with aeration during the whole growth period or with aeration for partial periods; positive growth effects of partial periods of aeration appears to persist and result in yield benefit.

  14. Image-based overlay and alignment metrology through optically opaque media with sub-surface probe microscopy

    Science.gov (United States)

    van Es, Maarten H.; Mohtashami, Abbas; Piras, Daniele; Sadeghian, Hamed

    2018-03-01

    Nondestructive subsurface nanoimaging through optically opaque media is considered to be extremely challenging and is essential for several semiconductor metrology applications including overlay and alignment and buried void and defect characterization. The current key challenge in overlay and alignment is the measurement of targets that are covered by optically opaque layers. Moreover, with the device dimensions moving to the smaller nodes and the issue of the so-called loading effect causing offsets between between targets and product features, it is increasingly desirable to perform alignment and overlay on product features or so-called on-cell overlay, which requires higher lateral resolution than optical methods can provide. Our recently developed technique known as SubSurface Ultrasonic Resonance Force Microscopy (SSURFM) has shown the capability for high-resolution imaging of structures below a surface based on (visco-)elasticity of the constituent materials and as such is a promising technique to perform overlay and alignment with high resolution in upcoming production nodes. In this paper, we describe the developed SSURFM technique and the experimental results on imaging buried features through various layers and the ability to detect objects with resolution below 10 nm. In summary, the experimental results show that the SSURFM is a potential solution for on-cell overlay and alignment as well as detecting buried defects or voids and generally metrology through optically opaque layers.

  15. Degradation of atrazine and isoproturon in surface and sub-surface soil materials undergoing different moisture and aeration conditions.

    Science.gov (United States)

    Issa, Salah; Wood, Martin

    2005-02-01

    The influence of different moisture and aeration conditions on the degradation of atrazine and isoproturon was investigated in environmental samples aseptically collected from surface and sub-surface zones of agricultural land. The materials were maintained at two moisture contents corresponding to just above field capacity or 90% of field capacity. Another two groups of samples were adjusted with water to above field capacity, and, at zero time, exposed to drying-rewetting cycles. Atrazine was more persistent (t(1/2) = 22-35 days) than isoproturon (t(1/2) = 5-17 days) in samples maintained at constant moisture conditions. The rate of degradation for both herbicides was higher in samples maintained at a moisture content of 90% of field capacity than in samples with higher moisture contents. The reduction in moisture content in samples undergoing desiccation from above field capacity to much lower than field capacity enhanced the degradation of isoproturon (t(1/2) = 9-12 days) but reduced the rate of atrazine degradation (t(1/2) = 23-35 days). This demonstrates the variability between different micro-organisms in their susceptibility to desiccation. Under anaerobic conditions generated in anaerobic jars, atrazine degraded much more rapidly than isoproturon in materials taken from three soil profiles (0-250 cm depth). It is suggested that some specific micro-organisms are able to survive and degrade herbicide under severe conditions of desiccation. Copyright (c) 2005 Society of Chemical Industry.

  16. Microplastics in Arctic polar waters: the first reported values of particles in surface and sub-surface samples

    Science.gov (United States)

    Lusher, Amy L.; Tirelli, Valentina; O'Connor, Ian; Officer, Rick

    2015-10-01

    Plastic, as a form of marine litter, is found in varying quantities and sizes around the globe from surface waters to deep-sea sediments. Identifying patterns of microplastic distribution will benefit an understanding of the scale of their potential effect on the environment and organisms. As sea ice extent is reducing in the Arctic, heightened shipping and fishing activity may increase marine pollution in the area. Microplastics may enter the region following ocean transport and local input, although baseline contamination measurements are still required. Here we present the first study of microplastics in Arctic waters, south and southwest of Svalbard, Norway. Microplastics were found in surface (top 16 cm) and sub-surface (6 m depth) samples using two independent techniques. Origins and pathways bringing microplastic to the Arctic remain unclear. Particle composition (95% fibres) suggests they may either result from the breakdown of larger items (transported over large distances by prevailing currents, or derived from local vessel activity), or input in sewage and wastewater from coastal areas. Concurrent observations of high zooplankton abundance suggest a high probability for marine biota to encounter microplastics and a potential for trophic interactions. Further research is required to understand the effects of microplastic-biota interaction within this productive environment.

  17. Fracture mechanics assessment of surface and sub-surface cracks in the RPV under non-symmetric PTS loading

    Energy Technology Data Exchange (ETDEWEB)

    Keim, E; Shoepper, A; Fricke, S [Siemens AG Unternehmensbereich KWU, Erlangen (Germany)

    1997-09-01

    One of the most severe loading conditions of a reactor pressure vessel (rpv) under operation is the loss of coolant accident (LOCA) condition. Cold water is injected through nozzles in the downcomer of the rpv, while the internal pressure may remain at a high level. Complex thermal hydraulic situations occur and the fluid and downcomer temperatures as well as the fluid to wall heat transfer coefficient at the inner surface are highly non-linear. Due to this non-symmetric conditions, the problem is investigated by three-dimensional non-linear finite element analyses, which allow for an accurate assessment of the postulated flaws. Transient heat transfer analyses are carried out to analyze the effect of non-symmetrical cooling of the inner surface of the pressure vessel. In a following uncoupled stress analysis the thermal shock effects for different types of defects, surface flaws and sub-surface flaws are investigated for linear elastic and elastic-plastic material behaviour. The obtained fracture parameters are calculated along the crack fronts. By a fast fracture analysis the fracture parameters at different positions along the crack front are compared to the material resistance. Safety margins are pointed out in an assessment diagram of the fracture parameters and the fracture resistance versus the transient temperature at the crack tip position. (author). 4 refs, 10 figs.

  18. Nocturnal soil CO2 uptake and its relationship to sub-surface soil and ecosystem carbon fluxes in a Chihuahuan Desert shrubland

    Science.gov (United States)

    Despite their prevalence, little attention has been given to quantifying aridland soil and ecosystem carbon fluxes over prolonged, annually occurring dry periods. We measured surface soil respiration (Rsoil), volumetric soil moisture and temperature in inter- and under-canopy soils, sub-surface soi...

  19. Tratamento de esgotos sanitários em sistemas reatores UASB/wetlands construídas de fluxo horizontal: eficiência e estabilidade de remoção de matéria orgânica, sólidos, nutrientes e coliformes Domestic wastewater treatment in UASB-horizontal flow constructed wetlands systems: organic matter, solids, nutrients and coliforms removal

    Directory of Open Access Journals (Sweden)

    Maria Lúcia Calijuri

    2009-09-01

    Full Text Available Este trabalho apresentou os resultados de um estudo realizado durante 19 meses sobre o comportamento de wetlands construídas na remoção de matéria orgânica, sólidos, nutrientes e coliformes, em unidades em escala piloto de fluxo horizontal, subsuperficial e superficial, com tempo de detenção hidráulica entre 1,3 a 5,3 dias, operando como pós-tratamento de efluentes de reatores UASB (esgotos sanitários. A remoção de matéria orgânica e de sólidos mostrou-se elevada e estável, com eficiências médias de 70, 80 e 60% para SST, DBO5 e DQO, respectivamente. A remoção de nutrientes, após início promissor, mostrou-se instável e aparentemente influenciada pela temperatura. O sistema de tratamento revelou elevado potencial de remoção de coliformes, embora com variações relativamente amplas ao longo do período de operação: ≈ 2 log10 de remoção de coliformes totais e 2-4 log10 de remoção de Escherichia coli.This work presented the results of a 19-month study on the performance of constructed wetlands in terms of organic matter, solids, nutrients and coliforms removal in pilot scale unities with horizontal, subsurface and surface flow, with hydraulic retention time from 1.3 to 5.3 days, as post-treatment of UASB effluents (domestic wastewater. Organic matter and solids were effectively and consistently removed, with average values of 70, 80 and 60% for TSS, BOD5 and COD, respectively. Nutrients removal, after a promising start up, became unstable and apparently influenced by temperature. The treatment system has also shown high potential to remove coliforms, although with relatively wide variations over the study period: ≈ 2 log10 reduction of total coliforms and 2-4 log10 reduction of Escherichia coli.

  20. NUMERICAL DETERMINATION OF HORIZONTAL SETTLERS PERFORMANCE

    Directory of Open Access Journals (Sweden)

    M. M. Biliaiev

    2015-08-01

    Full Text Available Purpose.Horizontal settlers are one of the most important elements in the technological scheme of water purification. Their use is associated with the possibility to pass a sufficiently large volume of water. The important task at the stage of their designing is evaluating of their effectiveness. Calculation of the efficiency of the settler can be made by mathematical modeling. Empirical, analytical models and techniques that are currently used to solve the problem, do not allow to take into account the shape of the sump and various design features that significantly affects the loyalty to a decision on the choice of the size of the settling tank and its design features. The use of analytical models is limited only to one-dimensional solutions, does not allow accounting for nonuniform velocity field of the flow in the settler. The use of advanced turbulence models for the calculation of the hydrodynamics in the settler complex forms now requires very powerful computers. In addition, the calculation of one variant of the settler may last for dozens of hours. The aim of the paper is to build a numerical model to evaluate the effectiveness of horizontal settling tank modified design. Methodology. Numerical models are based on: 1 equation of potential flow; 2 equation of inviscid fluid vortex flow; 3 equation of viscous fluid dynamics; 4 mass transfer equation. For numerical simulation the finite difference schemes are used. The numerical calculation is carried out on a rectangular grid. For the formation of the computational domain markers are used. Findings.The models allow calculating the clarification process in the settler with different form and different configuration of baffles. Originality. A new approach to investigate the mass transfer process in horizontal settler was proposed. This approach is based on the developed CFD models. Three fluid dynamics models were used for the numerical investigation of flows and waste waters purification

  1. On the Turbulent Mixing in Horizontal Axis Wind Turbine Wakes

    NARCIS (Netherlands)

    Lignarolo, L.E.M.

    2016-01-01

    The wake flow of a horizontal axis wind turbine is characterised by lower wind speed and higher turbulence than the free-stream conditions. When clustered in large wind farms, wind turbines regularly operate inside the wake of one or more upstream machines. This is a major cause of energy production

  2. Direct Numerical Simulation Sediment Transport in Horizontal Channel

    International Nuclear Information System (INIS)

    Uhlmann, M.

    2006-01-01

    We numerically simulate turbulent flow in a horizontal plane channel over a bed of mobile particles. All scales of fluid motion are resolved without modeling and the phase interface is accurately represented. Our results indicate a possible scenario for the onset of erosion through collective motion induced by buffer-layer streaks. (Author) 27 refs

  3. Ground-penetrating radar (GPR) responses for sub-surface salt contamination and solid waste: modeling and controlled lysimeter studies.

    Science.gov (United States)

    Wijewardana, Y N S; Shilpadi, A T; Mowjood, M I M; Kawamoto, K; Galagedara, L W

    2017-02-01

    The assessment of polluted areas and municipal solid waste (MSW) sites using non-destructive geophysical methods is timely and much needed in the field of environmental monitoring and management. The objectives of this study are (i) to evaluate the ground-penetrating radar (GPR) wave responses as a result of different electrical conductivity (EC) in groundwater and (ii) to conduct MSW stratification using a controlled lysimeter and modeling approach. A GPR wave simulation was carried out using GprMax2D software, and the field test was done on two lysimeters that were filled with sand (Lysimeter-1) and MSW (Lysimeter-2). A Pulse EKKO-Pro GPR system with 200- and 500-MHz center frequency antennae was used to collect GPR field data. Amplitudes of GPR-reflected waves (sub-surface reflectors and water table) were studied under different EC levels injected to the water table. Modeling results revealed that the signal strength of the reflected wave decreases with increasing EC levels and the disappearance of the subsurface reflection and wave amplitude reaching zero at higher EC levels (when EC >0.28 S/m). Further, when the EC level was high, the plume thickness did not have a significant effect on the amplitude of the reflected wave. However, it was also found that reflected signal strength decreases with increasing plume thickness at a given EC level. 2D GPR profile images under wet conditions showed stratification of the waste layers and relative thickness, but it was difficult to resolve the waste layers under dry conditions. These results show that the GPR as a non-destructive method with a relatively larger sample volume can be used to identify highly polluted areas with inorganic contaminants in groundwater and waste stratification. The current methods of MSW dumpsite investigation are tedious, destructive, time consuming, costly, and provide only point-scale measurements. However, further research is needed to verify the results under heterogeneous aquifer

  4. Stackelberg equilibria and horizontal differentiation

    OpenAIRE

    Lambertini, Luca

    1993-01-01

    This paper proposes a taxonomy of the Stackelberg equilibria emerging from a standard game of horizontal differentiation à la Hotelling in which the strategy set of the sellers in the location stage is the real axis. Repeated leadership appears the most advantageous position. Furthermore, this endogenously yields vertical differentiation between products at equilibrium.

  5. Horizontal Diplopia Following Upper Blepharoplasty

    Directory of Open Access Journals (Sweden)

    Tomás Ortiz-Basso

    2014-09-01

    Full Text Available Diplopia is an infrequent complication after blepharoplasty. Most of the cases are in its vertical form due to trauma of the extraocular muscles. In this article, we present a case of horizontal diplopia following cosmetic upper blepharoplasty; we review the literature on this unexpected complication and offer some recommendations to avoid it.

  6. Flow regimes

    International Nuclear Information System (INIS)

    Kh'yuitt, G.

    1980-01-01

    An introduction into the problem of two-phase flows is presented. Flow regimes arizing in two-phase flows are described, and classification of these regimes is given. Structures of vertical and horizontal two-phase flows and a method of their identification using regime maps are considered. The limits of this method application are discussed. The flooding phenomena and phenomena of direction change (flow reversal) of the flow and interrelation of these phenomena as well as transitions from slug regime to churn one and from churn one to annular one in vertical flows are described. Problems of phase transitions and equilibrium are discussed. Flow regimes in tubes where evaporating liquid is running, are described [ru

  7. A statistical model for horizontal mass flux of erodible soil

    International Nuclear Information System (INIS)

    Babiker, A.G.A.G.; Eltayeb, I.A.; Hassan, M.H.A.

    1986-11-01

    It is shown that the mass flux of erodible soil transported horizontally by a statistically distributed wind flow has a statistical distribution. Explicit expression for the probability density function, p.d.f., of the flux is derived for the case in which the wind speed has a Weibull distribution. The statistical distribution for a mass flux characterized by a generalized Bagnold formula is found to be Weibull for the case of zero threshold speed. Analytic and numerical values for the average horizontal mass flux of soil are obtained for various values of wind parameters, by evaluating the first moment of the flux density function. (author)

  8. Horizontal Gene Transfers in Mycoplasmas (Mollicutes).

    Science.gov (United States)

    Citti, C; Dordet-Frisoni, E; Nouvel, L X; Kuo, C H; Baranowski, E

    2018-04-12

    The class Mollicutes (trivial name "mycoplasma") is composed of wall-less bacteria with reduced genomes whose evolution was long thought to be only driven by gene losses. Recent evidences of massive horizontal gene transfer (HGT) within and across species provided a new frame to understand the successful adaptation of these minimal bacteria to a broad range of hosts. Mobile genetic elements are being identified in a growing number of mycoplasma species, but integrative and conjugative elements (ICEs) are emerging as pivotal in HGT. While sharing common traits with other bacterial ICEs, such as their chromosomal integration and the use of a type IV secretion system to mediate horizontal dissemination, mycoplasma ICEs (MICEs) revealed unique features: their chromosomal integration is totally random and driven by a DDE recombinase related to the Mutator-like superfamily. Mycoplasma conjugation is not restricted to ICE transmission, but also involves the transfer of large chromosomal fragments that generates progenies with mosaic genomes, nearly every position of chromosome being mobile. Mycoplasmas have thus developed efficient ways to gain access to a considerable reservoir of genetic resources distributed among a vast number of species expanding the concept of minimal cell to the broader context of flowing information.

  9. Plankton bloom controlled by horizontal stirring

    Science.gov (United States)

    McKiver, W.; Neufeld, Z.; Scheuring, I.

    2009-10-01

    Here we show a simple mechanism in which changes in the rate of horizontal stirring by mesoscale ocean eddies can trigger or suppress plankton blooms and can lead to an abrupt change in the average plankton density. We consider a single species phytoplankton model with logistic growth, grazing and a spatially non-uniform carrying capacity. The local dynamics have multiple steady states for some values of the carrying capacity that can lead to localized blooms as fluid moves across the regions with different properties. We show that for this model even small changes in the ratio of biological timescales relative to the flow timescales can greatly enhance or reduce the global plankton productivity. Thus, this may be a possible mechanism in which changes in horizontal mixing can trigger plankton blooms or cause regime shifts in some oceanic regions. Comparison between the spatially distributed model and Lagrangian simulations considering temporal fluctuations along fluid trajectories, demonstrates that small scale transport processes also play an important role in the development of plankton blooms with a significant influence on global biomass.

  10. MAXIMUM AIR SUCTION INTO HORIZONTAL OPEN ENDED CYLINDRICAL LOUVERED PIPE

    Directory of Open Access Journals (Sweden)

    SAMEER RANJAN SAHU

    2017-02-01

    Full Text Available The main approach behind the present numerical investigation is to estimate the mass flow rate of air sucked into a horizontal open-ended louvered pipe from the surrounding atmosphere. The present numerical investigation has been performed by solving the conservation equations for mass, momentum and energy along with two equation based k-ɛ model for a louvered horizontal cylindrical pipe by finite volume method. It has been found from the numerical investigation that mass suction rate of air into the pipe increases with increase in louvered opening area and the number of nozzles used. Keeping other parameters fixed, for a given mass flow rate there exists an optimum protrusion of nozzle for highest mass suction into the pipe. It was also found from the numerical investigation that increasing the pipe diameter the suction mass flow rate of air was increased.

  11. Study of parameters for safety assessment of sub-surface disposal. Tunnel-excavating speed and thickness of additional soil in residential land development by filling

    International Nuclear Information System (INIS)

    Ishitoya, Kimihide; Sugaya, Toshikatsu; Funabashi, Hideyuki

    2012-02-01

    Japan Atomic Energy Agency (JAEA) is making preparations for the sub-surface disposal of own low level radioactive wastes. In order to carry out the disposal, it is necessary to confirm the safety of the disposal. Nuclear Safety Commission of Japan (NSC) issued 'Policy of the Safety Assessment of Sub-surface Disposal after the Period for Active Control' (April 1, 2010). Then, we investigated the parameters for dose assessment in tunnel excavation scenario and large-scale land use scenario which were described in the 'Policy of the Safety Assessment', in order to perform the assessment based on actual conditions. To be concrete, we investigated the tunnel excavating speeds in Japan for the former scenario, and investigated technical standards of the filling for the latter scenario. We studied the realistic parameters for the dose assessment with the results of those investigations. (author)

  12. Modelling the horizontal steam generator with APROS

    Energy Technology Data Exchange (ETDEWEB)

    Ylijoki, J. [VTT Energy, Espoo (Finland); Palsinajaervi, C.; Porkholm, K. [IVO International Ltd, Vantaa (Finland)

    1995-12-31

    In this paper the capability of the five- and six-equation models of the simulation code APROS to simulate the behaviour of the horizontal steam generator is discussed. Different nodalizations are used in the modelling and the results of the stationary state runs are compared. Exactly the same nodalizations have been created for the five- and six-equation models. The main simulation results studied in this paper are void fraction and mass flow distributions in the secondary side of the steam generator. It was found that quite a large number of simulation volumes is required to simulate the distributions with a reasonable accuracy. The simulation results of the different models are presented and their validity is discussed. (orig.). 4 refs.

  13. Modelling the horizontal steam generator with APROS

    Energy Technology Data Exchange (ETDEWEB)

    Ylijoki, J [VTT Energy, Espoo (Finland); Palsinajaervi, C; Porkholm, K [IVO International Ltd, Vantaa (Finland)

    1996-12-31

    In this paper the capability of the five- and six-equation models of the simulation code APROS to simulate the behaviour of the horizontal steam generator is discussed. Different nodalizations are used in the modelling and the results of the stationary state runs are compared. Exactly the same nodalizations have been created for the five- and six-equation models. The main simulation results studied in this paper are void fraction and mass flow distributions in the secondary side of the steam generator. It was found that quite a large number of simulation volumes is required to simulate the distributions with a reasonable accuracy. The simulation results of the different models are presented and their validity is discussed. (orig.). 4 refs.

  14. Experimental study of buoyancy driven natural ventilation through horizontal openings

    DEFF Research Database (Denmark)

    Heiselberg, Per; Li, Zhigang

    2007-01-01

    An experimental study of buoyancy driven natural ventilation through single-sided horizontal openings was performed in a full-scale laboratory test rig. Measurements were made for opening ratios L/D range from 0.027 to 4.455, where L and D are the length and the diameter of the opening......, respectively. The bidirectional air flow rate was measured using constant injection tracer gas technique. Smoke visualizations showed that the air flow patterns are highly transient, unstable and complex, and that air flow rates oscillate with time. Correlations between the Froude number Fr and the L/D ratio...

  15. The Winfrith horizontal impact rig

    International Nuclear Information System (INIS)

    Barr, P.

    1985-12-01

    The Horizontal Impact Rig has been designed to allow studies of the impact of radioactive material transport containers and their associated transport vehicles and impact limiters, using large scale models, and to allow physically large missiles to be projected for studying the impact behaviour of metal and concrete structures. It provides an adequately rigid support structure for impact experiments with targets of large dimensions. Details of its design, instrumentation, performance prediction and construction are given. (U.K.)

  16. comparative evaluation of pressure distribution between horizontal

    African Journals Online (AJOL)

    user

    This paper presents comparative analysis between the pressure behavior of ... Green and source function were used to evaluate the performance of horizontal well and ..... Superscript. ' derivative. D = dimensionless. h = horizontal. = change.

  17. Principal permeability determination from multiple horizontal well tests

    Energy Technology Data Exchange (ETDEWEB)

    Economides, M. [Texas A and M Univ., TX (United States); Munoz, A.; Ehlig-Economides, C.

    1998-12-31

    A method for obtaining principal permeability magnitudes and direction that requires only the linear flow regime from transient tests in three horizontal wells oriented in three distinct and arbitrary directions, is described. Well design optimization strategies require knowledge of both the principal permeability orientation as well as the horizontal permeability magnitudes. When the degree of horizontal permeability anisotropy (i.e. permeability in the bedding plane with respect to direction) is significant, the productivity of a long horizontal well will depend greatly on its direction, especially when the well is first brought into production. Productivities have been found to deviate substantially among wells in the same reservoir and this deviation has been attributed to differences in well orientation. In view of this fact, measuring permeability anisotropy becomes a compelling necessity. The success of the proposed method is illustrated by a case study in which the principal permeability magnitudes and direction from three wells were used to predict the productivity of a fourth well within 10 per cent. Use of the computed principal permeabilities from the case study, it was possible to forecast the cumulative production to show the significance of well trajectory optimization on the discounted cash flow and the net present value. 20 refs., 3 figs.

  18. Environmental restoration using horizontal wells

    International Nuclear Information System (INIS)

    Looney, B.B.; Kaback, D.S.; Hazen, T.C.; Corey, J.C.

    1992-01-01

    This paper reports that under sponsorship from the U.S. Department of Energy, technical personnel from the Savannah River Laboratory and other DOE laboratories, universities and private industry have completed a full scale demonstration of environmental remediation using horizontal wells. The test successfully removed approximately 7250 kg of contaminants. A large amount of characterization and monitoring data was collected to aid in interpretation of the test and to provide the information needed for future environmental restorations that employ directionally drilled wells as extraction or delivery systems

  19. Horizontal gene transfer in chromalveolates

    Directory of Open Access Journals (Sweden)

    Bhattacharya Debashish

    2007-09-01

    Full Text Available Abstract Background Horizontal gene transfer (HGT, the non-genealogical transfer of genetic material between different organisms, is considered a potentially important mechanism of genome evolution in eukaryotes. Using phylogenomic analyses of expressed sequence tag (EST data generated from a clonal cell line of a free living dinoflagellate alga Karenia brevis, we investigated the impact of HGT on genome evolution in unicellular chromalveolate protists. Results We identified 16 proteins that have originated in chromalveolates through ancient HGTs before the divergence of the genera Karenia and Karlodinium and one protein that was derived through a more recent HGT. Detailed analysis of the phylogeny and distribution of identified proteins demonstrates that eight have resulted from independent HGTs in several eukaryotic lineages. Conclusion Recurring intra- and interdomain gene exchange provides an important source of genetic novelty not only in parasitic taxa as previously demonstrated but as we show here, also in free-living protists. Investigating the tempo and mode of evolution of horizontally transferred genes in protists will therefore advance our understanding of mechanisms of adaptation in eukaryotes.

  20. Improved waterflooding efficiency by horizontal wells

    Energy Technology Data Exchange (ETDEWEB)

    Popa, C. G. [Petroleum and Gas Univ., Ploesti (Romania); Clipea, M. [SNP Petrom SA, ICPT Campina (Romania)

    1998-12-31

    The influence of well pattern involving the use of horizontal wells on the overall efficiency of the waterflooding process was analyzed. Three different scenarios were examined: (1) a pattern of using two parallel horizontal wells, one for injection, the other for production, (2) a pattern of one horizontal well for water injection and several vertical wells for production, and (3) a pattern of using vertical wells for injection and one horizontal well for production. In each case, the waterflooding process was simulated using a two phase two dimensional numerical model. Results showed that the pressure loss along the horizontal section had a large influence on the sweep efficiency whether the horizontal well was used for injection or production. Overall, the most successful combination appeared to be using vertical wells for injection and horizontal wells for production. 4 refs., 1 tab., 15 figs.

  1. Evaporation heat transfer of hot water from horizontal free service

    International Nuclear Information System (INIS)

    Koizumi, Y.; Ebihara, Y.; Hirota, T.; Murase, M.

    2011-01-01

    Evaporation heat transfer from the hot water flow to the cold air flow in a horizontal duct was examined. Hot water was in the range of 35 o C ~ 65 o C. Cold air was approximately 25 o C. The air velocity was varied from 0.0656 m/s ~ 1.41 m/s. The heat transfer rate from the water flow to the air flow became large with an increase in the air velocity. The higher the water temperature was, the larger the heat transfer rate was. When the total heat flux from water to the air flow is divided into two terms; the evaporation term and the forced flow convection term, the evaporation term dominate main part and that is about 90 ~ 80 % of the total heat flux. The measured values of the evaporation term and the forced flow convection term were larger than the predicted because of the effect of the diffusion of evaporated vapor. The correlation to predict the heat transfer from the hot water flow to the cold air flow with the evaporation was developed by modifying the laminar flow mass transfer correlation and the laminar forced convection heat transfer correlation. Good results were obtained. (author)

  2. Evaporation heat transfer of hot water from horizontal free service

    Energy Technology Data Exchange (ETDEWEB)

    Koizumi, Y.; Ebihara, Y.; Hirota, T. [Shinshu Univ., Ueda, Nagano (Japan); Murase, M. [INSS, Mihama-cho, Fukui (Japan)

    2011-07-01

    Evaporation heat transfer from the hot water flow to the cold air flow in a horizontal duct was examined. Hot water was in the range of 35{sup o}C ~ 65{sup o}C. Cold air was approximately 25{sup o}C. The air velocity was varied from 0.0656 m/s ~ 1.41 m/s. The heat transfer rate from the water flow to the air flow became large with an increase in the air velocity. The higher the water temperature was, the larger the heat transfer rate was. When the total heat flux from water to the air flow is divided into two terms; the evaporation term and the forced flow convection term, the evaporation term dominate main part and that is about 90 ~ 80 % of the total heat flux. The measured values of the evaporation term and the forced flow convection term were larger than the predicted because of the effect of the diffusion of evaporated vapor. The correlation to predict the heat transfer from the hot water flow to the cold air flow with the evaporation was developed by modifying the laminar flow mass transfer correlation and the laminar forced convection heat transfer correlation. Good results were obtained. (author)

  3. Investigation of Horizontal Velocity Fields in Stirred Vessels with Helical Coils by PIV

    Directory of Open Access Journals (Sweden)

    Volker Bliem

    2014-01-01

    Full Text Available Horizontal velocity flow fields were measured by particle image velocimetry for a stirred vessel with baffles and two helical coils for enlargement of heat transfer area. The investigation was carried out in a cylindrical vessel with flat base and two different stirrers (radial-flow Rushton turbine and axial-flow propeller stirrer. Combined velocity plots for flow fields at different locations are presented. It was found that helical coils change the flow pattern significantly. Measurements for the axial-flow Rushton turbine showed a strong deflection by the coils, leading to a mainly tangential flow pattern. Behind baffles large areas of unused heat transfer area were found. First results for the axial-flow propeller reveal an extensive absence of fluid movement in the horizontal plane. Improved design considerations for enhanced heat transfer by more compatible equipment compilation are proposed.

  4. Ecotoxicity testing and environmental risk assessment of iron nanomaterials for sub-surface remediation – Recommendations from the FP7 project NanoRem

    DEFF Research Database (Denmark)

    Hjorth, Rune; Coutris, Claire; Nguyen, Nhung

    2017-01-01

    engineered Fe nanomaterials, specifically, Nano-Goethite, Trap-Ox Fe-zeolites, Carbo-Iron® and FerMEG12, developed within the European FP7 project NanoRem for sub-surface remediation towards a test battery consisting of eight ecotoxicity tests on bacteria (V. fisheri, E. coli), algae (P. subcapitata...... milled nZVI (FerMEG12), showed no toxicity in the test battery when tested in concentrations up to 100 mg/L, which is the cutoff for hazard labeling in chemicals regulation in Europe. However it should be noted that Fe nanomaterials proved challenging to test adequately due to their turbidity...

  5. Shallow sub-surface structure of the central volcanic complex of Tenerife, Canary Islands: implications for the evolution and the recent reactivation of the Las Canadas caldera

    Energy Technology Data Exchange (ETDEWEB)

    Gottsmann, J [Department of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol BS8 1RJ (United Kingdom); Camacho, A G; Fernandez, J [Instituto de Astronomia y Geodesia (CSIC-UCM), Ciudad Universitaria, Pza. de Ciencias, 3, 28040 Madrid (Spain); MartI, J [Institute of Earth Sciences ' Jaume Almera' , CSIC, Lluis Sole SabarIs s/n, Barcelona 08028 (Spain); Wooller, L; Rymer, H [Department of Earth and Environmental Sciences, Open University, Walton Hall, Milton Keynes, MK7 6AA (United Kingdom); GarcIa, A [Department of Volcanology, Museo Nacional de Ciencias Naturales, CSIC, C/ Jose Gutierrez Abascal, 2, 28006 Madrid (Spain)], E-mail: j.gottsmann@bristol.ac.uk

    2008-10-01

    We present a new local Bouguer anomaly map of the Central Volcanic Complex (CVC) of Tenerife, Spain. The high-density core of the CVC and the pronounced gravity low centred in the Las Canadas caldera (LCC) in greater detail than previously available. Mathematical construction of a subsurface model from the local anomaly data, employing a 3-D inversion enables mapping of the shallow structure beneath the complex, giving unprecedented insights into the sub-surface architecture of the complex, and shedding light on its evolution.

  6. Experimental study of buoyancy driven natural ventilation through horizontal openings

    OpenAIRE

    Heiselberg, Per; Li, Zhigang

    2007-01-01

    An experimental study of buoyancy driven natural ventilation through single-sided horizontal openings was performed in a full-scale laboratory test rig. Measurements were made for opening ratios L/D range from 0.027 to 4.455, where L and D are the length and the diameter of the opening, respectively. The bidirectional air flow rate was measured using constant injection tracer gas technique. Smoke visualizations showed that the air flow patterns are highly transient, unstable and complex, and ...

  7. Explorando nuevos horizontes en NASA

    Science.gov (United States)

    Villanueva, G. L.

    A pesar de la incesante expansión del Universo iniciada con el Big Bang 14 mil millones de años atrás, nuestro Universo se siente cada día más cercano. La inquebrantable vocación de la humanidad por descubrir nuevos horizontes ha permitido el acercamiento de civilizaciones en nuestro planeta y nos ha permitido conocer nuestro lugar en el Universo como nunca antes. En este artículo presento una breve sinopsis de nuestro trabajo que se relaciona con diversas investigaciones con implicaciones astrobiológicas, desde el origen de los ingredientes de la "sopa de la vida", hasta la evolución y composición de la atmósfera de Marte.

  8. Nuclear component horizontal seismic restraint

    International Nuclear Information System (INIS)

    Snyder, G.J.

    1988-01-01

    In a nuclear reactor having a reactor vessel, a reactor guard vessel, a thermal insulation shell and a horizontal seismic restraint, a restraint is described comprising: a. a first ring on the wall of the reactor vessel; b. a second ring on the wall of the reactor guard vessel in alignment with the first ring; c. a first block attached to the second ring proximate the first ring so as to provide a predetermined clearance between the first block and the first ring which is reduced to zero during thermal expansion; d. motion limit means extending through an aperture in the thermal insulation shell in alignment with the second ring and the first block; the e. a second block attached to the motion limit means proximate the second ring and in alignment the first block so as to provide a predetermined clearance between the second block and the second ring which is reduced to zero during thermal expansion

  9. INVESTIGATION OF ADMIXTURE SEDIMENTATION IN THE HORIZONTAL SETTLER

    Directory of Open Access Journals (Sweden)

    V. A. Kozachyna

    2016-08-01

    Full Text Available Purpose.Sedimentation by gravity is the most common and extensively applied treatment process for the removal of solids from water and wastewater and it has been used for over one hundred years. Sedimentation tanks are one of the major parts of a treatment plant especially in purification of turbid flows. Horizontal settlers are mainly used for purification of high quantity of water. In these tanks, the low speed turbid water will flow through the length of the tank and suspended particle have enough time to settle. Finding new and useful methods for calculating and increasing hydraulic efficiency of horizontal settlers is the objective of many theoretical, experimental and numerical studies.But currently used models and methods in Ukraine do not allow taking into account geometrical form and various design features. In this paper the numerical model was developed to evaluate the effectiveness of horizontal settler with modified structure. Methodology. Numerical model is based on: 1 equation of viscous fluid dynamics; 2 mass transfer equation. For numerical simulation the finite difference schemes are used. The numerical calculation is carried out on a rectangular grid. For the formation of the computational domain markers are used. Findings.The model allows obtaining the purification process in the settler with different form and different configuration of baffles. Originality. A new approach to investigate the mass transfer process in horizontal settler was proposed. This approach is based on the developed CFD model. The fluid dynamics model was used for the numerical investigation of flows and waste waters purification. To investigate influence of baffles on settler efficiency physical experiment was carried out. Practical value.The developed model has more capacity than the existing models in Ukraine. The developed model allows computing quickly the efficiency of water purification in settlers. The model is not computationally expensive

  10. Heat transfer during forced convection condensation inside horizontal tube

    Energy Technology Data Exchange (ETDEWEB)

    Tandon, T.N. [M.M.M. Engineering College, Gorakhpur, Uttar Pradesh (India). Dept. of Mechanical Engineering; Varma, H.K.; Gupta, C.P. [Roorkee Univ., Uttar Pradesh (India). Dept. of Mechanical and Industrial Engineering

    1995-03-01

    This paper presents the results of an experimental investigation on heat transfer behaviour during forced convection condensation inside a horizontal tube for wavy, semi-annular and annular flows. A qualitative study was made of the effect of various parameters - refrigerant mass flux, vapour quality, condensate film temperature drop and average vapour mass velocity - on average condensing-heat transfer coefficient. Akers-Rosson correlations have been found to predict the heat transfer coefficients within {+-} 25% for the entire range of data. A closer examination of the data revealed that the nature of the relation for the heat transfer coefficient changes from annular and semi-annular flow to wavy flow. Akers-Rosson correlations with changed constant and power have been recommended for the two flow regimes. (author)

  11. Penetrating particles in horizontal air showers

    International Nuclear Information System (INIS)

    Wohlenberg, J.; Boehm, E.

    1975-01-01

    Particle density and arrival time of muons has been measured in Horizontal Air Showers. 5,600 showers have been recorded in 7,800 hours. Using stringent selection criteria 155 showers have been found horizontal (zenith angle larger 70 0 ) in the size range 4.1 > lg N > 5.5. The muons observed in these showers can be explained by purely electromagnetic origin of horizontal showers. (orig.) [de

  12. Flooding in a loop with a vertical and a horizontal tube connected by an elbow

    International Nuclear Information System (INIS)

    Yan Changqi

    1994-01-01

    The experimental research of flooding and flow-reverse in a test loop which a vertical and a horizontal tube connected by an elbow is introduced. According to the experimental results, the effects of the elbow on flooding and flow-reverse is analyzed. The experimental results is compared with the results obtained in vertical tubes. The effect of horizontal tube length and hysteresis in de-flooding are analyzed. Dimensionless parameters was used in data process. The correlations for predicting the flooding point, de-flooding point, completed carry up and flow reverse points are given

  13. Bubble growth in a narrow horizontal space

    Energy Technology Data Exchange (ETDEWEB)

    Stutz, Benoit; Goulet, Remi [CETHIL, UMR5008, CNRS, INSA-Lyon, Universite Lyon1 (France); Passos, Julio Cesar [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. de Engenharia Mecanica. LABSOLAR

    2009-07-01

    The purpose of this work is to develop an axis-symmetric two-phase flow model describing the growth of a single bubble squeezed between a horizontal heated upward-facing disc and an insulating surface placed parallel to the heated surface. Heat transfers at the liquid-vapour interfaces are predicted by the kinetic limit of vaporisation. The depths of the liquid films deposed on the surfaces (heated surface and confinement space) are determined using the Moriyama and Inoue correlation (1996). Transient heat transfers within the heated wall are taken into account. The model is applied to pentane bubble growth. The influence of the gap size, the initial temperature of the system, the thermal effusivity of the heated wall and the kinetic limit of vaporisation are studied. The results show that the expansion of the bubbles strongly depends on the gap size and can be affected by the effusivity of the material. Mechanical inertia effects are mainly dominant at the beginning of the bubble expansion. Pressure drop induced by viscous effects have to be taken into account for high capillary numbers. Heat transfers at the meniscus are negligible except at the early stages of the bubble growth. (author)

  14. Bubble growth in a narrow horizontal space

    International Nuclear Information System (INIS)

    Stutz, Benoit; Goulet, Remi; Passos, Julio Cesar

    2009-01-01

    The purpose of this work is to develop an axis-symmetric two-phase flow model describing the growth of a single bubble squeezed between a horizontal heated upward-facing disc and an insulating surface placed parallel to the heated surface. Heat transfers at the liquid-vapour interfaces are predicted by the kinetic limit of vaporisation. The depths of the liquid films deposed on the surfaces (heated surface and confinement space) are determined using the Moriyama and Inoue correlation (1996). Transient heat transfers within the heated wall are taken into account. The model is applied to pentane bubble growth. The influence of the gap size, the initial temperature of the system, the thermal effusivity of the heated wall and the kinetic limit of vaporisation are studied. The results show that the expansion of the bubbles strongly depends on the gap size and can be affected by the effusivity of the material. Mechanical inertia effects are mainly dominant at the beginning of the bubble expansion. Pressure drop induced by viscous effects have to be taken into account for high capillary numbers. Heat transfers at the meniscus are negligible except at the early stages of the bubble growth. (author)

  15. Vertical and horizontal access configurations

    International Nuclear Information System (INIS)

    Spampinato, P.T.

    1987-01-01

    A number of configuration features and maintenance operations are influenced by the choice of whether a design is based on vertical or horizontal access for replacing reactor components. The features which are impacted most include the first wall/blanket segmentation, the poloidal field coil locations, the toroidal field coil number and size, access port size for in-vessel components, and facilities. Since either configuration can be made to work, the choice between the two is not clear cut because both have certain advantages. It is apparent that there are large cost benefits in the poloidal field coil system for ideal coil locations for high elongation plasmas and marginal savings for the INTOR case. If we assume that a new tokamak design will require a higher plasma elongation, the recommendation is to arrange the poloidal field coils in a cost-effective manner while providing reasonable midplane access for heating interfaces and test modules. If a new design study is not based on a high elongation plasma, it still appears prudent to consider this approach so that in-vessel maintenance can be accomplished without moving very massive structures such as the bulk shield. 10 refs., 29 figs., 3 tabs

  16. Horizontal vortex single chamber hydroturbine

    Directory of Open Access Journals (Sweden)

    Sergio Antonio Zarate-Orrego

    2016-01-01

    Full Text Available Se evaluó una máquina con alta resistencia de forma para extraer energía de una quebrada, río o corriente marina, y generar electricidad. Sin instrumentos adecuados, la investigación fue cualitativa. Se supuso que si aun así funcionaba, su comportamiento podía mejorar suavizándose la forma. El aparato tiene una tobera semi-convergente de paredes planas, una cámara de vórtice cilíndrica y un rodete. Capta agua por su sección mayor y la descarga tangencialmente por su sección menor en la cámara de vórtice; ésta tiene un orificio en una de sus paredes laterales. Así forma un vórtice horizontal que hace girar un rodete cuyo eje acciona un generador eléctrico. El trabajo experimental realizado mostró que sí es posible producir energía eléctrica con este dispositivo pese a las condiciones adversas en que se ensayó.

  17. Horizontal gene transfer between bacteria.

    Science.gov (United States)

    Heuer, Holger; Smalla, Kornelia

    2007-01-01

    Horizontal gene transfer (HGT) refers to the acquisition of foreign genes by organisms. The occurrence of HGT among bacteria in the environment is assumed to have implications in the risk assessment of genetically modified bacteria which are released into the environment. First, introduced genetic sequences from a genetically modified bacterium could be transferred to indigenous micro-organisms and alter their genome and subsequently their ecological niche. Second, the genetically modified bacterium released into the environment might capture mobile genetic elements (MGE) from indigenous micro-organisms which could extend its ecological potential. Thus, for a risk assessment it is important to understand the extent of HGT and genome plasticity of bacteria in the environment. This review summarizes the present state of knowledge on HGT between bacteria as a crucial mechanism contributing to bacterial adaptability and diversity. In view of the use of GM crops and microbes in agricultural settings, in this mini-review we focus particularly on the presence and role of MGE in soil and plant-associated bacteria and the factors affecting gene transfer.

  18. An Analysis of Saturated Film Boiling Heat Transfer from a Vertical Slab with Horizontal Bottom Surface

    OpenAIRE

    茂地, 徹; 山田, たかし

    1997-01-01

    The film boiling heat transfer from a vertical slab with horizontal bottom surface to saturated liquids was analyzed theoretically. Bromley's solution for the vertical surface was modified to accommodate the continuity of the vapor mass flow rate around the lower corner of the vertical slab. The thickness of the vapor film covering the vertical surface of the slab was increased owing to the inflow of vapor generated under the horizontal bottom surface and resulted in a decrease in the heat tr...

  19. The Process of Horizontal Differentiation: Two Models.

    Science.gov (United States)

    Daft, Richard L.; Bradshaw, Patricia J.

    1980-01-01

    Explores the process of horizontal differentiation by examining events leading to the establishment of 30 new departments in five universities. Two types of horizontal differentiation processes--administrative and academic--were observed and each was associated with different organizational conditions. (Author/IRT)

  20. Horizontal drilling assessment in Western Canada

    International Nuclear Information System (INIS)

    Catania, Peter; Wilson, Malcolm

    1999-01-01

    The first horizontal well was drilled in Saskatchewan in 1987. Since then, the number of horizontal wells drilled has escalated rapidly, averaging approximately 500 per year since 1993. When combined with horizontal wells drilled in Alberta, the major Canadian oil-producing province, the total number drilled in 1995 was 978. This total exceeds the National Energy Board (NEB) projected maximum of 816 wells per year. The NEB projections were based on a break-even point for the drilling of horizontal wells of a return of CDN $285,000 using a discount rate of 15%. This corresponded to a cumulative production from each individual well of some 11,000 m 3 . The introduction of a royalty-free production volume of 12,000 m 3 per horizontal well in Saskatchewan was instrumental in stimulating the rapid expansion in the use of horizontal wells and helping Canada to exceed the forecasted drilling level. Within Saskatchewan, daily production from 1964 active horizontal wells is in excess of 20,000 m 3 . Comparative analysis indicates that the average daily production per well has increased from approximately by 40% with the advent of horizontal wells. In total production terms, provincial production has increased from 11.7 million cubic metres in 1989 to 20.9 million m 3 in 1996. This represents an increase of almost 79% based primarily on the extensive use of horizontal wells. In 1996, horizontal wells produced 36% of the province's oil from 12% of the active wells. In the southeastern producing areas of Saskatchewan, the Williston Basin, declining oil-production has jumped 100%, with horizontal wells accounting for approximately 50% of total regional production. Pay zones in this areas, as in most of the province, tend to be relatively thin, with net pay frequently less that 5 m. The modest investment of some CDN $5 million in government research funding 10 years ago to stimulate the development of horizontal wells, combined with a favourable royalty structure, has been at

  1. Potential for horizontal well technology in the U.S

    International Nuclear Information System (INIS)

    Biglarbigi, K.; Mohan, H.; Ray, R.M.; Meehan, D.N.

    2000-01-01

    In the past decade, the use of horizontal well technology has increased significantly in the U.S., contributing to the drilling of 600 to 1000 horizontal oil wells annually. A total of 86 per cent of the existing horizontal wells have been drilled in three formations, the Austin chalk in Texas, the Bakken shale in North Dakota, and the Niobrara in Colorado and Wyoming. A unique analytical system has been developed by the United States Department of Energy, National Petroleum Technology Office (USDOE/NPTO) to assess the potential for greater use of horizontal well technology for other oil resources in other geological formations. The analytical system is designed to be used in association with other enhanced recovery methods that make up the DOE's Total Oil Recovery Information System (TORIS). The DOE/NPTO collaborated with industry to identify the target resource for horizontal well technology and to evaluate its future recovery potential under different economic and technological conditions. This paper provides a national summary of the potential for additional production and reserves with more diverse application of horizontal wells in various types of U.S. oil resources, including the rest of the fractured reservoirs in the Austin chalk, other fractured reservoirs in the north and northwestern states, thin-bed reservoirs, and mature waterflood field. The results were presented in terms of production, reserves and national economic benefits with a full cash-flow analysis at oil prices in the range of $16 to $24 U.S. per bbl. It is estimated that 541 million to 1 billion bbls of new reserves are economically producible at these prices. The reserves estimates pertain to future horizontal wells in known fields only and are in addition to the reserves for the existing wells as of 1 January 1998. Potential production is substantial, ranging from 50 million to 85 million bbl per year by 2004 and then declining at a rate of 8 per cent per year in the following years

  2. Intelligent sensors for evaluating reservoir and well profiles in horizontal wells : Saudi Arabia case histories

    Energy Technology Data Exchange (ETDEWEB)

    Al-Buali, M.H.; Dashash, A.A. [Saudi Aramco, Dhahran (Saudi Arabia); El Gammal, T.; Arevalo, F.; Torne, J. [Halliburton Energy Services, Calgary, AB (Canada)

    2010-07-01

    Horizontal wells are commonly used in Saudi Arabia because they have proven advantages in optimizing production and cost. However, in order to ensure proper production, these wells occasionally require downhole measurements of the flow profile; wellbore parameters such as water entry points; and productivity index for remedial action, such as water shut off or well stimulation. Evaluating the performance of a well also contributes to a better understanding of sweep, water production and cross flow, particularly in long reach wells. The most common flow regime at downhole conditions is a stratified flow regime in which lighter oil flows on top and heavier water flows on bottom. Slugging and bubbling flow regimes are typical of low oil flow rate and are considered unstable flow regimes. This paper described a new generation of production logging tools (PLTs) that have been used on some horizontal wet producers located in Saudi Arabia. The new PLTs consists of arrays of spinners and sensors to log the entire cross section to describe the horizontal flow regime and measure the downhole production and phases. In an effort to find the best logging procedure, the PLT was tested using two methods, notably coiled tubing (CT) and wireline tractor. It was concluded that PLTs are reliable and accurate. Case studies involving planning, deployment, data acquisition, and detailed analysis of PLTs were presented. 35 refs., 1 tab., 20 figs.

  3. Horizontal subsurface flow constructed wetlands for mitigation of ...

    African Journals Online (AJOL)

    2008-12-22

    Dec 22, 2008 ... Results indicated that 39% of the total initially added amount of ametryn ... characteristics (Table 1), may result in the detection of poten- ... Water solubility at 20oC (g∙m-3) 204 ... culture, part of the resident liquid in CWs was lost, therefore ..... LIN T, WEN y, JIANG L, LI J, yANG S and ZHOu Q (2008) Study.

  4. Warm season performance of horizontal subsurface flow constructed ...

    African Journals Online (AJOL)

    user

    2013-06-14

    Jun 14, 2013 ... degradation and population risk of diseases particularly ..... 5G: gravel substrate with a HRT of 5 days; 5S: sand substrate with a HRT of 5 days; 10G: gravel substrate with a .... American Public Health Association; American.

  5. Materials and proportion's design of self-compacting mortar used for low diffusion layer in sub-surface radioactive waste disposal facility in Japan

    International Nuclear Information System (INIS)

    Niwase, Kazuhito; Sugihashi, Naoyuki; Tsuji, Yukikazu

    2010-01-01

    This paper describes the design procedure for the material selection and mix proportion of the self-compacting mortar used for low diffusion layer cementitious material in the sub-surface radioactive waste disposal facility in Japan. The low diffusion layer is required for reducing transportation by controlling diffusion of a radionuclide. Therefore the low diffusion, cracks control, and low leaching are the important matters in the mix design. The process to select mortar mix design of the low diffusion layer is explained in detail. Of 33 kinds mix proportions used in laboratory comparative testing, the combinations of low heat portland cement, fly ash, lime powder and expansive addition was provisionally set to the mix proportion of the self-compacting mortar used for low diffusion layer. (author)

  6. The role of the northward-directed (sub)surface limb of the Atlantic Meridional Overturning Circulation during the 8.2 ka Event

    Science.gov (United States)

    Tegzes, A. D.; Jansen, E.; Telford, R. J.

    2014-02-01

    The so-called "8.2 ka Event" has been widely regarded as a major climate perturbation over the Holocene. It is most readily identifiable in the oxygen-isotope records from Greenland ice cores as an approximately 160 yr-long cold interval between 8250-8090 yr BP. The prevailing view has been that the cooling over Greenland, and potentially over the northern North Atlantic at least, was triggered by the catastrophic final drainage of the Agassiz-Ojibway proglacial lake as part of the remnant Laurentide Ice Sheet collapsed over Hudson Bay at around 8420 ± 80 yr BP. The consequent freshening of surface waters in the northern North Atlantic Ocean and the Nordic Seas resulted in weaker overturning, hence reduced northward heat transport. Here we present proxy records from site JM97-MD95-2011 on the mid-Norwegian Margin indicating a (sharp) decline in the strength of the eastern branch of the Atlantic Inflow into the Nordic Seas immediately following a uniquely large drop in (sub)surface ocean temperatures coeval with the lake outbursts. We propose that the final drainage of Lake Agassiz-Ojibway was accompanied by a major iceberg discharge from Hudson Bay, which resulted in the cooling of the northward-directed northern Gulf Stream-North Atlantic Drift-Norwegian Atlantic Current system. Since our current-strength proxy records from the mid-Norwegian Margin do not evidence an exceptionally strong reduction in the main branch of the Atlantic Inflow into the Nordic Seas at the time, we argue that a chilled northward-directed (sub)surface-current system and an already colder background climate state could be the main factors responsible for the 8.2 ka climate perturbation.

  7. Productivity and injectivity of horizontal wells. Annual report for the period, March 10, 1994--March 9, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Fayers, F.J.

    1995-07-01

    Contents of this annual report include the following: (1) detailed well model for reservoir simulation--task 1; (2) comparative aspects of coning behavior in vertical and horizontal wells--task 1; (3) skin factor calculations for vertical, deviated, and horizontal wells--task 2; (4) a dissipation-based coarse grid system and its application to the scaleup of two phase problems--tasks 2 and 4; (5) analyses of experiments at Marathon Oil Company--task 3; (6) development of mechanistic model for multiphase flow in horizontal wells--task 3; and (7) sensitivity studies of wellbore friction and inflow for a horizontal well--task 8.

  8. Interpretation of horizontal well performance in complicated systems by the boundary element method

    Energy Technology Data Exchange (ETDEWEB)

    Jongkittinarukorn, K.; Tiab, D. [Oklahoma Univ., School of Petroleum and Geological Engineering (United States); Escobar, F. H. [Surcolombiana Univ., Dept. of Petroleum Engineering (Colombia)

    1998-12-31

    A solution obtained by using the boundary element method to simulate pressure behaviour of horizontal wells in complicated reservoir-wellbore configurations is presented. Three different types of well bore and reservoir models were studied, i.e. a snake-shaped horizontal wellbore intersecting a two-layer reservoir with cross flow, a horizontal well in a three-layer reservoir with cross flow, and a vertical well intersecting a two-layer reservoir without cross flow. In each case, special attention was paid to the influence of wellbore inclination angle, the distance from the wellbore to the different boundaries and the permeability ratio. Performance of each of these types of wells are discussed. 9 refs., 18 figs.

  9. Nucleate boiling heat transfer on horizontal tubes in bundles

    International Nuclear Information System (INIS)

    Fujital, Y.; Ohta, H.; Hidaka, S.; Nishikawa, K.

    1986-01-01

    In order to clarify the heat transfer mechanisms of the flooded type horizontal tube bundle evaporator, heat transfer characteristics of tube bundles of experimental scale which consist both of smooth and enhanced tubes were investigated in detail. The experiments of saturated nucleate boiling were performed by using Freon 113 under pressures 0.1 to 1 MPa, and the effects of various parameters, for example, bundle arrangement, heat flux, pressure on the characteristics of an individual tube are clarified. Experimental data is reproduced well by a proposed heat transfer model in which convective heat transfer coefficients due to rising bubbles are estimated as a function of their volumetric flow rate

  10. Evacuation of children - movement on stairs and on Horizontal Plane

    DEFF Research Database (Denmark)

    Larusdottir, Aldis Run; Dederichs, Anne

    2012-01-01

    in full scale evacuation experiments where two age groups 0-2 years and 3-6 years were analyzed separately. It was found that flow through doors, walking speeds and densities were age-dependent and differed strongly from the data in existing literature. The results showed higher walking speeds in spiral...... slower in horizontal plane than adults, however they were keen to run during the evacuations, in the latter case their travel speed increased and exceeded the adults’. Since the evacuation characteristics of children differ in many ways from those of adults, nowadays models badly comprehend...

  11. Maximum allowable heat flux for a submerged horizontal tube bundle

    International Nuclear Information System (INIS)

    McEligot, D.M.

    1995-01-01

    For application to industrial heating of large pools by immersed heat exchangers, the socalled maximum allowable (or open-quotes criticalclose quotes) heat flux is studied for unconfined tube bundles aligned horizontally in a pool without forced flow. In general, we are considering boiling after the pool reaches its saturation temperature rather than sub-cooled pool boiling which should occur during early stages of transient operation. A combination of literature review and simple approximate analysis has been used. To date our main conclusion is that estimates of q inch chf are highly uncertain for this configuration

  12. Ferrofluid meniscus in a horizontal or vertical magnetic field

    International Nuclear Information System (INIS)

    Rosensweig, R.E.; Elborai, S.; Lee, S.-H.; Zahn, M.

    2005-01-01

    An optical system using reflections of a narrow laser beam to measure the height and shape of a ferrofluid meniscus in response to uniform applied magnetic fields finds that meniscus height on a vertical flat wall decreases in horizontal applied field and increases in vertical applied field. An approximate energy minimization analysis predicts meniscus height in directional agreement with measurements. This study is a first step in calculating the tangential surface force acting in flows where magnetization magnitude and direction lag a changing magnetic field direction, and the meniscus shape is magnetically perturbed

  13. Full-scale fire experiments on vertical horizontal cable trays

    International Nuclear Information System (INIS)

    Mangs, J.; Keski-Rahkonen, O.

    1997-10-01

    Two full-scale fire experiments on PVC cables used in nuclear power plants were carried out, one with cables in vertical position and one with cables in horizontal position. The vertical cable bundle, 3 m high, 300 mm wide and 30 mm thick, was attached to a steel cable ladder. The vertical bundle experiment was carried out in nearly free space with three walls near the cable ladder guiding air flow in order to stabilise flames. The horizontal cable experiment was carried out in a small room with five cable bundles attached to steel cable ladders. Three of the 2 m long cable bundles were located in an array, equally spaced above each other near one long side of the room and two correspondingly near the opposite long side. The vertical cable bundle was ignited with a small propane gas burner beneath the lower edge of the bundle. The horizontal cable bundles were ignited with a small propane burner beneath the lowest bundle in an array of three bundles. Rate of heat release by means of oxygen consumption calorimetry, mass change, CO 2 , CO and smoke production rate and gas, wall and cable surface temperatures were measured as a function of time, as well as time to sprinkler operation and failure of test voltage in cables. Additionally, the minimum rate of heat release needed to ignite the bundle was determined. This paper concentrates on describing and recording the experimental set-up and the data obtained. (orig.)

  14. Horizontal steam generator thermal-hydraulics

    Energy Technology Data Exchange (ETDEWEB)

    Ubra, O. [SKODA Praha Company, Prague (Czechoslovakia); Doubek, M. [Czech Technical Univ., Prague (Czechoslovakia)

    1995-09-01

    Horizontal steam generators are typical components of nuclear power plants with pressure water reactor type VVER. Thermal-hydraulic behavior of horizontal steam generators is very different from the vertical U-tube steam generator, which has been extensively studied for several years. To contribute to the understanding of the horizontal steam generator thermal-hydraulics a computer program for 3-D steady state analysis of the PGV-1000 steam generator has been developed. By means of this computer program, a detailed thermal-hydraulic and thermodynamic study of the horizontal steam generator PGV-1000 has been carried out and a set of important steam generator characteristics has been obtained. The 3-D distribution of the void fraction and 3-D level profile as functions of load and secondary side pressure have been investigated and secondary side volumes and masses as functions of load and pressure have been evaluated. Some of the interesting results of calculations are presented in the paper.

  15. Horizontal cooperation in transport and logistics

    NARCIS (Netherlands)

    Cruijssen, F.C.A.M.

    2006-01-01

    This thesis deals with horizontal cooperation in transport and logistics. It contains a comprehensive discussion of the available academic literature on this topic, many practical examples, and an empirical investigation of opportunities and impediments. Furthermore, three enabling concepts for

  16. Removal of nutrients from septic tank effluent with baffle subsurface-flow constructed wetlands

    Science.gov (United States)

    Lihu Cui; Ying Ouyang; Weizhi Yang; Zhujian Huang; Qiaoling Xu; Guangwei Yu

    2015-01-01

    Three new baffle flow constructed wetlands (CWs), namely the baffle horizontal flow CW (Z1), baffle vertical flow CW (Z2) and baffle hybrid flow CW (Z3), along with one traditional horizontal subsurface flow CW (Z4) were designed to test the removal efficiency of nitrogen (N) and phosphorus (P) from the septic tank effluent under varying hydraulic retention times (HRTs...

  17. Warming Effects on Enzyme Activities are Predominant in Sub-surface Soils of an Arctic Tundra Ecosystem over 6-Year Field Manipulation

    Science.gov (United States)

    Kang, H.; Seo, J.; Kim, M.; Jung, J. Y.; Lee, Y. K.

    2017-12-01

    Arctic tundra ecosystems are of great importance because they store a large amount of carbon as un-decomposed organic matter. Global climate change is expected to affect enzyme activities and heterotrophic respiration in Arctic soils, which may accelerate greenhouse gas (GHG) emission through positive biological feedbacks. Unlike laboratory-based incubation experiments, field measurements often show different warming effects on decomposition of organic carbon and releases of GHGs. In the present study, we conducted a field-based warming experiment in Cambridge Bay, Canada (69°07'48″N, 105°03'36″W) by employing passive chambers during growing seasons over 6 years. A suite of enzyme activities (ß-glucosidase, cellobiohydrolase, N-acetylglucosaminidase, leucine aminopeptidase and phenol oxidase), microbial community structure (NGS), microbial abundances (gene copy numbers of bacteria and fungi), and soil chemical properties have been monitored in two depths (0-5 cm and 5-10 cm) of tundra soils, which were exposed to four different treatments (`control', `warming-only', `water-addition only', and both `warming and water-addition'). Phenol oxidase activity increased substantially, and bacterial community structure and abundance changed in the early stage (after 1 year's warming manipulation), but these changes disappeared afterwards. Most hydrolases were enhanced in surface soils by `water-addition only' over the period. However, the long-term effects of warming appeared in sub-surface soils where both `warming only' and `warming and water addition' increased hydrolase activities. Overall results of this study indicate that the warming effects on enzyme activities in surface soils are only short-term (phenol oxidase) or masked by water-limitation (hydrolases). However, hydrolases activities in sub-surface soils are more strongly enhanced than surface soils by warming, probably due to the lack of water limitation. Meanwhile, negative correlations between hydrolase

  18. Influence of stiffness on CHF for horizontal tubes under LPLF conditions

    Energy Technology Data Exchange (ETDEWEB)

    Baburajan, P.K. [Nuclear Safety Analysis Division, AERB, Niyamak Bhavan, 400094 (India); Bisht, Govind Singh [Department of Mechanical Engineering, IIT Bombay, 400076 (India); Gaikwad, Avinash J. [Nuclear Safety Analysis Division, AERB, Niyamak Bhavan, 400094 (India); Prabhu, S.V., E-mail: svprabhu@iitb.ac.in [Department of Mechanical Engineering, IIT Bombay, 400076 (India)

    2014-10-01

    Highlights: • Effect of stiffness on the CHF in horizontal tube under LPLF conditions is studied. • CHF increases with the increase in stiffness. • Correlation for the prediction of CHF as a function of stiffness is developed. • Correlation for mass flux at CHF in terms of stiffness and initial mass flux is given. • RELAP5 is capable of predicting the effect of stiffness on CHF. - Abstract: Studies reported in the past on critical heat flux (CHF) are mostly limited to vertical flow, large channel diameter, high pressure and high mass flux. Since horizontal flow is commonly encountered in boiler tubes, refrigerating equipments and nuclear reactor fuel channels (PHWR), there is a need to understand horizontal flow CHF, generate sufficient experimental database and to develop reliable predictive method. Few studies are reported on the effect of upstream flow restrictions on flow instabilities and CHF. The present work investigates the effect of upstream flow restriction on CHF in horizontal flow at near atmospheric pressure conditions. In the present study, stiffness is defined as the ratio of upstream flow restriction pressure drop to the test section pressure drop. The classification of a flow boiling system as soft or stiff on the basis of quantification of the stiffness is attempted. Experimental data shows an increase in the CHF with the increase in the stiffness for a given initial mass flux. A correlation for the prediction of CHF under various stiffness conditions is developed. A correlation is suggested to predict the mass flux at CHF as a function of stiffness and initial mass flux. Modeling and transient analysis of the stiffness effect on CHF is carried out using the thermal hydraulic system code RELAP5. The predicted phenomena are in agreement with the experimental observations.

  19. Optical and electronic properties of sub-surface conducting layers in diamond created by MeV B-implantation at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Willems van Beveren, L. H., E-mail: laurensw@unimelb.edu.au; Bowers, H.; Ganesan, K.; Johnson, B. C.; McCallum, J. C.; Prawer, S. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Liu, R. [SIMS Facility, Office of the Deputy-Vice Chancellor (Research and Development) Western Sydney University, Locked Bag 1797, Penrith, New South Wales 2751 (Australia)

    2016-06-14

    Boron implantation with in-situ dynamic annealing is used to produce highly conductive sub-surface layers in type IIa (100) diamond plates for the search of a superconducting phase transition. Here, we demonstrate that high-fluence MeV ion-implantation, at elevated temperatures avoids graphitization and can be used to achieve doping densities of 6 at. %. In order to quantify the diamond crystal damage associated with implantation Raman spectroscopy was performed, demonstrating high temperature annealing recovers the lattice. Additionally, low-temperature electronic transport measurements show evidence of charge carrier densities close to the metal-insulator-transition. After electronic characterization, secondary ion mass spectrometry was performed to map out the ion profile of the implanted plates. The analysis shows close agreement with the simulated ion-profile assuming scaling factors that take into account an average change in diamond density due to device fabrication. Finally, the data show that boron diffusion is negligible during the high temperature annealing process.

  20. NEWTON - NEW portable multi-sensor scienTific instrument for non-invasive ON-site characterization of rock from planetary surface and sub-surfaces

    Science.gov (United States)

    Díaz-Michelena, M.; de Frutos, J.; Ordóñez, A. A.; Rivero, M. A.; Mesa, J. L.; González, L.; Lavín, C.; Aroca, C.; Sanz, M.; Maicas, M.; Prieto, J. L.; Cobos, P.; Pérez, M.; Kilian, R.; Baeza, O.; Langlais, B.; Thébault, E.; Grösser, J.; Pappusch, M.

    2017-09-01

    In space instrumentation, there is currently no instrument dedicated to susceptibly or complete magnetization measurements of rocks. Magnetic field instrument suites are generally vector (or scalar) magnetometers, which locally measure the magnetic field. When mounted on board rovers, the electromagnetic perturbations associated with motors and other elements make it difficult to reap the benefits from the inclusion of such instruments. However, magnetic characterization is essential to understand key aspects of the present and past history of planetary objects. The work presented here overcomes the limitations currently existing in space instrumentation by developing a new portable and compact multi-sensor instrument for ground breaking high-resolution magnetic characterization of planetary surfaces and sub-surfaces. This new technology introduces for the first time magnetic susceptometry (real and imaginary parts) as a complement to existing compact vector magnetometers for planetary exploration. This work aims to solve the limitations currently existing in space instrumentation by means of providing a new portable and compact multi-sensor instrument for use in space, science and planetary exploration to solve some of the open questions on the crustal and more generally planetary evolution within the Solar System.

  1. Transport of plutonium in surface and sub-surface waters from the Arctic shelf to the North Pole via the Lomonosov Ridge

    International Nuclear Information System (INIS)

    Leon Vintro, L.; McMahon, C.A.; Mitchell, P.I.; Josefsson, D.; Holm, E.; Roos, P.

    2002-01-01

    New data on the levels and long-range transport of plutonium in the Arctic Ocean, recorded in the course of two expeditions to this zone in 1994 and 1996, are discussed in this paper. Specifically, approximately 100 plutonium measurements in surface and sub-surface water sampled at 58 separate stations throughout the Kara, Laptev and East Siberian Seas, as well as along latitudinal transects across the Lomonosov Ridge, are reported and interpreted in terms of the circulation pathways responsible for the transport of this element from the North Atlantic to the Arctic Shelf and into the Arctic interior. In addition, the behaviour of plutonium in its transit through the vast Arctic shelf seas to open waters under extreme environmental conditions is discussed in terms of the partitioning of plutonium between filtered (<0.45 μm) seawater and suspended particulate, and its association with colloidal matter. Finally, limited evidence of the presence of a colloidal plutonium component in Arctic waters subject to direct riverine input is adduced

  2. Molecular and risk-based approach to nutrient development for a proposed sub-surface biogasification field trial in a biogenic gas field

    Energy Technology Data Exchange (ETDEWEB)

    Lambo, Adewale J.; Strapoc, Dariusz; Pittenger, Michelle; Huizinga, Bradley [ConocoPhillips (Canada); Wood, Ladonna; Ashby, Matt [Taxon Biosciences (Canada)

    2011-07-01

    This paper presents the molecular and risk-based approach to nutrient development for a proposed sub-surface biogasification field trial in a biogenic gas field. From field sampling, variability was seen in water chemistry and environmental parameters across the field; DNA yield also varied across the field and showed distinct spatial variation. The composition of microbial populations and relative distribution of archaea populations in the Cooks Inlet water is represented using pie and bar charts. The nutrient recipe was developed using known information on nutrient requirements of mathematically correlated microbial associations. The process of on-site nutrient injection is explained. Some of the mitigation plans for the risks involved during the process include, among others, limiting biofilm prevalence and avoiding bio-plugging and bio-corrosion. Biofilm is likely to develop in the injection line but less likely in nutrient mixing due to the high nutrient concentration. From the study, it can be concluded that community composition correlates with field geochemical parameters and methane pathways.

  3. Mid-infrared thermal imaging for an effective mapping of surface materials and sub-surface detachments in mural paintings: integration of thermography and thermal quasi-reflectography

    Science.gov (United States)

    Daffara, C.; Parisotto, S.; Mariotti, P. I.

    2015-06-01

    Cultural Heritage is discovering how precious is thermal analysis as a tool to improve the restoration, thanks to its ability to inspect hidden details. In this work a novel dual mode imaging approach, based on the integration of thermography and thermal quasi-reflectography (TQR) in the mid-IR is demonstrated for an effective mapping of surface materials and of sub-surface detachments in mural painting. The tool was validated through a unique application: the "Monocromo" by Leonardo da Vinci in Italy. The dual mode acquisition provided two spatially aligned dataset: the TQR image and the thermal sequence. Main steps of the workflow included: 1) TQR analysis to map surface features and 2) to estimate the emissivity; 3) projection of the TQR frame on reference orthophoto and TQR mosaicking; 4) thermography analysis to map detachments; 5) use TQR to solve spatial referencing and mosaicking for the thermal-processed frames. Referencing of thermal images in the visible is a difficult aspect of the thermography technique that the dual mode approach allows to solve in effective way. We finally obtained the TQR and the thermal maps spatially referenced to the mural painting, thus providing the restorer a valuable tool for the restoration of the detachments.

  4. The use of chemical analyses of borehole samples in sub-surface mapping: an example of the Delmas-Bapsfontein area is given

    International Nuclear Information System (INIS)

    Rudman, R.A.

    1989-01-01

    The East Rand Dolomites around Delmas-Bapsfontein underlie an area of about 1000 sq. km. but do not outcrop. An intensive ground water exploration programme had been carried out and the percussion samples obtained were analysed in an attempt to differentiate the sub-surface geology based on the chemistry of the samples. The gross chemistry of the various rock types has been well defined and various computer-aided graphical methods were used to highlight changes in the chemistry. Samples were analysed by means of x-ray fluorescence. The chert-rich dolomite formations near surface have been leached to the extent that all of the carbonate minerals have been removed, leaving a chert residium of commonly 80 m thick. The carbonates in this area can be regarded as 'pure' dolomites. There are however two discretely different CaO/MgO ratios present in the study area. Intrusives with up to 16% Na 2 O are noted. The effect of de-dolomitization at the contacts of the intrusives is clearly illustrated. 4 refs., 7 figs., 1 tab

  5. Horizontal alveolar bone loss: A periodontal orphan

    Science.gov (United States)

    Jayakumar, A.; Rohini, S.; Naveen, A.; Haritha, A.; Reddy, Krishnanjeneya

    2010-01-01

    Background: Attempts to successfully regenerate lost alveolar bone have always been a clinician’s dream. Angular defects, at least, have a fairer chance, but the same cannot be said about horizontal bone loss. The purpose of the present study was to evaluate the prevalence of horizontal alveolar bone loss and vertical bone defects in periodontal patients; and later, to correlate it with the treatment modalities available in the literature for horizontal and vertical bone defects. Materials and Methods: The study was conducted in two parts. Part I was the radiographic evaluation of 150 orthopantomographs (OPGs) (of patients diagnosed with chronic periodontitis and seeking periodontal care), which were digitized and read using the AutoCAD 2006 software. All the periodontitis-affected teeth were categorized as teeth with vertical defects (if the defect angle was ≤45° and defect depth was ≥3 mm) or as having horizontal bone loss. Part II of the study comprised search of the literature on treatment modalities for horizontal and vertical bone loss in four selected periodontal journals. Results: Out of the 150 OPGs studied, 54 (36%) OPGs showed one or more vertical defects. Totally, 3,371 teeth were studied, out of which horizontal bone loss was found in 3,107 (92.2%) teeth, and vertical defects were found only in 264 (7.8%) of the teeth, which was statistically significant (P<.001). Search of the selected journals revealed 477 papers have addressed the treatment modalities for vertical and horizontal types of bone loss specifically. Out of the 477 papers, 461 (96.3%) have addressed vertical bone loss, and 18 (3.7%) have addressed treatment options for horizontal bone loss. Two papers have addressed both types of bone loss and are included in both categories. Conclusion: Horizontal bone loss is more prevalent than vertical bone loss but has been sidelined by researchers as very few papers have been published on the subject of regenerative treatment modalities for

  6. Horizontal well impact on heavy oil supply

    International Nuclear Information System (INIS)

    Bowers, B.; Bielecki, J.; Hu, J.; Wall, B.; Drummond, K.

    1993-01-01

    Horizontal wells can take advantage of gravity drainage mechanisms, which can be important in conventional heavy oil and bitumen recovery. Horizontal drilling will impact on the development of established conventional heavy oil pools by infill drilling and application of enhanced recovery techniques. There will also be an impact on the development of extensions to established and newly discovered heavy oil pools, as well as a major impact on development of bitumen resources. To assess the impact of horizontal drilling on heavy oil supply, high-impact and low-impact scenarios were evaluated under specified oil-price assumptions for four heavy oil areas in Saskatchewan and Alberta. Horizontal well potential for infill drilling, waterflood projects, and thermal projects was assessed and estimates were made of such developments as reserves additions and heavy oil development wells under the two scenarios. In the low case, projected supply of conventional heavy oil and bitumen stabilizes at a level in the 90,000-94,000 m 3 /d after 1994. In the high case, overall supply continuously grows from 80,000 m 3 /d in 1992 to 140,000 m 3 /d in 2002. Through application of horizontal drilling, reserves additions in western Canada could be improved by ca 100 million m 3 by 2002. 14 figs., 6 tabs

  7. Process analysis and optimization of direct horizontal-row roughing filtration

    NARCIS (Netherlands)

    Ahsan, T.

    1995-01-01

    There is a growing demand for appropriate water treatment technology for towns and small cities in developing countries. This study developed a pretreatment technology for highly turbid river water, called direct horizontal-flow roughing filtration, by combining the principles of direct filtration

  8. Computation of Added Mass and Damping Coefficients of a Horizontal Circular Cylinder in Open Foam

    DEFF Research Database (Denmark)

    Chen, Hao; Christensen, Erik Damgaard

    2016-01-01

    This paper presents numerical computation of added massand damping coefficients of a slender horizontal cylinder in thefree surface zone, which typically serves as a fish cage floater. A fully viscous two phase flow solver in OpenFOAM was employed in the numerical computation. The purpose...

  9. Cobalt ions inhibit negative feedback in the outer retina by blocking hemichannels on horizontal cells

    NARCIS (Netherlands)

    Fahrenfort, I.; Sjoerdsma, T.; Ripps, H.; Kamermans, M.

    2004-01-01

    In goldfish, negative feedback from horizontal cells to cones shifts the activation function of the Ca2+ current of the cones to more negative potentials. This shift increases the amount of Ca2+ flowing into the cones, resulting in an increase in glutamate release. The increased glutamate release

  10. HORIZONTAL WELL DRILL-IN FLUIDS

    Directory of Open Access Journals (Sweden)

    Nediljka Gaurina-Međimurec

    1998-12-01

    Full Text Available Main objective of horizontal driling is to place a drain-hole for a long distance within the pay zone to enhance productivity or injectivity. In drilling horizontal wells, more serious problems appear than in drilling vertical wells. These problems are: poor hole cleaning, excessive torque and drag, hole filling, pipe stucking, wellbore instability, loss of circulation, formation damage, poor cement job, and difficulties at logging jobs. From that reason, successful drilling and production of horizontal well depends largely on the fluid used during drilling and completion phases. Several new fluids, that fulfill some or all of required properties (hole cleaning, cutting suspension, good lubrication, and relative low formation damage, are presented in this paper.

  11. Heavy crude production from shallow formations: long horizontal wells versus horizontal fractures

    Energy Technology Data Exchange (ETDEWEB)

    Valko, P.; Economides, M. J. [Texas A and M Univ., TX (United States)

    1998-12-31

    The feasibility of producing heavy oil from shallow formations using either horizontal wells or short horizontal wells fractured horizontally is demonstrated. The problem of optimum proppant placement is solved in two steps. In step one, the finite productivity performance is considered in general terms showing that the performance is a function of two dimensionless parameters. Following derivation of optimum conditions, the solution is applied to the horizontal fracture consideration. The limiting factor is that to create an effective finite conductivity fracture, the dimensionless fracture conductivity must be on the order of unity, a fracture that is difficult to realize in higher permeability formations. The best candidates for the suggested configuration are shallow or moderate formations, or formations otherwise proven to accept horizontal fractures, and formations with low permeability/viscosity ratio. 7 refs., 2 tabs., 10 figs., 2 appendices.

  12. Fourth international seminar on horizontal steam generators

    Energy Technology Data Exchange (ETDEWEB)

    Tuomisto, H. [ed.] [IVO Group, Vantaa (Finland); Purhonen, H. [ed.] [VTT, Espoo (Finland); Kouhia, V. [ed.] [Lappeenranta Univ. of Technology (Finland)

    1997-12-31

    The general objective of the International Seminars of Horizontal Steam Generator Modelling has been the improvement in understanding of realistic thermal hydraulic behaviour of the generators when performing safety analyses for VVER reactors. The main topics presented in the fourth seminar were: thermal hydraulic experiments and analyses, primary collector integrity, feedwater distributor replacement, management of primary-to-secondary leakage accidents and new developments in the VVER safety technology. The number of participants, representing designers and manufacturers of the horizontal steam generators, plant operators, engineering companies, research organizations, universities and regulatory authorities, was 70 from 10 countries.

  13. Fourth international seminar on horizontal steam generators

    Energy Technology Data Exchange (ETDEWEB)

    Tuomisto, H [ed.; IVO Group, Vantaa (Finland); Purhonen, H [ed.; VTT, Espoo (Finland); Kouhia, V [ed.; Lappeenranta Univ. of Technology (Finland)

    1998-12-31

    The general objective of the International Seminars of Horizontal Steam Generator Modelling has been the improvement in understanding of realistic thermal hydraulic behaviour of the generators when performing safety analyses for VVER reactors. The main topics presented in the fourth seminar were: thermal hydraulic experiments and analyses, primary collector integrity, feedwater distributor replacement, management of primary-to-secondary leakage accidents and new developments in the VVER safety technology. The number of participants, representing designers and manufacturers of the horizontal steam generators, plant operators, engineering companies, research organizations, universities and regulatory authorities, was 70 from 10 countries.

  14. Fourth international seminar on horizontal steam generators

    International Nuclear Information System (INIS)

    Tuomisto, H.; Purhonen, H.; Kouhia, V.

    1997-01-01

    The general objective of the International Seminars of Horizontal Steam Generator Modelling has been the improvement in understanding of realistic thermal hydraulic behaviour of the generators when performing safety analyses for VVER reactors. The main topics presented in the fourth seminar were: thermal hydraulic experiments and analyses, primary collector integrity, feedwater distributor replacement, management of primary-to-secondary leakage accidents and new developments in the VVER safety technology. The number of participants, representing designers and manufacturers of the horizontal steam generators, plant operators, engineering companies, research organizations, universities and regulatory authorities, was 70 from 10 countries

  15. Transient natural convection with density inversion from a horizontal cylinder

    Science.gov (United States)

    Wang, P.; Kahawita, R.; Nguyen, D. L.

    1992-01-01

    This paper is devoted to a numerical investigation of the free convection flow about a horizontal cylinder maintained at 0 °C in a water ambient close to the point of maximum density. Complete numerical solutions covering both the transient as well as steady state have been obtained. Principal results indicate that the proximity of the ambient temperature to the point of maximum density plays an important role in the type of convection pattern that may be obtained. When the ambient temperature is within 4.7 °Cflow'' appears around the cylinder with both upward and downward flow occurring in proximity to the cylinder in two distinct recirculating zones, generally separated by the 4 °C isotherm when Tamb<5.7 °C. The dual flow behavior is significantly modified as the ambient temperature is altered, disappearing when the ambient temperature is above 8 °C, or below 4.7 °C. Furthermore, when the ambient temperature is within about 4.8 °C

  16. Wetting phase permeability in a partially saturated horizontal fracture

    International Nuclear Information System (INIS)

    Nicholl, M.J.; Glass, R.J.

    1994-01-01

    Fractures within geologic media can dominate the hydraulic properties of the system. Therefore, conceptual models used to assess the potential for radio-nuclide migration in unsaturated fractured rock such as that composing Yucca Mountain, Nevada, must be consistent with flow processes in individual fractures. A major obstacle to the understanding and simulation of unsaturated fracture flow is the paucity of physical data on both fracture aperture structure and relative permeability. An experimental procedure is developed for collecting detailed data on aperture and phase structure from a transparent analog fracture. To facilitate understanding of basic processes and provide a basis for development of effective property models, the simplest possible rough-walled fracture is used. Stable phase structures of varying complexity are created within the horizontal analog fracture. Wetting phase permeability is measured under steady-state conditions. A process based model for wetting phase relative permeability is then explored. Contributions of the following processes to reduced wetting phase permeability under unsaturated conditions are considered: reduction in cross-sectional flow area, increased path length, localized flow restriction, and preferential occupation of large apertures by the non-wetting phase

  17. Calculation of vapour bubble growth on the lower generatrix of horizontal tubes

    International Nuclear Information System (INIS)

    Chajka, V.D.

    1987-01-01

    The known models of vapour bubble growth are compared with experimental data. Cinematographic study of vapour formation during water boiling was carried out with elements of horizontal tubes of copper 10, 16, 24, 34 and 70 mm in diameter under the pressure of 100 kPa and specific thermal loadings of 20 and 40 kW/m 2 . According to the experimental data the main volume of vapour phase is occupied by vapour bubbles from the lower part of the horizontal tube. Five stages of vapour bubble growth on the lower generatrix of the horizontal tube: nucleation, growth to the point of breaking off from nucleate centre, the breaking off from the nucleate centre, the tube surface flowing around during floating up, the breaking off from the tube surface, were singled out. The shape of vapour volume varied during the whole period of the bubble growth and it was mainly determined by the horizontal tube diameter. The change of vapour bubble radius in time is the function of the horizontal tube diameter. Comparison of the experimental data with the known models of vapour bubble growth has shown, that every stage of vapour bubble growth on the lower generatrix of the tube is determined by the complex of thermal and hydrodynamic conditions, the effect of which depends on the horizontal tube diameter

  18. Increase globe artichoke cropping sustainability using sub-surface drip-irrigation systems in a Mediterranean coastal area for reducing groundwater withdrawal

    Science.gov (United States)

    Mantino, Alberto; Marchina, Chiara; Bonari, Enrico; Fabbrizzi, Alessandro; Rossetto, Rudy

    2017-04-01

    During the last decades in coastal areas of the Mediterranean basin, human growth posed severe stresses on freshwater resources due to increasing demand by agricultural, industrial and civil activities, in particular on groundwater. This in turn led to worsening of water quality, loss/reduction of wetlands, up to soil salinization and abandonment of agricultural areas. Within the EU LIFE REWAT project a number of demonstration measures will take place in the lower Cornia valley (Livorno, Italy), both structural (pilot) and non-structural (education, dissemination and capacity building), aiming at achieving sustainable and participated water management. In particular, the five demonstration actions are related to: (1) set up of a managed aquifer recharge facility, (2) restoration of a Cornia river reach, (3) water saving in the civil water supply sector, (4) water saving in agriculture, (5) reuse of treated wastewater for irrigation purposes. Thus, the REWAT project general objective is to develop a new model of governance for sustainable development of the lower Cornia valley based on the water asset at its core. As per water use in agriculture, the lower Cornia valley is well known for the horticultural production. In this regard, globe artichoke (Cynara cardunculus L. var. scolymus L. (Fiori)) crops, a perennial cool-season vegetable, cover a surface of about 600 ha. In order to increase stability and productivity of the crop, about 2000 - 4000 m3 ha-1 yr-1 of irrigation water is required. Recent studies demonstrated that yield of different crops increases using Sub-surface Drip-Irrigation (SDI) system under high frequency irrigation management enhancing water use efficiency. In the SDI systems, the irrigation water is delivered to the plant root zone, below the soil surface by buried plastic tubes containing embedded emitters located at regular spacing. Within the LIFE REWAT, the specific objectives of the pilot on irrigation efficiency is to (i) demonstrate the

  19. Dissipation of triclosan, triclocarban, carbamazepine and naproxen in agricultural soil following surface or sub-surface application of dewatered municipal biosolids

    International Nuclear Information System (INIS)

    Al-Rajab, Abdul Jabbar; Sabourin, Lyne; Lapen, David R.; Topp, Edward

    2015-01-01

    In many jurisdictions land application of municipal biosolids is a valued source of nutrients for crop production. The practice must be managed to ensure that crops and adjacent water are not subject to contamination by pharmaceuticals or other organic contaminants. The broad spectrum antimicrobial agents triclosan (TCS) and triclocarban (TCC), the anti-epileptic drug carbamazepine (CBZ), and the nonsteroidal anti-inflammatory drug naproxen (NAP) are widely used and are carried in biosolids. In the present study, the effect of biosolids and depth of placement in the soil profile on the rates of TCS, TCC, CBZ, and NAP dissipation were evaluated under semi-field conditions. Aggregates of dewatered municipal biosolids (DMBs) supplemented with 14 C-labeled residues were applied either on the soil surface or in the subsurface of the soil profile, and incubated over several months under ambient outdoor conditions. The dissipation of TCS, TCC and NAP was significantly faster in sub-surface than surface applied biosolid aggregates. In contrast the dissipation rate for CBZ was the same in surface applied and incorporated aggregates. Overall, the present study has determined a significant effect of depth of placement on the dissipation rate of biodegradable molecules. - Highlights: • We characterized the soil fate of four organic contaminants carried in biosolids. • Biosolids were placed on the soil surface or incorporated within the soil profile. • Naproxen, triclosan and triclocarban were dissipated more rapidly when incorporated. • Depth of placement did not influence the rate of carbamazepine dissipation. • Soil incorporation of biosolids will result in more rapid dissipation of contaminants

  20. Dissipation of triclosan, triclocarban, carbamazepine and naproxen in agricultural soil following surface or sub-surface application of dewatered municipal biosolids

    Energy Technology Data Exchange (ETDEWEB)

    Al-Rajab, Abdul Jabbar; Sabourin, Lyne [Agriculture and Agri-Food Canada, London, ON N5V 4T3 (Canada); Lapen, David R. [Agriculture and Agri-Food Canada, Ottawa, ON K1A 0C6 (Canada); Topp, Edward, E-mail: ed.topp@agr.gc.ca [Agriculture and Agri-Food Canada, London, ON N5V 4T3 (Canada); Department of Biology, Western University, London, ON N6A 5B7 (Canada)

    2015-04-15

    In many jurisdictions land application of municipal biosolids is a valued source of nutrients for crop production. The practice must be managed to ensure that crops and adjacent water are not subject to contamination by pharmaceuticals or other organic contaminants. The broad spectrum antimicrobial agents triclosan (TCS) and triclocarban (TCC), the anti-epileptic drug carbamazepine (CBZ), and the nonsteroidal anti-inflammatory drug naproxen (NAP) are widely used and are carried in biosolids. In the present study, the effect of biosolids and depth of placement in the soil profile on the rates of TCS, TCC, CBZ, and NAP dissipation were evaluated under semi-field conditions. Aggregates of dewatered municipal biosolids (DMBs) supplemented with {sup 14}C-labeled residues were applied either on the soil surface or in the subsurface of the soil profile, and incubated over several months under ambient outdoor conditions. The dissipation of TCS, TCC and NAP was significantly faster in sub-surface than surface applied biosolid aggregates. In contrast the dissipation rate for CBZ was the same in surface applied and incorporated aggregates. Overall, the present study has determined a significant effect of depth of placement on the dissipation rate of biodegradable molecules. - Highlights: • We characterized the soil fate of four organic contaminants carried in biosolids. • Biosolids were placed on the soil surface or incorporated within the soil profile. • Naproxen, triclosan and triclocarban were dissipated more rapidly when incorporated. • Depth of placement did not influence the rate of carbamazepine dissipation. • Soil incorporation of biosolids will result in more rapid dissipation of contaminants.