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Sample records for volumetric fuel flow

  1. Volumetric velocimetry for fluid flows

    Science.gov (United States)

    Discetti, Stefano; Coletti, Filippo

    2018-04-01

    In recent years, several techniques have been introduced that are capable of extracting 3D three-component velocity fields in fluid flows. Fast-paced developments in both hardware and processing algorithms have generated a diverse set of methods, with a growing range of applications in flow diagnostics. This has been further enriched by the increasingly marked trend of hybridization, in which the differences between techniques are fading. In this review, we carry out a survey of the prominent methods, including optical techniques and approaches based on medical imaging. An overview of each is given with an example of an application from the literature, while focusing on their respective strengths and challenges. A framework for the evaluation of velocimetry performance in terms of dynamic spatial range is discussed, along with technological trends and emerging strategies to exploit 3D data. While critical challenges still exist, these observations highlight how volumetric techniques are transforming experimental fluid mechanics, and that the possibilities they offer have just begun to be explored.

  2. Non-uniform volumetric structures in Richtmyer-Meshkov flows

    NARCIS (Netherlands)

    Staniç, M.; McFarland, J.; Stellingwerf, R.F.; Cassibry, J.T.; Ranjan, D.; Bonazza, R.; Greenough, J.A.; Abarzhi, S.I.

    2013-01-01

    We perform an integrated study of volumetric structures in Richtmyer-Meshkov (RM) flows induced by moderate shocks. Experiments, theoretical analyses, Smoothed Particle Hydrodynamics simulations, and ARES Arbitrary Lagrange Eulerian simulations are employed to analyze RM evolution for fluids with

  3. High volumetric power density, non-enzymatic, glucose fuel cells.

    Science.gov (United States)

    Oncescu, Vlad; Erickson, David

    2013-01-01

    The development of new implantable medical devices has been limited in the past by slow advances in lithium battery technology. Non-enzymatic glucose fuel cells are promising replacement candidates for lithium batteries because of good long-term stability and adequate power density. The devices developed to date however use an "oxygen depletion design" whereby the electrodes are stacked on top of each other leading to low volumetric power density and complicated fabrication protocols. Here we have developed a novel single-layer fuel cell with good performance (2 μW cm⁻²) and stability that can be integrated directly as a coating layer on large implantable devices, or stacked to obtain a high volumetric power density (over 16 μW cm⁻³). This represents the first demonstration of a low volume non-enzymatic fuel cell stack with high power density, greatly increasing the range of applications for non-enzymatic glucose fuel cells.

  4. 100KE/KW fuel storage basin surface volumetric factors

    International Nuclear Information System (INIS)

    Conn, K.R.

    1996-01-01

    This Supporting Document presents calculations of surface Volumetric factors for the 100KE and 100KW Fuel Storage Basins. These factors relate water level changes to basin loss or additions of water, or the equivalent water displacement volumes of objects added to or removed from the basin

  5. Designing remote web-based mechanical-volumetric flow meter ...

    African Journals Online (AJOL)

    Today, in water and wastewater industry a lot of mechanical-volumetric flow meters are used for the navigation of the produced water and the data of these flow meters, due to use in a wide geographical range, is done physically and by in person presence. All this makes reading the data costly and, in some cases, due to ...

  6. A volumetric flow sensor for automotive injection systems

    International Nuclear Information System (INIS)

    Schmid, U; Krötz, G; Schmitt-Landsiedel, D

    2008-01-01

    For further optimization of the automotive power train of diesel engines, advanced combustion processes require a highly flexible injection system, provided e.g. by the common rail (CR) injection technique. In the past, the feasibility to implement injection nozzle volumetric flow sensors based on the thermo-resistive measurement principle has been demonstrated up to injection pressures of 135 MPa (1350 bar). To evaluate the transient behaviour of the system-integrated flow sensors as well as an injection amount indicator used as a reference method, hydraulic simulations on the system level are performed for a CR injection system. Experimentally determined injection timings were found to be in good agreement with calculated values, especially for the novel sensing element which is directly implemented into the hydraulic system. For the first time pressure oscillations occurring after termination of the injection pulse, predicted theoretically, could be verified directly in the nozzle. In addition, the injected amount of fuel is monitored with the highest resolution ever reported in the literature

  7. A volumetric flow sensor for automotive injection systems

    Science.gov (United States)

    Schmid, U.; Krötz, G.; Schmitt-Landsiedel, D.

    2008-04-01

    For further optimization of the automotive power train of diesel engines, advanced combustion processes require a highly flexible injection system, provided e.g. by the common rail (CR) injection technique. In the past, the feasibility to implement injection nozzle volumetric flow sensors based on the thermo-resistive measurement principle has been demonstrated up to injection pressures of 135 MPa (1350 bar). To evaluate the transient behaviour of the system-integrated flow sensors as well as an injection amount indicator used as a reference method, hydraulic simulations on the system level are performed for a CR injection system. Experimentally determined injection timings were found to be in good agreement with calculated values, especially for the novel sensing element which is directly implemented into the hydraulic system. For the first time pressure oscillations occurring after termination of the injection pulse, predicted theoretically, could be verified directly in the nozzle. In addition, the injected amount of fuel is monitored with the highest resolution ever reported in the literature.

  8. Novel monorail infusion catheter for volumetric coronary blood flow measurement in humans: in vitro validation

    NARCIS (Netherlands)

    van 't Veer, M.; Adjedj, J.; Wijnbergen, I.; Tóth, G.G.; Rutten, M.C.M.; Barbato, E.; van Nunen, L.X.; Pijls, N.H.J.; de Bruyne, B.

    2016-01-01

    AIMS: The aim of this study is to validate a novel monorail infusion catheter for thermodilution-based quantitative coronary flow measurements. METHODS AND RESULTS: Based on the principles of thermodilution, volumetric coronary flow can be determined from the flow rate of a continuous saline

  9. Ignition of hydrocarbon-air supersonic flow by volumetric ionization

    Science.gov (United States)

    Goldfeld, Marat A.; Pozdnyakov, George A.

    2015-11-01

    The paper describes the results of the electron-beam initiation of the combustion in the mixtures of hydrogen, natural gas or kerosene vapors with air. Electron beam characteristics were studied in closed volume with immobile gas. The researches included definition of an integrated current of an electronic beam, distribution of a current density and an estimation of average energy of electrons. Possibility of fuel mixtures ignition by means of this approach in the combustor at high velocity at the entrance was demonstrated. Experiments were carried out at Mach numbers of 4 and 5. Process of ignition and combustion under electron beam action was researched. It was revealed that ignition of mixture occurs after completion of electron gun operation. Data obtained have confirmed effectiveness of electron beam application for ignition of hydrogen and natural gas. The numerical simulation of the combustion of mixture in channel was carried out by means of ANSYS CFD 12.0 instrumentation on the basis of Reynolds averaged Navier-Stokes equation using SST/k-ω turbulence model. For combustion modeling, a detailed kinetic scheme with 38 reactions of 8 species was implemented taking into account finite rate chemistry. Computations have shown that the developed model allow to predict ignition of a mixture and flame propagation even at low flow temperatures.

  10. Spatial distribution of bacterial communities on volumetric and planar anodes in single-chamber air-cathode microbial fuel cells

    KAUST Repository

    Vargas, Ignacio T.; Albert, Istvan U.; Regan, John M.

    2013-01-01

    Pyrosequencing was used to characterize bacterial communities in air-cathode microbial fuel cells across a volumetric (graphite fiber brush) and a planar (carbon cloth) anode, where different physical and chemical gradients would be expected

  11. Correlation of volumetric flow rate and skin blood flow with cold intolerance in digital replantation.

    Science.gov (United States)

    Zhao, Gang; Mi, Jingyi; Rui, Yongjun; Pan, Xiaoyun; Yao, Qun; Qiu, Yang

    2017-12-01

    Cold intolerance is a common complication of digital replantation. The exact etiology is unclear, but it is considered to be multifactorial, including nonsurgical characteristics, vascular, and neurologic conditions. Blood flow may play a significant role in cold intolerance. This study was designed to evaluate the correlation of digital blood flow, including volumetric flow rate (VFR) and skin blood flow (SkBF), with cold intolerance in replanted fingers.A retrospective study was conducted among patients who underwent digital replantation between 2010 and 2013. Patients were selected into study cohort based on the inclusion criteria. Surgical data was collected on each patient, including age, sex, injury mechanism, amputation level, ischemia time, number of arteries repaired, and whether or not vascular crisis occurred. Patients were included as study cohort with both nerves repaired and without chronic disease. Cold intolerance was defined as a Cold Intolerance Symptom Severity (CISS) score over 30. The arterial flow velocity and caliber were measured by Color Doppler Ultrasound and the digital VFR was calculated. The SkBF was measured by Laser Speckle Imager. Both VFR and SkBF were calculated as a percentage of the contralateral fingers. Comparative study of surgical data and blood flow was performed between the patient with and without cold intolerance. Correlation between VFR and SkBF was also analyzed.A total of 93 patients met inclusion criteria for the study. Approximately, 42 patients were identified as having cold intolerance. Fingers that survived vascular crisis had a higher incidence of cold intolerance with a lower VFR and SkBF. The VFR was higher in 2-artery replantation, but the SkBF and incidence of cold intolerance did not differ significantly. No differences were found in age, sex, injury mechanism, amputation level, or ischemia time. Furthermore, no correlation was found between VFR and SkBF.Cold intolerance of digital replantation is associated

  12. Microfluidic volumetric flow determination using optical coherence tomography speckle: An autocorrelation approach

    Energy Technology Data Exchange (ETDEWEB)

    De Pretto, Lucas R., E-mail: lucas.de.pretto@usp.br; Nogueira, Gesse E. C.; Freitas, Anderson Z. [Instituto de Pesquisas Energéticas e Nucleares, IPEN–CNEN/SP, Avenida Lineu Prestes, 2242, 05508-000 São Paulo (Brazil)

    2016-04-28

    Functional modalities of Optical Coherence Tomography (OCT) based on speckle analysis are emerging in the literature. We propose a simple approach to the autocorrelation of OCT signal to enable volumetric flow rate differentiation, based on decorrelation time. Our results show that this technique could distinguish flows separated by 3 μl/min, limited by the acquisition speed of the system. We further perform a B-scan of gradient flow inside a microchannel, enabling the visualization of the drag effect on the walls.

  13. Fuel cell with internal flow control

    Science.gov (United States)

    Haltiner, Jr., Karl J.; Venkiteswaran, Arun [Karnataka, IN

    2012-06-12

    A fuel cell stack is provided with a plurality of fuel cell cassettes where each fuel cell cassette has a fuel cell with an anode and cathode. The fuel cell stack includes an anode supply chimney for supplying fuel to the anode of each fuel cell cassette, an anode return chimney for removing anode exhaust from the anode of each fuel cell cassette, a cathode supply chimney for supplying oxidant to the cathode of each fuel cell cassette, and a cathode return chimney for removing cathode exhaust from the cathode of each fuel cell cassette. A first fuel cell cassette includes a flow control member disposed between the anode supply chimney and the anode return chimney or between the cathode supply chimney and the cathode return chimney such that the flow control member provides a flow restriction different from at least one other fuel cell cassettes.

  14. Coarse Grid Modeling of Turbine Film Cooling Flows Using Volumetric Source Terms

    Science.gov (United States)

    Heidmann, James D.; Hunter, Scott D.

    2001-01-01

    The recent trend in numerical modeling of turbine film cooling flows has been toward higher fidelity grids and more complex geometries. This trend has been enabled by the rapid increase in computing power available to researchers. However, the turbine design community requires fast turnaround time in its design computations, rendering these comprehensive simulations ineffective in the design cycle. The present study describes a methodology for implementing a volumetric source term distribution in a coarse grid calculation that can model the small-scale and three-dimensional effects present in turbine film cooling flows. This model could be implemented in turbine design codes or in multistage turbomachinery codes such as APNASA, where the computational grid size may be larger than the film hole size. Detailed computations of a single row of 35 deg round holes on a flat plate have been obtained for blowing ratios of 0.5, 0.8, and 1.0, and density ratios of 1.0 and 2.0 using a multiblock grid system to resolve the flows on both sides of the plate as well as inside the hole itself. These detailed flow fields were spatially averaged to generate a field of volumetric source terms for each conservative flow variable. Solutions were also obtained using three coarse grids having streamwise and spanwise grid spacings of 3d, 1d, and d/3. These coarse grid solutions used the integrated hole exit mass, momentum, energy, and turbulence quantities from the detailed solutions as volumetric source terms. It is shown that a uniform source term addition over a distance from the wall on the order of the hole diameter is able to predict adiabatic film effectiveness better than a near-wall source term model, while strictly enforcing correct values of integrated boundary layer quantities.

  15. Novel monorail infusion catheter for volumetric coronary blood flow measurement in humans: in vitro validation.

    Science.gov (United States)

    van 't Veer, Marcel; Adjedj, Julien; Wijnbergen, Inge; Tóth, Gabor G; Rutten, Marcel C M; Barbato, Emanuele; van Nunen, Lokien X; Pijls, Nico H J; De Bruyne, Bernard

    2016-08-20

    The aim of this study is to validate a novel monorail infusion catheter for thermodilution-based quantitative coronary flow measurements. Based on the principles of thermodilution, volumetric coronary flow can be determined from the flow rate of a continuous saline infusion, the temperature of saline when it enters the coronary artery, and the temperature of the blood mixed with the saline in the distal part of the coronary artery. In an in vitro set-up of the systemic and coronary circulation at body temperature, coronary flow values were varied from 50-300 ml/min in steps of 50 ml/min. At each coronary flow value, thermodilution-based measurements were performed at infusion rates of 15, 20, and 30 ml/min. Temperatures and pressures were simultaneously measured with a pressure/temperature sensor-tipped guidewire. Agreement of the calculated flow and the measured flow as well as repeatability were assessed. A total of five catheters were tested, with a total of 180 measurements. A strong correlation (ρ=0.976, p<0.0001) and a difference of -6.5±15.5 ml/min were found between measured and calculated flow. The difference between two repeated measures was 0.2%±8.0%. This novel infusion catheter used in combination with a pressure/temperature sensor-tipped guidewire allows accurate and repeatable absolute coronary flow measurements. This opens a window to a better understanding of the coronary microcirculation.

  16. Numerical Modeling of Surface and Volumetric Cooling using Optimal T- and Y-shaped Flow Channels

    Science.gov (United States)

    Kosaraju, Srinivas

    2017-11-01

    The layout of T- and V-shaped flow channel networks on a surface can be optimized for minimum pressure drop and pumping power. The results of the optimization are in the form of geometric parameters such as length and diameter ratios of the stem and branch sections. While these flow channels are optimized for minimum pressure drop, they can also be used for surface and volumetric cooling applications such as heat exchangers, air conditioning and electronics cooling. In this paper, an effort has been made to study the heat transfer characteristics of multiple T- and Y-shaped flow channel configurations using numerical simulations. All configurations are subjected to same input parameters and heat generation constraints. Comparisons are made with similar results published in literature.

  17. Quantification of smoothing requirement for 3D optic flow calculation of volumetric images

    DEFF Research Database (Denmark)

    Bab-Hadiashar, Alireza; Tennakoon, Ruwan B.; de Bruijne, Marleen

    2013-01-01

    Complexities of dynamic volumetric imaging challenge the available computer vision techniques on a number of different fronts. This paper examines the relationship between the estimation accuracy and required amount of smoothness for a general solution from a robust statistics perspective. We show...... that a (surprisingly) small amount of local smoothing is required to satisfy both the necessary and sufficient conditions for accurate optic flow estimation. This notion is called 'just enough' smoothing, and its proper implementation has a profound effect on the preservation of local information in processing 3D...... dynamic scans. To demonstrate the effect of 'just enough' smoothing, a robust 3D optic flow method with quantized local smoothing is presented, and the effect of local smoothing on the accuracy of motion estimation in dynamic lung CT images is examined using both synthetic and real image sequences...

  18. Volumetric 3-component velocimetry measurements of the flow field on the rear window of a generic car model

    Directory of Open Access Journals (Sweden)

    Tounsi Nabil

    2012-01-01

    Full Text Available Volumetric 3-component Velocimetry measurements are carried out in the flow field around the rear window of a generic car model, the so-called Ahmed body. This particular flow field is known to be highly unsteady, three dimensional and characterized by strong vortices. The volumetric velocity measurements from the present experiments provide the most comprehensive data for this flow field to date. The present study focuses on the wake flow modifications which result from using a simple flow control device, such as the one recently employed by Fourrié et al. [1]. The mean data clearly show the structure of this complex flow and confirm the drag reduction mechanism suggested by Fourrié et al. The results show that strengthening the separated flow leads to weakening the longitudinal vortices and vice versa. The present paper shows that the Volumetric 3-component Velocimetry technique is a powerful tool used for a better understanding of a threedimensional unsteady complex flow such that developing around a bluffbody.

  19. Characterization of volumetric flow rate waveforms at the carotid bifurcations of older adults

    International Nuclear Information System (INIS)

    Hoi, Yiemeng; Xie, Yuanyuan J; Steinman, David A; Wasserman, Bruce A; Najjar, Samer S; Lakatta, Edward G; Ferruci, Luigi; Gerstenblith, Gary

    2010-01-01

    While it is widely appreciated that volumetric blood flow rate (VFR) dynamics change with age, there has been no detailed characterization of the typical shape of carotid bifurcation VFR waveforms of older adults. Toward this end, retrospectively gated phase contrast magnetic resonance imaging was used to measure time-resolved VFR waveforms proximal and distal to the carotid bifurcations of 94 older adults (age 68 ± 8 years) with little or no carotid artery disease, recruited from the BLSA cohort of the VALIDATE study of factors in vascular aging. Timings and amplitudes of well-defined feature points from these waveforms were extracted automatically and averaged to produce representative common, internal and external carotid artery (CCA, ICA and ECA) waveform shapes. Relative to young adults, waveforms from older adults were found to exhibit a significantly augmented secondary peak during late systole, resulting in significantly higher resistance index (RI) and flow augmentation index (FAI). Cycle-averaged VFR at the CCA, ICA and ECA were 389 ± 74, 245 ± 61 and 125 ± 49 mL min −1 , respectively, reflecting a significant cycle-averaged outflow deficit of 5%, which peaked at around 10% during systole. A small but significant mean delay of 13 ms between arrivals of ICA versus CCA/ECA peak VFR suggested differential compliance of these vessels. Sex and age differences in waveform shape were also noted. The characteristic waveforms presented here may serve as a convenient baseline for studies of VFR waveform dynamics or as suitable boundary conditions for models of blood flow in the carotid arteries of older adults

  20. Three-dimensional three-component particle velocimetry for microscale flows using volumetric scanning

    International Nuclear Information System (INIS)

    Klein, S A; Moran, J L; Posner, J D; Frakes, D H

    2012-01-01

    We present a diagnostic platform for measuring three-dimensional three-component (3D3C) velocity fields in microscopic volumes. The imaging system uses high-speed Nipkow spinning disk confocal microscopy. Confocal microscopy provides optical sectioning using pinhole spatial filtering which rejects light originating from out-of-focus objects. The system accomplishes volumetric scanning by rapid translation of the high numerical aperture objective using a piezo objective positioner. The motion of fluorescent microspheres is quantified using 3D3C super resolution particle-imaging velocimetry with instantaneous spatial resolutions of the order of 5 µm or less in all three dimensions. We examine 3D3C flow in a PDMS microchannel with an expanding section at 3D acquisition rates of 30 Hz, and find strong agreement with a computational model. Equations from the PIV and PTV literature adapted for a scanning objective provide estimates of maximum measurable velocity. The technique allows for isosurface visualization of 3D particle motion and robust high spatial resolution velocity measurements without requiring a calibration step or reconstruction algorithms. (paper)

  1. Spatial distribution of bacterial communities on volumetric and planar anodes in single-chamber air-cathode microbial fuel cells

    KAUST Repository

    Vargas, Ignacio T.

    2013-05-29

    Pyrosequencing was used to characterize bacterial communities in air-cathode microbial fuel cells across a volumetric (graphite fiber brush) and a planar (carbon cloth) anode, where different physical and chemical gradients would be expected associated with the distance between anode location and the air cathode. As expected, the stable operational voltage and the coulombic efficiency (CE) were higher for the volumetric anode than the planar anode (0.57V and CE=22% vs. 0.51V and CE=12%). The genus Geobacter was the only known exoelectrogen among the observed dominant groups, comprising 57±4% of recovered sequences for the brush and 27±5% for the carbon-cloth anode. While the bacterial communities differed between the two anode materials, results showed that Geobacter spp. and other dominant bacterial groups were homogenously distributed across both planar and volumetric anodes. This lends support to previous community analysis interpretations based on a single biofilm sampling location in these systems. © 2013 Wiley Periodicals, Inc.

  2. Fuel Rod Flow-Induced Vibration Overview

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kang Hee; Kang, Heung Seok; Kim, Hyung Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2010-10-15

    To ensure fuel design safety and structural integrity requires the response prediction of fuel rod to reactor coolant flow excitation. However, there are many obstacles in predicting the response as described. Even if the response can be predicted, the design criteria on wear failure, including correlation with the vibration, may be difficult to establish because of a variety of related parameters, such as material, surface condition and environmental factors. Thus, a prototype test for each new fuel assembly design, i.e. a long-term endurance test, is performed for design validation with respect to flow-induced vibration (FIV) and wear. There are still needs of theoretical prediction methods for the response and anticipated failure. This paper revisits the general aspect on the response prediction, mathematical description, analysis procedure and wear correlation aspect of fuel rod's FIV

  3. Fluid flow test for KMRR fuel assemblies

    International Nuclear Information System (INIS)

    Chung, Moon Ki; Yang, Sun Kyu; Chung, Chang Hwan; Chun, See Young; Song, Chul Hha; Jun, Hyung Gil; Chung, Heung Joon; Won, Soon Yeun; Cho, Young Rho; Kim, Bok Deuk

    1991-01-01

    Hydraulic and velocity measurment tests were carried out for the KMRR fuel assembly. Two types of the KMRR fuel assembly are consist of longitudinally finned rods. Experimental data of the pressure drops and friction factors for the KMRR fuel assemlby were produced. The measurement technique for the turbulent flow structure in subchannels using the LDV was obtained. The measurement of the experimental constant of the thermal hydraulic analysis code was investigated. The results in this study are used as the basic data for the development of an analysis code. The measurement technique acquired in this study can be applied to the KMRR thermal hydraulic commissioning test and development of the domestic KMRR fuel fabrication. (Author)

  4. Biventricular MR volumetric analysis and MR flow quantification in the ascending aorta and pulmonary trunk for quantification of valvular regurgitation

    International Nuclear Information System (INIS)

    Rominger, M.B.

    2004-01-01

    Purpose: To test the value of biventricular volumetric analysis and the combination of biventricular volumetric analysis with flow quantification in the ascending aorta (Ao) and pulmonary trunk (Pu) for quantification of regurgitation volume and cardiac function in valvular regurgitation (VR) according to location and presence of single or multivalvular disease. Materials and Methods: In 106 patients, the stroke volumes were assessed by measuring the biventricular volumes and the forward-stroke volumes in the great and small circulation by measuring the flow in the Ao and Pu. Valve regurgitation volumes and quotients were calculated for single and multivalvular disease and correlated with semiquantitative 2D-echocardiography (grade I-IV). For the assessment of the cardiac function in VR, the volumetric parameters of ejection fraction and end-diastolic (EDV) and end-systolic (ESV) volumes were determined. Results: The detection rate was 49% for left ventricular (LV) VR and 42% for right ventricular (RV) VR. Low LV VR and RV VR usually could not be detected quantitatively, with the detection rate improving with echocardiographically higher insufficiency grades. Quantitative MRI could detect a higher grade solitary aortic valve insufficiency (≥2) in 11 of 12 patients and higher grade mitral valve insufficiency in 4 of 10 patients. A significant increase in RV and LV ventricular EDV and ESV was seen more often with increased MR regurgitation volumes. Aortic stenosis did not interfere with flow measurements in the Ao. Conclusions: Biventricular volumetry combined with flow measurements in Ao and Pu is a robust, applicable and simple method to assess higher grade regurgitation volumes and the cardiac function in single and multivalvular regurgitation at different locations. It is an important application for the diagnosis of VR by MRI [de

  5. Validation of the generalized model of two-phase thermosyphon loop based on experimental measurements of volumetric flow rate

    Science.gov (United States)

    Bieliński, Henryk

    2016-09-01

    The current paper presents the experimental validation of the generalized model of the two-phase thermosyphon loop. The generalized model is based on mass, momentum, and energy balances in the evaporators, rising tube, condensers and the falling tube. The theoretical analysis and the experimental data have been obtained for a new designed variant. The variant refers to a thermosyphon loop with both minichannels and conventional tubes. The thermosyphon loop consists of an evaporator on the lower vertical section and a condenser on the upper vertical section. The one-dimensional homogeneous and separated two-phase flow models were used in calculations. The latest minichannel heat transfer correlations available in literature were applied. A numerical analysis of the volumetric flow rate in the steady-state has been done. The experiment was conducted on a specially designed test apparatus. Ultrapure water was used as a working fluid. The results show that the theoretical predictions are in good agreement with the measured volumetric flow rate at steady-state.

  6. 40 CFR 1065.220 - Fuel flow meter.

    Science.gov (United States)

    2010-07-01

    ... follows: (1) Use the actual value of calculated raw exhaust flow rate in the following cases: (i) For... ENGINE-TESTING PROCEDURES Measurement Instruments Flow-Related Measurements § 1065.220 Fuel flow meter. (a) Application. You may use fuel flow in combination with a chemical balance of carbon (or oxygen...

  7. Fuel bundle movement due to reverse flow

    Energy Technology Data Exchange (ETDEWEB)

    Wahba, N N; Akalin, O [Ontario Hydro, Toronto, ON (Canada)

    1996-12-31

    When a break occurs in the inlet feeder or inlet header, the rapid depressurization will cause the channel flow to reverse forcing the string of bundles to accelerate and impact with upstream shield plug. A model has been developed to predict the bundle motion due to the channel flow reversal. The model accounts for various forces acting on the bundle. A series of five reverse flow, bundle acceleration experiments have been conducted simulating a break in the inlet feeder of a CANDU fuel channel. The model has been validated against the experiments. The predicted impact velocities are in good agreement with the measured values. It is demonstrated that the model may be successfully used in predicting bundle relocation timing following a large LOCA (loss of coolant). (author). 7 refs., 3 tabs., 11 figs.

  8. Influence of georeference for saturated excess overland flow modelling using 3D volumetric soft geo-objects

    Science.gov (United States)

    Izham, Mohamad Yusoff; Muhamad Uznir, Ujang; Alias, Abdul Rahman; Ayob, Katimon; Wan Ruslan, Ismail

    2011-04-01

    Existing 2D data structures are often insufficient for analysing the dynamism of saturation excess overland flow (SEOF) within a basin. Moreover, all stream networks and soil surface structures in GIS must be preserved within appropriate projection plane fitting techniques known as georeferencing. Inclusion of 3D volumetric structure of the current soft geo-objects simulation model would offer a substantial effort towards representing 3D soft geo-objects of SEOF dynamically within a basin by visualising saturated flow and overland flow volume. This research attempts to visualise the influence of a georeference system towards the dynamism of overland flow coverage and total overland flow volume generated from the SEOF process using VSG data structure. The data structure is driven by Green-Ampt methods and the Topographic Wetness Index (TWI). VSGs are analysed by focusing on spatial object preservation techniques of the conformal-based Malaysian Rectified Skew Orthomorphic (MRSO) and the equidistant-based Cassini-Soldner projection plane under the existing geodetic Malaysian Revised Triangulation 1948 (MRT48) and the newly implemented Geocentric Datum for Malaysia (GDM2000) datum. The simulated result visualises deformation of SEOF coverage under different georeference systems via its projection planes, which delineate dissimilar computation of SEOF areas and overland flow volumes. The integration of Georeference, 3D GIS and the saturation excess mechanism provides unifying evidence towards successful landslide and flood disaster management through envisioning the streamflow generating process (mainly SEOF) in a 3D environment.

  9. Stress Analysis of Fuel Rod under Axial Coolant Flow

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Hai Lan; Lee, Young Shin; Lee, Hyun Seung [Chungnam National University, Daejeon (Korea, Republic of); Park, Num Kyu; Jeon, Kyung Rok [Kerea Nuclear Fuel., Daejeon (Korea, Republic of)

    2010-05-15

    A pressurized water reactor(PWR) fuel assembly, is a typical bundle structure, which uses light water as a coolant in most commercial nuclear power plants. Fuel rods that have a very slender and long clad are supported by fuel assembly which consists of several spacer grids. A coolant is a fluid which flows through device to prevent its overheating, transferring the heat produced by the device to other devices that use or dissipate it. But at the same time, the coolant flow will bring out the fluid induced vibration(FIV) of fuel rods and even damaged the fuel rod. This study has been conducted to investigate the flow characteristics and nuclear reactor fuel rod stress under effect of coolant. Fluid structure interaction(FSI) analysis on nuclear reactor fuel rod was performed. Fluid analysis of the coolant which flow along the axial direction and structural analysis under effect of flow velocity were carried out under different output flow velocity conditions

  10. Stress Analysis of Fuel Rod under Axial Coolant Flow

    International Nuclear Information System (INIS)

    Jin, Hai Lan; Lee, Young Shin; Lee, Hyun Seung; Park, Num Kyu; Jeon, Kyung Rok

    2010-01-01

    A pressurized water reactor(PWR) fuel assembly, is a typical bundle structure, which uses light water as a coolant in most commercial nuclear power plants. Fuel rods that have a very slender and long clad are supported by fuel assembly which consists of several spacer grids. A coolant is a fluid which flows through device to prevent its overheating, transferring the heat produced by the device to other devices that use or dissipate it. But at the same time, the coolant flow will bring out the fluid induced vibration(FIV) of fuel rods and even damaged the fuel rod. This study has been conducted to investigate the flow characteristics and nuclear reactor fuel rod stress under effect of coolant. Fluid structure interaction(FSI) analysis on nuclear reactor fuel rod was performed. Fluid analysis of the coolant which flow along the axial direction and structural analysis under effect of flow velocity were carried out under different output flow velocity conditions

  11. Upgrade of Dhruva fuel channel flow instrumentation

    International Nuclear Information System (INIS)

    Gadgil, Kaustubh; Awale, P.K.; Sengupta, C.; Sumanth, P.; Roy, Kallol

    2014-01-01

    Dhruva, a 100 MW Heavy Water moderated and cooled, vertical tank-type Research Reactor, using metallic natural Uranium fuel has flow instrumentation for all the 144 fuel channels, consisting of venturi and triplicate DP gauges for each fuel channel. These gauges provide contacts for generation of reactor trip on low flow through fuel channel. These DP gauges were facing numerous generic and ageing related failures over the years and was also difficult to maintain owing to obsolescence. While considering an upgrade for these DP gauges, it was also planned to replace the existing Coolant Low Flow Trip (CLFT) system with a computer based Reactor Trip Logic System (RTLS). Being a retrofit job, the existing panels for mounting the gauges, cable layout, impulse tubing layout, etc. were retained, thereby simplifying the site execution, reducing reactor down time and also reducing person-milli-Sievert consumption. A customized Electronic DP Indicating Switch (EDPIS) was conceptualized for achieving these objectives. Such a design, utilizing a standard DP transmitter with customized electronic circuitry, was developed, evaluated and finalized after a series of factory trials, field trials and prototyping. The instrument design included contact input for existing CLFT system and also provision for 4-20 mA current output for the proposed computer based RTLS. The display and form factor of the instrument remained identical to older one and ensures familiarity of O and M personnel. Since EDPIS is classified as Safety Class IA, stringent type tests, hardware FMEA and V and V of the micro-controller software were carried out as per the requirements laid down by relevant standards for qualification of these instruments. Being a customized instrument, the manufacturing process was closely monitored and was followed by stringent QA plan and acceptance tests. A total of 396 gauges were replaced in a phased manner during scheduled fuelling outages and thereby did not affect reactor

  12. Sodium flow distribution in test fuel assembly P-23B

    International Nuclear Information System (INIS)

    Taylor, J.P.S.

    1978-08-01

    Relatively large cladding diametral increases in the exterior fuel pins of HEDL's test fuel subassembly P-23B were successfully explained by a thermal-hydraulic/solid mechanics analysis. This analysis indicates that while at power, the subassembly flow was less than planned and that the fuel pins were considerably displaced and bowed from their nominal position. In accomplishing this analysis, a method was developed to estimate the sodium flow distribution and pin distortions in a fuel subassembly at power

  13. Evaluation of Accordance of Magnetic Resonance Volumetric and Flow Measurements in Determining Ventricular Stroke Volume in Cardiac Patients

    International Nuclear Information System (INIS)

    Jeltsch, M.; Ranft, S.; Klass, O.; Aschoff, A.J.; Hoffmann, M.H.K.

    2008-01-01

    Background: Cardiovascular magnetic resonance imaging (CMR) has become an established noninvasive method for evaluating ventricular function utilizing three-dimensional volumetry. Postprocessing of volumetric measurements is still tedious and time consuming. Stroke volumes obtained by flow quantification across the aortic root or pulmonary trunk could be utilized to increase both speed of workflow and accuracy. Purpose: To assess accuracy of stroke volume quantification using MR volumetric imaging compared to flow quantification in patients with various cardiac diseases. Strategies for the augmentation of accuracy in clinical routine were deduced. Material and Methods: 78 patients with various cardiac diseases -excluding intra- or extracardiac shunts, regurgitant valvular defects, or heart rhythm disturbance -underwent cardiac function analysis with flow measurements across the aortic root and cine imaging of the left ventricle. Forty-six patients additionally underwent flow measurements in the pulmonary trunk and cine imaging of the right ventricle. Results: Left ventricular stroke volume (LVSV) and stroke volume of the aortic root (SVAo) correlated with r=0.97, and Bland-Altman analysis showed a mean difference of 0.11 ml and a standard error of estimation (SEE) of 4.31 ml. Ninety-two percent of the data were within the 95% limits of agreement. Right ventricular stroke volume (RVSV) and stroke volume of the pulmonary trunk (SVP) correlated with a factor of r=0.86, and mean difference in the Bland-Altman analysis was fixed at -2.62 ml (SEE 8.47 ml). For RVSV and SVP, we calculated r=0.82, and Bland-Altman analysis revealed a mean difference of 1.27 ml (SEE 9.89 ml). LVSV and RVSV correlated closely, with r=0.91 and a mean difference of 2.79 ml (SEE 7.17 ml). SVAo and SVP correlated with r=0.95 and a mean difference of 0.50 ml (SEE 5.56 ml). Conclusion: Flow quantification can be used as a guidance tool, providing accurate and reproducible stroke volumes of both

  14. Catalyst volumetric fraction simulation in a riser of a cold flow pilot unit with aid of transmission gamma technique

    International Nuclear Information System (INIS)

    Santos, Kamylla A.L. dos; Lima Filho, Hilario J.B. de; Benachour, Mohand; Dantas, Carlos C.; Santos, Valdemir A. dos

    2013-01-01

    Was obtained the radial profile of the catalyst volume fraction in a riser of the cold flow pilot unit of the Fluid Catalytic Cracking (FCC) unit, which was used for adjustment of the entrance conditions of the catalyst in a simulation program by Computational Fluid Dynamics (CFD). The height of the riser of the Cold Flow Pilot Unity (CFPU) utilized is 6.0m and its inner diameter is 0.097 m. A radiation-γ source of Am-241 and a NaI (Tl) detector, with shielding made of lead, have been installed on a steel backing that maintains the geometry of the source-detector-riser and allows to vary the distance from the source to the detector and the radial position in a given cross section of the riser. The data associated with the simulation of volume fraction radial profile of the catalyst were: Fluent software, version 12.0; preprocessor GAMBIT, version 2.3.16; Eulerian approach; structured mesh, cell number of 60000; turbulence model used was k-ε and kinetic theory of granular flow (KTGF) was implemented to describe the solid phase. Comparison of radial profiles simulated and experimental of the catalyst volumetric fraction in the CFPU riser allowed the identification of needs adjustments in the simulation for the input of catalyst, with consequent validation for the proposed model simulation. (author)

  15. Compositional and volumetric development of a monogenetic lava flow field: The historical case of Paricutin (Michoacán, Mexico)

    Science.gov (United States)

    Larrea, Patricia; Salinas, Sergio; Widom, Elisabeth; Siebe, Claus; Abbitt, Robbyn J. F.

    2017-12-01

    Paricutin volcano is the youngest and most studied monogenetic volcano in the Michoacán-Guanajuato volcanic field (Mexico), with an excellent historical record of its nine years (February 1943 to March 1952) of eruptive activity. This eruption offered a unique opportunity to observe the birth of a new volcano and document its entire eruption. Geologists surveyed all of the eruptive phases in progress, providing maps depicting the volcano's sequential growth. We have combined all of those previous results and present a new methodological approach, which utilizes state of the art GIS mapping tools to outline and identify the 23 different eruptive phases as originally defined by Luhr and Simkin (1993). Using these detailed lava flow distribution maps, the volume of each of the flows was estimated with the aid of pre- and post-eruption digital elevation models. Our procedure yielded a total lava flow volume ranging between 1.59 and 1.68 km3 DRE, which is larger than previous estimates based on simpler methods. In addition, compositional data allowed us to estimate magma effusion rates and to determine variations in the relative proportions of the different magma compositions issued during the eruption. These results represent the first comprehensive documentation of the combined chemical, temporal, and volumetric evolution of the Paricutin lava field and provide key constraints for petrological interpretations of the nature of the magmatic plumbing system that fed the eruption.

  16. Evaluation of the effect of temperature, concentration and volumetric flow in the hydrolysis of sucrose by an immobilized invertase in a spherical reactor

    International Nuclear Information System (INIS)

    Zamora Leiton, Maria Monserrath; Molina Cordoba, Manuel; Chacon Valle, Gerardo

    2011-01-01

    The effect of the volumetric flow, the temperature and the initial concentration of sucrose in the reaction of hydrolysis of sucrose by immobilized invertase were evaluated in the laboratory. Invertase was immobilized in 20 g of support of mesh size between 120 and 140. The maximum quantity of immobilized invertase obtained has been 0,130 mg/g of support at 220 min. The first experimental stage has consisted in the evaluation of the effect of the initial concentration of sucrose (1,0 and 1,5 mol/L), the volumetric flow (3,0 mL/min and 4,0 mL/min) and the temperature (45 degrees C and 50 degrees C). The effect of the above three variable has been statistically significant. The conversion has been favorable for a concentration of sucrose 1,0 mol/L, a volumetric flow of 3 mL/min and a temperature of 50 degrees C. The maximum conversion obtained has been 95,4 %. The second experimental stage has analyzed the effect of the initial concentration of sucrose (0,75 and 1,0 mol/L), the volumetric flow (2,5 mL/min and 3,0 mL/min) and the temperature (50 degrees C and 55 degrees C). The variable of volumetric flow and the interaction concentration of sucrose - temperature are found statistically significant. The conversion has been favorable for a volumetric flow of 2,5 mL/min, and it has been preferable to work at a temperature of 50 degrees C with an initial concentration of sucrose of 1,0 mol/L. The maximum conversion has been 94,8 %. The effect of the concentration was analyzed in the last experimental stage, it was found that the maximum conversion percentage was 95,0 % for a concentration of 1,1 mol/L, for a temperature of 50 degrees C and for a volumetric flow of 2,5 mL/min. (author) [es

  17. Preliminary performance analysis of a transverse flow spectrally selective two-slab packed bed volumetric receiver

    CSIR Research Space (South Africa)

    Roos, TH

    2016-05-01

    Full Text Available for the transparent slab 1 and SiC for the opaque slab 2 – which are ordered in a hexagonally close-packed bed. The flow direction has been changed from parallel to the incident radiation and perpendicular to the window, to parallel to the window and perpendicular...

  18. Sequential flow membraneless microfluidic fuel cell with porous electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Salloum, Kamil S.; Posner, Jonathan D. [Department of Mechanical and Aerospace Engineering, Arizona State University, Tempe, AZ 85287-6106 (United States); Hayes, Joel R.; Friesen, Cody A. [School of Materials, Arizona State University, Tempe, AZ 85287-8706 (United States)

    2008-05-15

    A novel convective flow membraneless microfluidic fuel cell with porous disk electrodes is described. In this fuel cell design, the fuel flows radially outward through a thin disk shaped anode and across a gap to a ring shaped cathode. An oxidant is introduced into the gap between anode and cathode and advects radially outward to the cathode. This fuel cell differs from previous membraneless designs in that the fuel and the oxidant flow in series, rather than in parallel, enabling independent control over the fuel and oxidant flow rate and the electrode areas. The cell uses formic acid as a fuel and potassium permanganate as the oxidant, both contained in a sulfuric acid electrolyte. The flow velocity field is examined using microscale particle image velocimetry and shown to be nearly axisymmetric and steady. The results show that increasing the electrolyte concentration reduces the cell Ohmic resistance, resulting in larger maximum currents and peak power densities. Increasing the flow rate delays the onset of mass transport and reduces Ohmic losses resulting in larger maximum currents and peak power densities. An average open circuit potential of 1.2 V is obtained with maximum current and power densities of 5.35 mA cm{sup -2} and 2.8 mW cm{sup -2}, respectively (cell electrode area of 4.3 cm{sup 2}). At a flow rate of 100 {mu}L min{sup -1} a fuel utilization of 58% is obtained. (author)

  19. Complete Flow Blockage of a Fuel Channel for Research Reactor

    International Nuclear Information System (INIS)

    Lee, Byeonghee; Park, Suki

    2015-01-01

    The CHF correlation suitable for narrow rectangular channels are implemented in RELAP5/MOD3.3 code for the analyses, and the behavior of fuel temperatures and MCHFR(minimum critical heat flux ratio) are compared between the original and modified codes. The complete flow blockage of fuel channel for research reactor is analyzed using original and modified RELAP5/MOD3.3 and the results are compared each other. The Sudo-Kaminaga CHF correlation is implemented into RELAP5/MOD3.3 for analyzing the behavior of fuel adjacent to the blocked channel. A flow blockage of fuel channels can be postulated by a foreign object blocking cooling channels of fuels. Since a research reactor with plate type fuel has isolated fuel channels, a complete flow blockage of one fuel channel can cause a failure of adjacent fuel plates by the loss of cooling capability. Although research reactor systems are designed to prevent foreign materials from entering into the core, partial flow blockage accidents and following fuel failures are reported in some old research reactors. In this report, an analysis of complete flow blockage accident is presented for a 15MW pool-type research reactor with plate type fuels. The fuel surface experience different heat transfer regime in the results from original and modified RELAP5/MOD3.3. By the discrepancy in heat transfer mode of two cases, a fuel melting is expected by the modified RELAP5/MOD3.3, whereas the fuel integrity is ensured by the original code

  20. Volumetric flow imaging reveals the importance of vortex ring formation in squid swimming tail-first and arms-first.

    Science.gov (United States)

    Bartol, Ian K; Krueger, Paul S; Jastrebsky, Rachel A; Williams, Sheila; Thompson, Joseph T

    2016-02-01

    Squids use a pulsed jet and fin movements to swim both arms-first (forward) and tail-first (backward). Given the complexity of the squid multi-propulsor system, 3D velocimetry techniques are required for the comprehensive study of wake dynamics. Defocusing digital particle tracking velocimetry, a volumetric velocimetry technique, and high-speed videography were used to study arms-first and tail-first swimming of brief squid Lolliguncula brevis over a broad range of speeds [0-10 dorsal mantle lengths (DML) s(-1)] in a swim tunnel. Although there was considerable complexity in the wakes of these multi-propulsor swimmers, 3D vortex rings and their derivatives were prominent reoccurring features during both tail-first and arms-first swimming, with the greatest jet and fin flow complexity occurring at intermediate speeds (1.5-3.0 DML s(-1)). The jet generally produced the majority of thrust during rectilinear swimming, increasing in relative importance with speed, and the fins provided no thrust at speeds >4.5 DML s(-1). For both swimming orientations, the fins sometimes acted as stabilizers, producing negative thrust (drag), and consistently provided lift at low/intermediate speeds (swimming orientation, and η for swimming sequences with clear isolated jet vortex rings was significantly greater (η=78.6±7.6%, mean±s.d.) than that for swimming sequences with clear elongated regions of concentrated jet vorticity (η=67.9±19.2%). This study reveals the complexity of 3D vortex wake flows produced by nekton with hydrodynamically distinct propulsors. © 2016. Published by The Company of Biologists Ltd.

  1. Flow-induced plastic collapse of stacked fuel plates

    Energy Technology Data Exchange (ETDEWEB)

    Davis, D C; Scarton, H A

    1985-03-01

    Flow-induced plastic collapse of stacked fuel plate assemblies was first noted in experimental reactors such as the ORNL High Flux Reactor Assembly and the Engineering Test Reactor (ETR). The ETR assembly is a stack of 19 thin flat rectangular fuel plates separated by narrow channels through which a coolant flows to remove the heat generated by fission of the fuel within the plates. The uranium alloyed plates have been noted to buckle laterally and plastically collapse at the system design coolant flow rate of 10.7 m/s, thus restricting the coolant flow through adjacent channels. A methodology and criterion are developed for predicting the plastic collapse of ETR fuel plates. The criterion is compared to some experimental results and the Miller critical velocity theory.

  2. Molar exergy and flow exergy of pure chemical fuels

    International Nuclear Information System (INIS)

    Zanchini, Enzo; Terlizzese, Tiziano

    2009-01-01

    Expressions of the molar exergy and of the molar flow exergy of a pure chemical fuel are deduced rigorously from the basic principles of thermodynamics. It is shown that molar exergy and molar flow exergy coincide when the temperature T and the pressure p of the fuel are equal to the temperature T B and the pressure p B of the environment; a general relation between exergy and flow exergy is proved as a consequence. The deduction of the expression of the molar exergy of a chemical fuel for non-standard values of T B and p B is clarified. For hydrogen, carbon dioxide and several hydrocarbons, tables are reported to allow a simple calculation of the molar exergy of the fuel for any value of the temperature T B and the relative humidity φ B of the environment, in the range 268.15 K ≤ T B ≤ 313.15 K and 0.1 ≤ φ B ≤ 1, with reference to the standard atmospheric pressure. Additional tables are provided to evaluate the difference between the exergy or the flow exergy of the fuel in its given initial state and the exergy at T = T B and p = p B . In these tables, it is assumed that fuel and environment have the same temperature and that the fuel pressure varies in the range 1.01325 bar ≤ p ≤ 200 bar; the fuel may be gas or liquid.

  3. Development and Characterization of Fast Burning Solid Fuels/Propellants for Hybrid Rocket Motors with High Volumetric Efficiency

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this proposed work is to develop several fast burning solid fuels/fuel-rich solid propellants for hybrid rocket motor applications. In the...

  4. The development of flow test technology for PWR fuel assembly

    International Nuclear Information System (INIS)

    Chung, Moon Ki; Cha, Chong Hee; Chung, Chang Hwan; Chun, Se Young; Song, Chul Hwa; Chung, Heung Joon; Won, Soon Yeun; Cho, Yeong Rho; Kim, Bok Deuk

    1988-05-01

    KAERI has an extensive program to develope PWR fuel assembly. In relation to the program, development of flow test technology is needed to evaluate the thermal hydraulic compactibility and mechanical integrity of domestically fabricated nuclear fuels. A high-pressure and high-temperature flow test facility was designed to test domestically fabricated fuel assembly. The test section of the facility has capacity of a 6x6 full length PWR fuel assembly. A flow test rig was designed and installed at Cold Test Loop to carry out model experiments with 5x5 rod assembly under atmosphere pressure to get information about the characteristics of pressure loss of spacer grids and velocity distribution in the subchannels. LDV measuring technology was established using TSI's Laser Dopper Velocimeter 9100-3 System

  5. Modeling two-phase flow in PEM fuel cell channels

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yun; Basu, Suman; Wang, Chao-Yang [Electrochemical Engine Center (ECEC), and Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States)

    2008-05-01

    This paper is concerned with the simultaneous flow of liquid water and gaseous reactants in mini-channels of a proton exchange membrane (PEM) fuel cell. Envisaging the mini-channels as structured and ordered porous media, we develop a continuum model of two-phase channel flow based on two-phase Darcy's law and the M{sup 2} formalism, which allow estimate of the parameters key to fuel cell operation such as overall pressure drop and liquid saturation profiles along the axial flow direction. Analytical solutions of liquid water saturation and species concentrations along the channel are derived to explore the dependences of these physical variables vital to cell performance on operating parameters such as flow stoichiometric ratio and relative humility. The two-phase channel model is further implemented for three-dimensional numerical simulations of two-phase, multi-component transport in a single fuel-cell channel. Three issues critical to optimizing channel design and mitigating channel flooding in PEM fuel cells are fully discussed: liquid water buildup towards the fuel cell outlet, saturation spike in the vicinity of flow cross-sectional heterogeneity, and two-phase pressure drop. Both the two-phase model and analytical solutions presented in this paper may be applicable to more general two-phase flow phenomena through mini- and micro-channels. (author)

  6. CANFLEX fuel bundle cross-flow endurance test (test report)

    International Nuclear Information System (INIS)

    Hong, Sung Deok; Chung, C. H.; Chang, S. K.; Kim, B. D.

    1997-04-01

    As part of the normal refuelling sequence of CANDU nuclear reactor, both new and irradiated bundles can be parked in the cross-flow region of the liner tubes. This situation occurs normally for a few minutes. The fuel bundle which is subjected to the cross-flow should be capable of withstanding the consequences of cross flow for normal periods, and maintain its mechanical integrity. The cross-flow endurance test was conducted for CANFLEX bundle, latest developed nuclear fuel, at CANDU-Hot Test Loop. The test was carried out during 4 hours at the inlet cross-flow region. After the test, the bundle successfully met all acceptance criteria after the 4 hours cross-flow test. (author). 2 refs., 3 tabs

  7. CANFLEX fuel bundle cross-flow endurance test (test report)

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sung Deok; Chung, C. H.; Chang, S. K.; Kim, B. D.

    1997-04-01

    As part of the normal refuelling sequence of CANDU nuclear reactor, both new and irradiated bundles can be parked in the cross-flow region of the liner tubes. This situation occurs normally for a few minutes. The fuel bundle which is subjected to the cross-flow should be capable of withstanding the consequences of cross flow for normal periods, and maintain its mechanical integrity. The cross-flow endurance test was conducted for CANFLEX bundle, latest developed nuclear fuel, at CANDU-Hot Test Loop. The test was carried out during 4 hours at the inlet cross-flow region. After the test, the bundle successfully met all acceptance criteria after the 4 hours cross-flow test. (author). 2 refs., 3 tabs.

  8. Buoyancy-driven flow excursions in fuel assemblies

    International Nuclear Information System (INIS)

    Laurinat, J.E.; Paul, P.K.; Menna, J.D.

    1995-01-01

    A power limit criterion was developed for a postulated Loss of Pumping Accident (LOPA) in one of the recently shut down heavy water production reactors at the Savannah River Site. These reactors were cooled by recirculating heavy water moderator downward through channels in cylindrical fuel tubes. Powers were limited to safeguard against a flow excursion in one of more of these parallel channels. During-full-power operation, limits safeguarded against a boiling flow excursion. At low flow rates, during the addition of emergency cooling water, buoyant forces reverse the flow in one of the coolant channels before boiling occurs. As power increased beyond the point of flow reversal, the maximum wall temperature approaches the fluid saturation temperature, and a thermal excursion occurs. The power limit criterion for low flow rates was the onset of flow reversal. To determine conditions for flow reversal, tests were performed in a mock-up of a fuel assembly that contained two electrically heated concentric tubes surrounded by three flow channels. These tests were modeled using a finite difference thermal-hydraulic code. According to code calculations, flow reversed in the outer flow channel before the maximum wall temperature reached the local fluid saturation temperature. Thermal excursions occurred when the maximum wall temperature approximately equaled the saturation temperature. For a postulated LOPA, the flow reversal criterion for emergency cooling water addition was more limiting than the boiling excursion criterion for full power operation. This criterion limited powers to 37% of the limiting power for previous long-term reactor operations

  9. Buoyancy-driven flow excursions in fuel assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Laurinat, J.E.; Paul, P.K.; Menna, J.D. [Westinghouse Savannah River Company, Aiken, SC (United States)

    1995-09-01

    A power limit criterion was developed for a postulated Loss of Pumping Accident (LOPA) in one of the recently shut down heavy water production reactors at the Savannah River Site. These reactors were cooled by recirculating heavy water moderator downward through channels in cylindrical fuel tubes. Powers were limited to safeguard against a flow excursion in one of more of these parallel channels. During-full-power operation, limits safeguarded against a boiling flow excursion. At low flow rates, during the addition of emergency cooling water, buoyant forces reverse the flow in one of the coolant channels before boiling occurs. As power increased beyond the point of flow reversal, the maximum wall temperature approaches the fluid saturation temperature, and a thermal excursion occurs. The power limit criterion for low flow rates was the onset of flow reversal. To determine conditions for flow reversal, tests were performed in a mock-up of a fuel assembly that contained two electrically heated concentric tubes surrounded by three flow channels. These tests were modeled using a finite difference thermal-hydraulic code. According to code calculations, flow reversed in the outer flow channel before the maximum wall temperature reached the local fluid saturation temperature. Thermal excursions occurred when the maximum wall temperature approximately equaled the saturation temperature. For a postulated LOPA, the flow reversal criterion for emergency cooling water addition was more limiting than the boiling excursion criterion for full power operation. This criterion limited powers to 37% of the limiting power for previous long-term reactor operations.

  10. Buoyancy-driven flow excursions in fuel assemblies

    International Nuclear Information System (INIS)

    Laurinat, J.E.; Paul, P.K.; Menna, J.D.

    1995-01-01

    A power limit criterion was developed for a postulated Loss of Pumping Accident (LOPA) in one of the recently shut down heavy water production reactors at the Savannah River Site. These reactors were cooled by recirculating moderator downward through channels in cylindrical fuel tubes. Powers were limited to prevent a flow excursion from occurring in one or more of these parallel channels. During full-power operation, limits prevented a boiling flow excursion from taking place. At low flow rates, during the addition of emergency cooling water, buoyant forces reverse the flow in one of the coolant channels before boiling occurs. As power increases beyond the point of flow reversal, the maximum wall temperature approaches the fluid saturation temperature, and a thermal excursion occurs. The power limit criterion for low flow rates was the onset of flow reversal. To determine conditions for flow reversal, tests were performed in a mock-up of a fuel assembly that contained two electrically heated concentric tubes surrounded by three flow channels. These tests were modeled using a finite difference thermal-hydraulic code. According to code calculations, flow reversed in the outer flow channel before the maximum wall temperature reached the local fluid saturation temperature. Thermal excursions occurred when the maximum wall temperature approximately equaled the saturation temperature. For a postulated LOPA, the flow reversal criterion for emergency cooling water addition was more limiting than the boiling excursion criterion for full power operation. This criterion limited powers to 37% of historical levels

  11. Improved Flow-Field Structures for Direct Methanol Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Gurau, Bogdan [Nuvant Systems Inc., Crown Point, IN (United States)

    2013-05-31

    The direct methanol fuel cell (DMFC) is ideal if high energy-density liquid fuels are required. Liquid fuels have advantages over compressed hydrogen including higher energy density and ease of handling. Although state-of-the-art DMFCs exhibit manageable degradation rates, excessive fuel crossover diminishes system energy and power density. Although use of dilute methanol mitigates crossover, the concomitant lowering of the gross fuel energy density (GFED) demands a complex balance-of-plant (BOP) that includes higher flow rates, external exhaust recirculation, etc. An alternative approach is redesign of the fuel delivery system to accommodate concentrated methanol. NuVant Systems Inc. (NuVant) will maximize the GFED by design and assembly of a DMFC that uses near neat methanol. The approach is to tune the diffusion of highly concentrated methanol (to the anode catalytic layer) to the back-diffusion of water formed at the cathode (i.e. in situ generation of dilute methanol at the anode layer). Crossover will be minimized without compromising the GFED by innovative integration of the anode flow-field and the diffusion layer. The integrated flow-field-diffusion-layers (IFDLs) will widen the current and potential DMFC operating ranges and enable the use of cathodes optimized for hydrogen-air fuel cells.

  12. Nozzle flow and atomization characteristics of ethanol blended biodiesel fuel

    Energy Technology Data Exchange (ETDEWEB)

    Park, Su Han; Suh, Hyun Kyu; Lee, Chang Sik [Department of Mechanical Engineering, Graduate School of Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul, 133-791 (Korea)

    2010-01-15

    This study was conducted to investigate the injection and atomization characteristics of biodiesel-ethanol blended fuel. The injection performance of biodiesel-ethanol blended fuel was analyzed from the injection rate characteristics using the injection rate measuring system, and the effective injection velocity and effective spray diameter using the nozzle flow model. Moreover, the atomization characteristics, such as local and overall SMD distributions, overall axial velocity and droplet arrival time were analyzed and compared with these from diesel and biodiesel fuels to obtain the atomization characteristics of biodiesel-ethanol blended fuel. It was revealed that ethanol fuel affects the decrease of the peak injection rate and the shortening of the injection delay due to the decrease of fuel properties, such as fuel density and dynamic viscosity. In addition, the ethanol addition improved the atomization performance of biodiesel fuel, because the ethanol blended fuel has a low kinematic viscosity and surface tension, then that has more active interaction with the ambient gas, compared to BD100. (author)

  13. Kilohertz VLIF (volumetric laser induced fluorescence) measurements in a seeded free gas-phase jet in the transitionally turbulent flow regime

    Science.gov (United States)

    Wu, Yue; Xu, Wenjiang; Ma, Lin

    2018-03-01

    This paper reports the demonstration of instantaneous three-dimension (3D) measurements in turbulent flows at repetition rates up to 10 kHz using VLIF (volumetric laser induced fluorescence). The measurements were performed based on the LIF signal of iodine (I2) vapor seeded in the flow. The LIF signals of I2 vapor were generated volumetrically by a thick laser slab and then simultaneously captured by a total of seven cameras from different perspectives, based on which a 3D tomographic reconstruction was performed to obtain the 3D distribution of I2 vapor concentration. Single-shot measurements obtained in a duration of hundreds of nanoseconds (limited by the pulse duration of the excitation laser) were demonstrated in a 50 × 50 × 50 mm3 at a repetition rate up to 10 kHz. These measurements demonstrated the feasibility and potential of VLIF for resolving the 4D spatiotemporal dynamics of turbulent flows. Based on the experimental results obtained, this work also studied the VLIF signal level and its effects on the reconstruction accuracy under different the measurement conditions, illustrating the capabilities and limitations of performing high speed VLIF measurements.

  14. Experimental investigation two phase flow in direct methanol fuel cells

    International Nuclear Information System (INIS)

    Mat, M. D.; Kaplan, Y.; Celik, S.; Oeztural, A.

    2007-01-01

    Direct methanol fuel cells (DMFC) have received many attentions specifically for portable electronic applications since it utilize methanol which is in liquid form in atmospheric condition and high energy density of the methanol. Thus it eliminates the storage problem of hydrogen. It also eliminates humidification requirement of polymeric membrane which is a problem in PEM fuel cells. Some electronic companies introduced DMFC prototypes for portable electronic applications. Presence of carbon dioxide gases due to electrochemical reactions in anode makes the problem a two phase problem. A two phase flow may occur at cathode specifically at high current densities due to the excess water. Presence of gas phase in anode region and liquid phase in cathode region prevents diffusion of fuel and oxygen to the reaction sites thus reduces the performance of the system. Uncontrolled pressure buildup in anode region increases methanol crossover through membrane and adversely effect the performance. Two phase flow in both anode and cathode region is very effective in the performance of DMYC system and a detailed understanding of two phase flow for high performance DMFC systems. Although there are many theoretical and experimental studies available on the DMFC systems in the literature, only few studies consider problem as a two-phase flow problem. In this study, an experimental set up is developed and species distributions on system are measured with a gas chromatograph. System performance characteristics (V-I curves) is measured depending on the process parameters (temperature, fuel ad oxidant flow rates, methanol concentration etc)

  15. 16 x 16 Vantage+ Fuel Assembly Flow Vibrational Testing

    International Nuclear Information System (INIS)

    Chambers, Martin; Kurincic, Bojan

    2014-01-01

    Nuklearna Elektrarna Krsko (NEK) has experienced leaking fuel after increasing the cycle duration to 18 months. The leaking fuel mechanism has predominantly been consistent over multiple cycles and is typically observed in highly irradiated Fuel Assemblies (FA) after around 4 years of continuous operation that were located at the core periphery (baffle). The cause of the leaking fuel is due to Grid-To-Rod-Fretting (GRTF) and occasional debris fretting. NEK utilises a 16x16 Vantage+ FA design with all Inconel structural mixing vane grids (8 in total), Zirlo thimbles, Integral Fuel Burnable Absorber (IFBA) rods with enriched ZrB2, enriched Annular Blanket, Debris Filter Bottom Nozzle (DFBN), Removable Top Nozzle (RTN) and Zirlo fuel cladding material with a high burnup capability of 60 GWD/MTU. Numerous design and operational changes are thought to have reduced the original 16x16 FA design margin to fretting resistance of either vibration or its wear work rate, such as significant power uprate (spring force loss, rod creep down...), operational cycle duration increase from 12 to 18 months (increasing residence time as well as lead FA and fuel rod burnup values), Reactor Coolant System flow increase (increased vibration), removal of Thimble Plugs (increased bypass flow, increased vibration) and Zirc-4 to Zirlo cladding change (decreasing wear work rate). The fuel rod to grid spring as well as dimple contact areas are relatively smaller than other FA designs that exhibit good in-reactor fretting performance. A FA design change project to address the small rod to dimple / spring contact area and utilise fuel cladding oxide coating is currently being pursued with the fuel supplier. The FA vibrational properties are very important to the in-reactor FA performance and reliability. The 16x16 Vantage+ vibrational testing was performed with a full size FA in the Fuel Assembly Compatibility Testing (FACTS) loop that is able to provide full flow rates at elevated temperature

  16. Flow analysis of tubular fuel assembly using CFD code

    International Nuclear Information System (INIS)

    Park, J. H.; Park, C.; Chae, H. T.

    2004-01-01

    Based on the experiences of HANARO, a new research reactor is under conceptual design preparing for future needs of research reactor. Considering various aspects such as nuclear physics, thermal-hydraulics, mechanical structure and the applicability of HANARO technology, a tubular type fuel has been considered as that of a new research reactor. Tubular type fuel has several circular fuel layers, and each layer consists of 3 curved fuel plates arranged with constant small gap to build up cooling channels. In the thermal-hydraulic point, it is very important to maintain each channel flow velocity be equal as much as possible, because the small gaps between curved thin fuel plates independently forms separate coolant channels, which may cause a thermal-hydraulic problem in certain conditions. In this study, commercial CFD(Computational Fluid Dynamics) code, Fluent, has been used to investigate flow characteristics of tubular type fuel assembly. According to the computation results for the preliminary conceptual design, there is a serious lack of uniformity of average velocity on the each coolant channel. Some changes for initial conceptual design were done to improve the balance of velocity distribution, and analysis was done again, too. The results for the revised design showed that the uniformity of each channel velocity was improved significantly. The influence of outermost channel gap width on the velocity distribution was also examined

  17. Experimental study of water flow in nuclear fuel elements

    International Nuclear Information System (INIS)

    Rodrigues, Lorena Escriche; Rezende, Hugo Cesar; Mattos, Joao Roberto Loureiro de; Barros Filho, Jose Afonso; Santos, Andre Augusto Campagnole dos

    2013-01-01

    This work aims to develop an experimental methodology for investigating the water flow through rod bundles after spacer grids of nuclear fuel elements of PWR type reactors. Speed profiles, with the device LDV (Laser Doppler Velocimetry), and the pressure drop between two sockets located before and after the spacer grid, using pressure transducers were measured

  18. Cooling flow measurement in fuel elements of the RA-6

    International Nuclear Information System (INIS)

    Brollo, F; Silin, N

    2009-01-01

    Under the UBERA6 project for the core change and power increase of the RA-6 reactor, the total coolant flow was increased to meet the requirements imposed by the new operating conditions. The flow through the fuel elements is an important parameter and is difficult to determine due to the geometric complexity of the core. To ensure safe operation of the reactor, adequate safety margins must be kept for all operating conditions. In the present work we performed the direct measurement of the cooling flow rate of a fuel in the reactor core, for which we used a turbine flowmeter built specifically for this use. This helped to confirm previous results obtained during the launch, made by an indirect method based on measuring the pressure difference of the core. The turbine flowmeter was chosen due to its robustness, ease of operation and low disturbance of the input stream to the fuel. We describe the calibration of this instrument and the results of flow measurements made on some of the RA6 reactor fuel elements under conditions of zero power. [es

  19. Experimental investigation of the liquid volumetric mass transfer coefficient for upward gas-liquid two-phase flow in rectangular microchannels

    Directory of Open Access Journals (Sweden)

    X. Y. Ji

    2010-12-01

    Full Text Available The gas-liquid two-phase mass transfer process in microchannels is complicated due to the special dynamical characteristics. In this work, a novel method was explored to measure the liquid side volumetric mass transfer coefficient kLa. Pressure transducers were utilized to measure the pressure variation of upward gas-liquid two-phase flow in three vertical rectangular microchannels and the liquid side volumetric mass transfer coefficient kLa was calculated through the Pressure-Volume-Temperature correlation of the gas phase. Carbon dioxide-water, carbon dioxide-ethanol and carbon dioxide-n-propanol were used as working fluids, respectively. The dimensions of the microchannels were 40 µm×240 µm (depth×width, 100 µm×800 µm and 100 µm×2000 µm, respectively. Results showed that the channel diameter and the capillary number influence kLa remarkably and that the maximum value of kLa occurs in the annular flow regime. A new correlation of kLa was proposed based on the Sherwood number, Schmidt number and the capillary number. The predicted values of kLa agreed well with the experimental data.

  20. The effect of the volumetric heat source distribution of the fuel pellet on the minimum DNBR ratio

    International Nuclear Information System (INIS)

    Hordosy, G.; Kereszturi, A.; Maroti, L.; Trosztel, I.

    1995-01-01

    The radial power distribution in a VVER-440 type fuel assembly is strongly non-uniform as a result of the water-gap between the shrouds and the moderator filled central tube. Consequently, it can be expected that the power density inside a single fuel rod is inhomogeneous, as well. In the paper the methodology and the results of coupled thermohydraulic and neutronic calculations are presented. The objective of the analysis was the investigation of the heat source distribution and the determination of the possible extent of the power non-uniformity in a corner rod which has always the highest peaking factor in a VVER-440 type assembly. The results of the analysis revealed that there can be a strong non-uniformity of power distribution inside a fuel pellet, and the effect depends first of all on the general assembly conditions, while the local subchannel parameters have only a slight influence on the pellet heat source distribution. (author)

  1. Polymer electrolyte fuel cells: flow field for efficient air operation

    Energy Technology Data Exchange (ETDEWEB)

    Buechi, F N; Tsukada, A; Haas, O; Scherer, G G [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    A new flow field was designed for a polymer electrolyte fuel cell stack with an active area of 200 cm{sup 2} for operation at low air stoichiometry and low air over pressure. Optimum of gas flow and channel dimensions were calculated based on the required pressure drop in the fluid. Single cells and a bi-cell stack with the new flow field show an improved current/voltage characteristic when operated at low air stoichiometries as compared to that of the previous non optimized design. (author) 4 figs., 3 refs.

  2. Characterization of dispersed type fuel miniplates based in alloy UMo by evaluation of changes volumetrics and thermal conductivity

    International Nuclear Information System (INIS)

    Salinas Valero, Pablo Ignacio

    2016-01-01

    The development of new technologies in the nuclear area is extremely important to achieve greater efficiency and security in the production of electrical energy in the case of power reactors and for the production of radioisotopes and neutrons in research reactors. Throughout history, uranium-based nuclear fuels evolved in parallel with the requirements of nuclear reactors, this emphasis was increased when the RERTR program was created, which restricts the use of fuels with a maximum enrichment of 20% of the isotope U 235 (fissile isotope), which makes it necessary to increase the mass of uranium to compensate the amount of fissile material to maintain a neutron flux necessary for the reactors to operate with the same power. The search for new nuclear fuels has reached the UMo alloy with which densities of 18 gU/cm 3 are achieved in type fuels and 8 gU/cm 3 in dispersed type fuels, properties under irradiation due to their cubic crystalline structure. This type of fuel, when used dispersed in an aluminum matrix, becomes thermodynamically unstable by increasing the fission temperature of the U 235 isotope, due to this, compounds of lower density are formed, which causes an increase in volume (swelling). ). This swelling is studied throughout the present work, to relate the changes of UMo-Al / 4% volume of thermally induced miniecography in thermal treatments, with the purpose of evaluating changes in the thermal conductivity of the material. In this study it was detected that the swelling in miniplates is related in some way to the reduction of thermal conductivity, it was also recorded that the volume of change is irregular increasing and decreasing its volume according to the hours of induced swelling. The purpose of this work is to contribute to the development of dispersed fuels based on the UMo alloy in order to control the variables and reduce the probability of faults and possible accidents, such as fission products, or an increase in temperature in the core

  3. Mass Flow Data Comparison for Comprehensive Fuel Cycle Options

    International Nuclear Information System (INIS)

    Kim, T.K.; Taiwo, T.A.; Wigeland, R.A.; Dixon, B.W.; Gehin, J.C.; Todosow, M.

    2015-01-01

    One of the key objectives stated in the United States Department of Energy, Nuclear Energy R and D road-map is the development of sustainable nuclear fuel cycles that improve natural resource utilisation and provide adequate capability and capacity to manage wastes produced by the fuel cycle. In order to inform this objective, an evaluation and screening of nuclear fuel cycle options has been conducted. As part of that effort, the entire fuel cycle options space was represented by 40 Evaluation Groups (EGs), and mass flow information for each of the EGs was provided by using an Analysis Example (AE). In this paper, the mass flow data of the 40 AEs are compared to inform on trends in the natural resource utilisation and nuclear waste generation. For the AEs that need enriched uranium support, the natural uranium required is high and the natural resource utilisation is generally lower than 2% regardless of the fuel cycle strategy (i.e., once-through, limited recycle, or continuous recycle). However, the utilisation could be improved by avoiding enriched uranium fuel support. The natural resource utilisation increases to more than 80% by recycling the nuclear fuel continuously without enriched uranium support. The combined mass of spent nuclear fuel (SNF) and high-level waste (HLW), i.e., SNF+HLW mass, is lower by using a continuous recycle option compared to a once-through fuel cycle option, because SNF mass is converted to mass of recycled products and only fission products and other process losses need to be disposed. The combined disposed mass of depleted uranium (DU), recovered uranium (RU) and thorium (RTh), i.e. DU+RU+RTh mass, has a similar trend to the uranium utilisation. For the AEs that need enriched uranium fuel, the DU and RU are the major fraction by mass of the DU+RU+RTh, which are two orders of magnitude higher in mass compared to those for the AEs that do not need enriched uranium fuel. (authors)

  4. Bruce B fuelling-with-flow operations: fuel damage investigation

    Energy Technology Data Exchange (ETDEWEB)

    Manzer, A.M. [CANTECH Associates Ltd., Burlington, Ontario (Canada); Morikawa, D. [Atomic Energy of Canada Limited, Mississauga, Ontario (Canada); Hains, A.J.; Cichowlas, W.M. [Nuclear Safety Solutions Limited, Toronto, Ontario (Canada); Roberts, J.G.; Wylie, J. [Bruce Power, Ontario (Canada)

    2005-07-01

    This paper summarizes the fuel bundle damage characterization done by Nuclear Safety Solutions Limited (NSS) and the out-reactor flow visualization tests done at Atomic Energy of Canada Limited (AECL) to reproduce the damage observed on irradiated fuel bundles. The bearing pad damage mechanism was identified and the tests showed that a minor change to the fuelling sequence would eliminate the mechanical interaction. The change was implemented in January 2005. Since then, the bearing pad damage appears to have been greatly reduced based on the small number of discharged bundles inspected to date. (author)

  5. Bruce B fuelling-with-flow operations: fuel damage investigation

    International Nuclear Information System (INIS)

    Manzer, A.M.; Morikawa, D.; Hains, A.J.; Cichowlas, W.M.; Roberts, J.G.; Wylie, J.

    2005-01-01

    This paper summarizes the fuel bundle damage characterization done by Nuclear Safety Solutions Limited (NSS) and the out-reactor flow visualization tests done at Atomic Energy of Canada Limited (AECL) to reproduce the damage observed on irradiated fuel bundles. The bearing pad damage mechanism was identified and the tests showed that a minor change to the fuelling sequence would eliminate the mechanical interaction. The change was implemented in January 2005. Since then, the bearing pad damage appears to have been greatly reduced based on the small number of discharged bundles inspected to date. (author)

  6. Intermediate flow mixing nonsupport grid for BWR fuel assembly

    International Nuclear Information System (INIS)

    Taleyarkhan, R.P.

    1987-01-01

    An intermediate flow mixing nonsupport grid is described for use in a nuclear reactor fuel assembly containing an array of elongated fuel rods. The grid comprises: (a) interleaved inner straps arranged in an egg-crate configuration to define inner cell openings for receiving respective ones of the fuel rods. The inner straps have outer terminal end portions; (b) an outer peripheral strap attached to the respective terminal end portions of the inner straps to define perimeter cell openings for receiving other ones of the fuel rods. The inner straps and outer strap together have opposite upstream and downstream sides; (c) a first group of mixing vanes disposed at the downstream side and being attached on portions of the outer strap and on respective portions of the inner straps. Together with the outer strap portions, they define the perimeter cell openings. Each of the mixing vanes of the first group extend generally in a downstream direction and inwardly toward the perimeter cell openings for deflecting coolant flowing; and (d) a second group of mixing vanes disposed at the downstream side and being attached on other portions of the inner straps. Together with the respective portions, they define the inner cell openings. Each of the mixing vanes of the second group extend generally in a downstream direction and inwardly toward the inner cell openings for deflecting coolant flowing therethrough; (e) the mixing vanes of the second group are substantially smaller in size than the mixing vanes of the first group so as to generate substantially less turbulence in the portions of the coolant flowing through the inner cell openings than in the portions of the coolant flowing through the perimeter cell openings

  7. CFD modeling of secondary flows in fuel rod bundles

    International Nuclear Information System (INIS)

    Baglietto, Emilio; Ninokata, Hisashi

    2004-01-01

    An optimized non-linear eddy viscosity model is introduced, for calculations of detailed coolant velocity distribution in a tight lattice fuel bundle. The low Reynolds formulation has been optimized based on DNS data for channel flow. The non-linear stress-strain relationship has been modified in the coefficients to model the flow anisotropy, which causes the formation of turbulence driven secondary flows inside the bundle subchannels. Predictions of the model are first compared to experimental measurements of secondary flows in a triangularly arrayed rod bundle with p/d=1.3. Subsequently wall shear stress and velocity predictions are compared with different experimental data for a rod bundle with p/d=1.17. The model shows to be able to correctly reproduce the scale of the secondary motion, and to accurately reproduce both wall shear stress and velocity distributions inside the rod bundle subchannels. (author)

  8. Dynamics of nuclear fuel assemblies in vertical flow channels

    International Nuclear Information System (INIS)

    Mason, V.A.

    1988-01-01

    DYNMOD is a computer program designed to predict the dynamic behaviour of nuclear fuel assemblies in axial flow. The calculations performed by DYNMOD and the input data required by the program are described in this report. Examples of DYNMOD usage and a brief assessment of the accuracy of the dynamic model are also presented. It is intended that the report will be used as a reference manual by users of DYNMOD

  9. Vibration mechanism of fuel rod in axial flow

    International Nuclear Information System (INIS)

    Kang, Heung Seok; Yoon, Kyung Ho; Kim, Hyung Kyu; Song, Kee Nam

    1998-08-01

    This is a review on the previous researches for the vibration of fuel rod induced by axial flow. The analysis methods are classified into three categories accordingly as the researchers postulate the vibration to be self-excited, forced and parametric; the self-excited mechanism by Burgreen and Quinn, the forced one by Reavis, Gorman, kanazawa, and S. Chen, and the parametric one by Y. Chen. Quinn supposed that the centrifugal force by flow exaggerated the natural bow in the cylinder, and the flexural force by it diminished the bow by turns; this interactive motion leaded cylinder to vibration. The supporters to the forced mechanism considered the forces arising from pressure perturbation within the boundary layers as vibrating sources. Y. Chen insisted that the cylinder could only be excited to vibration in resonance by the small oscillation of mean flow velocity. The previous studies were based on the simple boundary conditions such as hinged-hinged or fixed-fixed single span. Therefore, for the more accurate prediction of the fuel rod vibration in reactor, the further studies need to reflect the actual boundary conditions of the fuel rod like axial force and continuous supports by grids. (author). 25 refs

  10. Effect of induced cross flow on flow pattern and performance of proton exchange membrane fuel cell

    International Nuclear Information System (INIS)

    Jiao, Kui; Bachman, John; Zhou, Yibo; Park, Jae Wan

    2014-01-01

    Highlights: • 3D numerical works to study the effect of cross flow on the PEMFC performance. • The cross flow ensure more evenly distributed water and oxygen in the CL. • The optimal net power output can be identified by controlling the back pressure. • Results confirm that present design is effective in improving performance. - Abstract: The cross flow in proton exchange membrane fuel cells (PEMFCs) plays an important role in changing the transport pattern and performance. In this study, three-dimensional numerical simulations are carried out to investigate the effect of induced cross flow on the flow pattern and performance of a PEMFC with a previously proposed and experimentally studied novel parallel flow channel design. The numerical results indicate that the liquid water and oxygen become more evenly distributed in the catalyst layer (CL) as the pressure difference between the low-pressure and high-pressure flow channels increases. It has been found that, in the low-pressure channels, the cross flow drives a convective flow from the CL to the flow channel resulting in improved liquid water removal. The optimal net power output can be identified by controlling the back pressure on the high-pressure flow channels. The numerical results confirm that this novel parallel flow channel design is effective in improving PEMFC performance

  11. 3-D flow analyses for design of nuclear fuel spacer

    Energy Technology Data Exchange (ETDEWEB)

    Karouta, Z. [ABB Combustion Engineering, Windsor, CT (United States); GU, Chun-Yuan [ABB Corporate Research, Vaesteras (Sweden); Schoelin, B. [ABB Atom AB, Vaesteras (Sweden)

    1995-09-01

    The Computational Fluid Dynamics (CFD) code, CFDS-FLOW3D, was used to develop improved fuel designs for PWR cores. It was used primarily to understand the fluid dynamics of grid spacers, the mass transfer between subchannels caused by spacers and in the long term to develop two-phase models which enable prediction of critical heat flux in PWR fuel. A single subchannel of one grid span was modeled. In this model different spacer designs with mixing devices were analyzed. A special treatment of the boundary condition was developed making use of flow symmetry to model the mass transfer between different subchannels and minimize the size of the computational model. This reduced the computational model to a fraction of a subchannel using traditional periodic boundary conditions. The Navier-Stokes equation was solved for the liquid and the flow turbulence was modeled by k-{xi} turbulence model. The spacer and mixing device were treated as infinite thin surfaces in the model and a zero velocity condition and turbulent wall function were applied on each side of the thin surfaces. This approach simulated the swirl from the mixing devices well, but had the drawback of not predicting pressure drop accurately since the wake behind the plates and the acceleration effect of the spacers were ignored. CFDS-FLOW3D models with mixing devices were applied in the single-phase flow regime. Velocity profiles from the CFDS-FLOW3D models were compared to Laser Doppler Velocimeter measurements taken from the flow field downstream of spaces in a full scale, cold water test loop. The predicted axial and lateral velocity profiles were in good agreement with the measurements. The evaluation of the performance of different spacer devices was made by comparing the swirl ratio downstream of the grid spacers. It is planned to evaluate heat transfer coefficient downstream of the spaces, to implement two-phase flow models, and to model the superheated boundary layer on the surface of the fuel rod.

  12. Lateral Flow Field Behavior Downstream of Mixing Vanes In a Simulated Nuclear Fuel Rod Bundle

    International Nuclear Information System (INIS)

    Conner, Michael E.; Smith, L. David III; Holloway, Mary V.; Beasley, Donald E.

    2004-01-01

    To assess the fuel assembly performance of PWR nuclear fuel assemblies, average subchannel flow values are used in design analyses. However, for this highly complex flow, it is known that local conditions around fuel rods vary dependent upon the location of the fuel rod in the fuel assembly and upon the support grid design that maintains the fuel rod pitch. To investigate the local flow in a simulated nuclear fuel rod bundle, a testing technique has been employed to measure the lateral flow field in a 5 x 5 rod bundle. Particle Image Velocimetry was used to measure the lateral flow field downstream of a support grid with mixing vanes for four unique subchannels in the 5 x 5 bundle. The dominant lateral flow structures for each subchannel are compared in this paper including the decay of these flow structures. (authors)

  13. Fuel flow distribution in SOFC stacks revealed by impedance spectroscopy

    DEFF Research Database (Denmark)

    Mosbæk, Rasmus Rode; Hjelm, Johan; Barfod, Rasmus

    2014-01-01

    As SOFC technology is moving closer to a commercial break through, methods to measure the “state-of-health” of operating stacks are becoming of increasing interest. This requires application of advanced methods for detailed electrical and electrochemical characterization during operation. An oper......As SOFC technology is moving closer to a commercial break through, methods to measure the “state-of-health” of operating stacks are becoming of increasing interest. This requires application of advanced methods for detailed electrical and electrochemical characterization during operation...... utilizations. The fuel flow distribution provides important information about the operating limits of the stack when high electrical efficiency is required....

  14. Pressure data for various flow channels in proton exchange membrane (PEM) fuel cell

    International Nuclear Information System (INIS)

    Cho, Son Ah; Lee, Pil Hyong; Han, Sang Seok; Hwang, Sang Soon

    2008-01-01

    Micro flow channels in flow plates of fuel cells have become much narrower and longer to improve reactant flow distribution leading to increase of pumping power. Therefore it is very important to minimize the pressure drops in the flow channel because increased pumping power reduces overall efficiency. We investigated pressure drops in a micro flow channel at the anode and cathode compared to pressure losses for cold flow in straight, bended and serpentine channels. The results show that friction factors for cold flow channels could be used for parallel and bended flow channel designs for fuel cells. Pressure drop in the serpentine flow channel is the lowest among all flow channels due to bypass flow across the gas diffusion layer under reactive flow condition, although its pressure drop is highest for a cold flow condition. So the effect of bypass flow for serpentine flow channels should be considered when designing flow channels

  15. Coaxial volumetric velocimetry

    Science.gov (United States)

    Schneiders, Jan F. G.; Scarano, Fulvio; Jux, Constantin; Sciacchitano, Andrea

    2018-06-01

    This study describes the working principles of the coaxial volumetric velocimeter (CVV) for wind tunnel measurements. The measurement system is derived from the concept of tomographic PIV in combination with recent developments of Lagrangian particle tracking. The main characteristic of the CVV is its small tomographic aperture and the coaxial arrangement between the illumination and imaging directions. The system consists of a multi-camera arrangement subtending only few degrees solid angle and a long focal depth. Contrary to established PIV practice, laser illumination is provided along the same direction as that of the camera views, reducing the optical access requirements to a single viewing direction. The laser light is expanded to illuminate the full field of view of the cameras. Such illumination and imaging conditions along a deep measurement volume dictate the use of tracer particles with a large scattering area. In the present work, helium-filled soap bubbles are used. The fundamental principles of the CVV in terms of dynamic velocity and spatial range are discussed. Maximum particle image density is shown to limit tracer particle seeding concentration and instantaneous spatial resolution. Time-averaged flow fields can be obtained at high spatial resolution by ensemble averaging. The use of the CVV for time-averaged measurements is demonstrated in two wind tunnel experiments. After comparing the CVV measurements with the potential flow in front of a sphere, the near-surface flow around a complex wind tunnel model of a cyclist is measured. The measurements yield the volumetric time-averaged velocity and vorticity field. The measurements of the streamlines in proximity of the surface give an indication of the skin-friction lines pattern, which is of use in the interpretation of the surface flow topology.

  16. Low stoichiometry operation of a proton exchange membrane fuel cell employing the interdigitated flow field

    DEFF Research Database (Denmark)

    Berning, Torsten; Kær, Søren Knudsen

    2012-01-01

    A multiphase fuel cell model based on computational fluid dynamics is used to investigate the possibility of operating a proton exchange membrane fuel cell at low stoichiometric flow ratios (ξ gases. A case study...

  17. BWR fuel assembly bottom nozzle with one-way coolant flow valve

    International Nuclear Information System (INIS)

    Taleyarkhan, R.P.

    1987-01-01

    In a nuclear reactor having a flow of coolant/moderator fluid therein, at least one fuel assembly installed in the fluid flow, the fuel assembly is described comprising in combination: a bundle of elongated fuel rods disposed in side-by-side relationship so as to form an array of spaced fuel rods; an outer tubular flow channel surrounding the fuel rods so as to direct the flow of coolant/moderator fluid along the fuel rods; bottom and top nozzles mounted at opposite ends of the flow channel and having an inlet and outlet respectively for allowing entry and exit of the flow of coolant/moderator fluid into and from the flow channel and along the fuel rods therein; and a coolant flow direction control device operatively disposed in the bottom nozzle so as to open the inlet thereof to the flow of coolant/moderator fluid in an inflow direction into the flow channel through the bottom nozzle inlet but close the inlet to the flow of coolant/moderator fluid from the flow channel through the bottom nozzle inlet upon reversal of coolant/moderator fluid flow from the inflow direction

  18. Carpooling and Driver Responses to Fuel Price Changes: Evidence from Traffic Flows in Los Angeles

    OpenAIRE

    Antonio M. Bento; Jonathan E. Hughes; Daniel T. Kaffine

    2012-01-01

    Understanding how drivers respond to fuel price changes has important implications for highway congestion, accidents, carbon policy, local air pollution and taxation. We examine the underexplored relationship between fuel prices and carpooling. Using a simple theoretical model we show that traffic flows in mainline lanes decrease when fuel prices increase. However in carpool (HOV) lanes, flow can either increase or decrease. Traffic flows in mainline lanes are shown to be more responsive to p...

  19. Experimental and numerical investigations of BWR fuel bundle inlet flow

    International Nuclear Information System (INIS)

    Hoashi, E; Morooka, S; Ishitori, T; Komita, H; Endo, T; Honda, H; Yamamoto, T; Kato, T; Kawamura, S

    2009-01-01

    We have been studying the mechanism of the flow pattern near the fuel bundle inlet of BWR using both flow visualization test and computational fluid dynamics (CFD) simulation. In the visualization test, both single- and multi-bundle test sections were used. The former test section includes only a corner orifice facing two support beams and the latter simulates 16 bundles surrounded by four beams. An observation window is set on the side of the walls imitating the support beams upstream of the orifices in both test sections. In the CFD simulation, as well as the visualization test, the single-bundle model is composed of one bundle with a corner orifice and the multi-bundle model is a 1/4 cut of the test section that includes 4 bundles with the following four orifices: a corner orifice facing the corner of the two neighboring support beams, a center orifice at the opposite side from the corner orifice, and two side orifices. Twin-vortices were observed just upstream of the corner orifice in the multi-bundle test as well as the single-bundle test. A single-vortex and a vortex filament were observed at the side orifice inlet and no vortex was observed at the center orifice. These flow patterns were also predicted in the CFD simulation using Reynolds Stress Model as a turbulent model and the results were in good agreement with the test results mentioned above. (author)

  20. Flow blurring atomization for combustion of viscous (bio)fuels

    NARCIS (Netherlands)

    Pozarlik, Artur Krzysztof; Bouma, Wilmer; Ratering, Martijn; Brem, Gerrit

    2017-01-01

    In order to achieve efficient combustion of liquid fuel a proper atomization of the fuel is needed. In case of many biomass fuels the atomization process is obstructed and hindered by high viscosity of the fuel. Preheating to reduce the viscosity in many cases is not possible because of fuel

  1. Benchmark calculations for evaluation methods of gas volumetric leakage rate

    International Nuclear Information System (INIS)

    Asano, R.; Aritomi, M.; Matsuzaki, M.

    1998-01-01

    A containment function of radioactive materials transport casks is essential for safe transportation to prevent the radioactive materials from being released into environment. Regulations such as IAEA standard determined the limit of radioactivity to be released. Since is not practical for the leakage tests to measure directly the radioactivity release from a package, as gas volumetric leakages rates are proposed in ANSI N14.5 and ISO standards. In our previous works, gas volumetric leakage rates for several kinds of gas from various leaks were measured and two evaluation methods, 'a simple evaluation method' and 'a strict evaluation method', were proposed based on the results. The simple evaluation method considers the friction loss of laminar flow with expansion effect. The strict evaluating method considers an exit loss in addition to the friction loss. In this study, four worked examples were completed for on assumed large spent fuel transport cask (Type B Package) with wet or dry capacity and at three transport conditions; normal transport with intact fuels or failed fuels, and an accident in transport. The standard leakage rates and criteria for two kinds of leak test were calculated for each example by each evaluation method. The following observations are made based upon the calculations and evaluations: the choked flow model of ANSI method greatly overestimates the criteria for tests ; the laminar flow models of both ANSI and ISO methods slightly overestimate the criteria for tests; the above two results are within the design margin for ordinary transport condition and all methods are useful for the evaluation; for severe condition such as failed fuel transportation, it should pay attention to apply a choked flow model of ANSI method. (authors)

  2. MEASUREMENTS AND COMPUTATIONS OF FUEL DROPLET TRANSPORT IN TURBULENT FLOWS

    Energy Technology Data Exchange (ETDEWEB)

    Joseph Katz and Omar Knio

    2007-01-10

    The objective of this project is to study the dynamics of fuel droplets in turbulent water flows. The results are essential for development of models capable of predicting the dispersion of slightly light/heavy droplets in isotropic turbulence. Since we presently do not have any experimental data on turbulent diffusion of droplets, existing mixing models have no physical foundations. Such fundamental knowledge is essential for understanding/modeling the environmental problems associated with water-fuel mixing, and/or industrial processes involving mixing of immiscible fluids. The project has had experimental and numerical components: 1. The experimental part of the project has had two components. The first involves measurements of the lift and drag forces acting on a droplet being entrained by a vortex. The experiments and data analysis associated with this phase are still in progress, and the facility, constructed specifically for this project is described in Section 3. In the second and main part, measurements of fuel droplet dispersion rates have been performed in a special facility with controlled isotropic turbulence. As discussed in detail in Section 2, quantifying and modeling the of droplet dispersion rate requires measurements of their three dimensional trajectories in turbulent flows. To obtain the required data, we have introduced a new technique - high-speed, digital Holographic Particle Image Velocimetry (HPIV). The technique, experimental setup and results are presented in Section 2. Further information is available in Gopalan et al. (2005, 2006). 2. The objectives of the numerical part are: (1) to develop a computational code that combines DNS of isotropic turbulence with Lagrangian tracking of particles based on integration of a dynamical equation of motion that accounts for pressure, added mass, lift and drag forces, (2) to perform extensive computations of both buoyant (bubbles) and slightly buoyant (droplets) particles in turbulence conditions

  3. A new modified-serpentine flow field for application in high temperature polymer electrolyte fuel cell

    DEFF Research Database (Denmark)

    Singdeo, Debanand; Dey, Tapobrata; Gaikwad, Shrihari

    2017-01-01

    field design is proposed and its usefulness for the fuel cell applications are evaluated in a high-temperature polymer electrolyte fuel cell. The proposed geometry retains some of the features of serpentine flow field such as multiple bends, while modifications are made in its in-plane flow path...

  4. Fluid flow and fuel-air mixing in a motored two-dimensional Wankel rotary engine

    Science.gov (United States)

    Shih, T. I.-P.; Nguyen, H. L.; Stegeman, J.

    1986-01-01

    The implicit-factored method of Beam and Warming was employed to obtain numerical solutions to the conservation equations of mass, species, momentum, and energy to study the unsteady, multidimensional flow and mixing of fuel and air inside the combustion chambers of a two-dimensional Wankel rotary engine under motored conditions. The effects of the following engine design and operating parameters on fluid flow and fuel-air mixing during the intake and compression cycles were studied: engine speed, angle of gaseous fuel injection during compression cycle, and speed of the fuel leaving fuel injector.

  5. TREAT experimental data base regarding fuel dispersals in LMFBR loss-of-flow accidents

    International Nuclear Information System (INIS)

    Simms, R.; Fink, C.L.; Stanford, G.S.; Regis, J.P.

    1981-01-01

    The reactivity feedback from fuel relocation is a central issue in the analysis of loss-of-flow (LOF) accidents in LMFBRs. Fuel relocation has been studied in a number of LOF simulations in the TREAT reactor. In this paper the results of these tests are analyzed, using, as the principal figure of merit, the changes in equivalent fuel worth associated with the fuel motion. The equivalent fuel worth was calculated from the measured axial fuel distributions by weighting the data with a typical LMFBR fuel-worth function. At nominal power, the initial fuel relocation resulted in increases in equivalent fuel worth. Above nominal power the fuel motion was dispersive, but the dispersive driving forces could not unequivocally be identified from the experimental data

  6. Study on flow-induced vibration of the fuel rod in HTTR

    International Nuclear Information System (INIS)

    Takase, Kazuyuki

    1988-03-01

    This study was performed in order to investigate flow-induced vibration characteristics of a fuel rod in HTTR (High Temperature engineering Test Reactor) from both an experiment and a numerical simulation. Two kinds of fuel rods were used in this experiment: one was a graphite rod which simulated a specification of the HTTR's fuel rod and the other was an aluminum rod whose weight was a half of the graphite one. The experiment was carried out up to Re = 31000 using air at room temperature and pressure. Air flowed downstream in an annular passage which consisted of the fuel rod and the graphite channel. Numerical simulations by fluid and frequency equations were also carried out. Numerical and experimental results were then compared. The following conclusions were drived: (1) The fuel rod amplitudes increase with the flow rate and with a decrease of the fuel rod weight. (2) The fuel rod amplitudes are obtained by δ/De = 2.22 x 10 -10 Re 1.43 , 9000 ≤ Re ≤ 31000, where δ is a vibration amplitude, De is a hydraulic diameter and Reis Reynolds number. (3) The fuel rod frequencies shift from lower natural frequency to higher as the flow rate increases. (4) The flow-induced vibration behavior of the fuel rod can simulate well by simultaneous equations which used the turbulence model for fluid and the mass model for vibration of the fuel rod. (author)

  7. Prediction for the flow distribution and the pressure drop of a plate type fuel assembly

    International Nuclear Information System (INIS)

    Park, Jong Hark; Jo, Dea Sung; Chae, Hee Taek; Lee, Byung Chul

    2011-01-01

    A plate type fuel assembly widely used in many research reactors does not allow the coolant to mix with neighboring fuel channels due to the completely separated flow channels. If there is a serious inequality of coolant distribution among channels, it can reduce thermal-hydraulic safety margin, as well as it can cause a deformation of fuel plates by the pressure difference between neighboring channels, thus the flow uniformity in the fuel assembly should be confirmed. When designing a primary cooling system (PCS), the pressure drop through a reactor core is a dominant value to determine the PCS pump size. The major portion of reactor core pressure drop is caused by the fuel assemblies. However it is not easy to get a reasonable estimation of pressure drop due to the geometric complexity of the fuel assembly and the thin gaps between fuel assemblies. The flow rate through the gap is important part to determine the total flow rate of PCS, so it should be estimated as reasonable as possible. It requires complex and difficult jobs to get useful data. In this study CFD analysis to predict the flow distribution and the pressure drop were conducted on the plate type fuel assembly, which results would be used to be preliminary data to determine the PCS flow rate and to improve the design of a fuel assembly

  8. Design of the Flow Plates for a Dual Cooled Fuel Assembly

    International Nuclear Information System (INIS)

    Kim, Jae Yong; Yoon, Kyung Ho; Lee, Young Ho; Lee, Kang Hee; Kim, Hyung Kyu

    2009-01-01

    In a dual cooled fuel assembly, the array and position of fuels are changed from those of a conventional PWR fuel assembly to achieve a power uprating. The flow plate provides flow holes to direct the heated coolant into/out of the fuel assembly and structural intensity to insure that the fuel rod is axially restrained within the spacer grids. So, flow plates of top/bottom end pieces (TEP/BEP) have to be modified into proper shape. Because the flow holes' area of a flow plate affects pressure drop, the flow holes' area must be larger than/equal to that of conventional flow plates. And design criterion of the TEP/BEP says that the flow plate should withstand a 22.241 kN axial load during handling lest a calculated stress intensity should exceed the Condition I allowable stress. In this paper, newly designed flow plates of a TEP/BEP are suggested and stress analysis is conducted to evaluate strength robustness of the flow plates for the dual cooled fuel assembly

  9. Experimental study of flow induced vibration of the planar fuel assembly

    International Nuclear Information System (INIS)

    Wang Jinhua; Bo Hanliang; Jiang Shengyao; Jia Haijun; Zheng Wenxiang; Min Gang; Qu Xinxing

    2005-01-01

    The paper studied the flow-induced vibration of the planar fuel assembly under scour of coolant through experiments, the study includes: the characteristics of the inherent vibration, the response to the flow-induced vibration in rating condition and the confirmation of the critical flow velocity's scope of the flow flexible instability. The velocity distributions in different flow channels formed by fuel plates in the assembly were measured, and the velocity distribution in the same flow channel was also measured. The experimental conclusions includes: the inherent vibration frequency of the planar fuel assembly is different for a little in each direction. The damp ratio corresponding to the assembly each rank's inherent frequency is small, and the damp ratio decreased with the increase of the corresponding inherent frequency. The velocity in different flow channels decreased from outside to inside, and the velocity in the middle channel was the least; the velocity in the same channel decreased from inside to outside, and the velocity in the middle position was the most. The vibration swing of the fuel assembly was small at rating condition, and the vibration swing of the fuel plates was larger than side plates. The vibration of the fuel assembly increased with the increase of the velocity, the vibration of the middle fuel plate were larger than the border fuel plate, and the vibration of the border fuel plate was larger than the side plate. The large scale vibration of the flow flexible instability didn't occur in the velocity scope of 0-18.8 m/s in the experiment, so the critical flow velocity of the flow flexible instability was not in the flow velocity scope of the experiment. (authors)

  10. Experimental Study and Comparison of Various Designs of Gas Flow Fields to PEM Fuel Cells and Cell Stack Performance

    International Nuclear Information System (INIS)

    Liu, Hong; Li, Peiwen; Juarez-Robles, Daniel; Wang, Kai; Hernandez-Guerrero, Abel

    2014-01-01

    In this study, a significant number of experimental tests to proton exchange membrane (PEM) fuel cells were conducted to investigate the effect of gas flow fields on fuel cell performance. Graphite plates with various flow field or flow channel designs, from literature survey and also novel designs by the authors, were used for the PEM fuel cell assembly. The fabricated fuel cells have an effective membrane area of 23.5 cm 2 . The results showed that the serpentine flow channel design is still favorable, giving the best single fuel cell performance amongst all the studied flow channel designs. A novel symmetric serpentine flow field was proposed for a relatively large sized fuel cell application. Four fuel cell stacks each including four cells were assembled using different designs of serpentine flow channels. The output power performances of fuel cell stacks were compared and the novel symmetric serpentine flow field design is recommended for its very good performance.

  11. Development of a flow restrictor for CANDU fuel channels

    International Nuclear Information System (INIS)

    Schroeter, F.; Antonaccio, C.; Masciotra, H.; Klink, A.

    2013-01-01

    Due to the creep and neutron growth phenomena experienced by the components inside the reactor during operation of CNE it is expected that both the fuel channels and the Liquid Injection lances increase their permanent deformation. One of the deformation types that these two components experiment is the SAG, which is what happens with any beam supported on their extremes to which a load is applied, except for this case that due to creep and neutronic effect growth, part of the deformation is not elastic and increases with time To solve or avoid this condition, two solutions exist, one is to replace the pressure tubes, forcing the calandria tube to recover to a near to original position or to design a device that permits defueling of the channel without modifying the pressure drop and in this way not to affect the distribution of coolant in the core. In some channels it was decided to replace the pressure tube and in others it was decided to defuel them proposing a design for a flow restrictor. (author

  12. Fuel density effect on near nozzle flow field in small laminar coflow diffusion flames

    KAUST Repository

    Xiong, Yuan

    2015-01-01

    Flow characteristics in small coflow diffusion flames were investigated with a particular focus on the near-nozzle region and on the buoyancy force exerted on fuels with densities lighter and heavier than air (methane, ethylene, propane, and n-butane). The flow-fields were visualized through the trajectories of seed particles. The particle image velocimetry technique was also adopted for quantitative velocity field measurements. The results showed that the buoyancy force exerted on the fuel as well as on burnt gas significantly distorted the near-nozzle flow-fields. In the fuels with densities heavier than air, recirculation zones were formed very close to the nozzle, emphasizing the importance of the relative density of the fuel to that of the air on the flow-field. Nozzle heating influenced the near-nozzle flow-field particularly among lighter fuels (methane and ethylene). Numerical simulations were also conducted, focusing specifically on the effect of specifying inlet boundary conditions for fuel. The results showed that a fuel inlet boundary with a fully developed velocity profile for cases with long tubes should be specified inside the fuel tube to permit satisfactory prediction of the flow-field. The calculated temperature fields also indicated the importance of the selection of the location of the inlet boundary, especially in testing various combustion models that include soot in small coflow diffusion flames. © 2014 The Combustion Institute.

  13. Fuel dynamics loss-of-flow test L3. Final report

    International Nuclear Information System (INIS)

    Fischer, A.K.; Lo, R.K.; Barts, E.W.

    1976-06-01

    The behavior of FTR-type, mixed-oxide, preirradiated, ''intermediate-power-structure'' fuel during a simulation of an FTR loss-of-flow accident was studied in the Mark-IIA integral TREAT loop. Analysis of the data reported here leads to a postulated scenario (sequence and timing) of events in the test. This scenario is presented, together with the calculated timing of events obtained by use of the SAS code. The initial fuel motion, starting during the preheat phase, consisted of coherent motion of the entire intact fuel bundle toward the pump. Incoherence developed as temperature rose. The fuel motion was mostly upward, and the greatest was in the top third of the fuel column. Fuel fragments formed against the pump side of the fluted tube near the original fuel midplane. A penetration of fluted tube occurred. A sudden voiding of the central region of the fuel column occurred at 29.75 s and was largely completed within 150 ms. The lower steel blockage of the fuel elements occurred in the vicinity of the lower insulator pellets. The upper steel blockage just above the tops of the original fuel pins appeared to have channels through it. Cladding and spacer wires melted away in the fuel section. Fuel pellets were only evident at and above the top and at the bottom of the original fuel column, where a large mass of melted fuel was present. Over the length of the fuel column, most of the fluted tube had melted away

  14. Measurement of Quasi-periodic Oscillating Flow Motion in Simulated Dual-cooled Annular Fuel Bundle

    International Nuclear Information System (INIS)

    Lee, Chi Young; Shin, Chang Hwan; Park, Ju Yong; Oh, Dong Seok; Chun, Tae Hyun; In, Wang Kee

    2012-01-01

    In order to increase a significant amount of reactor power in OPR1000, KAERI (Korea Atomic Energy Research Institute) has been developing a dual-cooled annular fuel. The dual-cooled annular fuel is simultaneously cooled by the water flow through the inner and the outer channels. KAERI proposed the 12x12 dual-cooled annular fuel array which was designed to be structurally compatible with the 16x16 cylindrical solid fuel array by maintaining the same array size and the guide tubes in the same locations, as shown in Fig. 1. In such a case, due to larger outer diameter of dual-cooled annular fuel than conventional solid fuel, a P/D (Pitch-to-Diameter ratio) of dual cooled annular fuel assembly becomes smaller than that of cylindrical solid fuel. A change in P/D of fuel bundle can cause a difference in the flow mixing phenomena between the dual-cooled annular and conventional cylindrical solid fuel assemblies. In this study, the rod bundle flow motion appearing in a small P/D case is investigated preliminarily using PIV (Particle Image Velocimetry) for dual-cooled annular fuel application

  15. Use of multi-functional flexible micro-sensors for in situ measurement of temperature, voltage and fuel flow in a proton exchange membrane fuel cell.

    Science.gov (United States)

    Lee, Chi-Yuan; Chan, Pin-Cheng; Lee, Chung-Ju

    2010-01-01

    Temperature, voltage and fuel flow distribution all contribute considerably to fuel cell performance. Conventional methods cannot accurately determine parameter changes inside a fuel cell. This investigation developed flexible and multi-functional micro sensors on a 40 μm-thick stainless steel foil substrate by using micro-electro-mechanical systems (MEMS) and embedded them in a proton exchange membrane fuel cell (PEMFC) to measure the temperature, voltage and flow. Users can monitor and control in situ the temperature, voltage and fuel flow distribution in the cell. Thereby, both fuel cell performance and lifetime can be increased.

  16. A microfluidic-structured flow field for passive direct methanol fuel cells operating with highly concentrated fuels

    International Nuclear Information System (INIS)

    Wu, Q X; Zhao, T S; Chen, R; Yang, W W

    2010-01-01

    Conventional direct methanol fuel cells (DMFCs) have to operate with excessively diluted methanol solutions to limit methanol crossover and its detrimental consequences. Operation with such diluted methanol solutions not only results in a significant penalty in the specific energy of the power pack, limiting the runtime of this type of fuel cell, but also lowers the cell performance and operating stability. In this paper, a microfluidic-structured anode flow field for passive DMFCs with neither liquid pumps nor gas compressors/blowers is developed. This flow field consists of plural micro flow passages. Taking advantage of the liquid methanol and gas CO 2 two-phase counter flow, the unique fluidic structure enables the formation of a liquid–gas meniscus in each flow passage. The evaporation from the small meniscus in each flow passage can lead to an extremely large interfacial mass-transfer resistance, creating a bottleneck of methanol delivery to the anode CL. The fuel cell tests show that the innovative flow field allows passive DMFCs to achieve good cell performance with a methanol concentration as high as 18.0 M, increasing the specific energy of the DMFC system by about five times compared with conventional designs.

  17. Methodology for local verification of flow regimes in fuel assemblies charts

    International Nuclear Information System (INIS)

    Igor, Sharaevsky; Elena, Sharaevskaya; Domashev, E.D.; Alexander, Arkhypov; Vladimir, Kolochko

    2003-01-01

    The best estimate thermal hydraulic codes describe adequately two-phase flows in nuclear energy facilities if there is proper system of closed relations. It could be obtained from the reliable information on structure forms of two-phase flows, its boundaries and reliable regime charts. In the paper the methodology of automatic recognition of the boundaries of the main types of two phase flows for rod fuel assemblies is presented. The methodology is based on definition of thermal hydraulic parameters distribution in experimental fuel assembly. The measurements were carried out using ASD signals of acoustic noise. In the paper data on two-phase flow regimes boundaries recognition especially low boundaries of bubble flow are summarized for experimental fuel assembly. The methodology of flow regimes charts applied to recognition of upper boundaries of boiling crisis regime was verificated. The satisfactory coincidence with experimental results have been shown. (author)

  18. Fiber Optic Mass Flow Gauge for Liquid Cryogenic Fuel Facilities Monitoring and Control, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I proposal describes a fiber optic mass flow gauge that will aid in managing liquid hydrogen and oxygen fuel storage and transport. The increasing...

  19. Development of a detailed core flow analysis code for prismatic fuel reactors

    International Nuclear Information System (INIS)

    Bennett, R.G.

    1990-01-01

    The detailed analysis of the core flow distribution in prismatic fuel reactors is of interest for modular high-temperature gas-cooled reactor (MHTGR) design and safety analyses. Such analyses involve the steady-state flow of helium through highly cross-connected flow paths in and around the prismatic fuel elements. Several computer codes have been developed for this purpose. However, since they are proprietary codes, they are not generally available for independent MHTGR design confirmation. The previously developed codes do not consider the exchange or diversion of flow between individual bypass gaps with much detail. Such a capability could be important in the analysis of potential fuel block motion, such as occurred in the Fort St. Vrain reactor, or for the analysis of the conditions around a flow blockage or misloaded fuel block. This work develops a computer code with fairly general-purpose capabilities for modeling the flow in regions of prismatic fuel cores. The code, called BYPASS solves a finite difference control volume formulation of the compressible, steady-state fluid flow in highly cross-connected flow paths typical of the MHTGR

  20. Flow field bipolar plates in a proton exchange membrane fuel cell: Analysis & modeling

    International Nuclear Information System (INIS)

    Kahraman, Huseyin; Orhan, Mehmet F.

    2017-01-01

    Highlights: • Covers a comprehensive review of available flow field channel configurations. • Examines the main design considerations and limitations for a flow field network. • Explores the common materials and material properties used for flow field plates. • Presents a case study of step-by-step modeling for an optimum flow field design. - Abstract: This study investigates flow fields and flow field plates (bipolar plates) in proton exchange membrane fuel cells. In this regard, the main design considerations and limitations for a flow field network have been examined, along with a comprehensive review of currently available flow field channel configurations. Also, the common materials and material properties used for flow field plates have been explored. Furthermore, a case study of step-by-step modeling for an optimum flow field design has been presented in-details. Finally, a parametric study has been conducted with respect to many design and performance parameters in a flow field plate.

  1. Modeling two-phase flow in three-dimensional complex flow-fields of proton exchange membrane fuel cells

    Science.gov (United States)

    Kim, Jinyong; Luo, Gang; Wang, Chao-Yang

    2017-10-01

    3D fine-mesh flow-fields recently developed by Toyota Mirai improved water management and mass transport in proton exchange membrane (PEM) fuel cell stacks, suggesting their potential value for robust and high-power PEM fuel cell stack performance. In such complex flow-fields, Forchheimer's inertial effect is dominant at high current density. In this work, a two-phase flow model of 3D complex flow-fields of PEMFCs is developed by accounting for Forchheimer's inertial effect, for the first time, to elucidate the underlying mechanism of liquid water behavior and mass transport inside 3D complex flow-fields and their adjacent gas diffusion layers (GDL). It is found that Forchheimer's inertial effect enhances liquid water removal from flow-fields and adds additional flow resistance around baffles, which improves interfacial liquid water and mass transport. As a result, substantial improvements in high current density cell performance and operational stability are expected in PEMFCs with 3D complex flow-fields, compared to PEMFCs with conventional flow-fields. Higher current density operation required to further reduce PEMFC stack cost per kW in the future will necessitate optimizing complex flow-field designs using the present model, in order to efficiently remove a large amount of product water and hence minimize the mass transport voltage loss.

  2. Analysis of nuclear material flow for experimental DUPIC fuel fabrication process at DFDF

    International Nuclear Information System (INIS)

    Lee, H. H.; Park, J. J.; Shin, J. M.; Lee, J. W.; Yang, M. S.; Baik, S. Y.; Lee, E. P.

    1999-08-01

    This report describes facilities necessary for manufacturing experiment for DUPIC fuel, manufacturing process and equipment. Nuclear material flows among facilities, in PIEF and IMEF, for irradiation test, for post examination of DUPIC fuel, for quality control, for chemical analysis and for treatment of radioactive waste have been analyzed in details. This may be helpful for DUPIC project participants and facility engineers working in related facilities to understand overall flow for nuclear material and radioactive waste. (Author). 14 refs., 15 tabs., 41 figs

  3. Analysis of nuclear material flow for experimental DUPIC fuel fabrication process at DFDF

    Energy Technology Data Exchange (ETDEWEB)

    Lee, H. H.; Park, J. J.; Shin, J. M.; Lee, J. W.; Yang, M. S.; Baik, S. Y.; Lee, E. P

    1999-08-01

    This report describes facilities necessary for manufacturing experiment for DUPIC fuel, manufacturing process and equipment. Nuclear material flows among facilities, in PIEF and IMEF, for irradiation test, for post examination of DUPIC fuel, for quality control, for chemical analysis and for treatment of radioactive waste have been analyzed in details. This may be helpful for DUPIC project participants and facility engineers working in related facilities to understand overall flow for nuclear material and radioactive waste. (Author). 14 refs., 15 tabs., 41 figs.

  4. Time-resolved fuel injector flow characterisation based on 3D laser Doppler vibrometry

    OpenAIRE

    Crua, Cyril; Heikal, Morgan R.

    2015-01-01

    In order to enable investigations of the fuel flow inside unmodified injectors, we have developed a new experimental approach to measure time-resolved vibration spectra of diesel nozzles using a three dimensional laser vibrometer. The technique we propose is based on the triangulation of the vibrometer and fuel pressure transducer signals, and enables the quantitative characterisation of quasi-cyclic internal flows without requiring modifications to the injector, the working fluid, or limitin...

  5. Molten Fuel Mass Assessment for Channel Flow Blockage Event in CANDU6

    International Nuclear Information System (INIS)

    Lee, Kwang Ho; Kim, Yong Bae; Choi, Hoon; Park, Dong Hwan

    2011-01-01

    In CANDU6, a fuel channel flow blockage causes a sudden reduction of flow through the blocked channel. Depending on the severity of the blockage, the reduced flow through the channel can result in severe heat up of the fuel, hence possibly leading to pressure tube and calandria tube failure. If the calandria tube does not fail the fuel and sheath would continue to heat up, and ultimately melting could occur. Eventually, molten material runs down onto the pressure tube. Even a thin layer of molten material in contact with the pressure tube causes the pressure tube and calandreia tube to heat up rapidly. The thermal transient is so rapid that failure temperatures are reached quickly. After channel failure, the contents of the channel, consisting of superheated coolant, fission products and possibly overheated of molten fuel, are rapidly discharged into the moderator. Fuel discharged into the moderator is quenched and cooled. The rapid discharge of hot fuel and coolant into the calandria causes the moderator pressure and temperature to increase, which may cause damage to some in-core components. Thus, the assessment results of molten fuel mass are inputs to the in-core damage analysis. In this paper, the analysis methodology and results of molten fuel mass assessment for the channel flow blockage event are presented

  6. RESULTS OF AIRPLANE TU-204-300 OPERATED BY "VLADIVOSTOK AVIA" COMPANY FUEL FLOW MONITIRING

    Directory of Open Access Journals (Sweden)

    G. E. Maslennikova

    2014-01-01

    Full Text Available This article describes the results obtained from continuous monitoring of fuel flow on the airplanes Tu-204-300, operated by the aircompany "Vladivostok Avia". The reasons for the change in the cost of each copy of airplane and changes in fuel characteristics due to pilots manner of flying.

  7. A CFD numerical model for the flow distribution in a MTR fuel element

    International Nuclear Information System (INIS)

    Andrade, Delvonei Alves de; Santos, Pedro Henrique Di Giovanni; Oliveira, Fabio Branco Vaz de; Torres, Walmir Maximo; Umbehaun, Pedro Ernesto; Souza, Jose Antonio Batista de; Belchior Junior, Antonio; Sabundjian, Gaiane; Prado, Adelk de Carvalho; Angelo, Gabriel

    2015-01-01

    Previously, an instrumented dummy fuel element (DMPV-01), with the same geometric characteristics of a MTR fuel element, was designed and constructed for pressure drop and flow distribution measurement experiments at the IEA-R1 reactor core. This dummy element was also used to measure the flow distribution among the rectangular flow channels formed by element fuel plates. A CFD numerical model was developed to complement the studies. This work presents the proposed CFD model as well as a comparison between numerical and experimental results of flow rate distribution among the internal flow channels. Numerical results show that the model reproduces the experiments very well and can be used for the studies as a more convenient and complementary tool. (author)

  8. A CFD numerical model for the flow distribution in a MTR fuel element

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Delvonei Alves de; Santos, Pedro Henrique Di Giovanni; Oliveira, Fabio Branco Vaz de; Torres, Walmir Maximo; Umbehaun, Pedro Ernesto; Souza, Jose Antonio Batista de; Belchior Junior, Antonio; Sabundjian, Gaiane; Prado, Adelk de Carvalho, E-mail: acprado@ipen.br, E-mail: delvonei@ipen.br, E-mail: dpedro_digiovanni_s@hotmail.com, E-mail: fabio@ipen.br, E-mail: wmtorres@ipen.br, E-mail: umbehaun@ipen.br, E-mail: jasouza@ipen.br, E-mail: abelchior@ipen.br, E-mail: gdjian@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Engenharia Nuclear; Angelo, Edvaldo, E-mail: eangelo@mackenzie.br [Universidade Presbiteriana Mackenzie, Sao Paulo, SP (Brazil); Angelo, Gabriel, E-mail: gangelo@fei.edu.br [Fundacao Educacional Inaciana (FEI), Sao Bernardo do Campo, SP (Brazil)

    2015-07-01

    Previously, an instrumented dummy fuel element (DMPV-01), with the same geometric characteristics of a MTR fuel element, was designed and constructed for pressure drop and flow distribution measurement experiments at the IEA-R1 reactor core. This dummy element was also used to measure the flow distribution among the rectangular flow channels formed by element fuel plates. A CFD numerical model was developed to complement the studies. This work presents the proposed CFD model as well as a comparison between numerical and experimental results of flow rate distribution among the internal flow channels. Numerical results show that the model reproduces the experiments very well and can be used for the studies as a more convenient and complementary tool. (author)

  9. CFD Analysis on a Core Outlet Flow through the Fuel Alignment Plant of SMART

    International Nuclear Information System (INIS)

    Kim, Y. I.; Bae, Y. M.; Kim, K. K.

    2014-01-01

    CFD (Computational Fluid Dynamics) simulations were performed to confirm the core flow distribution for SMART, which acquired standard design approval in 2012. In this paper, CFD simulation is also used to calculate the pressure distribution of a core outlet, a Fuel Alignment Plate (FAP), for SMART. In SMART, the fluid discharged from the Steam Generator comes into a Flow Mixing Header Assembly (FMHA), and is rearranged and split into a very fine size. The FMHA is greatly important for enhancing the flow distribution of a downcomer during a normal operation, transient, and even accidents. Then, the fluid discharged from the FMHA flows into the core upstream through flow skirt holes. The Low Core Support Plate (LCSP) reallocates the flow introducing into the inlet core from the core upstream. The deviation of flow distribution becomes smaller or almost disappears by LCSP holes having relatively large loss coefficient compared to the downstream flow deviation. In an open core, the flow deviation at the core inlet region is diminished by cross flow as it goes upward. Near the core outlet, the flow distribution can be distorted by the influence of a Fuel Alignment Plate (FAP) installed above the fuels. In this paper, the effect of the core outlet flow structure such as the FAP holes of SMART is investigated. Before the calculation, the influences of mesh size and turbulence models are inspected. CFD simulations were performed to investigate the effect of FAP flow holes on the core outlet flow of SMART. As a preliminary study, the dependency of the mesh size and turbulence models was tested; a fine grid was applied, the effect of which is negligible, and the core outlet flow is not sensitive to the turbulence models. In brief, the flow resistance of FAP is less than 15% of that of the fuel assemblies. The flow resistance deviation between two flow path patterns is less than 1% of that of active core. Even two flow path patterns located at the downstream location of the

  10. Development of a detailed core flow analysis code for prismatic fuel reactors

    International Nuclear Information System (INIS)

    Bennett, R.G.

    1990-01-01

    The development of a computer code for the analysis of the detailed flow of helium in prismatic fuel reactors is reported. The code, called BYPASS, solves, a finite difference control volume formulation of the compressible, steady state fluid flow in highly cross-connected flow paths typical of the Modular High-Temperature Gas Cooled Reactor (MHTGR). The discretization of the flow in a core region typically considers the main coolant flow paths, the bypass gap flow paths, and the crossflow connections between them. 16 refs., 5 figs

  11. Numerical analysis of injector flow and spray characteristics from diesel injectors using fossil and biodiesel fuels

    International Nuclear Information System (INIS)

    Battistoni, Michele; Grimaldi, Carlo Nazareno

    2012-01-01

    Highlights: ► Fluid-dynamic simulation of injection process with biodiesel and diesel fuel. ► Coupling of Eulerian and Lagrangian spray CFD simulations. ► Effects of hole shaping: conical versus cylindrical and edge rounding effects. ► Prediction of spray characteristics improved using inner nozzle flow data. ► Explanation of mass flow differences depending on hole shape and fuel type. -- Abstract: The aim of the paper is the comparison of the injection process with two fuels, a standard diesel fuel and a pure biodiesel, methyl ester of soybean oil. Multiphase cavitating flows inside injector nozzles are calculated by means of unsteady CFD simulations on moving grids from needle opening to closure, using an Eulerian–Eulerian two-fluid approach which takes into account bubble dynamics. Afterward, spray evolutions are also evaluated in a Lagrangian framework using results of the first computing step, mapped onto the hole exit area, for the initialization of the primary breakup model. Two nozzles with cylindrical and conical holes are studied and their behaviors are discussed in relation to fuel properties. Nozzle flow simulations highlighted that the extent of cavitation regions is not much affected by the fuel type, whereas it is strongly dependent on the nozzle shape. Biodiesel provides a slightly higher mass flow in highly cavitating nozzles. On the contrary using hole shaped nozzles (to reduce cavitation) diesel provides similar or slightly higher mass flow. Comparing the two fuels, the effects of different viscosities and densities play main role which explains these behaviors. Simulations of the spray evolution are also discussed highlighting the differences between the use of fossil and biodiesel fuels in terms of spray penetration, atomization and cone-angle. Usage of diesel fuel in the conical convergent nozzle gives higher liquid penetration.

  12. ESBWR enhanced flow distribution with optimized orificing and related fuel cycle performance

    International Nuclear Information System (INIS)

    Pearson, G. J.; Karve, A. A.; Fawcett, R. M.

    2012-01-01

    The Economic Simplified Boiling Water Reactor (ESBWR) is GEH's latest Generation III+ reactor design with natural circulation coolant flow and passive safety features. Reliance on natural circulation as the sole means of core coolant driving force results in increased power-to-flow ratio and places increased importance on the efficient distribution of core flow in order to achieve optimum thermal margins and improved fuel cycle efficiency. In addition, the large core size of the ESBWR, containing 1132 bundles, greatly benefits from a more targeted distribution of flow, directing a higher fraction of flow to high power bundles in the 'ring of fire' region of typical BWR loading patterns and a lower fraction of flow to low power bundles on and near the core periphery. Desirable flow distributions can be achieved by modifying the hydraulic resistance of the inlet orifices to preferentially force flow to the targeted region. The inlet orifice is a feature that is incorporated into the fuel support piece of a typical BWR design. The majority of existing forced circulation BWR's rely on only two orifice types - a peripheral orifice located along the outermost row and a central orifice in all other locations. A more optimum distribution of core flow is achievable with the introduction of multiple inlet orifice types. Multi-zone orifice layouts comprised of two, three and four types have been evaluated for the ESBWR. An efficient radial distribution of flow can have a direct beneficial effect on the Minimum Critical Power Ratio (MCPR). An improved multi-zone orifice layout in the ESBWR has the potential of significantly increasing active flow in high power bundles. On average, this flow increase corresponds to a noteworthy MCPR improvement. Additional MCPR margin may be used to enhance operating flexibility and to achieve reduced fuel cycle costs over the plant lifetime. Combined with GNF's latest high performance fuel design for the ESBWR, GNF2E, and improved loading

  13. Non-Flow-Through Fuel Cell System Test Results and Demonstration on the SCARAB Rover

    Science.gov (United States)

    Scheidegger, Brianne, T.; Burke, Kenneth A.; Jakupca, Ian J.

    2012-01-01

    This paper describes the results of the demonstration of a non-flow-through PEM fuel cell as part of a power system on the SCARAB rover. A 16-cell non-flow-through fuel cell stack from Infinity Fuel Cell and Hydrogen, Inc. was incorporated into a power system designed to act as a range extender by providing power to the rover s hotel loads. This work represents the first attempt at a ground demonstration of this new technology aboard a mobile test platform. Development and demonstration were supported by the Office of the Chief Technologist s Space Power Systems Project and the Advanced Exploration System Modular Power Systems Project.

  14. The GC computer code for flow sheet simulation of pyrochemical processing of spent nuclear fuels

    International Nuclear Information System (INIS)

    Ahluwalia, R.K.; Geyer, H.K.

    1996-01-01

    The GC computer code has been developed for flow sheet simulation of pyrochemical processing of spent nuclear fuel. It utilizes a robust algorithm SLG for analyzing simultaneous chemical reactions between species distributed across many phases. Models have been developed for analysis of the oxide fuel reduction process, salt recovery by electrochemical decomposition of lithium oxide, uranium separation from the reduced fuel by electrorefining, and extraction of fission products into liquid cadmium. The versatility of GC is demonstrated by applying the code to a flow sheet of current interest

  15. CFD prediction of flow and phase distribution in fuel assemblies with spacers

    Energy Technology Data Exchange (ETDEWEB)

    Anglart, H.; Nylund, O. [ABB Atom AB, Vasteras (Switzerland); Kurul, N. [Rensselaer Polytechnic Institute, Troy, NY (United States)] [and others

    1995-09-01

    This paper is concerned with the modeling and computation of multi-dimensional two-phase flows in BWR fuel assemblies. The modeling principles are presented based on using a two-fluid model in which lateral interfacial effects are accounted for. This model has been used to evaluate the velocity fields of both vapor and liquid phases, as well as phase distribution, between fuel elements in geometries similar to BWR fuel bundles. Furthermore, this model has been used to predict, in a detailed mechanistic manner, the effects of spacers on flow and phase distribution between, and pressure drop along, fuel elements. The related numerical simulations have been performed using a CFD computer code, CFDS-FLOW3D.

  16. Theoretical investigations of the gas flow in ballooning LWR-fuel rods

    International Nuclear Information System (INIS)

    Gaballah, I.

    1978-09-01

    A theory is developed for the calculation of gas flow in a fuel rod simulator or in a fuel rod with round- or cracked pellets. The fundamental equations are formulated, simplified, reformed, and then numerically solved. The numerical investigations show, that a quasi steady incompressible flow model can be used without great error. The effect of the deformation form is studied. A uniform deformation along the whole length causes small pressure difference. A power profile and rod spacers cause non-uniform clad deformation of the fuel rod simulator or the fuel rod. This deformation leads to greater pressure differences. Finally the effect of the cracked pellets is studied. The cracked pellets cause great pressure differences along the fuel rod. (orig.) 891 HP [de

  17. Study of visualized simulation and analysis of nuclear fuel cycle system based on multilevel flow model

    International Nuclear Information System (INIS)

    Liu Jingquan; Yoshikawa, H.; Zhou Yangping

    2005-01-01

    Complex energy and environment system, especially nuclear fuel cycle system recently raised social concerns about the issues of economic competitiveness, environmental effect and nuclear proliferation. Only under the condition that those conflicting issues are gotten a consensus between stakeholders with different knowledge background, can nuclear power industry be continuingly developed. In this paper, a new analysis platform has been developed to help stakeholders to recognize and analyze various socio-technical issues in the nuclear fuel cycle sys- tem based on the functional modeling method named Multilevel Flow Models (MFM) according to the cognition theory of human being, Its character is that MFM models define a set of mass, energy and information flow structures on multiple levels of abstraction to describe the functional structure of a process system and its graphical symbol representation and the means-end and part-whole hierarchical flow structure to make the represented process easy to be understood. Based upon this methodology, a micro-process and a macro-process of nuclear fuel cycle system were selected to be simulated and some analysis processes such as economics analysis, environmental analysis and energy balance analysis related to those flows were also integrated to help stakeholders to understand the process of decision-making with the introduction of some new functions for the improved Multilevel Flow Models Studio, and finally the simple simulation such as spent fuel management process simulation and money flow of nuclear fuel cycle and its levelised cost analysis will be represented as feasible examples. (authors)

  18. Study of visualized simulation and analysis of nuclear fuel cycle system based on multilevel flow model

    Institute of Scientific and Technical Information of China (English)

    LIU Jing-Quan; YOSHIKAWA Hidekazu; ZHOU Yang-Ping

    2005-01-01

    Complex energy and environment system, especially nuclear fuel cycle system recently raised social concerns about the issues of economic competitiveness, environmental effect and nuclear proliferation. Only under the condition that those conflicting issues are gotten a consensus between stakeholders with different knowledge background, can nuclear power industry be continuingly developed. In this paper, a new analysis platform has been developed to help stakeholders to recognize and analyze various socio-technical issues in the nuclear fuel cycle system based on the functional modeling method named Multilevel Flow Models (MFM) according to the cognition theory of human being. Its character is that MFM models define a set of mass, energy and information flow structures on multiple levels of abstraction to describe the functional structure of a process system and its graphical symbol representation and the means-end and part-whole hierarchical flow structure to make the represented process easy to be understood. Based upon this methodology, a micro-process and a macro-process of nuclear fuel cycle system were selected to be simulated and some analysis processes such as economics analysis, environmental analysis and energy balance analysis related to those flows were also integrated to help stakeholders to understand the process of decision-making with the introduction of some new functions for the improved Multilevel Flow Models Studio, and finally the simple simulation such as spent fuel management process simulation and money flow of nuclear fuel cycle and its levelised cost analysis will be represented as feasible examples.

  19. Measurement and analysis of vibrational behaviour of an SNR-fuel element in sodium flow

    International Nuclear Information System (INIS)

    Hess, B.F.H.; Ruppert, E.; Schmidt, H.; Vinzens, K.

    1975-01-01

    Within the framework of SNR-300 fuel element development programme a complete full size fuel element dummy has been tested thoroughly for nearly 3000 hours at 650 0 C system temperature in the AKB sodium loop at Interatom, Bensberg. Investigations of the hydraulic characteristics by measurements of specific pressure losses, flow velocities, leakage flow through the piston rings and investigations of its vibrational behaviour were part of this endurance test at elevated temperatures. The pressure drop versus flow and the leakage measurement are mentioned briefly to confirm the correctness of the test hydraulics. The vibrational behaviour of the element and the approach to analysis is the main object of this report. (Auth.)

  20. Combustor with two stage primary fuel tube with concentric members and flow regulating

    Science.gov (United States)

    Parker, David Marchant; Whidden, Graydon Lane; Zolyomi, Wendel

    1999-01-01

    A combustor for a gas turbine having a centrally located fuel nozzle and inner, middle and outer concentric cylindrical liners, the inner liner enclosing a primary combustion zone. The combustor has an air inlet that forms two passages for pre-mixing primary fuel and air to be supplied to the primary combustion zone. Each of the pre-mixing passages has a circumferential array of swirl vanes. A plurality of primary fuel tube assemblies extend through both pre-mixing passages, with each primary fuel tube assembly located between a pair of swirl vanes. Each primary fuel tube assembly is comprised of two tubular members. The first member supplies fuel to the first pre-mixing passage, while the second member, which extends through the first member, supplies fuel to the second pre-mixing passage. An annular fuel manifold is divided into first and second chambers by a circumferentially extending baffle. The proximal end of the first member is attached to the manifold itself while the proximal end of the second member is attached to the baffle. The distal end of the first member is attached directly to the second member at around its mid-point. The inlets of the first and second members are in flow communication with the first and second manifold chambers, respectively. Control valves separately regulate the flow of fuel to the two chambers and, therefore, to the two members of the fuel tube assemblies, thereby allowing the flow of fuel to the first and second pre-mixing passages to be separately controlled.

  1. Experimental studies of flow induced vibrations of the fuel assembly for the PEC reactor

    International Nuclear Information System (INIS)

    Pitimada, D.; Presaghi, M.; Tampone, O.; Cesari, F.

    1977-01-01

    The vibration behaviour of an assembly of seven mock-up fuel bundles of PEC reactor has been investigated. The assembly was excited by a parallel flow of water simulating sodium. The motion of the group (or of a single bundle in the group) has been measured in transverse sections detecting two orthogonal components of displacement. During the experiences the following parameters were varied: bundle foot and pads restraints, flow rate condition, coolant flow outlet conditions at the head of fuel bundles. Experimental data were processed in order to obtain: trajectories of three points of fuel bundle axis, power density spectra of measured vibration amplitudes, correlations between coolant flow rate and vibration amplitude R.M.S. (author)

  2. Parallel two-phase-flow-induced vibrations in fuel pin model

    International Nuclear Information System (INIS)

    Hara, Fumio; Yamashita, Tadashi

    1978-01-01

    This paper reports the experimental results of vibrations of a fuel pin model -herein meaning the essential form of a fuel pin from the standpoint of vibration- in a parallel air-and-water two-phase flow. The essential part of the experimental apparatus consisted of a flat elastic strip made of stainless steel, both ends of which were firmly supported in a circular channel conveying the two-phase fluid. Vibrational strain of the fuel pin model, pressure fluctuation of the two-phase flow and two-phase-flow void signals were measured. Statistical measures such as power spectral density, variance and correlation function were calculated. The authors obtained (1) the relation between variance of vibrational strain and two-phase-flow velocity, (2) the relation between variance of vibrational strain and two-phase-flow pressure fluctuation, (3) frequency characteristics of variance of vibrational strain against the dominant frequency of the two-phase-flow pressure fluctuation, and (4) frequency characteristics of variance of vibrational strain against the dominant frequency of two-phase-flow void signals. The authors conclude that there exist two kinds of excitation mechanisms in vibrations of a fuel pin model inserted in a parallel air-and-water two-phase flow; namely, (1) parametric excitation, which occurs when the fundamental natural frequency of the fuel pin model is related to the dominant travelling frequency of water slugs in the two-phase flow by the ratio 1/2, 1/1, 3/2 and so on; and (2) vibrational resonance, which occurs when the fundamental frequency coincides with the dominant frequency of the two-phase-flow pressure fluctuation. (auth.)

  3. Pressure drop and flow distribution characteristics of single and parallel serpentine flow fields for polymer electrolyte membrane fuel cells

    International Nuclear Information System (INIS)

    Baek, Seung Man; Kim, Charn Jung; Jeon, Dong Hyup; Nam, Jin Hyun

    2012-01-01

    This study numerically investigates pressure drop and flow distribution characteristics of serpentine flow fields (SFFs) that are designed for polymer electrolyte membrane fuel cells, which consider the Poiseuille flow with secondary pressure drop in the gas channel (GC) and the Darcy flow in the porous gas diffusion layer (GDL). The numerical results for a conventional SFF agreed well with those obtained via computational fluid dynamics simulations, thus proving the validity of the present flow network model. This model is employed to characterize various single and parallel SFFs, including multi-pass serpentine flow fields (MPSFFs). Findings reveal that under rib convection (convective flow through GDL under an interconnector rib) is an important transport process for conventional SFFs, with its intensity being significantly enhanced as GDL permeability increases. The results also indicate that under rib convection can be significantly improved by employing MPSFFs as the reactant flow field, because of the closely interlaced structure of GC regions that have different path lengths from the inlet. However, reactant flow rate through GCs proportionally decreases as under rib convection intensity increases, suggesting that proper optimization is required between the flow velocity in GCs and the under rib convection intensity in GDLs

  4. Fuel Cooling in Absence of Forced Flow at Shutdown Condition with PHTS Partially Drained

    Energy Technology Data Exchange (ETDEWEB)

    Parasca, L.; Pecheanu, D.L., E-mail: laurentiu.parasca@cne.ro, E-mail: doru.pecheanu@cne.ro [Cernavoda Nuclear Power Plant, Cernavoda (Romania)

    2014-09-15

    During the plant outage for maintenance on primary side (e.g. for the main Heat Transport System pumps maintenance, the Steam Generators inspection), there are situations which require the primary heat transport system (HTS) drainage to a certain level for opening the circuit. The primary fuel heat sink for this configuration is provided by the shutdown cooling system (SDCS). In case of losing the forced cooling (e.g. due to the loss of SDCS, design basis earthquake-DBE), flow conditions in the reactor core may become stagnant. Inside the fuel channels, natural circulation phenomena known as Intermittent Buoyancy Induced Flow (IBIF) will initiate, providing an alternate heat sink mechanism for the fuel. However, this heat sink is effective only for a limited period of time (recall time). The recall time is defined as the elapsed time until the water temperature in the HTS headers exceeds a certain limit. Until then, compensatory measures need to be taken (e.g. by re-establishing the forced flow or initiate Emergency Core Cooling system injection) to preclude fuel failures. The present paper briefly presents the results of an analysis performed to demonstrate that fuel temperature remains within acceptable limits during IBIF transient. One of the objectives of this analysis was to determine the earliest moment since the reactor shut down when maintenance activities on the HTS can be started such that IBIF is effective in case of losing the forced circulation. The resulting peak fuel sheath and pressure tube temperatures due to fuel heat up shall be within the acceptable limits to preclude fuel defect or fuel channel defects.Thermalhydraulic circuit conditions were obtained using a CATHENA model for the primary side of HTS (drained to a certain level), an ECC system model and a system model for SDCS. A single channel model was developed in GOTHIC code for the fuel assessment analysis. (author)

  5. Fuel bundle impact velocities due to reverse flow

    International Nuclear Information System (INIS)

    Wahba, N.N.; Locke, K.E.

    1996-01-01

    If a break should occur in the inlet feeder or inlet header of a CANDU reactor, the rapid depressurization will cause the channel flow(s) to reverse. Depending on the gap between the upstream bundle and shield plug, the string of bundles will accelerate in the reverse direction and impact with the upstream shield plug. The reverse flow impact velocities have been calculated for various operating states for the Bruce NGS A reactors. The sensitivity to several analysis assumptions has been determined. (author)

  6. REFCO83, Nuclear Fuel Cycle Cost Economics Using Discounted Cash Flow Analysis

    International Nuclear Information System (INIS)

    Delene, J.G.; Hermann, O.W.

    2001-01-01

    1 - Description of program or function: REFCO83 utilizes a discounted cash flow (DCF) analysis procedure to calculate batch, cycle, and lifetime levelized average nuclear fuel cycle costs. The DCF analysis establishes an energy 'cost' associated with the fuel by requiring that the revenues from the sale of energy be adequate to pay the required return on outstanding capital, to pay all expenses including taxes, and to retire the outstanding investment to zero by the end of the economic life of the set of fuel investments. The program uses reactor mass flow information together with individual fuel cost parameters and utility capital structure and money costs to calculate levelized costs cumulatively through any batch or cycle. 2 - Method of solution: A fuel cycle cost component is considered to be any fuel material purchase, processing cost, or discharge material credit in the complete fuel cycle. The costs for each individual component, i.e. uranium, enrichment, etc., may either be expensed or capitalized for tax purposes or, in the case of waste disposal, the cost may also be made proportional to power production. To properly account for the effect of income taxes, all calculations in REFCO83 are done using 'then' current dollars, including price escalations caused by inflation. The database used for the default values for REFCO83 was taken from the Nuclear Energy Cost Data Base. 3 - Restrictions on the complexity of the problem: The maximum number of fuel batches is 120

  7. Lattice Boltzmann modeling of transport phenomena in fuel cells and flow batteries

    Science.gov (United States)

    Xu, Ao; Shyy, Wei; Zhao, Tianshou

    2017-06-01

    Fuel cells and flow batteries are promising technologies to address climate change and air pollution problems. An understanding of the complex multiscale and multiphysics transport phenomena occurring in these electrochemical systems requires powerful numerical tools. Over the past decades, the lattice Boltzmann (LB) method has attracted broad interest in the computational fluid dynamics and the numerical heat transfer communities, primarily due to its kinetic nature making it appropriate for modeling complex multiphase transport phenomena. More importantly, the LB method fits well with parallel computing due to its locality feature, which is required for large-scale engineering applications. In this article, we review the LB method for gas-liquid two-phase flows, coupled fluid flow and mass transport in porous media, and particulate flows. Examples of applications are provided in fuel cells and flow batteries. Further developments of the LB method are also outlined.

  8. Internal Nozzle Flow Simulations of Gasoline-Like Fuels under Diesel Operating Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Torelli, R.; Som, S.; Pei, Y.; Zhang, Yu; Traver, Michael

    2017-05-15

    Spray formation in internal combustion engines with direct injection is strictly correlated with internal nozzle flow characteristics, which are in turn influenced by fuel physical properties and injector needle motion. This paper pre-sents a series of 3D simulations that model the in-nozzle flow in a 5-hole mini-sac diesel injector. Two gasoline-like naphtha fuels, namely full-range and light naphtha, were tested under operating conditions typical of diesel applica-tions and were compared with n-dodecane, selected from a palette used as diesel surrogates. Validated methodolo-gies from our previous work were employed to account for realistic needle motion. The multi-phase nature of the problem was described by the mixture model assumption with the Volume of Fluid method. Cavitation effects were included by means of the Homogeneous Relaxation Model and turbulence closure was achieved with the Standard k-ε model in an Unsteady Reynolds-Averaged Navier-Stokes formulation. The results revealed that injector perfor-mance and propensity to cavitation are influenced by the fuel properties. Analyses of several physical quantities were carried out to highlight the fuel-to-fuel differences in terms of mass flow rate, discharge coefficients, and fuel vapor volume fraction inside the orifices. A series of parametric investigations was also performed to assess the fuel response to varied fuel injection temperature, injection pressure, and cross-sectional orifice area. For all cases, the strict correlation between cavitation magnitude and saturation pressure was confirmed. Owing to their higher volatil-ity, the two gasoline-like fuels were characterized by higher cavitation across all the simulated conditions. Occur-rence of cavitation was mostly found at the needle seat and at the orifice inlets during the injection event’s transient, when very small gaps exist between the needle and its seat. This behavior tended to disappear at maximum needle lift, where cavitation was

  9. An assessment of the energetic flows in a commercial PEM fuel-cell system

    International Nuclear Information System (INIS)

    Jovan, Vladimir; Perne, Matija; Petrovcic, Janko

    2010-01-01

    Some primary issues have not yet been fully investigated on the way towards the commercialization of fuel-cell-based systems (FCS), e.g., their actual efficiency, reliability, safety, degradation, maintainability, etc. This article deals with an estimation of the real energetic flows and the corresponding electrical efficiency of a commercial proton-exchange-membrane fuel-cell hydrogen-fed generator set (PEMFCS). The fuel-cell power system considered here is planned to be the source of both electrical and thermal energy in a mobile dwelling container unit with in-built fuel-cell-based cogeneration system, and for the design of a cogeneration unit the actual amount of disposable energy from the PEMFC unit should be estimated. The assessment of the actual energetic flows, the disposable energy and the consequent electrical efficiency of the case-study PEMFCS is carried out using commercial technical data for the PEMFCS.

  10. Design verification of the CANFLEX fuel bundle - quality assurance requirements for mechanical flow testing

    International Nuclear Information System (INIS)

    Alavi, P.; Oldaker, I.E.; Chung, C.H.; Suk, H.C.

    1997-01-01

    As part of the design verification program for the new fuel bundle, a series of out-reactor tests was conducted on the CANFLEX 43-element fuel bundle design. These tests simulated current CANDU 6 reactor normal operating conditions of flow, temperature and pressure. This paper describes the Quality Assurance (QA) Program implemented for the tests that were run at the testing laboratories of Atomic Energy of Canada Limited (AECL) and Korea Atomic energy Research Institute (KAERI). (author)

  11. Polymer electrolyte membrane fuel cell (PEMFC) flow field plate: design, materials and characterisation

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton, P.J.; Pollet, B.G. [PEM Fuel Cell Research Group, School of Chemical Engineering, University of Birmingham, Edgbaston, B15 2TT (United Kingdom)

    2010-08-15

    This review describes some recent developments in the area of flow field plates (FFPs) for proton exchange membrane fuel cells (PEMFCs). The function, parameters and design of FFPs in PEM fuel cells are outlined and considered in light of their performance. FFP materials and manufacturing methods are discussed and current in situ and ex situ characterisation techniques are described. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  12. Analysis of coolant flow in central tube of WWER-440 fuel assemblies

    International Nuclear Information System (INIS)

    Zsiros, G.; Toth, S.; Attila Aszodi, A.

    2011-01-01

    Three dimensional computational fluid dynamics model has been built to investigate the coolant flow in the central tube of the WWER-440 fuel assemblies. The model was verified based on measured data of the Kurchatov Institute. With the model calculations were performed for two fuel assemblies used in PAKS NPP. One of them has symmetrical and another has inclined pin power profile. Ratios of the outlet mass fluxes of the central tube to the inlet mass fluxes of the rod bundle were determined. Heat up ratios of the tube and rod bundle flows were calculated too. Sensitivity of the results on the assembly power distribution, inlet temperature and mass flow rate was investigated. The results of these simulations can be used as boundary conditions of central tube in studies of coolant mixing in fuel assembly heads. (Authors)

  13. The Test for Flow Characteristics of Tubular Fuel Assembly(II) - Experimental results and CFD analysis

    International Nuclear Information System (INIS)

    Park, Jong Hark; Chae, H. T.; Park, C.; Kim, H.

    2006-12-01

    A test facility had been established for the experiment of velocity distribution and pressure drop in a tubular fuel. A basic test had been conducted to examine the performance of the test loop and to verify the accuracy of measurement by pitot-tube. In this report, test results and CFD analysis for the hydraulic characteristics of a tubular fuel, following the previous tests, are described. Coolant velocities in all channels were measured using pitot-tube and the effect of flow rate change on the velocity distribution was also examined. The pressure drop through the tubular fuel was measured for various flow rates in range of 1 kg/s to 21 kg/s to obtain a correlation of pressure drop with variation of flow rate. In addition, a CFD(Computational Fluid Dynamics) analysis was also done to find out the hydraulic characteristics of tubular fuel such as velocity distribution and pressure drop. As the results of CFD analysis can give us a detail insight on coolant flow in the tubular fuel, the CFD method is a very useful tool to understand the flow structure and phenomena induced by fluid flow. The CFX-10, a commercial CFD code, was used in this study. The two results by the experiment and the CFD analysis were investigated and compared with each other. Overall trend of velocity distribution by CFD analysis was somewhat different from that of experiment, but it would be reasonable considering measurement uncertainties. The CFD prediction for pressure drop of a tubular fuel shows a tolerably good agreement with experiment within 8% difference

  14. Plenoptic Flow Imaging for Ground Testing, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Instantaneous volumetric flow imaging is crucial to aerodynamic development and testing. Simultaneous volumetric measurement of flow parameters enables accurate...

  15. Loss-of-flow transient characterization in carbide-fueled LMFBRs

    International Nuclear Information System (INIS)

    Rothrock, R.B.; Morgan, M.M.; Baars, R.E.; Elson, J.S.; Wray, M.L.

    1985-01-01

    One of the benefits derived from the use of carbide fuel in advanced Liquid Metal Fast Breeder Reactors (LMFBRs) is a decreased vulnerability to certain accidents. This can be achieved through the combination of advanced fuel performance with the enhanced reactivity feedback effects and passive shutdown cooling systems characteristic of the current 'inherently safe' plant concepts. The calculated core response to an unprotected loss of flow (ULOF) accident has frequently been used as a benchmark test of these designs, and the advantages of a high-conductivity fuel in relation to this type of transient have been noted in previous analyses. To evaluate this benefit in carbide-fueled LMFBRs incorporating representative current plant design features, limited calculations have been made of a ULOF transient in a small ('modular') carbide-fueled LMFBR

  16. Calculation of local characteristics of velocity field in turbulent coolant flow in fast reactor fuel assembly

    International Nuclear Information System (INIS)

    Muehlbauer, P.

    1981-08-01

    Experience is described gained with the application of computer code VELASCO in calculating the velocity field in fast reactor fuel assemblies taking into account configuration disturbances due to fuel pin displacement. Theoretical results are compared with the results of experiments conducted by UJV on aerodynamic models HEM-1 (model of the fuel assembly central part) and HEM-2 (model of the fuel assembly peripheral part). The results are reported of calculating the distribution of shear stress in wetted rod surfaces and in the assembly wall (model HEM-2) and the corresponding experimental results are shown. The shear stress distribution in wetted surfaces obtained using the VELASCO code allowed forming an opinion on the code capability of comprising local parameters of turbulent flow through a fuel rod bundle. The applicability was also tested of the code for calculating mean velocities in the individual zones, eg., in elementary cells. (B.S.)

  17. Heat transfer and fluid flow aspects of fuel--coolant interactions

    International Nuclear Information System (INIS)

    Corradini, M.L.

    1978-09-01

    A major portion of the safety analysis effort for the LMFBR is involved in assessing the consequences of a Hypothetical Core Disruptive Accident (HCDA). The thermal interaction of the hot fuel and the sodium coolant during the HCDA is investigated in two areas. A postulated loss of flow transient may produce a two-phase fuel at high pressures. The thermal interaction phenomena between fuel and coolant as the fuel is ejected into the upper plenum are investigated. A postulated transient overpower accident may produce molten fuel being released into sodium coolant in the core region. An energetic coolant vapor explosion for these reactor materials does not seem likely. However, experiments using other materials (e.g., Freon/water, tin/water) have demonstrated the possibility of this phenomenon

  18. CFD Simulation of Heat and Fluid Flow for Spent Fuel in a Dry Storage

    International Nuclear Information System (INIS)

    In, Wangkee; Kwack, Youngkyun; Kook, Donghak; Koo, Yanghyun

    2014-01-01

    A dry storage system is used for the interim storage of spent fuel prior to permanent depository and/or recycling. The spent fuel is initially stored in a water pool for more than 5 years at least after dispatch from the reactor core and is transported to dry storage. The dry cask contains a multiple number of spent fuel assemblies, which are cooled down in the spent fuel pool. The dry cask is usually filled up with helium gas for increasing the heat transfer to the environment outside the cask. The dry storage system has been used for more than a decade in United States of America (USA) and the European Union (EU). Korea is also developing a dry storage system since its spent fuel pool is anticipated to be full within 10 years. The spent fuel will be stored in a dry cask for more than 40 years. The integrity and safety of spent fuel are important for long-term dry storage. The long-term storage will experience the degradation of spent fuel such as the embrittlement of fuel cladding, thermal creep and hydride reorientation. High burn-up fuel may expedite the material degradation. It is known that the cladding temperature has a strong influence on the material degradation. Hence, it is necessary to accurately predict the local distribution of the cladding temperature using the Computational Fluid Dynamics (CFD) approach. The objective of this study is to apply the CFD method for predicting the three-dimensional distribution of fuel temperature in a dry cask. This CFD study simulated the dry cask for containing the 21 fuel assemblies under development in Korea. This paper presents the fluid velocity and temperature distribution as well as the fuel temperature. A two-step CFD approach was applied to simulate the heat and fluid flow in a dry storage of 21 spent fuel assemblies. The first CFD analysis predicted the helium flow and temperature in a dry cask by a assuming porous body of the spent fuel. The second CFD analysis was to simulate a spent fuel assembly in the

  19. Numerical simulations of helium flow through prismatic fuel elements of very high temperature reactors

    International Nuclear Information System (INIS)

    Ribeiro, Felipe Lopes; Pinto, Joao Pedro C.T.A.

    2013-01-01

    The 4 th generation Very High Temperature Reactor (VHTR) most popular concept uses a graphite-moderated and helium cooled core with an outlet gas temperature of approximately 1000 deg C. The high output temperature allows the use of the process heat and the production of hydrogen through the thermochemical iodine-sulfur process as well as highly efficient electricity generation. There are two concepts of VHTR core: the prismatic block and the pebble bed core. The prismatic block core has two popular concepts for the fuel element: multihole and annular. In the multi-hole fuel element, prismatic graphite blocks contain cylindrical flow channels where the helium coolant flows removing heat from cylindrical fuel rods positioned in the graphite. In the other hand, the annular type fuel element has annular channels around the fuel. This paper shows the numerical evaluations of prismatic multi-hole and annular VHTR fuel elements and does a comparison between the results of these assembly reactors. In this study the analysis were performed using the CFD code ANSYS CFX 14.0. The simulations were made in 1/12 fuel element models. A numerical validation was performed through the energy balance, where the theoretical and the numerical generated heat were compared for each model. (author)

  20. Stress Linearization and Strength Evaluation of the BEP's Flow Plates for a Dual Cooled Fuel Assembly

    International Nuclear Information System (INIS)

    Kim, Jae Yong; Yoon, Kyung Ho; Kang, Heung Seok; Lee, Young Ho; Lee, Kang Hee; Kim, Hyung Kyu

    2009-01-01

    A fuel assembly is composed of 5 major components, such as a top end piece (TEP), a bottom end piece (BEP), spacer grids (SGs), guide tubes (GTs) and an instrumentation tube (IT) and fuel rods (FRs). There are no ASME criteria about all components except for a TEP/BEP. The TEP/BEP should satisfy stress intensity limits in case of condition A and B of ASME, Section III, Division 1 . Subsection NB. In a dual cooled fuel assembly, the array and position of fuels are changed from those of a conventional PWR fuel assembly to achieve a power uprating. The flow plates of top/bottom end pieces (TEP/BEP) have to be modified into proper shape to provide flow holes to direct the heated coolant into/out of the fuel assembly but structural intensity of these plates within a 22.241 kN axial loading should satisfy Tresca stress limits in ASME code. In this paper, stress linearization procedure and strength evaluation of a newly designed BEP for the dual cooled fuel assembly are described

  1. Loss-of-flow test L5 on FFTF-type irradiated fuel

    International Nuclear Information System (INIS)

    Simms, R.; Gehl, S.M.; Lo, R.K.; Rothman, A.B.

    1978-03-01

    Test L5 simulated a hypothetical loss-of-flow accident in an LMFBR using three (Pu, U)O 2 fuel elements of the FTR type. The test elements were irradiated before TREAT Test L5 in the General Electric Test Reactor to 8 at. % burnup at about 40 kW/m. The preirradiation in GETR caused a fuel-restructuring range characteristic of moderate-power structure relative to the FTR. The test transient was devised so that a power burst would be initiated at incipient cladding melting after the loss of flow. The test simulation corresponds to a scenario for FTR in which fuel in high-power-structure subassemblies slump, resulting in a power excursion. The remaining subassemblies are subjected to this power burst. Test L5 addressed the fuel-motion behavior of the subassemblies in this latter category. Data from test-vehicle sensors, hodoscope, and post-mortem examinations were used to construct the sequence of events within the test zone. From these observations, the fuel underwent a predominantly dispersive event just after reaching a peak power six times nominal at, or after, scram. The fuel motion was apparently driven by the release of entrained fission-product gases, since fuel vapor pressure was deliberately kept below significant levels for the transient. The test remains show a wide range of microstructural evolution, depending on the extent of heat deposition along the active fuel column. Extensive fuel swelling was also observed as a result of the lack of the cladding restraint. The results of the thermal-hydraulic calculations with the SAS3A code agreed qualitatively with the postmortem results with respect to the extent of the melting and the dispersal of cladding and fuel. However, the calculated times of certain events did not agree with the observed times

  2. Forest fuel reduces the nitrogen load - calculations of nitrogen flows

    International Nuclear Information System (INIS)

    Burstroem, F.; Johansson, Jan.

    1995-12-01

    Nitrogen deposition in Sweden has increased strongly during recent decades, particularly in southern Sweden. Nitrogen appears to be largely accumulated in biomass and in the soil. It is therefore desirable to check the accumulation of nitrogen in the forest. The most suitable way of doing this is to remove more nitrogen-rich biomass from the forest, i.e., increase the removal of felling residues from final fellings and cleanings. An ecological condition for intensive removal of fuel is that the ashes are returned. The critical load for nitrogen, CL(N), indicates the level of nitrogen deposition that the forest can withstand without leading to ecological changes. Today, nitrogen deposition is higher than the CL(N) in almost all of Sweden. CL(N) is calculated in such a manner that nitrogen deposition should largely be balanced by nitrogen losses through harvesting during a forest rotation. The value of CL(N) thus largely depends on how much nitrogen is removed with the harvested biomass. When both stems and felling residues are harvested, the CL(N) is about three times higher than in conventional forestry. The increase is directly related to the amount of nitrogen in the removed biofuel. Use of biofuel also causes a certain amount of nitrogen emissions. From the environmental viewpoint there is no difference between the sources of the nitrogen compounds. An analysis of the entire fuel chain shows that, compared with the amount of nitrogen removed from the forest with the fuel, about 5 % will be emitted as nitrogen oxides or ammonia during combustion, and a further ca 5 % during handling and transports. A net amount of about 90 % of biomass nitrogen is removed from the system and becomes inert nitrogen (N 2 ). 60 refs, 3 figs, 4 tabs, 11 appendices

  3. ESBWR enhanced flow distribution with optimized orificing and related fuel cycle performance

    Energy Technology Data Exchange (ETDEWEB)

    Pearson, G. J.; Karve, A. A.; Fawcett, R. M. [Global Nuclear Fuel - America, 3901 Castle Hayne Road, Wilmington, NC 28401 (United States)

    2012-07-01

    The Economic Simplified Boiling Water Reactor (ESBWR) is GEH's latest Generation III+ reactor design with natural circulation coolant flow and passive safety features. Reliance on natural circulation as the sole means of core coolant driving force results in increased power-to-flow ratio and places increased importance on the efficient distribution of core flow in order to achieve optimum thermal margins and improved fuel cycle efficiency. In addition, the large core size of the ESBWR, containing 1132 bundles, greatly benefits from a more targeted distribution of flow, directing a higher fraction of flow to high power bundles in the 'ring of fire' region of typical BWR loading patterns and a lower fraction of flow to low power bundles on and near the core periphery. Desirable flow distributions can be achieved by modifying the hydraulic resistance of the inlet orifices to preferentially force flow to the targeted region. The inlet orifice is a feature that is incorporated into the fuel support piece of a typical BWR design. The majority of existing forced circulation BWR's rely on only two orifice types - a peripheral orifice located along the outermost row and a central orifice in all other locations. A more optimum distribution of core flow is achievable with the introduction of multiple inlet orifice types. Multi-zone orifice layouts comprised of two, three and four types have been evaluated for the ESBWR. An efficient radial distribution of flow can have a direct beneficial effect on the Minimum Critical Power Ratio (MCPR). An improved multi-zone orifice layout in the ESBWR has the potential of significantly increasing active flow in high power bundles. On average, this flow increase corresponds to a noteworthy MCPR improvement. Additional MCPR margin may be used to enhance operating flexibility and to achieve reduced fuel cycle costs over the plant lifetime. Combined with GNF's latest high performance fuel design for the ESBWR, GNF2E

  4. FLATT - a computer programme for calculating flow and temperature transients in nuclear fuels

    International Nuclear Information System (INIS)

    Venkat Raj, V.; Koranne, S.M.

    1976-01-01

    FLATT is a computer code written in Fortran language for BESM-6 computer. The code calculates the flow transients in the coolant circuit of a nuclear reactor, caused by pump failure, and the consequent temperature transients in the fuel, clad, and the coolant. In addition any desired flow transient can be fed into the programme and the resulting temperature transients can be calculated. A case study is also presented. (author)

  5. Calculation of Heat-Bearing Agent’s Steady Flow in Fuel Bundle

    Science.gov (United States)

    Amosova, E. V.; Guba, G. G.

    2017-11-01

    This paper introduces the result of studying the heat exchange in the fuel bundle of the nuclear reactor’s fuel magazine. The article considers the fuel bundle of the infinite number of fuel elements, fuel elements are considered in the checkerboard fashion (at the tops of a regular triangle a fuel element is a plain round rod. The inhomogeneity of volume energy release in the rod forms the inhomogeneity of temperature and velocity fields, and pressure. Computational methods for studying hydrodynamics in magazines and cores with rod-shape fuel elements are based on a significant simplification of the problem: using basic (averaged) equations, isobaric section hypothesis, porous body model, etc. This could be explained by the complexity of math description of the three-dimensional fluid flow in the multi-connected area with the transfer coefficient anisotropy, curved boundaries and technical computation difficulties. Thus, calculative studying suggests itself as promising and important. There was developed a method for calculating the heat-mass exchange processes of inter-channel fuel element motions, which allows considering the contribution of natural convection to the heat-mass exchange based on the Navier-Stokes equations and Boussinesq approximation.

  6. The post-irradiation examination of fuel in support of Bruce A Nuclear Division fueling with flow program

    International Nuclear Information System (INIS)

    Montin, J.; Sagat, S.

    1995-10-01

    Bruce A Nuclear Division (BAND) units are operating at ∼ 75% of full power, because of the potential of a power pulse in the event of an inlet header break. As a result, BAND is converting to fueling with flow, to eliminate the potential of a power pulse and to allow for full-power operation. Concerns regarding the integrity of the end-of-life (EOL) bundles interacting with the latch at the downstream end of the fuel channel were raised. BAND carried out a test program in which EOL bundles in the upstream position of 13 of Unit 2 were cascaded into the downstream latch position 1 of another channel. Six of twelve cascaded bundles and two typical EOL position 13 (benchmark) bundles were selected for post-irradiation examination (PIE). Incipient cracks were found in the benchmark bundles. Metallographic and fractographic examination, along with crack dating, and hydrogen and deuterium analyses, indicated that the incipient cracks were the result of delayed-hydride assisted cracking at the EOL. Consequently, Ontario Hydro changed the design of the outlet shield plug to support all three rings of the fuel bundle, to minimize stress and prevent end plate cracking. Also, an ultrasonic end plate inspection tool (UT) was developed and located in the fuel bay, to inspect fuel-bundle end plates for cracks. A second test was done involving a series of four bundle cascades in BAND Unit 4 channels that had new outlet shield plugs. The latch bundles were discharged after a hot shutdown. The cascaded Unite 2 and Unit 4 latch bundles were checked for cracks using the UT. The PIE found incipient cracks or less-than-ideal welds in the assembly welds of fuel elements from Unit 2 (latch-supported fuel bundles) that had been identified by the UT as having incipient cracks. No incipient cracks were found in the assemble welds of fuel elements from Unit 4 (new outlet shield-supported fuel bundles) confirming the UT results. (author). 5 refs., 8 figs

  7. Three-dimensional flow phenomena in a wire-wrapped 37-pin fuel bundle for SFR

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Jae Ho; Yoo, Jin; Lee, Kwi Lim; Ha, Kwi Seok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-08-15

    Three-dimensional flow phenomena in a wire-wrapped 37-pin fuel assembly mock-up of a Japanese loop-type sodium-cooled fast reactor, Monju, were investigated with a numerical analysis using a general-purpose commercial computational fluid dynamics code, CFX. Complicated and vortical flow phenomena in the wire-wrapped 37-pin fuel assembly were captured by a Reynolds-averaged Navier-Stokes flow simulation using a shear stress transport turbulence model. The main purpose of the current study is to understand the three-dimensional complex flow phenomena in a wire-wrapped fuel assembly to support the license issue for the core design. Computational fluid dynamics results show good agreement with friction factor correlation models. The secondary flow in the corner and edge subchannels is much stronger than that in an interior subchannel. The axial velocity averaged in the corner and edge subchannels is higher than that averaged in the interior subchannels. Three-dimensional multiscale vortex structures start to be formed by an interaction between secondary flows around each wire-wrapped pin. Behavior of the large-scale vortex structures in the corner and edge subchannels is closely related to the relative position between the hexagonal duct wall and the helically wrapped wire spacer. The small-scale vortex is axially developed in the interior subchannels. Furthermore, a driving force on each wire spacer surface is closely related to the relative position between the hexagonal duct wall and the wire spacer.

  8. Development of 3-D Flow Analysis Code for Fuel Assembly using Unstructured Grid System

    Energy Technology Data Exchange (ETDEWEB)

    Myong, Hyon Kook; Kim, Jong Eun; Ahn, Jong Ki; Yang, Seung Yong [Kookmin Univ., Seoul (Korea, Republic of)

    2007-03-15

    The flow through a nuclear rod bundle with mixing vanes are very complex and required a suitable turbulence model to be predicted accurately. Final objective of this study is to develop a CFD code for fluid flow and heat transfer analysis in a nuclear fuel assembly using unstructured grid system. In order to develop a CFD code for fluid flow and heat transfer analysis in a nuclear fuel assembly using unstructured grid system, the following researches are made: - Development of numerical algorithm for CFD code's solver - Grid and geometric connectivity data - Development of software(PowerCFD code) for fluid flow and heat transfer analysis in a nuclear fuel assembly using unstructured grid system - Modulation of software(PowerCFD code) - Development of turbulence model - Development of analysis module of RANS/LES hybrid models - Analysis of turbulent flow and heat transfer - Basic study on LES analysis - Development of main frame on pre/post processors based on GUI - Algorithm for fully-developed flow.

  9. Development of 3-D Flow Analysis Code for Fuel Assembly using Unstructured Grid System

    International Nuclear Information System (INIS)

    Myong, Hyon Kook; Kim, Jong Eun; Ahn, Jong Ki; Yang, Seung Yong

    2007-03-01

    The flow through a nuclear rod bundle with mixing vanes are very complex and required a suitable turbulence model to be predicted accurately. Final objective of this study is to develop a CFD code for fluid flow and heat transfer analysis in a nuclear fuel assembly using unstructured grid system. In order to develop a CFD code for fluid flow and heat transfer analysis in a nuclear fuel assembly using unstructured grid system, the following researches are made: - Development of numerical algorithm for CFD code's solver - Grid and geometric connectivity data - Development of software(PowerCFD code) for fluid flow and heat transfer analysis in a nuclear fuel assembly using unstructured grid system - Modulation of software(PowerCFD code) - Development of turbulence model - Development of analysis module of RANS/LES hybrid models - Analysis of turbulent flow and heat transfer - Basic study on LES analysis - Development of main frame on pre/post processors based on GUI - Algorithm for fully-developed flow

  10. Experimental study of a reverse flow catalytic converter for a duel fuel engine

    Energy Technology Data Exchange (ETDEWEB)

    Liu, B.; Checkel, M. D. [Alberta Univ., Dept. of Mechanical Engineering, Edmonton, ANB (Canada); Hayes, R. E. [Alberta Univ., Dept, of Chemical and Materials Engineering, Edmonton, AB, (Canada)

    2001-08-01

    Performance of a reverse flow catalytic converter for a methane/diesel dual fuel engine is evaluated under steady and transient engine conditions. The converter is of the monolith honeycomb type with palladium catalyst washcoat. Results of the reverse flow converter's performance was found to be superior for several steady state engine operations when compared to unidirectional flow operation. In transient operations following a step change in engine operating conditions, reverse flow was found to be better than unidirectional flow when the change in engine operation was such as to reduce the exhaust gas temperature. When exhaust gas temperature was increased, reverse flow decreased the rate of increase in the reactor temperature. Testing was done using the transient Japanese 6-Mode tests. Best results were achieved with a switch time in the five seconds to fifteen seconds range. 31 refs., 9 tabs., 24 figs.

  11. Material Flow Analysis of Fossil Fuels in China during 2000–2010

    Science.gov (United States)

    Wang, Sheng; Dai, Jing; Su, Meirong

    2012-01-01

    Since the relationship between the supply and demand of fossil fuels is on edge in the long run, the contradiction between the economic growth and limited resources will hinder the sustainable development of the Chinese society. This paper aims to analyze the input of fossil fuels in China during 2000–2010 via the material flow analysis (MFA) that takes hidden flows into account. With coal, oil, and natural gas quantified by MFA, three indexes, consumption and supply ratio (C/S ratio), resource consumption intensity (RCI), and fossil fuels productivity (FFP), are proposed to reflect the interactions between population, GDP, and fossil fuels. The results indicated that in the past 11 years, China's requirement for fossil fuels has been increasing continuously because of the growing mine productivity in domestic areas, which also leads to a single energy consumption structure as well as excessive dependence on the domestic exploitation. It is advisable to control the fossil fuels consumption by energy recycling and new energy facilities' popularization in order to lead a sustainable access to nonrenewable resources and decrease the soaring carbon emissions. PMID:23365525

  12. Material flow analysis of fossil fuels in China during 2000-2010.

    Science.gov (United States)

    Wang, Sheng; Dai, Jing; Su, Meirong

    2012-01-01

    Since the relationship between the supply and demand of fossil fuels is on edge in the long run, the contradiction between the economic growth and limited resources will hinder the sustainable development of the Chinese society. This paper aims to analyze the input of fossil fuels in China during 2000-2010 via the material flow analysis (MFA) that takes hidden flows into account. With coal, oil, and natural gas quantified by MFA, three indexes, consumption and supply ratio (C/S ratio), resource consumption intensity (RCI), and fossil fuels productivity (FFP), are proposed to reflect the interactions between population, GDP, and fossil fuels. The results indicated that in the past 11 years, China's requirement for fossil fuels has been increasing continuously because of the growing mine productivity in domestic areas, which also leads to a single energy consumption structure as well as excessive dependence on the domestic exploitation. It is advisable to control the fossil fuels consumption by energy recycling and new energy facilities' popularization in order to lead a sustainable access to nonrenewable resources and decrease the soaring carbon emissions.

  13. A Development of Technical Specification of a Research Reactor with Plate Fuels Cooled by Upward Flow

    International Nuclear Information System (INIS)

    Park, Sujin; Kim, Jeongeun; Kim, Hyeonil

    2016-01-01

    The contents of the TS(Technical Specifications) are definitions, safety limits, limiting safety system settings, limiting conditions for operation, surveillance requirements, design features, and administrative controls. TS for Nuclear Power Plants (NPPs) have been developed since many years until now. On the other hands, there are no applicable modernized references of TS for research reactors with many differences from NPPs in purpose and characteristics. Fuel temperature and Departure from Nuclear Boiling Ratio (DNBR) are being used as references from the thermal-hydraulic analysis point of view for determining whether the design of research reactors satisfies acceptance criteria for the nuclear safety or not. Especially for research reactors using plate-type fuels, fuel temperature and critical heat flux, however, are very difficult to measure during the reactor operation. This paper described the outline of main contents of a TS for open-pool research reactor with plate-type fuels using core cooling through passive systems, where acceptance criteria for nuclear safety such as CHF and fuel temperature cannot be directly measured, different from circumstances in NPPs. Thus, three independent variables instead of non-measurable acceptance criteria: fuel temperature and CHF are considered as safety limits, i.e., power, flow, and flow temperature

  14. Design of flow-field patterns for proton exchange membrane fuel cell application

    International Nuclear Information System (INIS)

    Rosli, M.I.; Wan Ramli Wan Daud; Kamaruzzaman Sopian; Jaafar Sahari

    2006-01-01

    Fuel cells are electrochemical devices that produce electricity at high efficiency without combustion. Fuel cells are emerging as viable candidates as power sources in many applications, including road vehicles, small-scale power stations, and possibly even portable electronics. This paper addresses the design of flow-field patterns for proton exchange membrane fuel cell (PEMFC). The PEMFC is a low-temperature fuel cell, in which a proton conductive polymer membrane is used as the electrolyte. In PEMFC, flow-field pattern is one important thing that effects the performance of PEMFC. This paper present three types of flow-field pattern that will be consider to be testing using CFD analysis and by experimental. The design look detail on to their shape and dimension to get the best pattern in term of more active electrode area compare to electrode area that will be used. Another advantage and disadvantage for these three type of flow-field patterns from literature also compared in this paper

  15. Low stoichiometry operation of a polymer electrolyte membrane fuel cell employing the interdigitated flow field design

    DEFF Research Database (Denmark)

    Berning, Torsten; Odgaard, Madeleine; Kær, Søren Knudsen

    2011-01-01

    Fuel cell operation on dry reactant gases under low stoichiometry conditions employing the interdigitated flow field is investigated using a multi-fluid model. It is assumed that the MEA contains a water uptake layer which facilitates water absorption to the membrane and hence prevents the anode...

  16. Model-based Fuel Flow Control for Fossil-fired Power Plants

    DEFF Research Database (Denmark)

    Niemczyk, Piotr

    2010-01-01

    -fired power plants represent the largest reserve of such controllable power sources in several countries. However, their production take-up rates are limited, mainly due to poor fuel flow control. The thesis presents analysis of difficulties and potential improvements in the control of the coal grinding...

  17. Flow channel shape optimum design for hydroformed metal bipolar plate in PEM fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Linfa; Lai, Xinmin; Liu, Dong' an; Hu, Peng [State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai 200240 (China); Ni, Jun [Department of Mechanical Engineering and Applied Mechanics, University of Michigan, Ann Arbor, MI 48109 (United States)

    2008-03-15

    Bipolar plate is one of the most important and costliest components of polymer electrolyte membrane (PEM) fuel cells. Micro-hydroforming is a promising process to reduce the manufacturing cost of PEM fuel cell bipolar plates made of metal sheets. As for hydroformed bipolar plates, the main defect is the rupture because of the thinning of metal sheet during the forming process. The flow channel section decides whether high quality hydroformed bipolar plates can be successively achieved or not. Meanwhile, it is also the key factor that is related with the reaction efficiency of the fuel cell stacks. In order to obtain the optimum flow channel section design prior the experimental campaign, some key geometric dimensions (channel depth, channel width, rib width and transition radius) of flow channel section, which are related with both reaction efficiency and formability, are extracted and parameterized as the design variables. By design of experiments (DOE) methods and an adoptive simulated annealing (ASA) optimization method, an optimization model of flow channel section design for hydroformed metal bipolar plate is proposed. Optimization results show that the optimum dimension values for channel depth, channel width, rib width and transition radius are 0.5, 1.0, 1. 6 and 0.5 mm, respectively with the highest reaction efficiency (79%) and the acceptable formability (1.0). Consequently, their use would lead to improved fuel cell efficiency for low cost hydroformed metal bipolar plates. (author)

  18. Flow measurement by Laser Doppler Anemometry in a nuclear fuel assembly

    International Nuclear Information System (INIS)

    Kehoe, A.

    1984-12-01

    Development of a Laser Doppler Anemometer measurement system and its operation are examined in this research. The system is designed for flow measurement in laboratory models of nuclear fuel assemblies. Use of the system is demonstrated by measuring turbulent velocity profiles in the laboratory model at full scale reactor flow rates. The reactors at the Savanah River Plant (SRP) are heavy water moderated and operate at low temperatures and pressures. Reactor power is currently limited by the temperature of the water in the nuclear fuel assembly. These temperature limits are conservatively calculated without allowing for any turbulent mixing. This research incorporates the design, fabriction and operation of a plexiglas model fuel assembly for the purpose of making turbulent velocity measurement via a Laser Doppler Anemometer System

  19. Solid oxide fuel cell having monolithic cross flow core and manifolding

    International Nuclear Information System (INIS)

    Poeppel, R.B.; Dusek, J.T.

    1984-01-01

    This invention discloses a monolithic core construction having the flow passageways for the fuel and for the oxidant gases extended transverse to one another, whereby full face core manifolding can be achieved for these gases and their reaction products. The core construction provides that only anode material surround each fuel passageway and only cathode material surround each oxidant passageway, each anode and each cathode further sandwiching at spaced opposing sides electrolyte and interconnect materials to define electrolyte and interconnect walls. Webs of the cathode and anode material hold the electrolyte and interconnect walls spaced apart to define the flow passages. The composite anode and cathode wall structures are further alternately stacked on one another (with the separating electrolyte or interconnect material typically being a single common layer) whereby the fuel passageway and the oxidant passageways are disposed transverse to one another

  20. Mass transport aspects of polymer electrolyte fuel cells under two-phase flow conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, D.

    2007-03-15

    This well-illustrated, comprehensive dissertation by Dr. Ing. Denis Kramer takes an in-depth look at polymer electrolyte fuel cells (PEFC) and the possibilities for their application. First of all, the operating principles of polymer electrolyte fuel cells are described and discussed, whereby thermodynamics aspects and loss mechanisms are examined. The mass transport diagnostics made with respect to the function of the cells are discussed. Field flow geometry, gas diffusion layers and, amongst other things, liquid distribution, the influence of flow direction and the low-frequency behaviour of air-fed PEFCs are discussed. Direct methanol fuel cells are examined, as are the materials chosen. The documentation includes comprehensive mathematical and graphical representations of the mechanisms involved.

  1. LES and experimental studies of cold and reacting flow in a swirled partially remixed burner with and without fuel modulation

    NARCIS (Netherlands)

    Sengissen, A.X.; van Kampen, J.F.; Huls, R.A.; Stoffels, Genie G.M.; Kok, Jacobus B.W.; Poinsot, T.J.

    2007-01-01

    In devices where air and fuel are injected separately, combustion processes are influenced by oscillations of the air flow rate but may also be sensitive to fluctuations of the fuel flow rate entering the chamber. This paper describes a joint experimental and numerical study of the mechanisms

  2. The post irradiation examination of fuel in support of Bruce A nuclear division fueling with flow program

    International Nuclear Information System (INIS)

    Montin, J.; Sagat, S.; Day, R.; Novak, J.; Bromfield, H.

    1995-01-01

    Bruce A Nuclear Division (BAND) units are operating at ∼ 75% of full power, because of the potential of a power pulse in the event of an inlet header break. As a result, BAND is converting to fueling with flow, to eliminate the potential of a power pulse and to allow for full-power operation. Concerns regarding the integrity of the end-of-life (EOL) bundles interacting with the latch at the downstream end of the fuel channel were raised. BAND carried out a test program in which EOL bundles in the upstream position 13 of Unit 2 were cascaded into the downstream latch position 1 of another channel. Six of twelve cascaded bundles and two typical EOL position 13 (benchmark) bundles were selected for post-irradiation examination (PIE). Incipient cracks were found in the assembly welds (endplateto-endcap welds) of all six cascaded bundles. No incipient cracks were found in the benchmark bundles. Metallographic and fractographic examination, along with crack dating, and hydrogen and deuterium analyses, indicated that the incipient cracks were the result of delayed-hydride assisted cracking at the EOL. Consequently, Ontario Hydro changed the design of the outlet shield plug to support all three rings of the fuel bundle, to minimize stress and prevent endplate cracking. Also, an ultrasonic endplate inspection tool (UT) was developed and located in the fuel bay. to inspect fuelbundle endplates for cracks. A second test was done involving a series of four bundle cascades in BAND Unit 4 channels that had new outlet shield plugs. The latch bundles were discharged after a hot shutdown. The cascaded Unit 2 and Unit 4 latch bundles were checked for cracks using the UT. The PIE found incipient cracks or less-than-ideal welds in the assembly welds of fuel elements from Unit 2 (latch-supported fuel bundles) that had been identified by the UT as having incipient cracks. No incipient cracks were found in the assembly welds of fuel elements from Unit 4 (new outlet shield

  3. Computer simulation of fuel behavior during loss-of-flow accidents in a gas-cooled fast reactor

    International Nuclear Information System (INIS)

    Wehner, T.R.

    1980-01-01

    The sequence of events in a loss-of-flow accident without reactor shutdown in a gas-cooled fast breeder reactor is strongly influenced by the manner in which the fuel deforms. In order to predict the mode of initial gross fuel deformation, welling, melting or cracking, a thermomechanical computer simulation program was developed. Methods and techniques used make the simulation an economical, efficient, and flexible engineering tool. An innovative application of the enthalpy model within a finite difference scheme is used to caculate temperatures in the fuel rod. The method of successive elastic solutions is used to calculate the thermoelastic-creep response. Calculated stresses are compared with a brittle-fracture stress criterion. An independent computer code is used to calculate fission-gas-induced fuel swelling. Results obtained with the computer simulation indicate that swelling is not a mode of initial fuel deformation. Faster transients result in fuel melting, while slower transients result in fuel cracking. For investigated faster coolant flow coastdowns with time constants of 1 second and 10 seconds, compressive stresses in the outer radial portion of the fuel limit fuel swelling and inhibit fuel cracking. For a slower coolant flow coastdown with a 300 second time constant, tensile stresses in the outer radial portion of the fuel induce early fuel cracking before any melting or significant fuel swelling has occurred. Suggestions for further research are discussed. A derived noniterative solution for mechanics calculations may offer an order of magnitude decrease in computational effort

  4. Gravity-driven flow and heat transfer in a spent nuclear fuel storage pool

    International Nuclear Information System (INIS)

    Gay, R.R.

    1983-01-01

    The GFLOW code analyzes a three-dimensional rectangular porous medium by dividing the porous medium into a number of nodes or cells specified by the user. The finite difference form of the fluid conservation equations is solved for each node by application of a modified ''marker and cell'' numerical technique. The existence of spent nuclear fuel in any node is modeled by using a porosity value less than unity in that node and by including a surface heat transfer term in the fluid energy equation. In addition, local pressure losses due to grid spaces or other planar flow obstructions can be modeled by local loss coefficients. Heat conduction in the fuel is simulated by a fast running implicit finite difference model of the fuel, gap, and clad regions of the fuel rod

  5. Modelling of integrated effect of volumetric heating and magnetic field on tritium transport in a U-bend flow as applied to HCLL blanket concept

    International Nuclear Information System (INIS)

    Valls, E.Mas de les; Batet, L.; Medina, V. de; Fradera, J.; Sedano, L.

    2011-01-01

    Highlights: → 3D transient CFD code based on OpenFOAM toolbox and accounting for MHD and thermal et al. effects. → Hydrodynamic instabilities caused by the jet (generated at the gap narrowing) are found at Reynolds 480. → Hartmann 1740 is able to stabilise the flow. → A heat deposition corresponding to Gr = 5.21 x 10 9 is sufficient for buoyancy to be predominant at the bend region. Flow becomes unstable. → Tritium permeation ratio cannot be accurately predicted due to major uncertainties in Sievert's coefficient. - Abstract: Under fusion reactor operational conditions, heat deposition might cause a complex buoyant liquid metal flow in the HCLL blanket, what has a direct influence on tritium permeation ratio. In order to characterise the nature of this flow, a simplified HCLL channel, including the U-bend near the reactor first wall, is analysed using a finite volume CFD code, based on OpenFOAM toolbox, following an electric potential based formulation. Code validation results for developed MHD flow and magneto-convective flow are exposed. The influence of the HCLL U-bend on the flow pattern is studied with the validated code, covering the range of possible Reynolds numbers in HCLL-ITER blanket, and considering either electrically insulating or perfectly conducting walls. It can be stated that, despite the very low velocities and the high Hartmann number, flow pattern is complex and unsteady vortices are formed by the action of buoyancy forces together with the influence of the U-bend. Through the analysis, the flow physics is decoupled in order to identify the exact origin of vortex formation. A simplified tritium transport analysis, considering tritium as a passive scalar, has been carried out including a study on boundary conditions influence and a sensitivity analysis of tritium permeation fluxes to diffusivity and solubility parameters. Results show the relevance of Sievert's coefficient uncertainties, which alters the permeation ratio by an order of

  6. Modelling of integrated effect of volumetric heating and magnetic field on tritium transport in a U-bend flow as applied to HCLL blanket concept

    Energy Technology Data Exchange (ETDEWEB)

    Valls, E.Mas de les, E-mail: elisabet.masdelesvalls@gits.ws [Technical University of Catalonia (UPC), Jordi Girona 1-3, 08034 Barcelona (Spain); Technology for Fusion (T4F) Research Group, GREENER, Dept. of Heat Engines (UPC) (Spain); Batet, L. [Technical University of Catalonia (UPC), Jordi Girona 1-3, 08034 Barcelona (Spain); Technology for Fusion (T4F) Research Group, GREENER, Dept. of Physics and Nuclear Engineering (UPC) (Spain); Medina, V. de [Technical University of Catalonia (UPC), Jordi Girona 1-3, 08034 Barcelona (Spain); Sediment Transport Research Group, Dept. of Engineering Hydraulic, Marine and Environmental Engineering (UPC) (Spain); Fradera, J. [Technical University of Catalonia (UPC), Jordi Girona 1-3, 08034 Barcelona (Spain); Technology for Fusion (T4F) Research Group, GREENER, Dept. of Physics and Nuclear Engineering (UPC) (Spain); Sedano, L. [EURATOM-CIEMAT Fusion Association, Av. Complutense 22, 28040 Madrid (Spain)

    2011-06-15

    Highlights: > 3D transient CFD code based on OpenFOAM toolbox and accounting for MHD and thermal et al. effects. > Hydrodynamic instabilities caused by the jet (generated at the gap narrowing) are found at Reynolds 480. > Hartmann 1740 is able to stabilise the flow. > A heat deposition corresponding to Gr = 5.21 x 10{sup 9} is sufficient for buoyancy to be predominant at the bend region. Flow becomes unstable. > Tritium permeation ratio cannot be accurately predicted due to major uncertainties in Sievert's coefficient. - Abstract: Under fusion reactor operational conditions, heat deposition might cause a complex buoyant liquid metal flow in the HCLL blanket, what has a direct influence on tritium permeation ratio. In order to characterise the nature of this flow, a simplified HCLL channel, including the U-bend near the reactor first wall, is analysed using a finite volume CFD code, based on OpenFOAM toolbox, following an electric potential based formulation. Code validation results for developed MHD flow and magneto-convective flow are exposed. The influence of the HCLL U-bend on the flow pattern is studied with the validated code, covering the range of possible Reynolds numbers in HCLL-ITER blanket, and considering either electrically insulating or perfectly conducting walls. It can be stated that, despite the very low velocities and the high Hartmann number, flow pattern is complex and unsteady vortices are formed by the action of buoyancy forces together with the influence of the U-bend. Through the analysis, the flow physics is decoupled in order to identify the exact origin of vortex formation. A simplified tritium transport analysis, considering tritium as a passive scalar, has been carried out including a study on boundary conditions influence and a sensitivity analysis of tritium permeation fluxes to diffusivity and solubility parameters. Results show the relevance of Sievert's coefficient uncertainties, which alters the permeation ratio by an

  7. Heat and mass transfer of a fuel droplet evaporating in oscillatory flow

    International Nuclear Information System (INIS)

    Jangi, M.; Kobayashi, H.

    2009-01-01

    A numerical study of the heat and mass transfer from an evaporating fuel droplet in oscillatory flow was performed. The flow was assumed to be laminar and axisymmetric, and the droplet was assumed to maintain its spherical shape during its lifetime. Based on these assumptions, the conservation equations in a general curvilinear coordinate were solved numerically. The behaviors of droplet evaporation in the oscillatory flow were investigated by analyzing the effects of flow oscillation on the evaporation process of a n-heptane fuel droplet at high pressure. The response of the time history of the square of droplet diameter and space-averaged Nusselt numbers to the main flow oscillation were investigated in frequency band of 1-75 Hz with various oscillation amplitudes. Results showed that, depending on the frequency and amplitude of the oscillation, there are different modes of response of the evaporation process to the flow oscillation. One response mode is synchronous with the main flow oscillation, and thus the quasi-steady condition is attained. Another mode is asynchronous with the flow oscillation and is highly unsteady. As for the evaporation rate, however, in all conditions is more greatly enhanced in oscillatory flow than in quiescent air. To quantify the conditions of the transition from quasi-steady to unsteady, the response of the boundary layer around the droplet surface to the flow oscillation was investigated. The results led to including the oscillation Strouhal number as a criteria for the transition. The numerical results showed that at a low Strouhal number, a quasi-steady boundary layer is formed in response to the flow oscillation, whereas by increasing the oscillation Strouhal number, the phenomena become unsteady.

  8. Opposed-flow Flame Spread Over Solid Fuels in Microgravity: the Effect of Confined Spaces

    Science.gov (United States)

    Wang, Shuangfeng; Hu, Jun; Xiao, Yuan; Ren, Tan; Zhu, Feng

    2015-09-01

    Effects of confined spaces on flame spread over thin solid fuels in a low-speed opposing flow is investigated by combined use of microgravity experiments and computations. The flame behaviors are observed to depend strongly on the height of the flow tunnel. In particular, a non-monotonic trend of flame spread rate versus tunnel height is found, with the fastest flame occurring in the 3 cm high tunnel. The flame length and the total heat release rate from the flame also change with tunnel height, and a faster flame has a larger length and a higher heat release rate. The computation analyses indicate that a confined space modifies the flow around the spreading flame. The confinement restricts the thermal expansion and accelerates the flow in the streamwise direction. Above the flame, the flow deflects back from the tunnel wall. This inward flow pushes the flame towards the fuel surface, and increases oxygen transport into the flame. Such a flow modification explains the variations of flame spread rate and flame length with tunnel height. The present results suggest that the confinement effects on flame behavior in microgravity should be accounted to assess accurately the spacecraft fire hazard.

  9. Ignition of an organic water-coal fuel droplet floating in a heated-air flow

    Science.gov (United States)

    Valiullin, T. R.; Strizhak, P. A.; Shevyrev, S. A.; Bogomolov, A. R.

    2017-01-01

    Ignition of an organic water-coal fuel (CWSP) droplet floating in a heated-air flow has been studied experimentally. Rank B2 brown-coal particles with a size of 100 μm, used crankcase Total oil, water, and a plasticizer were used as the main CWSP components. A dedicated quartz-glass chamber has been designed with inlet and outlet elements made as truncated cones connected via a cylindrical ring. The cones were used to shape an oxidizer flow with a temperature of 500-830 K and a flow velocity of 0.5-5.0 m/s. A technique that uses a coordinate-positioning gear, a nichrome thread, and a cutter element has been developed for discharging CWSP droplets into the working zone of the chamber. Droplets with an initial size of 0.4 to 2.0 mm were used. Conditions have been determined for a droplet to float in the oxidizer flow long enough for the sustainable droplet burning to be initiated. Typical stages and integral ignition characteristics have been established. The integral parameters (ignition-delay times) of the examined processes have been compared to the results of experiments with CWSP droplets suspended on the junction of a quick-response thermocouple. It has been shown that floating fuel droplets ignite much quicker than the ones that sit still on the thermocouple due to rotation of an CWSP droplet in the oxidizer flow, more uniform heating of the droplet, and lack of heat drainage towards the droplet center. High-speed video recording of the peculiarities of floatation of a burning fuel droplet makes it possible to complement the existing models of water-coal fuel burning. The results can be used for a more substantiated modeling of furnace CWSP burning with the ANSYS, Fluent, and Sigma-Flow software packages.

  10. Computational fluid dynamics modeling of two-phase flow in a BWR fuel assembly

    International Nuclear Information System (INIS)

    Andrey Ioilev; Maskhud Samigulin; Vasily Ustinenko; Simon Lo; Adrian Tentner

    2005-01-01

    Full text of publication follows: The goal of this project is to develop an advanced Computational Fluid Dynamics (CFD) computer code (CFD-BWR) that allows the detailed analysis of the two-phase flow and heat transfer phenomena in a Boiling Water Reactor (BWR) fuel bundle under various operating conditions. This code will include more fundamental physical models than the current generation of sub-channel codes and advanced numerical algorithms for improved computational accuracy, robustness, and speed. It is highly desirable to understand the detailed two-phase flow phenomena inside a BWR fuel bundle. These phenomena include coolant phase changes and multiple flow regimes which directly influence the coolant interaction with fuel assembly and, ultimately, the reactor performance. Traditionally, the best analysis tools for the analysis of two-phase flow phenomena inside the BWR fuel assembly have been the sub-channel codes. However, the resolution of these codes is still too coarse for analyzing the detailed intra-assembly flow patterns, such as flow around a spacer element. Recent progress in Computational Fluid Dynamics (CFD), coupled with the rapidly increasing computational power of massively parallel computers, shows promising potential for the fine-mesh, detailed simulation of fuel assembly two-phase flow phenomena. However, the phenomenological models available in the commercial CFD programs are not as advanced as those currently being used in the sub-channel codes used in the nuclear industry. In particular, there are no models currently available which are able to reliably predict the nature of the flow regimes, and use the appropriate sub-models for those flow regimes. The CFD-BWR code is being developed as a customized module built on the foundation of the commercial CFD Code STAR-CD which provides general two-phase flow modeling capabilities. The paper describes the model development strategy which has been adopted by the development team for the

  11. Numerical Simulation for Flow Distribution in ACE7 Fuel Assemblies affected by a Spacer Grid Deformation

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jongpil; Jeong, Ji Hwan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    In spite of various efforts to understand hydraulic phenomena in a rod bundle containing deformed rods due to swelling and/or ballooning of clad, the studies for flow blockage due to spacer grid deformation have been limited. In the present work, 3D CFD analysis for flow blockage was performed to evaluate coolant flow within ACE7 fuel assemblies (FAs) containing a FA affected by a spacer grid deformation. The real geometry except for inner grids was used in the simulation and the region including inner grid was replaced by porous media. In the present work, the numerical simulation was performed to predict coolant flow within ACE7 FAs affected by a Mid grid deformation. The 3D CFD result shows that approximately 60 subchannel hydraulic diameter is required to fully recover coolant flow under normal operating condition.

  12. CONCHAS-SPRAY, Reactive Flows with Fuel Sprays

    International Nuclear Information System (INIS)

    Cloutman, L.D.; Dukowicz, J.K.; Ramshaw, J.D.; Amsden, A.A.

    2001-01-01

    Description of program or function: CONCHAS-SPRAY solves the equations of transient, multicomponent, chemically reactive fluid dynamics, together with those for the dynamics of an evaporating liquid spray. The program was developed with applications to internal combustion engines in mind. The formulation is spatially two-dimensional, and encompasses both planar and axisymmetric geometries. In the latter case, the flow is permitted to swirl about the axis of symmetry. CONCHAS-SPRAY is a time-marching, finite- difference program that uses a partially implicit numerical scheme. Spatial differences are formed with respect to a generalized two- dimensional mesh of arbitrary quadrilaterals whose corner locations are specified functions of time. This feature allows a Lagrangian, Eulerian, or mixed description, and is particularly useful for representing curved or moving boundary surfaces. Arbitrary numbers of species and chemical reactions are allowed. The latter are subdivided into kinetic and equilibrium reactions, which are treated by different algorithms. A turbulent law-of-the-wall boundary layer option is provided. CONCHAS-SPRAY calls a number of LANL system subroutines to display graphic or numerical information on microfiche. These routines are not included, but are described in the reference report. Several routines called from LINPACK and SLATEC1.0 are included

  13. Modeling and simulation of PEM fuel cell's flow channels using CFD techniques

    International Nuclear Information System (INIS)

    Cunha, Edgar F.; Andrade, Alexandre B.; Robalinho, Eric; Bejarano, Martha L.M.; Linardi, Marcelo; Cekinski, Efraim

    2007-01-01

    Fuel cells are one of the most important devices to obtain electrical energy from hydrogen. The Proton Exchange Membrane Fuel Cell (PEMFC) consists of two important parts: the Membrane Electrode Assembly (MEA), where the reactions occur, and the flow field plates. The plates have many functions in a fuel cell: distribute reactant gases (hydrogen and air or oxygen), conduct electrical current, remove heat and water from the electrodes and make the cell robust. The cost of the bipolar plates corresponds up to 45% of the total stack costs. The Computational Fluid Dynamic (CFD) is a very useful tool to simulate hydrogen and oxygen gases flow channels, to reduce the costs of bipolar plates production and to optimize mass transport. Two types of flow channels were studied. The first type was a commercial plate by ELECTROCELL and the other was entirely projected at Programa de Celula a Combustivel (IPEN/CNEN-SP) and the experimental data were compared with modelling results. Optimum values for each set of variables were obtained and the models verification was carried out in order to show the feasibility of this technique to improve fuel cell efficiency. (author)

  14. Modeling and simulation of PEM fuel cell's flow channels using CFD techniques

    Energy Technology Data Exchange (ETDEWEB)

    Cunha, Edgar F.; Andrade, Alexandre B.; Robalinho, Eric; Bejarano, Martha L.M.; Linardi, Marcelo [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)]. E-mails: efcunha@ipen.br; abodart@ipen.br; eric@ipen.br; mmora@ipen.br; mlinardi@ipen.br; Cekinski, Efraim [Instituto de Pesquisas Tecnologicas (IPT-SP), Sao Paulo, SP (Brazil)]. E-mail: cekinski@ipt.br

    2007-07-01

    Fuel cells are one of the most important devices to obtain electrical energy from hydrogen. The Proton Exchange Membrane Fuel Cell (PEMFC) consists of two important parts: the Membrane Electrode Assembly (MEA), where the reactions occur, and the flow field plates. The plates have many functions in a fuel cell: distribute reactant gases (hydrogen and air or oxygen), conduct electrical current, remove heat and water from the electrodes and make the cell robust. The cost of the bipolar plates corresponds up to 45% of the total stack costs. The Computational Fluid Dynamic (CFD) is a very useful tool to simulate hydrogen and oxygen gases flow channels, to reduce the costs of bipolar plates production and to optimize mass transport. Two types of flow channels were studied. The first type was a commercial plate by ELECTROCELL and the other was entirely projected at Programa de Celula a Combustivel (IPEN/CNEN-SP) and the experimental data were compared with modelling results. Optimum values for each set of variables were obtained and the models verification was carried out in order to show the feasibility of this technique to improve fuel cell efficiency. (author)

  15. Study of thermal hydraulic behavior of supercritical water flowing through fuel rod bundles

    International Nuclear Information System (INIS)

    Thakre, Sachin; Lakshmanan, S.P.; Kulkarni, Vinayak; Pandey, Manmohan

    2009-01-01

    Investigations on thermal-hydraulic behavior in Supercritical Water Reactor (SCWR) fuel assembly have obtained a significant attention in the international SCWR community because of its potential to obtain high thermal efficiency and compact design. Present work deals with CFD analysis to study the flow and heat transfer behavior of supercritical water in 4 metre long 7-pin fuel bundle using commercial CFD package ANSYS CFX for single phase steady state conditions. Considering the symmetric conditions, 1/12th part of the fuel rod bundle is taken as a domain of analysis. RNG K-epsilon model with scalable wall functions is used for modeling the turbulence behavior. Constant heat flux boundary condition is applied at the fuel rod surface. IAPWS equations of state are used to compute thermo-physical properties of supercritical water. Sharp variations in its thermo-physical properties (specific heat, density) are observed near the pseudo-critical temperature causing sharp change in heat transfer coefficient. The pseudo-critical point initially appears in the gaps among heated fuel rods, and then spreads radially outward reaching the adiabatic wall as the flow goes downstream. The enthalpy gain in the centre of the channel is much higher than that in the wall region. Non-uniformity in the circumferential distribution of surface temperature and heat transfer coefficient is observed which is in agreement with published literature. Heat transfer coefficient is high on the rod surface near the tight region and decreases as the distance between rod surfaces increases. (author)

  16. Analysis of fluid fuel flow to the neutron kinetics on molten salt reactor FUJI-12

    Energy Technology Data Exchange (ETDEWEB)

    Aji, Indarta Kuncoro, E-mail: indartaaji@s.itb.ac.id [Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesa 10 Bandung 40132 (Indonesia); Waris, Abdul, E-mail: awaris@fi.itb.ac.id; Permana, Sidik [Nuclear Physics & Biophysics Research Division, Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesa 10 Bandung 40132 (Indonesia)

    2015-09-30

    Molten Salt Reactor is a reactor are operating with molten salt fuel flowing. This condition interpret that the neutron kinetics of this reactor is affected by the flow rate of the fuel. This research analyze effect by the alteration velocity of the fuel by MSR type Fuji-12, with fuel composition LiF-BeF{sub 2}-ThF{sub 4}-{sup 233}UF{sub 4} respectively 71.78%-16%-11.86%-0.36%. Calculation process in this study is performed numerically by SOR and finite difference method use C programming language. Data of reactivity, neutron flux, and the macroscopic fission cross section for calculation process obtain from SRAC-CITATION (Standard thermal Reactor Analysis Code) and JENDL-4.0 data library. SRAC system designed and developed by JAEA (Japan Atomic Energy Agency). This study aims to observe the effect of the velocity of fuel salt to the power generated from neutron precursors at fourth year of reactor operate (last critical condition) with number of multiplication effective; 1.0155.

  17. Analysis of fluid fuel flow to the neutron kinetics on molten salt reactor FUJI-12

    International Nuclear Information System (INIS)

    Aji, Indarta Kuncoro; Waris, Abdul; Permana, Sidik

    2015-01-01

    Molten Salt Reactor is a reactor are operating with molten salt fuel flowing. This condition interpret that the neutron kinetics of this reactor is affected by the flow rate of the fuel. This research analyze effect by the alteration velocity of the fuel by MSR type Fuji-12, with fuel composition LiF-BeF 2 -ThF 4 - 233 UF 4 respectively 71.78%-16%-11.86%-0.36%. Calculation process in this study is performed numerically by SOR and finite difference method use C programming language. Data of reactivity, neutron flux, and the macroscopic fission cross section for calculation process obtain from SRAC-CITATION (Standard thermal Reactor Analysis Code) and JENDL-4.0 data library. SRAC system designed and developed by JAEA (Japan Atomic Energy Agency). This study aims to observe the effect of the velocity of fuel salt to the power generated from neutron precursors at fourth year of reactor operate (last critical condition) with number of multiplication effective; 1.0155

  18. Prediction of droplet deposition around BWR fuel spacer by FEM flow analysis

    International Nuclear Information System (INIS)

    Yamamoto, Yasushi; Morooka, Shinichi

    1997-01-01

    The critical power of the BWR fuel assembly has been remarkably increased. That increase mainly depends on the improvement of the spacer which keeps fixed gaps between fuel rods. So far, these improvements have been carried out on the basis of what developers consider to be appropriate and the results of mockup tests of the BWR fuel assembly. However, continued reliance on these approaches for the development of a higher performance fuel assembly will prove time-consuming and costly. Therefore, it is hoped that the spacer effects for the critical power can be investigated by computer simulation, and it is significantly important to develop the critical power prediction method. Direct calculation of the two-phase flow in a BWR fuel channel s still difficult. Accordingly, a new method for predicting the critical power was proposed. Our method consists of CFD (computer fluid dynamics) code based on the single-phase flow analysis method and the subchannel analysis code. To verify our method, the critical power predictions for various spacer geometries were performed. The predicted results of the critical power were compared with the experimental data. The result of the comparison showed a good agreement and the applicability of our method for various spacer geometries. (author)

  19. Numerical simulation of ambient flow and thermal distributions in a spent fuel storage cask array

    International Nuclear Information System (INIS)

    Michener, T.; Trent, D.S.; Guttmann, J.; Bajwa, C.

    2001-01-01

    At the request of the U.S. Nuclear Regulatory Commission (USNRC), the staff at the Pacific Northwest National Laboratory (PNNL) analyzed the thermal performance of the Utah Private Fuel Storage (PFS) using the TEMPEST computational fluid dynamics software. A three-dimensional section of the PFS with a total of 20 casks was modeled to estimate the ambient flow and temperature distributions surrounding the casks. The purpose of this analysis was to compute the cask inlet vent air temperature to be used for boundary conditions in a detailed analysis of an individual Holtec Hi-Storm 100 cask using the COBRA-SFS (Spent Fuel Storage) thermal hydraulic computer software. (author)

  20. Dynamics of nuclear fuel assemblies in vertical flow channels: computer modelling and associated studies

    International Nuclear Information System (INIS)

    Mason, V.A.; Pettigrew, M.J.; Lelli, G.; Kates, L.; Reimer, E.

    1978-10-01

    A computer model, designed to predict the dynamic behaviour of nuclear fuel assemblies in axial flow, is described in this report. The numerical methods used to construct and solve the matrix equations of motion in the model are discussed together with an outline of the method used to interpret the fuel assembly stability data. The mathematics developed for forced response calculations are described in detail. Certain structural and hydrodynamic modelling parameters must be determined by experiment. These parameters are identified and the methods used for their evaluation are briefly described. Examples of typical applications of the dynamic model are presented towards the end of the report. (author)

  1. Modeling of proton exchange membrane fuel cell with variable distance gas flow in anode and cathode

    International Nuclear Information System (INIS)

    Mohd Shahbudin Masdar; Wan Ramli Wan Daud; Kamaruzzaman Sopian; Jaafar Sahari

    2006-01-01

    A number of fundamental studies have been directed towards increasing our understanding of PEM fuel cell and their performance. Mathematical modeling is one of the way and very essential component in the development of this fuel cell. Model validation is presented, the validated model is then used to investigate the behavior of mole fraction of gases, current density, and the performances of stack using polarization curve depending on distance gases flow in channel. The model incorporates a complete cell with both the membrane electrode assembly (MEA) and the serpentine gas distributor channel. Finally, the parametric studies in single stack design are illustrated

  2. Modeling a Distributed Power Flow Controller with a PEM Fuel Cell for Power Quality Improvement

    Directory of Open Access Journals (Sweden)

    J. Chakravorty

    2018-02-01

    Full Text Available Electrical power demand is increasing at a relatively fast rate over the last years. Because of this increasing demand the power system is becoming very complex. Both electric utilities and end users of electric power are becoming increasingly concerned about power quality. This paper presents a new concept of distributed power flow controller (DPFC, which has been implemented with a proton exchange membrane (PEM fuel cell. In this paper, a PEM fuel cell has been simulated in Simulink/MATLAB and then has been used in the proposed DPFC model. The new proposed DPFC model has been tested on a IEEE 30 bus system.

  3. Experimental study of fuel bundle vibrations with rods subjected to mixed axial flow and cross-flow provided by a narrow gap (baffle jetting interaction)

    International Nuclear Information System (INIS)

    Boulanger, P.; Jacques, Y.; Fardeau, P.; Barbier, D.; Rigaudeau, J.

    1997-01-01

    The Hydraulic Core Laboratory (LHC) performs experimental studies of PWR fuel assembly mechanical behaviour submitted to representative flows in PWR core. Cross-flows prove particularly troublesome by generating on rods, in special cases, vibratory levels high enough to induce early grid to rod fretting. The fluid-structure interaction under mixed axial and cross-flow is also a major topic for analysis. The authors present a test loop devoted to the mixed axial-cross-flow fluid-structure interaction on representative half-scale mockup which is able to simulate, under ambient conditions, any complex flow (direction and flow rates) representative of PWR core flows. Despite its reduced size, the mockup retains the overall structure of a PWR fuel assembly. Rods displacement/velocity and velocity flow field are measured by laser techniques

  4. Parametric study of natural circulation flow in molten salt fuel in molten salt reactor

    Energy Technology Data Exchange (ETDEWEB)

    Pauzi, Anas Muhamad, E-mail: Anas@uniten.edu.my [Centre of Nuclear Energy, Universiti Tenaga Nasional (UNITEN), Jalan IKRAM-UNITEN, 43000 Kajang, Selangor (Malaysia); Cioncolini, Andrea; Iacovides, Hector [School of Mechanical, Aerospace, and Civil Engineering (MACE), University of Manchester, Oxford Road, M13 9PL Manchester (United Kingdom)

    2015-04-29

    The Molten Salt Reactor (MSR) is one of the most promising system proposed by Generation IV Forum (GIF) for future nuclear reactor systems. Advantages of the MSR are significantly larger compared to other reactor system, and is mainly achieved from its liquid nature of fuel and coolant. Further improvement to this system, which is a natural circulating molten fuel salt inside its tube in the reactor core is proposed, to achieve advantages of reducing and simplifying the MSR design proposed by GIF. Thermal hydraulic analysis on the proposed system was completed using a commercial computation fluid dynamics (CFD) software called FLUENT by ANSYS Inc. An understanding on theory behind this unique natural circulation flow inside the tube caused by fission heat generated in molten fuel salt and tube cooling was briefly introduced. Currently, no commercial CFD software could perfectly simulate natural circulation flow, hence, modeling this flow problem in FLUENT is introduced and analyzed to obtain best simulation results. Results obtained demonstrate the existence of periodical transient nature of flow problem, hence improvements in tube design is proposed based on the analysis on temperature and velocity profile. Results show that the proposed system could operate at up to 750MW core power, given that turbulence are enhanced throughout flow region, and precise molten fuel salt physical properties could be defined. At the request of the authors and the Proceedings Editor the name of the co-author Andrea Cioncolini was corrected from Andrea Coincolini. The same name correction was made in the Acknowledgement section on page 030004-10 and in reference number 4. The updated article was published on 11 May 2015.

  5. In-core fuel element temperature and flow measurment of HFETR

    International Nuclear Information System (INIS)

    Chen Daolong; Jiang Pei

    1988-02-01

    The HFETR in-core fuel element temperature-flow measurement facility and its measurement system are expounded. The applications of the instrumented fuel element to stationary and transient states measurements during the lift of power, the operation test of all lifetime at first load, and the deepening burn-up test at second load are described. The method of determination of the hot point temperature under the fin is discussed. The error analysis is made. The fuel element out-of-pile water deprivation test is described. The development of this measurement facility and succesful application have made important contribution to high power and deep burn-up safe operation at two load, in-core fuel element irradiation, and varied investigation of HFETR. After operation at two loads, the integrated power of this instrumented fuel element arrives at 90.88 MWd, its maximum point burn-up is about 64.9%, so that the economy of fuel use of HFETR is raised very much

  6. Influence of Chemical Blends on Palm Oil Methyl Esters’ Cold Flow Properties and Fuel Characteristics

    Directory of Open Access Journals (Sweden)

    Obed M. Ali

    2014-07-01

    Full Text Available Alternative fuels, like biodiesel, are being utilized as a renewable energy source and an effective substitute for the continuously depleting supply of mineral diesel as they have similar combustion characteristics. However, the use of pure biodiesel as a fuel for diesel engines is currently limited due to problems relating to fuel properties and its relatively poor cold flow characteristics. Therefore, the most acceptable option for improving the properties of biodiesel is the use of a fuel additive. In the present study, the properties of palm oil methyl esters with increasing additive content were investigated after addition of ethanol, butanol and diethyl ether. The results revealed varying improvement in acid value, density, viscosity, pour point and cloud point, accompanied by a slight decrease in energy content with an increasing additive ratio. The viscosity reductions at 5% additive were 12%, 7%, 16.5% for ethanol, butanol and diethyl ether, respectively, and the maximum reduction in pour point was 5 °C at 5% diethyl ether blend. Engine test results revealed a noticeable improvement in engine brake power and specific fuel consumption compared to palm oil biodiesel and the best performance was obtained with diethyl ether. All the biodiesel-additive blend samples meet the requirements of ASTM D6751 biodiesel fuel standards for the measured properties.

  7. Volumetric composition of nanocomposites

    DEFF Research Database (Denmark)

    Madsen, Bo; Lilholt, Hans; Mannila, Juha

    2015-01-01

    is presented, using cellulose/epoxy and aluminosilicate/polylactate nanocomposites as case materials. The buoyancy method is used for the accurate measurements of materials density. The accuracy of the method is determined to be high, allowing the measured nanocomposite densities to be reported with 5...... significant figures. The plotting of the measured nanocomposite density as a function of the nanofibre weight content is shown to be a first good approach of assessing the porosity content of the materials. The known gravimetric composition of the nanocomposites is converted into a volumetric composition...

  8. Highly conductive composites for fuel cell flow field plates and bipolar plates

    Science.gov (United States)

    Jang, Bor Z; Zhamu, Aruna; Song, Lulu

    2014-10-21

    This invention provides a fuel cell flow field plate or bipolar plate having flow channels on faces of the plate, comprising an electrically conductive polymer composite. The composite is composed of (A) at least 50% by weight of a conductive filler, comprising at least 5% by weight reinforcement fibers, expanded graphite platelets, graphitic nano-fibers, and/or carbon nano-tubes; (B) polymer matrix material at 1 to 49.9% by weight; and (C) a polymer binder at 0.1 to 10% by weight; wherein the sum of the conductive filler weight %, polymer matrix weight % and polymer binder weight % equals 100% and the bulk electrical conductivity of the flow field or bipolar plate is at least 100 S/cm. The invention also provides a continuous process for cost-effective mass production of the conductive composite-based flow field or bipolar plate.

  9. A numerical investigation of turbulent flow in an 18-plate nuclear fuel assembly

    International Nuclear Information System (INIS)

    Yu, R.; Lightstone, M.F.

    2003-01-01

    A numerical simulation of the fluid flow in the core of the McMaster Nuclear Reactor (MNR) was performed. The standard k - ε turbulence model together with a two-layer wall boundary model was used in the current study. A two-dimensional numerical model for the MNR 18-plate nuclear fuel assembly was developed using the advanced commercial computational fluid dynamics (CFD) code CFX-TASCflow. The numerical predictions were compared with experimental data for the MNR 18-plate assembly at the same flow conditions. In general, the code over predicts the pressure drop for the range of the mass flow rate investigated, however, the difference decreases as the mass flow rate (or Reynolds number) increases. Errors of less than 4% were obtained for mass flows greater than 4.0 kg/s. The comparison shows that the predicted flow distribution and velocities are very close to the measured data for the high Reynolds number flows. It is found that the k - ε model with the two-layer wall boundary model can predict the flow in the vertical parallel plate channels in the low Reynolds number region (Re=3000 to 10,000) very well. (author)

  10. Near limit flame spread over thick fuels in a concurrent forced flow

    International Nuclear Information System (INIS)

    Di Blasi, C.; Crescitelli, S.; Russo, G.

    1988-01-01

    The influence of the ambient level of oxygen concentration on the flow assisted flame spread over thick solid fuels and the extinction of the fame is studied by means of numerical modeling. The pyrolysis spread rate decreases with the oxygen concentration, showing qualitative agreement with experimental data. In fact, as the oxygen level decreases, the flame temperature decreases, causing lower heat fluxes at the fuel surfaces and lower pyrolysis mass rates so that the spread process is slowed. The effects due to finite kinetics are of increasing importance as extinction is approached. These effects appear mainly at the upstream flame leading edge, where the extinction length (distance of the flame leading edge from the edge of the fuel slab) increases. However, the spread process continues, that is, the flame and pyrolysis lengths increase with time, until the pyrolysis spread rate is greater than the upstream extinction rate. Complete extinction occurs when the extinction distance extends to the position of the pyrolysis front

  11. A computer model to predict temperatures and gas flows during AGR fuel handling

    International Nuclear Information System (INIS)

    Bishop, D.C.; Bowler, P.G.

    1986-01-01

    The paper describes the development of a comprehensive computer model (HOSTAGE) that has been developed for the Heysham II/Torness AGRs to predict temperature transients for all the important components during normal and fault conditions. It models not only the charge and discharge or fuel from an on-load reactor but also follows the fuel down the rest of the fuel route until it is dismantled. The main features of the physical model of gas and heat flow are described. Experimental results are used where appropriate and an indication will be given of how the predictions by HOSTAGE correlate with operating AGR reactors. The role of HOSTAGE in the Heysham II/Torness safety case is briefly discussed. (author)

  12. Volumetric studies and thermodynamics of viscous flow of hydroxamic acids in acetone + water solvent at temperatures 303.15 and 313.15 K

    International Nuclear Information System (INIS)

    Tiwari, Vaishali; Pande, Rama

    2006-01-01

    Densities ρ and viscosities η of two hydroxamic acids, N-phenyl-2-chlorobenzo- and N-o-tolyl-4-chlorobenzo-, have been determined as a function of their concentration in aqueous acetone solution at temperatures 303.15 and 313.15 K. Apparent molar volumes, standard-state partial molar volumes and relative viscosities have been calculated. The viscosity data have been analyzed using Jones-Dole equation. The activation thermodynamic parameters of viscous flow have been evaluated using Feakins equation. These were obtained to throw light on the mechanism of viscous flow. Thermodynamic interactions in solutions have been studied in terms of a number of excess functions calculated from the experimental data. The effect of hydroxamic acid concentration and temperature on these parameters has been discussed. The results were interpreted in the light of solute-solvent interactions in aquo-organic media

  13. A three-dimensional model of PEM fuel cells with serpentine flow channels

    International Nuclear Information System (INIS)

    Nguyen, P.T.; Berning, T.; Bang, M.; Djilali, N.

    2003-01-01

    A three-dimensional computational model of PEM fuel cell with serpentine flow field channels is presented in this paper. This model presents a comprehensive account for all important transport phenomena in fuel cell such as heat transfer, mass transfer, electrode kinetics, and potential fields in the membrane and gas diffusion layers. A new approach of solving for the potential losses across the cell was also developed in this model. The dependency of local current density on oxygen concentration and activation overpotential is fully addressed in this model. The computational domain consists of serpentine gas flow channels, porous gas diffusion layers, catalyst layers, and a membrane. Results obtained from this model are in good agreement with experimental results. (author)

  14. Numerical investigation of flow field configuration and contact resistance for PEM fuel cell performance

    Energy Technology Data Exchange (ETDEWEB)

    Akbari, Mohammad Hadi; Rismanchi, Behzad [Department of Mechanical Engineering, Shiraz University, Shiraz 71348-51154 (Iran)

    2008-08-15

    A steady-state three-dimensional non-isothermal computational fluid dynamics (CFD) model of a proton exchange membrane fuel cell is presented. Conservation of mass, momentum, species, energy, and charge, as well as electrochemical kinetics are considered. In this model, the effect of interfacial contact resistance is also included. The numerical solution is based on a finite-volume method. In this study the effects of flow channel dimensions on the cell performance are investigated. Simulation results indicate that increasing the channel width will improve the limiting current density. However, it is observed that an optimum shoulder size of the flow channels exists for which the cell performance is the highest. Polarization curves are obtained for different operating conditions which, in general, compare favorably with the corresponding experimental data. Such a CFD model can be used as a tool in the development and optimization of PEM fuel cells. (author)

  15. Continuous-Flow Processes in Heterogeneously Catalyzed Transformations of Biomass Derivatives into Fuels and Chemicals

    Directory of Open Access Journals (Sweden)

    Antonio A. Romero

    2012-07-01

    Full Text Available Continuous flow chemical processes offer several advantages as compared to batch chemistries. These are particularly relevant in the case of heterogeneously catalyzed transformations of biomass-derived platform molecules into valuable chemicals and fuels. This work is aimed to provide an overview of key continuous flow processes developed to date dealing with a series of transformations of platform chemicals including alcohols, furanics, organic acids and polyols using a wide range of heterogeneous catalysts based on supported metals, solid acids and bifunctional (metal + acidic materials.

  16. Modelling multiphase flow inside the porous media of a polymer electrolyte membrane fuel cell

    DEFF Research Database (Denmark)

    Berning, Torsten; Kær, Søren Knudsen

    2011-01-01

    Transport processes inside polymer electrolyte membrane fuel cells (PEMFC’s) are highly complex and involve convective and diffusive multiphase, multispecies flow through porous media along with heat and mass transfer and electrochemical reactions in conjunction with water transport through...... an electrolyte membrane. We will present a computational model of a PEMFC with focus on capillary transport of water through the porous layers and phase change and discuss the impact of the liquid phase boundary condition between the porous gas diffusion layer and the flow channels, where water droplets can...

  17. Determination of Critical Properties of Endothermic Hydrocarbon Fuel RP-3 Based on Flow Visualization

    Science.gov (United States)

    Wang, Ning; Zhou, Jin; Pan, Yu; Wang, Hui

    2014-01-01

    The critical pressure and temperature of an endothermic hydrocarbon fuel RP-3 were determined by flow visualization. The flow pattern images of RP-3 at different pressures and temperatures were obtained. The critical pressure is identified by disappearance of the phase change while the critical temperature is determined by appearance of the opalescence phenomenon under the critical pressure. The opalescence phenomenon is unique to the critical point. The critical pressure and temperature of RP-3 are determined to be 2.3 MPa and 646 K, respectively.

  18. Combustion characteristics and turbulence modeling of swirling reacting flow in solid fuel ramjet

    Science.gov (United States)

    Musa, Omer; Xiong, Chen; Changsheng, Zhou

    2017-10-01

    This paper reviews the historical studies have been done on the solid-fuel ramjet engine and difficulties associated with numerical modeling of swirling flow with combustible gases. A literature survey about works related to numerical and experimental investigations on solid-fuel ramjet as well as using swirling flow and different numerical approaches has been provided. An overview of turbulence modeling of swirling flow and the behavior of turbulence at streamline curvature and system rotation are presented. A new and simple curvature/correction factor is proposed in order to reduce the programming complexity of SST-CC turbulence model. Finally, numerical and experimental investigations on the impact of swirling flow on SFRJ have been carried out. For that regard, a multi-physics coupling code is developed to solve the problems of multi-physics coupling of fluid mechanics, solid pyrolysis, heat transfer, thermodynamics, and chemical kinetics. The connected-pipe test facility is used to carry out the experiments. The results showed a positive impact of swirling flow on SFRJ along with, three correlations are proposed.

  19. Cost and performance prospects for composite bipolar plates in fuel cells and redox flow batteries

    Science.gov (United States)

    Minke, Christine; Hickmann, Thorsten; dos Santos, Antonio R.; Kunz, Ulrich; Turek, Thomas

    2016-02-01

    Carbon-polymer-composite bipolar plates (BPP) are suitable for fuel cell and flow battery applications. The advantages of both components are combined in a product with high electrical conductivity and good processability in convenient polymer forming processes. In a comprehensive techno-economic analysis of materials and production processes cost factors are quantified. For the first time a technical cost model for BPP is set up with tight integration of material characterization measurements.

  20. Simulations and measurements of adiabatic annular flows in triangular, tight lattice nuclear fuel bundle model

    Energy Technology Data Exchange (ETDEWEB)

    Saxena, Abhishek, E-mail: asaxena@lke.mavt.ethz.ch [ETH Zurich, Laboratory for Nuclear Energy Systems, Department of Mechanical and Process Engineering, Sonneggstrasse 3, 8092 Zürich (Switzerland); Zboray, Robert [Laboratory for Thermal-hydraulics, Nuclear Energy and Safety Department, Paul Scherrer Institute, 5232 Villigen PSI (Switzerland); Prasser, Horst-Michael [ETH Zurich, Laboratory for Nuclear Energy Systems, Department of Mechanical and Process Engineering, Sonneggstrasse 3, 8092 Zürich (Switzerland); Laboratory for Thermal-hydraulics, Nuclear Energy and Safety Department, Paul Scherrer Institute, 5232 Villigen PSI (Switzerland)

    2016-04-01

    High conversion light water reactors (HCLWR) having triangular, tight-lattice fuels bundles could enable improved fuel utilization compared to present day LWRs. However, the efficient cooling of a tight lattice bundle has to be still proven. Major concern is the avoidance of high-quality boiling crisis (film dry-out) by the use of efficient functional spacers. For this reason, we have carried out experiments on adiabatic, air-water annular two-phase flows in a tight-lattice, triangular fuel bundle model using generic spacers. A high-spatial-resolution, non-intrusive measurement technology, cold neutron tomography, has been utilized to resolve the distribution of the liquid film thickness on the virtual fuel pin surfaces. Unsteady CFD simulations have also been performed to replicate and compare with the experiments using the commercial code STAR-CCM+. Large eddies have been resolved on the grid level to capture the dominant unsteady flow features expected to drive the liquid film thickness distribution downstream of a spacer while the subgrid scales have been modeled using the Wall Adapting Local Eddy (WALE) subgrid model. A Volume of Fluid (VOF) method, which directly tracks the interface and does away with closure relationship models for interfacial exchange terms, has also been employed. The present paper shows first comparison of the measurement with the simulation results.

  1. Measurement and analysis of vibrational behavior of an SNR-fuel element in sodium flow

    International Nuclear Information System (INIS)

    Hess, B.F.H.; Ruppert, E.; Schmidt, H.; Vinzens, K.

    1975-01-01

    Within the framework of SNR-300 fuel element development programme a complete full size fuel element dummy has been tested thoroughly for nearly 3000 hours at 650 deg C system temperature in the AKB sodium loop at Interatom, Bensberg. It is known that the coolant flow through a subassembly can induce flutter or vibrations of structural parts such as single pins, the wrapper and the total pin bundle all of which have been of interest during this test. To detect these vibrations of different structural parts simultaneously with a minimum of instrumentation only 3 weldable high temperature strain gauges were employed. These strain gauges were especially prepared and bent in such a way as to form a bridge between the inner wrapper and a fuel pin top and spot-welded to both the wrapper and the fuel pin. Although this arrangement seems to be a rather unusual one, the simultaneous-measurement of bundle, wrapper and pin vibrations was possible and periodic flow fluctuations were also detected. The presented results are only relative due to calibration difficulties with these deformed strain gauges which were first used during this test. It is, however, believed that this arrangement, in connection with the proposed anlytical approach, leads to a simple and technical representation of the vibrational behavior of core elements during sodium tests. Detailed information needed for check and calibration of computer codes are however displayed by the respective power spectral density functions

  2. Preliminary CFD analysis methodology for flow in a LFR fuel assembly

    International Nuclear Information System (INIS)

    Catana, A.; Ioan, M.; Serbanel, M.

    2013-01-01

    In this paper a preliminary Computational Fluid Dynamics (CFD) analysis was performed in order to setup a methodology to be used for more complex coolant flow analysis inside ALFRED nuclear reactor fuel assembly. The core contains 171 separated fuel assembly, each consisting in a hexagonal array of 127 fuel rods. Three honey comb spacer grids are proposed along fuel rods with the aim to keep flow geometry intact during reactor operation. The main goal of this paper is to compute some hydraulic parameters: pressure, velocity, wall shear stress and turbulence parameters with and without spacer grids. In this analysis we consider an adiabatic case, so far no heat transfer is considered but we pave the road toward more complex thermo hydraulic analysis for ALFRED (LFR in general). The CAELINUX CFD distribution was used with its main components: Salome-Meca (for geometry and mesh) and Code-Saturne as mono-phase CFD solver. Paraview and Visist Postprocessors were used for data extraction and graphical displays. (authors)

  3. Integral manifolding structure for fuel cell core having parallel gas flow

    Science.gov (United States)

    Herceg, Joseph E.

    1984-01-01

    Disclosed herein are manifolding means for directing the fuel and oxidant gases to parallel flow passageways in a fuel cell core. Each core passageway is defined by electrolyte and interconnect walls. Each electrolyte and interconnect wall consists respectively of anode and cathode materials layered on the opposite sides of electrolyte material, or on the opposite sides of interconnect material. A core wall projects beyond the open ends of the defined core passageways and is disposed approximately midway between and parallel to the adjacent overlaying and underlying interconnect walls to define manifold chambers therebetween on opposite sides of the wall. Each electrolyte wall defining the flow passageways is shaped to blend into and be connected to this wall in order to redirect the corresponding fuel and oxidant passageways to the respective manifold chambers either above or below this intermediate wall. Inlet and outlet connections are made to these separate manifold chambers respectively, for carrying the fuel and oxidant gases to the core, and for carrying their reaction products away from the core.

  4. Finite element analysis of turbulent flow in fast reactor fuel subassembly elementary flow cell

    International Nuclear Information System (INIS)

    Muehlbauer, P.

    1987-03-01

    The method is described of calculating fully developed longitudinal steady-state turbulent flow of an incompressible fluid through an infinite bundle of parallel smooth rods, based on the finite element method and one-equation turbulence model. Theoretical calculation results are compared with experimental results. (author). 5 figs., 3 refs

  5. CFD analysis of multiphase coolant flow through fuel rod bundles in advanced pressure tube nuclear reactors

    International Nuclear Information System (INIS)

    Catana, A.; Turcu, I.; Prisecaru, I.; Dupleac, D.; Danila, N.

    2010-01-01

    The key component of a pressure tube nuclear reactor core is pressure tube filled with a stream of fuel bundles. This feature makes them suitable for CFD thermal-hydraulic analysis. A methodology for CFD analysis applied to pressure tube nuclear reactors is presented in this paper, which is focused on advanced pressure tube nuclear reactors. The complex flow conditions inside pressure tube are analysed by using the Eulerian multiphase model implemented in FLUENT CFD computer code. Fuel rods in these channels are superheated but the liquid is under high pressure, so it is sub-cooled in normal operating conditions on most of pressure tube length. In the second half of pressure tube length, the onset of boiling occurs, so the flow consists of a gas liquid mixture, with the volume of gas increasing along the length of the channel in the direction of the flow. Limited computer resources enforced us to use CFD analysis for segments of pressure tube. Significant local geometries (junctions, spacers) were simulated. Main results of this work are: prediction of main thermal-hydraulic parameters along pressure tube including CHF evaluation through fuel assemblies. (authors)

  6. Confined dense particle-gas flow, application to nuclear fuel relocation

    International Nuclear Information System (INIS)

    Martin, A.

    2010-02-01

    In this work, we investigate particle-gas two-phase flows in the jamming regime where the flow stops in finite time. In this regime, which occurs quite often in nature and industrial applications, the flow is stochastic and needs therefore to be characterized by the jamming probability as well as the flow rate and its fluctuations that depend on the confining geometry, granular microstructure and gas properties. We developed a numerical approach based on the coupling of the Non Smooth Contact Dynamics for the solid phase and a mesoscopic method for the gas phase. We find that the flow rate as a function of the opening is well fit by a power law in agreement with reported experimental data. The presence of a gas affects only the mean flow rate, the flow statistics being sensibly the same as in the absence of the gas. We apply our quantitative statistical results in order to estimate the relocation rate of fragmented nuclear fuel inside its cladding tube as a result of a local balloon caused by an accident (loss-of-coolant accident). (author)

  7. Study of fuel bundle geometry on inter subchannel flow in a 19 pin wire wrapped bundle

    International Nuclear Information System (INIS)

    Naveen Raj, M.; Velusamy, D.K.

    2015-01-01

    In typical sodium cooled fast reactor (SFR) fuel pin bundle, gap between the pins is maintained by helically wound wire wrap around each pin. The presence of wire induces large inter-subchannel transverse flow, eventually promoting mixing and heat transfer. The magnitude of the transverse flow is highly dependent on the various pin-bundle dimensions. Appropriate modeling of these transverse flows in subchannel codes is necessary to predict realistic temperature distribution in pin bundle. Hence, detailed parametric study of transverse flow on pin-bundle geometric parameters has been conducted. The parameters taken for the present study are pin diameter, wire diameter, helical wire pitch and edge gap. Towards this 3-D computational fluid dynamic analysis on a structured mesh of 19 pin bundle is carried out using k-epsilon turbulence model. Periodic oscillations along the primacy flow direction were found in subchannel transverse flow and peripheral pin clad temperatures with periodicity over one pitch length. Based on parametric studies, correlations for transverse flow in central subchannels are proposed. (author)

  8. Adiabatic gas-liquid flow

    International Nuclear Information System (INIS)

    Mayinger, F.

    1982-01-01

    The author starts by discussing the gas-fluidic mixture, its application and its special characteristics. The conservation theorems for these mixtures are then presented, including the continuity equation, the impulse equation, and energy balance. The type of flow in vertical channels, vertical downwards flow and flow in horizontal and inclined tubes is discussed followed by a short section on local volumetric steam contents and slip. The expressions for the slip and for the local volumetric steam contents are explained before discussing phase separation in nonflowing fluids. Pressure loss in tubes and channels is followed by discussion of pressure loss in various types of moulded bodies with particular reference to fuel rod bundles. In conclusion the author discusses pressure wave expansion, critical discharge and cross exchange in sub-divided channels. (A.N.K.)

  9. Interior flow and near-nozzle spray development in a marine-engine diesel fuel injector

    Science.gov (United States)

    Hult, J.; Simmank, P.; Matlok, S.; Mayer, S.; Falgout, Z.; Linne, M.

    2016-04-01

    A consolidated effort at optically characterising flow patterns, in-nozzle cavitation, and near-nozzle jet structure of a marine diesel fuel injector is presented. A combination of several optical techniques was employed to fully transparent injector models, compound metal-glass and full metal injectors. They were all based on a common real-scale dual nozzle hole geometry for a marine two-stroke diesel engine. In a stationary flow rig, flow velocities in the sac-volume and nozzle holes were measured using PIV, and in-nozzle cavitation visualized using high-resolution shadowgraphs. The effect of varying cavitation number was studied and results compared to CFD predictions. In-nozzle cavitation and near-nozzle jet structure during transient operation were visualized simultaneously, using high-speed imaging in an atmospheric pressure spray rig. Near-nozzle spray formation was investigated using ballistic imaging. Finally, the injector geometry was tested on a full-scale marine diesel engine, where the dynamics of near-nozzle jet development was visualized using high-speed shadowgraphy. The range of studies focused on a single common geometry allows a comprehensive survey of phenomena ranging from first inception of cavitation under well-controlled flow conditions to fuel jet structure at real engine conditions.

  10. Effect of flow field with converging and diverging channels on proton exchange membrane fuel cell performance

    International Nuclear Information System (INIS)

    Zehtabiyan-Rezaie, Navid; Arefian, Amir; Kermani, Mohammad J.; Noughabi, Amir Karimi; Abdollahzadeh, M.

    2017-01-01

    Highlights: • Effect of converging and diverging channels on fuel cell performance. • Over rib flow is observed from converging channels to neighbors. • Proposed flow field enriches oxygen level and current density in catalyst layer. • Net output power is enhanced more than 16% in new flow field. - Abstract: In this study, a novel bipolar flow field design is proposed. This new design consists of placed sequentially converging and diverging channels. Numerical simulation of cathode side is used to investigate the effects of converging and diverging channels on the performance of proton exchange membrane fuel cells. Two models of constant and variable sink/source terms were implemented to consider species consumption and production. The distribution of oxygen mole fraction in gas diffusion and catalyst layers as a result of transverse over rib velocity is monitored. The results indicate that the converging channels feed two diverging neighbors. This phenomenon is a result of the over rib velocity which is caused by the pressure difference between the neighboring channels. The polarization curves show that by applying an angle of 0.3° to the channels, the net electrical output power increases by 16% compared to the base case.

  11. Flow of ideal fluid through a central region of a nuclear reactor wire-spaced fuel subassembly

    International Nuclear Information System (INIS)

    Schmid, J.

    1991-04-01

    The results are given of calculations of the flow of an ideal fluid through the central region of a nuclear reactor wire-spaced fuel subassembly. The computer code used is briefly described. (author). 10 figs., 4 refs

  12. In situ diagnostic of two-phase flow phenomena in polymer electrolyte fuel cells by neutron imaging

    International Nuclear Information System (INIS)

    Kramer, Denis; Zhang, Jianbo; Shimoi, Ryoichi; Lehmann, Eberhard; Wokaun, Alexander; Shinohara, Kazuhiko; Scherer, Guenther G.

    2005-01-01

    Neutron radiographical measurements have been performed on operating hydrogen-fueled polymer electrolyte fuel cells (PEFC). With the successful detection of liquid accumulation in flow field and gas diffusion layer (GDL) under various operating conditions a unique experimental approach for the investigation of two-phase flow phenomena in technical PEFC has been realized. The experimental setup will be described in detail. Algorithms for an enhanced quantitative evaluation of the obtained images are presented and successful application to the data demonstrated. Finally, results from PEFC investigations will be given. Different flow field geometries and their implications for liquid accumulation inside flow field and GDL are discussed

  13. Numerical study on channel size effect for proton exchange membrane fuel cell with serpentine flow field

    International Nuclear Information System (INIS)

    Wang Xiaodong; Yan Weimon; Duan Yuanyuan; Weng Fangbor; Jung Guobin; Lee Chiyuan

    2010-01-01

    This work numerically investigates the effect of the channel size on the cell performance of proton exchange membrane (PEM) fuel cells with serpentine flow fields using a three-dimensional, two-phase model. The local current densities in the PEM, oxygen mass flow rates and liquid water concentrations at the interface of the cathode gas diffusion layer and catalyst layer were analyzed to understand the channel size effect. The predictions show that smaller channel sizes enhance liquid water removal and increase oxygen transport to the porous layers, which improve cell performance. Additionally, smaller channel sizes also provide more uniform current density distributions in the cell. However, as the channel size decreases, the total pressure drops across the cell increases, which leads to more pump work. With taking into account the pressure losses, the optimal cell performance occurs for a cell with a flow channel cross-sectional area of 0.535 x 0.535 mm 2 .

  14. 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

  15. CANFLEX fuel bundle cross-flow endurance test 2 (test procedure)

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sung Deok; Chung, C. H.; Chang, S. K. [Korea Atomic Energy Research Institute, Taejon (Korea)

    1999-04-01

    This report describes test procedure of cross-flow 2 test for CANFLEX fuel. In October 1996. a cross-flow test was successfully performed in the KAERI Hot Test Loop for four hours at a water flow rate of 31kg/s, temperature of 266 deg C and inlet pressure of 11MPa, but it is requested more extended time periods to determine a realistic operational margin for the CANFLEX bundle during abnormal refuelling operations. The test shall be conducted for twenty two hours under the reactor conditions. After an initial period of ten hours, the test shall be stopped at the intervals of four hours for bundle inspection and inspect the test bundle end-plate to end-cap welds for failure or crack propagation using liquid penetrant examination. 2 refs., 1 fig. (Author)

  16. Test of Flow Characteristics in Tubular Fuel Assembly I - Establishment of test loop and measurement validation test

    International Nuclear Information System (INIS)

    Park, Jong Hark; Chae, H. T.; Park, C.; Kim, H.

    2005-12-01

    Tubular type fuel has been developed as one of candidates for Advanced HANARO Reactor(AHR). It is necessary to test the flow characteristics such as velocity in each flow channels and pressure drop of tubular type fuel. A hydraulic test-loop to examine the hydraulic characteristics for a tubular type fuel has been designed and constructed. It consists of three parts; a) piping-loop including pump and motor, magnetic flow meter and valves etc, b) test-section part where a simulated tubular type fuel is located, and 3) data acquisition system to get reading signals from sensors or instruments. In this report, considerations during the design and installation of the facility and the selection of data acquisition sensors and instruments are described in detail. Before doing the experiment to measure the flow velocities in flow channels, a preliminary tests have been done for measuring the coolant velocities using pitot-tube and for validating the measurement accuracy as well. Local velocities of the radial direction in circular tubes are measured at regular intervals of 60 degrees by three pitot-tubes. Flow rate inside the circular flow channel can be obtained by integrating the velocity distribution in radial direction. The measured flow rate was compared to that of magnetic flow meter. According to the results, two values had a good agreement, which means that the measurement of coolant velocity by using pitot-tube and the flow rate measured by the magnetic flow meter are reliable. Uncertainty analysis showed that the error of velocity measurement by pitot-tube is less than ±2.21%. The hydraulic test-loop also can be adapted to others such as HANARO 18 and 36 fuel, in-pile system of FTL(Fuel Test Loop), etc

  17. Numerical Investigation of Fuel Distribution Effect on Flow and Temperature Field in a Heavy Duty Gas Turbine Combustor

    Science.gov (United States)

    Deng, Xiaowen; Xing, Li; Yin, Hong; Tian, Feng; Zhang, Qun

    2018-03-01

    Multiple-swirlers structure is commonly adopted for combustion design strategy in heavy duty gas turbine. The multiple-swirlers structure might shorten the flame brush length and reduce emissions. In engineering application, small amount of gas fuel is distributed for non-premixed combustion as a pilot flame while most fuel is supplied to main burner for premixed combustion. The effect of fuel distribution on the flow and temperature field related to the combustor performance is a significant issue. This paper investigates the fuel distribution effect on the combustor performance by adjusting the pilot/main burner fuel percentage. Five pilot fuel distribution schemes are considered including 3 %, 5 %, 7 %, 10 % and 13 %. Altogether five pilot fuel distribution schemes are computed and deliberately examined. The flow field and temperature field are compared, especially on the multiple-swirlers flow field. Computational results show that there is the optimum value for the base load of combustion condition. The pilot fuel percentage curve is calculated to optimize the combustion operation. Under the combustor structure and fuel distribution scheme, the combustion achieves high efficiency with acceptable OTDF and low NOX emission. Besides, the CO emission is also presented.

  18. Investigation of gas flow characteristics in proton exchange membrane fuel cell

    International Nuclear Information System (INIS)

    Kwac, Lee Ku; Kim, Hong Gun

    2008-01-01

    An investigation of electrochemical behavior of PEMFC (proton exchange membrane fuel cell) is performed by using a single-phase two-dimensional finite element analysis. Equations of current balance, mass balance, and momentum balance are implemented to simulate the behavior of PEMFC. The analysis results for the co-flow and counterflow mode of gas flow direction are examined in detail in order to compare how the gas flow direction affects quantitatively. The characteristics of internal properties, such as gas velocity distribution, mass fraction of the reactants, fraction of water and current density distribution in PEMFC are illustrated in the electrode and GDL (gas diffusion layer). It is found that the dry reactant gases can be well internally humidified and maintain high performance in the case of the counter-flow mode without external humidification while it is not advantageous for highly humidified or saturated reactant gases. It is also found that the co-flow mode improves the current density distribution with humidified normal condition compared to the counter-flow mode

  19. Gothic simulation of single-channel fuel heatup following a loss of forced flow

    Energy Technology Data Exchange (ETDEWEB)

    Chen, X-Q; Tahir, A. [NSS, Dept. of Thermal Hydraulics Analysis, Toronto, Ontario (Canada); Parlatan, Y. [Ontario Power Generation, NSATD, Pickering, Ontario (Canada); Kwee, M. [Bruce Power, NSASD, Toronto, Ontario (Canada)

    2011-07-01

    GOTHIC v7.2 was used to develop a computer model for the simulation of 28- and 37-element fuel heat-up at a loss of forced flow. The model has accounted for the non-uniformity of both axial and radial power distributions along the fuel channel for a typical CANDU reactor. In addition, the model has also accounted for the fuel rods, end-fittings, feeders and headers. Experimental test conditions for both 28- and 37-element bundles at either low or high powers were used for model validation. GOTHIC predictions of the rod and/or pressure-tube temperatures at a variety of test locations were compared with the corresponding experimental measurements. It is found that the numerical results agree well with the experimental measurements for most of the test locations. Results have also shown that the channel venting time is sensitive to the initial temperature distribution in the feeders and headers. An imposed temperature asymmetry at the beginning will cause the channel flow to vent earlier. (author)

  20. Computational fluid dynamics modeling of two-phase flow in a BWR fuel assembly. Final CRADA Report

    International Nuclear Information System (INIS)

    Tentner, A.

    2009-01-01

    A direct numerical simulation capability for two-phase flows with heat transfer in complex geometries can considerably reduce the hardware development cycle, facilitate the optimization and reduce the costs of testing of various industrial facilities, such as nuclear power plants, steam generators, steam condensers, liquid cooling systems, heat exchangers, distillers, and boilers. Specifically, the phenomena occurring in a two-phase coolant flow in a BWR (Boiling Water Reactor) fuel assembly include coolant phase changes and multiple flow regimes which directly influence the coolant interaction with fuel assembly and, ultimately, the reactor performance. Traditionally, the best analysis tools for this purpose of two-phase flow phenomena inside the BWR fuel assembly have been the sub-channel codes. However, the resolution of these codes is too coarse for analyzing the detailed intra-assembly flow patterns, such as flow around a spacer element. Advanced CFD (Computational Fluid Dynamics) codes provide a potential for detailed 3D simulations of coolant flow inside a fuel assembly, including flow around a spacer element using more fundamental physical models of flow regimes and phase interactions than sub-channel codes. Such models can extend the code applicability to a wider range of situations, which is highly important for increasing the efficiency and to prevent accidents.

  1. Evaluation of the effect of reactant gases mass flow rates on power density in a polymer electrolyte membrane fuel cell

    Science.gov (United States)

    Kahveci, E. E.; Taymaz, I.

    2018-03-01

    In this study it was experimentally investigated the effect of mass flow rates of reactant gases which is one of the most important operational parameters of polymer electrolyte membrane (PEM) fuel cell on power density. The channel type is serpentine and single PEM fuel cell has an active area of 25 cm2. Design-Expert 8.0 (trial version) was used with four variables to investigate the effect of variables on the response using. Cell temperature, hydrogen mass flow rate, oxygen mass flow rate and humidification temperature were selected as independent variables. In addition, the power density was used as response to determine the combined effects of these variables. It was kept constant cell and humidification temperatures while changing mass flow rates of reactant gases. From the results an increase occurred in power density with increasing the hydrogen flow rates. But oxygen flow rate does not have a significant effect on power density within determined mass flow rates.

  2. Behavior of EBR-II Mk-V-type fuel elements in simulated loss-of-flow tests

    International Nuclear Information System (INIS)

    Liu, Y.Y.; Tsai, H.; Billone, M.C.; Holland, J.W.; Kramer, J.M.

    1993-01-01

    Three furnace heating tests were conducted with irradiated, HT9-clad and U-19wt%Pu-10wt%Zr-alloy, EBR-II Mk-V-type fuel elements to evaluate the behavior that could be expected during a loss-of-flow event in the reactor. In general, very significant safety margins for cladding breaching have been demonstrated in these tests, under conditions that would envelop a bounding unlikely loss-of-flow event in EBR-II. Highlights of the test results are presented, as are discussions of the cladding breaching mechanisms, axial fuel motion, and fuel surface liquefaction that were found in these tests. (orig.)

  3. Enhanced fuel efficiency on tractor-trailers using synthetic jet-based active flow control

    Science.gov (United States)

    Amitay, Michael; Menicovich, David; Gallardo, Daniele

    2016-04-01

    The application of piezo-electrically-driven synthetic-jet-based active flow control to reduce drag on tractor-trailers was explored experimentally in wind tunnel testing as well as full-scale road tests. Aerodynamic drag accounts for more than 50% of the usable energy at highway speeds, a problem that applies primarily to trailer trucks. Therefore, a reduction in aerodynamic drag results in large saving of fuel and reduction in CO2 emissions. The active flow control technique that is being used relies on a modular system comprised of distributed, small, highly efficient actuators. These actuators, called synthetic jets, are jets that are synthesized at the edge of an orifice by a periodic motion of a piezoelectric diaphragm(s) mounted on one (or more) walls of a sealed cavity. The synthetic jet is zero net mass flux (ZNMF), but it allows momentum transfer to flow. It is typically driven near diaphragm and/or cavity resonance, and therefore, small electric input [O(10W)] is required. Another advantage of this actuator is that no plumbing is required. The system doesn't require changes to the body of the truck, can be easily reconfigured to various types of vehicles, and consumes small amounts of electrical power from the existing electrical system of the truck. Preliminary wind tunnel results showed up to 18% reduction in fuel consumption, whereas road tests also showed very promising results.

  4. Aircraft dual-shaft jet engine with indirect action fuel flow controller

    Science.gov (United States)

    Tudosie, Alexandru-Nicolae

    2017-06-01

    The paper deals with an aircraft single-jet engine's control system, based on a fuel flow controller. Considering the engine as controlled object and its thrust the most important operation effect, from the multitude of engine's parameters only its rotational speed n is measurable and proportional to its thrust, so engine's speed has become the most important controlled parameter. Engine's control system is based on fuel injection Qi dosage, while the output is engine's speed n. Based on embedded system's main parts' mathematical models, the author has described the system by its block diagram with transfer functions; furthermore, some Simulink-Matlab simulations are performed, concerning embedded system quality (its output parameters time behavior) and, meanwhile, some conclusions concerning engine's parameters mutual influences are revealed. Quantitative determinations are based on author's previous research results and contributions, as well as on existing models (taken from technical literature). The method can be extended for any multi-spool engine, single- or twin-jet.

  5. Mathematical model of an indirect action fuel flow controller for aircraft jet engines

    Science.gov (United States)

    Tudosie, Alexandru-Nicolae

    2017-06-01

    The paper deals with a fuel mass flow rate controller with indirect action for aircraft jet engines. The author has identified fuel controller's main parts and its operation mode, then, based on these observations, one has determined motion equations of each main part, which have built system's non-linear mathematical model. In order to realize a better study this model was linearised (using the finite differences method) and then adimensionalized. Based on this new form of the mathematical model, after applying Laplace transformation, the embedded system (controller+engine) was described by the block diagram with transfer functions. Some Simulink-Matlab simulations were performed, concerning system's time behavior for step input, which lead to some useful conclusions and extension possibilities.

  6. Experiment studies of fuel rod vibration in coolant flow for substantiation of vibration stability of fuel rods with no fretting-wear

    International Nuclear Information System (INIS)

    Egorov, Yu. V.; Afanasiev, A. V.; Makarov, V. V.; Matvienko, I. V.

    2013-01-01

    For substantiation of vibration stability it is necessary to determine the ultimate permissible vibration levels which do not cause fretting, to compare them with the level of fuel rod vibration caused by coolant flow. Another approach is feasible if there is experience of successful operation of FA-prototypes. In this case in order to justify vibration stability it may be sufficient to demonstrate that the new element does not cause increased vibration of the fuel rod. It can be done by comparing the levels of hydro-dynamic fuel rod vibration and FA new designs. Program of vibration tests of TVS-2M model included studies of forced oscillations of 12 fuel rods in the coolant flow in the spans containing intensifiers, in the reference span without intensifiers, in the lower spans with assembled ADF and after its disassembly. The experimental results for TVS-2M show that in the spans with intensifier «Sector run» the level of movements is 6% higher on the average than in the span without intensifiers, in the spans with intensifier «Eddy» it is 2% higher. The level of fuel rod vibration movements in the spans with set ADF is 2 % higher on the average than without ADF. During the studies of TVS-KVADRAT fuel rod vibration, the following tasks were solved: determination of acceleration of the middle of fuel rod spans at vibration excited due to hydrodynamics; determination of influence of coolant thermal- hydraulic parameters (temperature, flowrate, dynamic pressure) on fuel rod vibration response; determination of influence of span lengths on the vibration level. Conclusions: 1) The vibration tests of the full-scale model of TVS-2M in the coolant flow showed that the new elements of TVS-2M design (intensifiers of heat exchange and ADF) are not the source of fuel rod increased vibration. Considering successful operation of similar fuel rod spans in the existing TVS-2M design, vibration stability of TVS-2M fuel rods with new elements is ensured on the mechanism of

  7. REFLOS, Fuel Loading and Cost from Burnup and Heavy Atomic Mass Flow Calculation in HWR

    International Nuclear Information System (INIS)

    Boettcher, W.; Schmidt, E.

    1969-01-01

    1 - Nature of physical problem solved: REFLOS is a programme for the evaluation of fuel-loading schemes in heavy water moderated reactors. The problems involved in this study are: a) Burn-up calculation for the reactor cell. b) Determination of reactivity behaviour, power distribution, attainable burn-up for both the running-in period and the equilibrium of a 3-dimensional heterogeneous reactor model; investigation of radial fuel movement schemes. c) Evaluation of mass flows of heavy atoms through the reactor and fuel cycle costs for the running-in, the equilibrium, and the shut down of a power reactor. If the subroutine for treating the reactor cell were replaced by a suitable routine, other reactors with weakly absorbing moderators could be analyzed. 2 - Method of solution: Nuclear constants and isotopic compositions of the different fuels in the reactor are calculated by the cell-burn-up programme and tabulated as functions of the burn-up rate (MWD/T). Starting from a known state of the reactor, the 3-dimensional heterogeneous reactor programme (applying an extension of the technique of Feinberg and Galanin) calculates reactivity and neutron flux distribution using one thermal and one or two fast neutron groups. After a given irradiation time, the new state of the reactor is determined, and new nuclear constants are assigned to the various defined locations in the reactor. Reloading of fuel may occur if the prescribed life of the reactor is reached or if the effective multiplication factor or the power form factor falls below a specified level. The scheme of reloading to be carried out is specified by a load vector, giving the number of channels to be discharged, the kind of movement from one to another channel and the type of fresh fuel to be charged for each single reloading event. After having determined the core states characterizing the equilibrium period, and having decided the fuel reloading scheme for the running-in period of the reactor life, the fuel

  8. 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)

  9. Time-resolved fuel injector flow characterisation based on 3D laser Doppler vibrometry

    Science.gov (United States)

    Crua, Cyril; Heikal, Morgan R.

    2014-12-01

    Hydrodynamic turbulence and cavitation are known to play a significant role in high-pressure atomizers, but the small geometries and extreme operating conditions hinder the understanding of the flow’s characteristics. Diesel internal flow experiments are generally conducted using x-ray techniques or on transparent, and often enlarged, nozzles with different orifice geometries and surface roughness to those found in production injectors. In order to enable investigations of the fuel flow inside unmodified injectors, we have developed a new experimental approach to measure time-resolved vibration spectra of diesel nozzles using a 3D laser vibrometer. The technique we propose is based on the triangulation of the vibrometer and fuel pressure transducer signals, and enables the quantitative characterisation of quasi-cyclic internal flows without requiring modifications to the injector, the working fluid, or limiting the fuel injection pressure. The vibrometer, which uses the Doppler effect to measure the velocity of a vibrating object, was used to scan injector nozzle tips during the injection event. The data were processed using a discrete Fourier transform to provide time-resolved spectra for valve-closed-orifice, minisac and microsac nozzle geometries, and injection pressures ranging from 60 to 160 MPa, hence offering unprecedented insight into cyclic cavitation and internal mechanical dynamic processes. A peak was consistently found in the spectrograms between 6 and 7.5 kHz for all nozzles and injection pressures. Further evidence of a similar spectral peak was obtained from the fuel pressure transducer and a needle lift sensor mounted into the injector body. Evidence of propagation of the nozzle oscillations to the liquid sprays was obtained by recording high-speed videos of the near-nozzle diesel jet, and computing the fast Fourier transform for a number of pixel locations at the interface of the jets. This 6-7.5 kHz frequency peak is proposed to be the

  10. Time-resolved fuel injector flow characterisation based on 3D laser Doppler vibrometry

    International Nuclear Information System (INIS)

    Crua, Cyril; Heikal, Morgan R

    2014-01-01

    Hydrodynamic turbulence and cavitation are known to play a significant role in high-pressure atomizers, but the small geometries and extreme operating conditions hinder the understanding of the flow’s characteristics. Diesel internal flow experiments are generally conducted using x-ray techniques or on transparent, and often enlarged, nozzles with different orifice geometries and surface roughness to those found in production injectors. In order to enable investigations of the fuel flow inside unmodified injectors, we have developed a new experimental approach to measure time-resolved vibration spectra of diesel nozzles using a 3D laser vibrometer. The technique we propose is based on the triangulation of the vibrometer and fuel pressure transducer signals, and enables the quantitative characterisation of quasi-cyclic internal flows without requiring modifications to the injector, the working fluid, or limiting the fuel injection pressure. The vibrometer, which uses the Doppler effect to measure the velocity of a vibrating object, was used to scan injector nozzle tips during the injection event. The data were processed using a discrete Fourier transform to provide time-resolved spectra for valve-closed-orifice, minisac and microsac nozzle geometries, and injection pressures ranging from 60 to 160 MPa, hence offering unprecedented insight into cyclic cavitation and internal mechanical dynamic processes. A peak was consistently found in the spectrograms between 6 and 7.5 kHz for all nozzles and injection pressures. Further evidence of a similar spectral peak was obtained from the fuel pressure transducer and a needle lift sensor mounted into the injector body. Evidence of propagation of the nozzle oscillations to the liquid sprays was obtained by recording high-speed videos of the near-nozzle diesel jet, and computing the fast Fourier transform for a number of pixel locations at the interface of the jets. This 6–7.5 kHz frequency peak is proposed to be the

  11. Forest biomass flow for fuel wood, fodder and timber security among tribal communities of Jharkhand.

    Science.gov (United States)

    Islam, M A; Quli, S M S; Rai, R; Ali, Angrej; Gangoo, S A

    2015-01-01

    The study investigated extraction and consumption pattern of fuel wood, fodder and timber and forest biomass flow for fuel wood, fodder and timber security among tribal communities in Bundu block of Ranchi district in Jharkhand (India). The study is based on personal interviews of the selected respondents through structured interview schedule, personal observations and participatory rural appraisal tools i.e. key informant interviews and focus group discussions carried out in the sample villages, using multi-stage random sampling technique. The study revealed that the total extraction of fuel wood from different sources in villages was 2978.40 tons annum(-1), at the rate of 0.68 tons per capita annum(-1), which was mostly consumed in cooking followed by cottage industries, heating, community functions and others. The average fodder requirement per household was around 47.77 kg day(-1) with a total requirement of 14227.34 tons annum(-1). The average timber requirement per household was computed to be 0.346 m3 annum(-1) accounting for a total timber demand of 282.49 m3 annum(-1), which is mostly utilized in housing, followed by agricultural implements, rural furniture, carts and carriages, fencing, cattle shed/ store house and others. Forest biomass is the major source of fuel wood, fodder and timber for the primitive societies of the area contributing 1533.28 tons annum(-1) (51.48%) of the total fuel wood requirement, 6971.55 tons annum(-1) (49.00%) of the total fodder requirement and 136.36 m3 annum(-1) (48.27%) of the total timber requirement. The forest biomass is exposed to enormous pressure for securing the needs by the aboriginal people, posing great threat to biodiversity and environment of the region. Therefore, forest biomass conservation through intervention of alternative avenues is imperative to keep pace with the current development and future challenges in the area.

  12. Effects of Cooling Fluid Flow Rate on the Critical Heat Flux and Flow Stability in the Plate Fuel Type 2 MW TRIGA Reactor

    OpenAIRE

    H. P. Rahardjo; V. I. Sri Wardhani

    2017-01-01

    The conversion program of the 2 MW TRIGA reactor in Bandung consisted of the replacement of cylindrical fuel (produced by General Atomic) with plate fuel (produced by BATAN). The replacement led into the change of core cooling process from upward natural convection type to downward forced convection type, and resulted in different thermohydraulic safety criteria, such as critical heat flux (CHF) limit, boiling limit, and cooling fluid flow stability. In this paper, a thermohydraulic safety an...

  13. A Comparison of Flow-Through Versus Non-Flow-Through Proton Exchange Membrane Fuel Cell Systems for NASA's Exploration Missions

    Science.gov (United States)

    Hoberecht, Mark A.

    2010-01-01

    As part of the Exploration Technology Development Program (ETDP) under the auspices of the Exploration Systems Mission Directorate (ESMD), NASA is developing both primary fuel cell power systems and regenerative fuel cell (RFC) energy storage systems within the fuel cell portion of the Energy Storage Project. This effort is being led by the NASA Glenn Research Center (GRC) in partnership with the NASA Johnson Space Center (JSC), Jet Propulsion Laboratory (JPL), NASA Kennedy Space Center (KSC), and industrial partners. The development goals are to improve fuel cell and electrolysis stack electrical performance, reduce system mass, volume, and parasitic power requirements, and increase system life and reliability. A major focus of this effort has been the parallel development of both flow-through and non-flow-through proton exchange membrane (PEM) primary fuel cell power systems. The plan has been, at the appropriate time, to select a single primary fuel cell technology for eventual flight hardware development. Ideally, that appropriate time would occur after both technologies have achieved a technology readiness level (TRL) of six, which represents an engineering model fidelity PEM fuel cell system being successfully tested in a relevant environment. Budget constraints in fiscal year 2009 and beyond have prevented NASA from continuing to pursue the parallel development of both primary fuel cell options. Because very limited data exists for either system, a toplevel, qualitative assessment based on engineering judgement was performed expeditiously to provide guidance for a selection. At that time, the non-flow-through technology was selected for continued development because of potentially major advantages in terms of weight, volume, parasitic power, reliability, and life. This author believes that the advantages are significant enough, and the potential benefits great enough, to offset the higher state of technology readiness of flow-through technology. This paper

  14. Reversing flow catalytic converter for a natural gas/diesel dual fuel engine

    Energy Technology Data Exchange (ETDEWEB)

    Liu, E.; Checkel, M.D. [Alberta Univ., Edmonton, AB (Canada). Dept. of Mechanical Engineering; Hayes, R.E. [Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical and Materials Engineering; Alberta Univ., Edmonton, AB (Canada). Dept. of Mechanical Engineering; Zheng, M.; Mirosh, E. [Alternative Fuel Systems Inc., Calgary, AB (Canada)

    2001-07-01

    An experimental and modelling study was performed for a reverse flow catalytic converter attached to a natural gas/diesel dual fuel engine. The catalytic converter had a segmented ceramic monolith honeycomb substrate and a catalytic washcoat containing a predominantly palladium catalyst. A one-dimensional single channel model was used to simulate the operation of the converter. The kinetics of the CO and methane oxidation followed first-order behaviour. The activation energy for the oxidation of methane showed a change with temperature, dropping from a value of 129 to 35 kJ/mol at a temperature of 874 K. The reverse flow converter was able to achieve high reactor temperature under conditions of low inlet gas temperature, provided that the initial reactor temperature was sufficiently high. (author)

  15. Approximate solutions of pulse transport in turbulent flow in narrow fuel element bundle geometries, using the FE method

    International Nuclear Information System (INIS)

    Kaiser, H.G.

    1985-01-01

    The author is concerned with the flow conditions in case of narrow fuel element grids of pressurised-water reactors. Starting from the mathematical formulation of the flow processes for incompressible, isothermal flows, models of the turbulence characteristics are being developed. Besides turbulence models, and network structure the finite element method is treated as numeric solution process. Finally the results are summarized and discussed. (HAG) [de

  16. Using Sankey diagrams to map energy flow from primary fuel to end use

    International Nuclear Information System (INIS)

    Subramanyam, Veena; Paramshivan, Deepak; Kumar, Amit; Mondal, Md. Alam Hossain

    2015-01-01

    Highlights: • Energy flows from both supply and demand sides shown through Sankey diagrams. • Energy flows from reserves to energy end uses for primary and secondary fuels shown. • Five main energy demand sectors in Alberta are analyzed. • In residential/commercial sectors, highest energy consumption is in space heating. • In the industrial sector, highest energy use is in the mining subsector. - Abstract: The energy sector is the largest contributor to gross domestic product (GDP), income, employment, and government revenue in both developing and developed nations. But the energy sector has a significant environmental footprint due to greenhouse gas (GHG) emissions. Efficient production, conversion, and use of energy resources are key factors for reducing the environmental footprint. Hence it is necessary to understand energy flows from both the supply and the demand sides. Most energy analyses focus on improving energy efficiency broadly without considering the aggregate energy flow. We developed Sankey diagrams that map energy flow for both the demand and supply sides for the province of Alberta, Canada. The diagrams will help policy/decision makers, researchers, and others to understand energy flow from reserves through to final energy end uses for primary and secondary fuels in the five main energy demand sectors in Alberta: residential, commercial, industrial, agricultural, and transportation. The Sankey diagrams created for this study show total energy consumption, useful energy, and energy intensities of various end-use devices. The Long-range Energy Alternatives Planning System (LEAP) model is used in this study. The model showed that Alberta’s total input energy in the five demand sectors was 189 PJ, 186 PJ, 828.5PJ, 398 PJ, and 50.83 PJ, respectively. On the supply side, the total energy input and output were found to be 644.84 PJ and 239 PJ, respectively. These results, along with the associated energy flows were depicted pictorially using

  17. Behavior of EBR-II Mk-V-type fuel elements in simulated loss-of-flow tests

    International Nuclear Information System (INIS)

    Liu, Y.Y.; Tsai, H.; Billone, M.C.; Holland, J.W.; Kramer, J.M.

    1992-11-01

    This report discusses three furnace heating tests which were conducted with irradiated, HT9-clad and U-19wt.%Pu-l0wt.%Zr-alloy fuel, Mk-V-type fuel elements in the Alpha-Gamma Hot Cell Facility at Argonne National Laboratory, Illinois. In general, very significant safety margins for fuel-element cladding breaching have been demonstrated in these tests, under conditions that would envelop a bounding unlikely loss-of-flow event in EBR-II. Highlights of the test results will be given, as well as discussions of the cladding breaching mechanisms, axial fuel motion, and fuel surface liquefaction found in high-temperature testing of irradiated metallic fuel elements

  18. Peclet number analysis of cross-flow in porous gas diffusion layer of polymer electrolyte membrane fuel cell (PEMFC).

    Science.gov (United States)

    Suresh, P V; Jayanti, Sreenivas

    2016-10-01

    Adoption of hydrogen economy by means of using hydrogen fuel cells is one possible solution for energy crisis and climate change issues. Polymer electrolyte membrane (PEM) fuel cell, which is an important type of fuel cells, suffers from the problem of water management. Cross-flow is induced in some flow field designs to enhance the water removal. The presence of cross-flow in the serpentine and interdigitated flow fields makes them more effective in proper distribution of the reactants on the reaction layer and evacuation of water from the reaction layer than diffusion-based conventional parallel flow fields. However, too much of cross-flow leads to flow maldistribution in the channels, higher pressure drop, and membrane dehydration. In this study, an attempt has been made to quantify the amount of cross-flow required for effective distribution of reactants and removal of water in the gas diffusion layer. Unit cells containing two adjacent channels with gas diffusion layer (GDL) and catalyst layer at the bottom have been considered for the parallel, interdigitated, and serpentine flow patterns. Computational fluid dynamics-based simulations are carried out to study the reactant transport in under-the-rib area with cross-flow in the GDL. A new criterion based on the Peclet number is presented as a quantitative measure of cross-flow in the GDL. The study shows that a cross-flow Peclet number of the order of 2 is required for effective removal of water from the GDL. Estimates show that this much of cross-flow is not usually produced in the U-bends of Serpentine flow fields, making these areas prone to flooding.

  19. Flow instability tests for a particle bed reactor nuclear thermal rocket fuel element

    Science.gov (United States)

    Lawrence, Timothy J.

    1993-05-01

    Recent analyses have focused on the flow stability characteristics of a particle bed reactor (PBR). These laminar flow instabilities may exist in reactors with parallel paths and are caused by the heating of the gas at low Reynolds numbers. This phenomena can be described as follows: several parallel channels are connected at the plenum regions and are stabilized by some inlet temperature and pressure; a perturbation in one channel causes the temperature to rise and increases the gas viscosity and reduces the gas density; the pressure drop is fixed by the plenum regions, therefore, the mass flow rate in the channel would decrease; the decrease in flow reduces the ability to remove the energy added and the temperature increases; and finally, this process could continue until the fuel element fails. Several analyses based on different methods have derived similar curves to show that these instabilities may exist at low Reynolds numbers and high phi's ((Tfinal Tinitial)/Tinitial). These analyses need to be experimentally verified.

  20. Steady state investigation on neutronics of a molten salt reactor considering the flow effect of fuel salt

    International Nuclear Information System (INIS)

    Zhang Dalin; Qiu Suizheng; Su Guanghui; Liu Changliang

    2008-01-01

    The Molten Salt Reactor (MSR), one of the 'Generation IV' concepts, is a liquid-fuel reactor, which is different from the conventional reactors using solid fissile materials due to the flow effect of fuel salt. The study on its neutronics considering the fuel salt flow, which is the base of the thermal-hydraulic calculation and safety analysis, must be done. In this paper, the theoretical model on neutronics under steady condition for a single-liquid-fueled MSR is conducted and calculated by numerical method. The neutronics model consists of two group neutron diffusion equations for fast and thermal neutron fluxes, and balance equations for six-group delayed neutron precursors considering the flow effect of fuel salt. The spatial discretization of the above models is based on the finite volume method, and the discretization equations are computed by the source iteration method. The distributions of neutron fluxes and the distributions of the delayed neutron precursors in the core are obtained. The numerical calculated results show that, the fuel salt flow has little effect on the distribution of fast and thermal neutron fluxes and the effective multiplication factor; however, it affects the distribution of the delayed neutron precursors significantly, especially the long-lived one. In addition, it could be found that the delayed neutron precursors influence the neutronics slightly under the steady condition. (authors)

  1. Steady state investigation on neutronics of a molten salt reactor considering the flow effect of fuel salt

    Institute of Scientific and Technical Information of China (English)

    ZHANG Da-Lin; QIU Sui-Zheng; LIU Chang-Liang; SU Guang-Hui

    2008-01-01

    The Molten Salt Reactor (MSR),one of the‘Generation Ⅳ'concepts,is a liquid-fuel reactor,which is different from the conventional reactors using solid fissile materials due to the flow effect of fuel salt.The study on its neutronice considering the fuel salt flow,which is the base of the thermal-hydraulic calculation and safety analysis,must be done.In this paper,the theoretical model on neutronics under steady condition for a single-liquid-fueled MSR is conducted and calculated by numerical method.The neutronics model consists of two group neutron diffusion equations for fast and thermal neutron fluxes,and balance equations for six-group delayed neutron precursors considering the flow effect of fuel salt. The spatial discretization of the above models is based on the finite volume method,and the discretization equations are computed by the source iteration method.The distributions of neutron fluxes and the distributions of the delayed neutron precursors in the core are obtained.The numerical calculated results show that,the fuel salt flow has little effect on the distribution of fast and thermal neutron fluxes and the effective multiplication factor;however,it affects the distribution of the delayed neutron precursors significantly,especially the long-lived one.In addition,it could be found that the delayed neutron precursors influence the nentronics slightly under the steady condition.

  2. Flow field optimization for proton exchange membrane fuel cells with varying channel heights and widths

    International Nuclear Information System (INIS)

    Wang Xiaodong; Huang Yuxian; Cheng, C.-H.; Jang, J.-Y.; Lee, D.-J.; Yan, W.-M.; Su Ay

    2009-01-01

    The optimal cathode flow field design of a single serpentine proton exchange membrane fuel cell is obtained by adopting a combined optimization procedure including a simplified conjugate-gradient method (SCGM) and a completely three-dimensional, two-phase, non-isothermal fuel cell model. The cell output power density P cell is the objective function to be maximized with channel heights, H 1 -H 5 , and channel widths, W 2 -W 5 as search variables. The optimal design has tapered channels 1, 3 and 4, and diverging channels 2 and 5, producing 22.51% increment compared with the basic design with all heights and widths setting as 1 mm. Reduced channel heights of channels 2-4 significantly enhance sub-rib convection to effectively transport oxygen to and liquid water out of diffusion layer. The final diverging channel prevents significant leakage of fuel to outlet via sub-rib convection from channel 4. Near-optimal design without huge loss in cell performance but is easily manufactured is discussed.

  3. Noise and DC balanced outlet temperature signals for monitoring coolant flow in LMFBR fuel elements

    International Nuclear Information System (INIS)

    Edelmann, M.

    1977-01-01

    Local cooling disturbances in LMFBR fuel elements may have serious safety implications for the whole reactor core. They have to be detected reliably in an early stage of their formation therefore. This can be accomplished in principle by individual monitoring of the coolant flow rate or the coolant outlet temperature of the sub-assemblies with high precision. In this paper a method is proposed to increase the sensitivity of outlet temperature signals to cooling disturbances. Using balanced temperature signals provides a means for eliminating the normal variations from the original signals which limit the sensitivity and speed of response to cooling disturbances. It is shown that a balanced signal can be derived easily from the original temperature signal by subtracting an inlet temperature and a neutron detector signal with appropriate time shift. The method was tested with tape-recorded noise signals of the KNK I reactor at Karlsruhe. The experimental results confirm the theoretical predictions. A significant reduction of the uncertainty of measured outlet temperatures was achieved. This enables very sensitive and fast response monitoring of coolant flow. Furthermore, it was found that minimizing the variance of the balanced signal offers the possibility for a rough determination of the heat transfer coefficient of the fuel rods during normal reactor operation at power. (author)

  4. Large Eddy Simulation of turbulent flow in wire wrapped fuel pin bundles cooled by sodium

    International Nuclear Information System (INIS)

    Saxena, Aakanksha; Cadiou, Thierry; Bieder, Ulrich; Viazzo, Stephane

    2013-06-01

    The objective of the study is to understand the thermal hydraulics in a core sub-assembly with liquid sodium as coolant by performing detailed numerical simulations. The passage for the coolant flow between the fuel rods is maintained by thin wires wrapped around the rods. The contact point between the fuel pin and the spacer wire is the region of creation of hot spots and a cyclic variation of temperature in hot spots can adversely affect the mechanical properties of the clad due to the phenomena like thermal stripping. The current status quo provides two different models to perform the numerical simulations, namely Reynolds Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES). The two models differ in the extent of modelling used to close the Navier-Stokes equations. LES is a filtered approach where the large scale of motions are explicitly resolved while the small scale motions are modelled whereas RANS is a time averaging approach where all scale of motions are modelled. Thus LES involves less modelling as compared to RANS and so the results are comparatively more accurate. An attempt has been made to use the LES model. The simulations have been performed using the code Trio-U (developed by CEA). The turbulent statistics of the flow and thermal quantities are calculated. Finally the goal is to obtain the frequency of temperature oscillations at the region of hot spots near the spacer wire. (authors)

  5. A CFD analysis of flow blockage phenomena in ALFRED LFR demo fuel assembly

    Energy Technology Data Exchange (ETDEWEB)

    Di Piazza, Ivan, E-mail: ivan.dipiazza@enea.it [Italian National Agency for New Technologies, Energy and Sustainable Economic Development, C.R. ENEA Brasimone (Italy); Magugliani, Fabrizio [Ansaldo Nucleare, ANN, Corso Perrone n.25, Genova (Italy); Tarantino, Mariano [Italian National Agency for New Technologies, Energy and Sustainable Economic Development, C.R. ENEA Brasimone (Italy); Alemberti, Alessandro [Ansaldo Nucleare, ANN, Corso Perrone n.25, Genova (Italy)

    2014-09-15

    Highlights: • URANS simulations were performed on internal flow blockage in HLM fuel assemblies. • Comparison with RELAP results for foot blockage shows a very good agreement. • The temperature peak behind the blockage is dominant for large blockages. • A blockage of ∼15% leads to a maximum clad temperature around 800 °C in 3–4 s. • Local clad temperatures around 1000 °C are reached for blockages of 30% or more. - Abstract: A CFD study was carried out on fluid flow and heat transfer in the Lead-cooled Fuel Pin Bundle of the ALFRED LFR DEMO. In the context of GEN-IV heavy liquid metal-cooled reactors safety studies, the flow blockage in a fuel sub-assembly is considered one of the main issues to be addressed and the most important and realistic accident for LFR fuel assembly. The present paper is a first step toward a detailed analysis of such phenomena, and a CFD model and approach are presented to have a detailed thermo-fluid dynamic picture in the case of blockage. In particular the closed hexagonal, grid-spaced fuel assembly of the LFR ALFRED was modeled and computed. At this stage, the details of the spacer grids were not included, but a conservative analysis has been carried out based on the current main geometrical and physical features. Reactivity feedback, as well as axial power profile, were not included in this analysis. Results indicate that critical conditions, with clad temperatures around ∼900 °C, are reached with blockage larger than 30% in terms of area fraction. Two main effects can be distinguished: a local effect in the wake/recirculation region downstream the blockage and a global effect due to the lower mass flow rate in the blocked subchannels; the former effect gives rise to a temperature peak behind the blockage and it is dominant for large blockages (>20%), while the latter effect determines a temperature peak at the end of the active region and it is dominant for small blockages (<10%). The blockage area was placed at

  6. Benchmark exercise for fluid flow simulations in a liquid metal fast reactor fuel assembly

    Energy Technology Data Exchange (ETDEWEB)

    Merzari, E., E-mail: emerzari@anl.gov [Mathematics and Computer Science Division, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, IL 60439 (United States); Fischer, P. [Mathematics and Computer Science Division, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, IL 60439 (United States); Yuan, H. [Nuclear Engineering Division, Argonne National Laboratory, Lemont, IL (United States); Van Tichelen, K.; Keijers, S. [SCK-CEN, Boeretang 200, Mol (Belgium); De Ridder, J.; Degroote, J.; Vierendeels, J. [Ghent University, Ghent (Belgium); Doolaard, H.; Gopala, V.R.; Roelofs, F. [NRG, Petten (Netherlands)

    2016-03-15

    Highlights: • A EUROTAM-US INERI consortium has performed a benchmark exercise related to fast reactor assembly simulations. • LES calculations for a wire-wrapped rod bundle are compared with RANS calculations. • Results show good agreement for velocity and cross flows. - Abstract: As part of a U.S. Department of Energy International Nuclear Energy Research Initiative (I-NERI), Argonne National Laboratory (Argonne) is collaborating with the Dutch Nuclear Research and consultancy Group (NRG), the Belgian Nuclear Research Centre (SCK·CEN), and Ghent University (UGent) in Belgium to perform and compare a series of fuel-pin-bundle calculations representative of a fast reactor core. A wire-wrapped fuel bundle is a complex configuration for which little data is available for verification and validation of new simulation tools. UGent and NRG performed their simulations with commercially available computational fluid dynamics (CFD) codes. The high-fidelity Argonne large-eddy simulations were performed with Nek5000, used for CFD in the Simulation-based High-efficiency Advanced Reactor Prototyping (SHARP) suite. SHARP is a versatile tool that is being developed to model the core of a wide variety of reactor types under various scenarios. It is intended both to serve as a surrogate for physical experiments and to provide insight into experimental results. Comparison of the results obtained by the different participants with the reference Nek5000 results shows good agreement, especially for the cross-flow data. The comparison also helps highlight issues with current modeling approaches. The results of the study will be valuable in the design and licensing process of MYRRHA, a flexible fast research reactor under design at SCK·CEN that features wire-wrapped fuel bundles cooled by lead-bismuth eutectic.

  7. Experimental and modelling study of reverse flow catalytic converters for natural gas/diesel dual fuel engine pollution control

    Energy Technology Data Exchange (ETDEWEB)

    Liu, B.

    2000-07-01

    There is renewed interest in the development of natural gas vehicles in response to the challenge to reduce urban air pollution and consumption of petroleum. The natural gas/diesel dual fuel engine is one way to apply natural gas to the conventional diesel engine. Dual fuel engines operating on natural gas and diesel emit less nitrogen oxides, and less carbon soot to the air compared to conventional diesel engines. The problem is that at light loads, fuel efficiency is reduced and emissions of hydrocarbons and carbon monoxide are increased. This thesis focused on control methods for emissions of hydrocarbons and carbon monoxide in the dual fuel engine at light loads. This was done by developing a reverse flow catalytic converter to complement dual fuel engine exhaust characteristics. Experimental measurements and numerical simulations of reverse flow catalytic converters were conducted. Reverse flow creates a high reactor temperature even when the engine is run at low exhaust temperature levels at light loads. The increase in reactor temperature from reverse flow could be 2 or 3 times higher than the adiabatic temperature increase, which is based on the reactor inlet temperature and concentration. This temperature makes it possible for greater than 90 per cent of the hydrocarbon and carbon monoxide to be converted with a palladium based catalyst. Reverse flow appears to be better than conventional unidirectional flow to deal with natural gas/diesel dual fuel engine pollution at light loads. Reverse flow could also maintain reactor temperature at over 800 K and hydrocarbon conversion at about 80 per cent during testing. The newly presented model simulates reactor performance with reasonable accuracy. Both carbon monoxide and methane oxidation over the palladium catalyst in excess oxygen and water were described using first order kinetics.

  8. Assembly and Stacking of Flow-through Enzymatic Bioelectrodes for High Power Glucose Fuel Cells.

    Science.gov (United States)

    Abreu, Caroline; Nedellec, Yannig; Gross, Andrew J; Ondel, Olivier; Buret, Francois; Goff, Alan Le; Holzinger, Michael; Cosnier, Serge

    2017-07-19

    Bioelectrocatalytic carbon nanotube based pellets comprising redox enzymes were directly integrated in a newly conceived flow-through fuel cell. Porous electrodes and a separating cellulose membrane were housed in a glucose/oxygen biofuel cell design with inlets and outlets allowing the flow of electrolyte through the entire fuel cell. Different flow setups were tested and the optimized single cell setup, exploiting only 5 mmol L -1 glucose, showed an open circuit voltage (OCV) of 0.663 V and provided 1.03 ± 0.05 mW at 0.34 V. Furthermore, different charge/discharge cycles at 500 Ω and 3 kΩ were applied to optimize long-term stability leading to 3.6 J (1 mW h) of produced electrical energy after 48 h. Under continuous discharge at 6 kΩ, about 0.7 mW h could be produced after a 24 h period. The biofuel cell design further allows a convenient assembly of several glucose biofuel cells in reduced volumes and their connection in parallel or in series. The configuration of two biofuel cells connected in series showed an OCV of 1.35 V and provided 1.82 ± 0.09 mW at 0.675 V, and when connected in parallel, showed an OCV of 0.669 V and provided 1.75 ± 0.09 mW at 0.381 V. The presented design is conceived to stack an unlimited amount of biofuel cells to reach the necessary voltage and power for portable electronic devices without the need for step-up converters or energy managing systems.

  9. Time-dependent tritium inventories and flow rates in fuel cycle components of a tokamak fusion reactor

    International Nuclear Information System (INIS)

    Kuan, W.

    1995-01-01

    Time-dependent inventories and flow rates for several components of the fuel cycle are modeled and studied through the use of a new modular-type model for the dynamic simulation of the fuel cycle in a fusion reactor. The complex dynamic behavior in the modeled subsystems is analyzed using this new model. Preliminary results using fuel cycle design configurations similar to ITER are presented and analyzed. The inventories and flow rates inside the primary vacuum pumping, fuel cleanup unit and isotope separation system are studied. Ways to minimize the tritium inventory are also assessed. This was performed by looking at various design options that could be used to minimize tritium inventory for specific components. (orig.)

  10. Co-flow anode/cathode supply heat exchanger for a solid-oxide fuel cell assembly

    Science.gov (United States)

    Haltiner, Jr., Karl J.; Kelly, Sean M.

    2005-11-22

    In a solid-oxide fuel cell assembly, a co-flow heat exchanger is provided in the flow paths of the reformate gas and the cathode air ahead of the fuel cell stack, the reformate gas being on one side of the exchanger and the cathode air being on the other. The reformate gas is at a substantially higher temperature than is desired in the stack, and the cathode gas is substantially cooler than desired. In the co-flow heat exchanger, the temperatures of the reformate and cathode streams converge to nearly the same temperature at the outlet of the exchanger. Preferably, the heat exchanger is formed within an integrated component manifold (ICM) for a solid-oxide fuel cell assembly.

  11. Fuel assembly outlet temperature profile influence on core by-pass flow and power distribution determination in WWER -440 reactors

    International Nuclear Information System (INIS)

    Petenyi, V.; Klucarova, K.; Remis, J.

    2003-01-01

    The in core instrumentation of the WWER-440 reactors consists of the thermocouple system and the system of self powered detectors (SPD). The thermocouple systems are positioned about 50 cm above the fuel bundle upper flow-mixing grid. The usual assumption is that, the coolant is well mixed in the Tc location, i.e. the temperature is constant through the flow cross-section area. The present evaluations by using the FLUENT 5.5.14 code reveal that, this assumption is not fulfilled. There exists a temperature profile that depends on fuel assembly geometry and on inner power profile of the fuel assembly. The paper presents the estimation of this effect and its influence on the core power distribution and the core by-pass flow determination. Comparison with measurements in Mochovce NPP will also be a part of this presentation (Authors)

  12. Design of experiment study of the parameters that affect performance of three flow plate configurations of a proton exchange membrane fuel cell

    International Nuclear Information System (INIS)

    Carton, J.G.; Olabi, A.G.

    2010-01-01

    Low temperature hydrogen fuel cells are electrochemical devices which offer a promising alternative to traditional power sources. Fuel cells produce electricity with a reaction of the fuel (hydrogen) and air. Fuel cells have the advantage of being clean; only producing water and heat as by products. The efficiency of a fuel cell varies depending on the type; SOFC with CHP for example, can have a system efficiency of up to 65%. What the Authors present here is a comparison between three different configurations of flow plates of a proton exchange membrane fuel cell, the manufacturer's serpentine flow plate and two new configurations; the maze flow plate and the parallel flow plate. A study of the input parameters affecting output responses of voltage, current, power and efficiency of a fuel cell is performed through experimentation. The results were taken from direct readings of the fuel cell and from polarisation curves produced. This information was then analysed through a design of experiment to investigate the effects of the changing parameters on different configurations of the fuel cell's flow plates. The results indicate that, in relation to current and voltage response of the polarisation curve and the corresponding graphs produced from the DOE, the serpentine flow plate design is a much more effective design than the maze or parallel flow plate design. It was noted that the parallel flow plate performed reasonably well at higher pressures but over all statically the serpentine flow plate performed better.

  13. New Approach to Study the Ignition Processes of Organic Coal-Water Fuels in an Oxidizer Flow

    Directory of Open Access Journals (Sweden)

    Valiullin T.R.

    2016-01-01

    Full Text Available To converge the conditions of organic water-coal fuel composition combustion in the typical power equipment we developed a new approach and installed an experimental setup, eliminating the traditional fixing the fuel droplets on the thermocouples or rods. Specialized cone-shaped chamber was used to implement the process of lingering of organic water-coal fuel droplets. Necessary and sufficient conditions for the lingering of organic water-coal fuel droplets were established. We determined the parameters of the system (droplet size of 0.4-0.6 mm, temperatures 823-903 K and the velocity of the oxidizer flow 1.5-6 m/s at which the droplets were consistently ignited in the process of lingering. Minimum temperatures and ignition delay times of organic water-coal fuel droplets based on brown coal, used motor, turbine, transformer oils, kerosene, gasoline and water were defined.

  14. Numerical and experimental investigation on effects of inlet humidity and fuel flow rate and oxidant on the performance on polymer fuel cell

    International Nuclear Information System (INIS)

    Takalloo, Pourya Karimi; Nia, Ehsan Shabahang; Ghazikhani, Mohsen

    2016-01-01

    Highlights: • The impact of alteration in humidification on performance of fuel cell. • The impact of variation of temperature on performance of fuel cell. • The effects of using pure oxygen on the polarity curve are studied. • Fuel cell has been investigated both experimentally and numerically. - Abstract: Considering the importance of water management in a fuel cell and in order to increase the rate of the electro-chemical process in fuel cells with polymer membrane, it is required to optimize the humidity and inlet flow rates on anode and cathode sides. In this study, the impact of alteration in humidification and inlet flow rates on performance improvements for polymer membrane fuel cells is investigated both experimentally and numerically. To obtain the objective, employing the results from experiments and simulations, polarity curve and power density are produced and further used to conduct the desired investigations. In addition, through the conducted simulations the effects of using pure oxygen in the cathode side and inlet gas temperatures on the polarity curve is studied. The results demonstrate that an increase in humidity of the inlet gases will lead to performance amelioration in the cell, due to reduction in ionic resistance at the membrane. Furthermore, with the aforementioned increment; molar fractions of hydrogen and oxygen are decreased through the channel which results in produced water increment. Amplification in inlet flow rates to a certain level will improve the penetration possibility for gaseous forms leading to betterment of the cell performance in this specified range. Performance improvements with inlet gases temperature increment conclude other results of this study.

  15. Flow sheet development for the dissolution of unirradiated Mark 42 fuel tubes in F-Canyon, Part II

    International Nuclear Information System (INIS)

    Murray, A.M.

    1999-01-01

    Two dissolution flow sheets were tested for the desorption of unirradiated Mark 42 fuel tubes. Both the aluminum (from the can, cladding, and fuel core) and the plutonium oxide (PuO 2 ) are dissolved simultaneously, i.e., a co-dissolution flow sheet. In the first series of tests, 0.15 and 0.20 molar (M) potassium fluoride (KF) solutions were used and the dissolution extended over several days. In the other series of tests, solutions with higher concentrations of fluoride (0.25 to 0.30 M) were used. Calcium fluoride (CaF 2 ) was used in those tests as the fluoride source

  16. Experimental and numerical study of temperature fields and flows in flame during the diffusion combustion of certain liquid fuels

    Science.gov (United States)

    Loboda, E. L.; Matvienko, O. V.; Agafontsev, M. V.; Reyno, V. V.

    2017-11-01

    The paper represents experimental studying the pulsations of temperature fields and the structure of a flow in the flame formed during the combustion of certain fuels. Also, the paper provides the mathematical modeling of a flow in the flame formed during the combustion of diesel fuels, as well as the comparison with experimental data and the estimation of the scale for turbulent vortices in flame. The experimental results are in satisfactory agreement with numerical modeling, which confirms the hypothesis of similarity for the pulsations of hydrodynamic and thermodynamic parameters.

  17. Flow Effects on the Flammability Diagrams of Solid Fuels: Microgravity Influence on Ignition Delay

    Science.gov (United States)

    Cordova, J. L.; Walther, D. C.; Fernandez-Pello, A. C.; Steinhaus, T.; Torero, J. L.; Quintere, J. G.; Ross, H. D.

    1999-01-01

    The possibility of an accidental fire in space-based facilities is a primary concern of space exploration programs. Spacecraft environments generally present low velocity air currents produced by ventilation and heating systems (of the order of 0.1 m/s), and fluctuating oxygen concentrations around that of air due to CO2 removal systems. Recent experiments of flame spread in microgravity show the spread rate to be faster and the limiting oxygen concentration lower than in normal-gravity. To date, there is not a material flammability-testing protocol that specifically addresses issues related to microgravity conditions. The present project (FIST) aims to establish a testing methodology that is suitable for the specific conditions of reduced gravity. The concepts underlying the operation of the LIFT apparatus, ASTM-E 1321-93, have been used to develop the Forced-flow Ignition and flame-Spread Test (FIST). As in the LIFT, the FIST is used to obtain the flammability diagrams of the material, i.e., graphs of ignition delay time and flame spread rate as a function of the externally applied radiant flux, but under forced flow rather than natural convection conditions, and for different oxygen concentrations. Although the flammability diagrams are similar, the flammability properties obtained with the FIST are found to depend on the flow characteristics. A research program is currently underway with the purpose of implementing the FIST as a protocol to characterize the flammability performance of solid materials to be used in microgravity facilities. To this point, tests have been performed with the FIST apparatus in both normal-gravity and microgravity conditions to determine the effects of oxidizer flow characteristics on the flammability diagrams of polymethylmethacrylate (PMMA) fuel samples. The experiments are conducted at reduced gravity in a KC- 135 aircraft following a parabolic flight trajectory that provides up to 25 seconds of low gravity. The objective of the

  18. Opposed-Flow Flame Spread over Thin Solid Fuels in a Narrow Channel under Different Gravity

    Science.gov (United States)

    Zhang, Xia; Yu, Yong; Wan, Shixin; Wei, Minggang; Hu, Wen-Rui

    Flame spread over solid surface is critical in combustion science due to its importance in fire safety in both ground and manned spacecraft. Eliminating potential fuels from materials is the basic method to protect spacecraft from fire. The criterion of material screening is its flamma-bility [1]. Since gas flow speed has strong effect on flame spread, the combustion behaviors of materials in normal and microgravity will be different due to their different natural convec-tion. To evaluate the flammability of materials used in the manned spacecraft, tests should be performed under microgravity. Nevertheless, the cost is high, so apparatus to simulate mi-crogravity combustion under normal gravity was developed. The narrow channel is such an apparatus in which the buoyant flow is restricted effectively [2, 3]. The experimental results of the horizontal narrow channel are consistent qualitatively with those of Mir Space Station. Quantitatively, there still are obvious differences. However, the effect of the channel size on flame spread has only attracted little attention, in which concurrent-flow flame spread over thin solid in microgravity is numerically studied[4], while the similarity of flame spread in different gravity is still an open question. In addition, the flame spread experiments under microgravity are generally carried out in large wind tunnels without considering the effects of the tunnel size [5]. Actually, the materials are always used in finite space. Therefore, the flammability given by experiments using large wind tunnels will not correctly predict the flammability of materials in the real environment. In the present paper, the effect of the channel size on opposed-flow flame spread over thin solid fuels in both normal and microgravity was investigated and compared. In the horizontal narrow channel, the flame spread rate increased before decreased as forced flow speed increased. In low speed gas flows, flame spread appeared the same trend as that in

  19. Flow field measurements using LDA and numerical computation for rod bundle of reactor fuel assembly

    International Nuclear Information System (INIS)

    Hu Jun; Zou Zunyu

    1995-02-01

    Local mean velocity and turbulence intensity measurements were obtained with DANTEC 55 X two-dimensional Laser Dopper Anemometry (LDA) for rod bundle of reactor fuel assembly test model which was a 4 x 4 rod bundle. The data were obtained from different experimental cross-sections both upstream and downstream of the model support plate. Measurements performed at test Reynolds numbers of 1.8 x 10 4 ∼3.6 x 10 4 . The results described the local and gross effects of the support plate on upstream and downstream flow distributions. A numerical computation was also given, the experimental results are in good agreement with the numerical one and the others in references. Finally, a few suggestions were proposed for how to use the LDA system well. (11 figs.)

  20. Numerical simulation of water flow through the bottom en piece of a nuclear fuel assembly

    International Nuclear Information System (INIS)

    Navarro, Moyses A.; Santos, Andre A. Campagnole dos

    2007-01-01

    The water flow through the bottom nozzle of a nuclear fuel assembly was simulated using a commercial CFD code, CFX 10.0. Previously, simulations with a perforated plate similar to the bottom nozzle plate were performed to define the appropriate mesh refinement and turbulence model (κ-ε or SST). Subsequently, the numerical simulation was performed with the optimized mesh using the turbulence model (κ-ε in a standard bottom nozzle with some geometric simplifications. The numerical results were compared with experimental results to determine the pressure drop through the bottom nozzle in the Reynolds range from ∼10500 to ∼95000. The agreement between the numerical simulations and experimental results may be considered satisfactory. The study indicated that the CFD codes can play an important role in the development of pieces with complex geometries, optimizing the planning of the experiments and aiding in the experimental analysis. (author)

  1. Numerical simulation of the flow field and fuel sprays in an IC engine

    Science.gov (United States)

    Nguyen, H. L.; Schock, H. J.; Ramos, J. I.; Carpenter, M. H.; Stegeman, J. D.

    1987-01-01

    A two-dimensional model for axisymmetric piston-cylinder configurations is developed to study the flow field in two-stroke direct-injection Diesel engines under motored conditions. The model accounts for turbulence by a two-equation model for the turbulence kinetic energy and its rate of dissipation. A discrete droplet model is used to simulate the fuel spray, and the effects of the gas phase turbulence on the droplets is considered. It is shown that a fluctuating velocity can be added to the mean droplet velocity every time step if the step is small enough. Good agreement with experimental data is found for a range of ambient pressures in Diesel engine-type microenvironments. The effects of the intake swirl angle in the spray penetration, vaporization, and mixing in a uniflow-scavenged two-stroke Diesel engine are analyzed. It is found that the swirl increases the gas phase turbulence levels and the rates of vaporization.

  2. Enhanced heat transfer with corrugated flow channel in anode side of direct methanol fuel cells

    International Nuclear Information System (INIS)

    Heidary, H.; Abbassi, A.; Kermani, M.J.

    2013-01-01

    Highlights: • Effect of corrugated flow channel on the heat exchange of DMFC is studied. • Corrugated boundary (except rectangular type) increase heat transfer up to 90%. • Average heat transfer in rectangular-corrugated boundary is less than straight one. • In Re > 60, wavy shape boundary has highest heat transfer. • In Re < 60, triangular shape boundary has highest heat transfer. - Abstract: In this paper, heat transfer and flow field analysis in anode side of direct methanol fuel cells (DMFCs) is numerically studied. To enhance the heat exchange between bottom cold wall and core flow, bottom wall of fluid delivery channel is considered as corrugated boundary instead of straight (flat) one. Four different shapes of corrugated boundary are recommended here: rectangular shape, trapezoidal shape, triangular shape and wavy (sinusoidal) shape. The top wall of the channel (catalyst layer boundary) is taken as hot boundary, because reaction occurs in catalyst layer and the bottom wall of the channel is considered as cold boundary due to coolant existence. The governing equations are numerically solved in the domain by the control volume approach based on the SIMPLE technique (1972). A wide spectrum of numerical studies is performed over a range of various shape boundaries, Reynolds number, triangle block number, and the triangle block amplitude. The performed parametric studies show that corrugated channel with trapezoidal, triangular and wavy shape enhances the heat exchange up to 90%. With these boundaries, cooling purpose of reacting flow in anode side of DMFCs would be better than straight one. Also, from the analogy between the heat and mass transfer problems, it is expected that the consumption of reacting species within the catalyst layer of DMFCs enhance. The present work provides helpful guidelines to the bipolar plate manufacturers of DMFCs to considerably enhance heat transfer and performance of the anode side of DMFC

  3. Numerical investigation on the effect of injection pressure on the internal flow characteristics for diethyl ether, dimethyl ether and diesel fuel injectors using CFD

    Directory of Open Access Journals (Sweden)

    Vijayakumar Thulasi

    2011-01-01

    Full Text Available The spray characteristics of the diesel fuel are greatly affected by the cavitation formed inside the injector due to the high pressure differential across the nozzle. Many researchers across the globe are exploring the potential of using diethyl ether and dimethyl ether as an alternate for diesel fuel to meet the strict emission norms. Due to the variation in the fuel properties the internal flow characteristics in injectors for ether fuels are expected to be different from that of the diesel fuel. In this paper computational technique is used to study and compare the internal flow characteristics of diethyl ether, dimethyl ether and diesel fuel. The two phase flow model considering the fuel as a mixture of liquid and vapor is adopted for the simulation study. The injection pressure is varied from 100 to 400 bar and the flow characteristics of all three fuels are simulated and compared. Results indicate that all three fuels have distinct cavitating patterns owing to different property values. The dimethyl ether is found to be more cavitating than diesel and diethyl ether fuels as expected. The mass of fuel injected are found to be decreasing for the ether fuels when compared with diesel fuel at all injection pressures.

  4. Combustion of Solid Fuel in a Vortex Furnace with Counter-swirling Flows

    Directory of Open Access Journals (Sweden)

    Redko A.A.

    2017-12-01

    Full Text Available The results of computer simulation of the processes of incineration of low-grade solid fuel-pulverized peat with a moisture content of 40%, an ash content of 6% are given. It has been determined the fields of distribution of temperature, velocity of gases and particles in the volume and at the outlet from the furnace. The three-dimensional temperature distribution in the combustion chamber indicates high-temperature combustion of peat particles at temperatures above 1700°C with liquid ash removal in the lower part of the furnace. It has been determined that when the furnace is cooled, it is not ensured combustion of the fuel completely. The value of the swirling flow rate at the outlet from the furnace (up to 370 m/s ensures the efficiency of separation of fuel particles, reducing heat losses from mechanical underburning. It is determined that the concentration of oxygen is close to zero over the entire height of the furnace, at an outlet from the furnace the oxygen concentration is 5...6%, since oxygen is supplied with excess (αв=1,2. The results of a numerical study showed that the diameter of peat particles affects the process of their combustion: coke particles with an initial diameter of 25 mkm to 250 mkm burn out by 96%. With an increase in particle diameter up to 1000 mkm, the degree of burn-out of coke decreases, but at the same time their removal decreases. It is shown that the furnace ensures the completeness of combustion of peat particles of peat 99.8%, volatiles is 100%.

  5. Analysis of cold flow fluidization test results for various biomass fuels

    Energy Technology Data Exchange (ETDEWEB)

    Abdullah, M.Z.; Husain, Z.; Pong, S.L.Y. [University Sains Malaysia, Penang (Malaysia). School of Mechanical Engineering

    2003-07-01

    A systematic theoretical and experimental study was conducted to obtain hydrodynamic properties such as particle size diameter, bulk density, fluidizing velocity, etc. for locally available biomass residue fuels in Malaysia like rice husk, sawdust, peanut shell, coconut shell, palm fiber as well as coal and bottom ash. The tests were carried out in a cold flow fluidization bed chamber of internal diameter 60 mm with air as fluidizing medium. Bed-pressure drop was measured as a function of superficial air velocity over a range of bed heights for each individual type of particle. The data were used to determine minimum fluidization velocity, which could be used to compare with theoretical values. The particle size of biomass residue fuel was classified according to Gildart's distribution diagram. The results show that Gildart's particle size (B) for sawdust, coal bottom ash, coconut shell have good fluidizing properties compared to rice husk, type (D) or palm fiber, type (A). The bulk density and voidage are found to be main factors contributing to fluidizing quality of the bed.

  6. Mass transport aspects of polymer electrolyte fuel cells under two-phase flow conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, D.

    2007-03-27

    This work deals with selected aspects of mass transport phenomena in PEFCs and DMFCs. Emphasis is placed on the implications originating from the occurrence of two-phase flow within these devices. Optimality of supply, distribution, and removal of the fuel, the oxidant, and the reaction products is of utmost importance for the stability, efficiency, and durability of the devices. Being a prerequisite for high current densities while maintaining sufficient voltage, mass transport optimization contributes to the development of cost effective as well as compact designs and hence competitive fuel cells. [German] Die Visualisierung und Quantifizierung von Fluessigwasseransammlungen in Polymerelektrolytmembran-Brennstoffzellen konnte mittels Neutronenradiographie erreicht werden. Dank dieser neuartigen diagnostischen Methode konnte erstmals die Fluessigwasseransammlung in den poroesen Gasdiffusionsschichten direkt nachgewiesen und quantifiziert werden. Die Kombination von Neutronenradiographie mit ortsaufgeloesten Stromdichtemessungen bzw. lokaler Impedanzspektroskopie erlaubte die Korrelation des inhomogenen Fluessigwasseranfalls mit dem lokalen elektrochemischen Leistungsverhalten. Systematische Untersuchungen an Polymerelektrolyt- und Direkt-Methanol-Brennstoffzellen verdeutlichen sowohl den Einfluss von Betriebsbedingungen als auch die Auswirkung von Materialeigenschaften auf die Ausbildung zweiphasiger Stroemungen.

  7. Rapid detection of defects in fuel-cell electrodes using infrared reactive-flow-through technique

    Science.gov (United States)

    Das, Prodip K.; Weber, Adam Z.; Bender, Guido; Manak, Austin; Bittinat, Daniel; Herring, Andrew M.; Ulsh, Michael

    2014-09-01

    As fuel cells become more prominent, new manufacturing and production methods will need to be developed to deal efficiently and effectively with increased demand. One necessary component of this industrial growth is the accurate measurement of the variability in the manufacturing process. In this study, we present a diagnostic system that combines infrared thermography with a reactive-flow-through technique to detect catalyst-loading defects in fuel-cell gas-diffusion electrodes accurately with high spatial and temporal resolutions. Experimental results are compared with model predictions of thermal response with good agreement. Data analysis, operating-condition impacts, and detection limits are explored using both experiments and simulation. Overall, the results demonstrate the potential of this technique to measure defects on the millimeter length scale with temporal resolutions appropriate for use on a web-line. Thus we present the first development stage of a next-generation non-destructive diagnostic tool, which may be amenable to eventual use on roll-to-roll manufacturing lines.

  8. Installation, test and non-linear vibratory analysis of an experiment with four fuel assembly models under axial flow

    International Nuclear Information System (INIS)

    Clement, Simon

    2014-01-01

    The present study is in the scope of pressurized water reactors (PWR) core response to earthquakes. The goal of this thesis is to measure the coupling between fuel assemblies caused an axial water flow. The design, production and installation a new test facility named ICARE EXPERIMENTAL are presented. ICARE EXPERIMENTAL was built in order to measure simultaneously the vibrations of four fuel assemblies (2 x 2) under an axial flow. Vibrations are produced by imposing the dynamic of one of the fuel assemblies and the displacements of the three others, induced by the fluid, are measured in the horizontal plane at grids level. A new data analysis method combining time-frequency analysis and orthogonal mode decomposition (POD) is described. This method, named Sliding Window POD (SWPOD), allows analysing multicomponent data, of which spatial repartition of energy and frequency content are time dependent. In the case of mechanical systems (linear and nonlinear), the link between the proper orthogonal modes obtained through SWPOD and the normal modes (linear and nonlinear) is studied. The SWPOD is applied to experimental tests of a steam generators U-tube, showing the appearance of internal resonances. The method is also applied to dynamic experimental tests of a fuel assembly under axial flow, the evolution of its normal modes is obtained as a function of the fluid velocity. The measures acquired with the ICARE EXPERIMENTAL installation are analysed using the SWPOD. The first results show characteristic behavior of the free fuel assemblies at their resonances. The coupling between fuel assemblies, induced by the fluid, is reproduced by simulations performed using the COEUR3D code. This code is based on a porous media model in order to simulate a fuel assemblies network under axial flow. (author) [fr

  9. Tandem Gravimetric and Volumetric Apparatus for Methane Sorption Measurements

    Science.gov (United States)

    Burress, Jacob; Bethea, Donald

    Concerns about global climate change have driven the search for alternative fuels. Natural gas (NG, methane) is a cleaner fuel than gasoline and abundantly available due to hydraulic fracturing. One hurdle to the adoption of NG vehicles is the bulky cylindrical storage vessels needed to store the NG at high pressures (3600 psi, 250 bar). The adsorption of methane in microporous materials can store large amounts of methane at low enough pressures for the allowance of conformable, ``flat'' pressure vessels. The measurement of the amount of gas stored in sorbent materials is typically done by measuring pressure differences (volumetric, manometric) or masses (gravimetric). Volumetric instruments of the Sievert type have uncertainties that compound with each additional measurement. Therefore, the highest-pressure measurement has the largest uncertainty. Gravimetric instruments don't have that drawback, but can have issues with buoyancy corrections. An instrument will be presented with which methane adsorption measurements can be performed using both volumetric and gravimetric methods in tandem. The gravimetric method presented has no buoyancy corrections and low uncertainty. Therefore, the gravimetric measurements can be performed throughout an entire isotherm or just at the extrema to verify the results from the volumetric measurements. Results from methane sorption measurements on an activated carbon (MSC-30) and a metal-organic framework (Cu-BTC, HKUST-1, MOF-199) will be shown. New recommendations for calculations of gas uptake and uncertainty measurements will be discussed.

  10. Flow induced deformation and collapse of a thin rectangular plate with application to the Engineering Test Reactor nuclear fuel elements

    International Nuclear Information System (INIS)

    Davis, C.D.

    1981-01-01

    This work examines a single flat fuel plate bounded by two channels and determines static plate deflections, resultant forces and bending stresses due to pressure differential and hydrodynamic loadings. The classical then reactangular plate equations are used to model the fuel plate. These equations contain as an input the hydrodynamic loading function for modeling the fluid-structural interaction. Two models of the channel flow are developed. One assumes the accelerating potential core flow is laminar with developing two-dimensional laminar boundary layers being formed on the channel walls. The Schlichting entry length solution for developing laminar flow is found to be valid the entire length of the channel. The second model assumes the core flow is fully-developed turbulent the entire length of the channel. Hydrodynamic loading functions are developed for both flow models containing parameters for fluid density, fluid velocity, Reynolds number and channel and plate dimensions. Hence the effects of each parameter can be examined independently. A criterion is developed for predicting ETR fuel plate collapse at high channel flow velocities, 1067 cm/s (420 in/sec) (R/sub e/ = 60,000). The criterion predicts that in order to prevent ETR plate collapse the inlet velocities between channels must not differ by more than 2%

  11. Performance Characteristics of a PEM Fuel Cell with Parallel Flow Channels at Different Cathode Relative Humidity Levels

    Directory of Open Access Journals (Sweden)

    Sang Soon Hwang

    2009-11-01

    Full Text Available In fuel cells flow configuration and operating conditions such as cell temperature, humidity at each electrode and stoichiometric number are very crucial for improving performance. Too many flow channels could enhance the performance but result in high parasite loss. Therefore a trade-off between pressure drop and efficiency of a fuel cell should be considered for optimum design. This work focused on numerical simulation of the effects of operating conditions, especially cathode humidity, with simple micro parallel flow channels. It is known that the humidity at the cathode flow channel becomes very important for enhancing the ion conductivity of polymer membrane because fully humidified condition was normally set at anode. To investigate the effect of humidity on the performance of a fuel cell, in this study humidification was set to 100% at the anode flow channel and was changed by 0–100% at the cathode flow channel. Results showed that the maximum power density could be obtained under 60% humidified condition at the cathode where oxygen concentration was moderately high while maintaining high ion conductivity at a membrane.

  12. Paper-based enzymatic microfluidic fuel cell: From a two-stream flow device to a single-stream lateral flow strip

    Science.gov (United States)

    González-Guerrero, Maria José; del Campo, F. Javier; Esquivel, Juan Pablo; Giroud, Fabien; Minteer, Shelley D.; Sabaté, Neus

    2016-09-01

    This work presents a first approach towards the development of a cost-effective enzymatic paper-based glucose/O2 microfluidic fuel cell in which fluid transport is based on capillary action. A first fuel cell configuration consists of a Y-shaped paper device with the fuel and the oxidant flowing in parallel over carbon paper electrodes modified with bioelectrocatalytic enzymes. The anode consists of a ferrocenium-based polyethyleneimine polymer linked to glucose oxidase (GOx/Fc-C6-LPEI), while the cathode contains a mixture of laccase, anthracene-modified multiwall carbon nanotubes, and tetrabutylammonium bromide-modified Nafion (MWCNTs/laccase/TBAB-Nafion). Subsequently, the Y-shaped configuration is improved to use a single solution containing both, the anolyte and the catholyte. Thus, the electrolytes pHs of the fuel and the oxidant solutions are adapted to an intermediate pH of 5.5. Finally, the fuel cell is run with this single solution obtaining a maximum open circuit of 0.55 ± 0.04 V and a maximum current and power density of 225 ± 17 μA cm-2 and 24 ± 5 μW cm-2, respectively. Hence, a power source closer to a commercial application (similar to conventional lateral flow test strips) is developed and successfully operated. This system can be used to supply the energy required to power microelectronics demanding low power consumption.

  13. On the calculation of flow and heat transfer characteristics for CANDU-type 19-rod fuel bundles

    International Nuclear Information System (INIS)

    Yuh-Shan Yueh; Ching-Chang Chieng

    1987-01-01

    A numerical study is reported of flow and heat transfer in a CANDU-type 19 rod fuel bundle. The flow domain of interest includes combinations of trangular, square, and peripheral subchannels. The basic equations of momentum and energy are solved with the standard k--ε model of turbulence. Isotropic turbulent viscosity is assumed and no secondary flow is considered for this steady-state, fully developed flow. Detailed velocity and temperature distributions with wall shear stress and Nusselt number distributions are obtained for turbulent flow of Re = 4.35 x 10 4 , 10 5 , 2 x 10 5 , and for laminar flow of Re--2400. Friction factor and heat transfer ceofficients of various subchannels inside the full bundle are compared with those of infinite rod arrays of triangular or square arrangements. The calculated velocity contours of peripheral subchannel agreed reasonably with measured data

  14. Peak expiratory flow rate (PEFR) among Nuclear Fuel Complex (NFC) employees

    International Nuclear Information System (INIS)

    Vijay Rao, J.; Venkaiah, K.; Mohan Rao, N.

    2010-01-01

    At Nuclear Fuel Complex (NFC), employees are exposed to ammonia, hydrofluoric acid, acetone, etc., which are respiratory toxicants and inhalation of these pollutants may produce irritation and obstruction in airways. Due to nature of their occupation, tradesman working in plants are having longer duration of exposure (LDE) and others, such as supervisors, scientific officers, helpers, etc., that occasionally visit plants are having shorter duration of exposure (SDE) to these pollutants. The peak expiratory flow rate (PEFR) is an index to diagnose obstruction in larger airways and this is metered with mini peak flow meter among 835 NFC employees. Using ANOVA test, PEFR value was compared according to age and smoking. The value was compared between LDE and SDE employees according to smoking and duration of employment. The multiple regression equation for prediction of PEFR was developed. Age, smokers and higher duration of LDE employees demonstrated significantly lower PEFR value. In comparison to 10 year duration, 30 and above year duration of employment, LDE employees showed a higher decline in PEFR, that is 95 L (17.6%) and in SDE employees, that is 41L (7.8%). This may be due to longer duration of employment of LD employees smoking prevention and follow up study is suggested. (author)

  15. Mapping Global Flows of Chemicals: From Fossil Fuel Feedstocks to Chemical Products.

    Science.gov (United States)

    Levi, Peter G; Cullen, Jonathan M

    2018-02-20

    Chemical products are ubiquitous in modern society. The chemical sector is the largest industrial energy consumer and the third largest industrial emitter of carbon dioxide. The current portfolio of mitigation options for the chemical sector emphasizes upstream "supply side" solutions, whereas downstream mitigation options, such as material efficiency, are given comparatively short shrift. Key reasons for this are the scarcity of data on the sector's material flows, and the highly intertwined nature of its complex supply chains. We provide the most up to date, comprehensive and transparent data set available publicly, on virgin production routes in the chemical sector: from fossil fuel feedstocks to chemical products. We map global mass flows for the year 2013 through a complex network of transformation processes, and by taking account of secondary reactants and by-products, we maintain a full mass balance throughout. The resulting data set partially addresses the dearth of publicly available information on the chemical sector's supply chain, and can be used to prioritise downstream mitigation options.

  16. An experimental and analytical study of fluid flow and critical heat flux in PWR fuel elements

    International Nuclear Information System (INIS)

    Bowditch, F.H.; Mogford, D.J.

    1987-02-01

    This report describes experiments that have been carried out at the Winfrith Establishment of the United Kingdom Atomic Energy Authority to determine the critical heat flux characteristics of pressurized water reactor fuel elements over an unusually wide range of coolant flow conditions that are relevant to both normal and fault conditions of reactor operation. The experiments were carried out in the TITAN loop using an electrically heated bundle of 25 rods of 9.5 mm diameter on a 12.7 mm pitch fitted with plain grids in order to provide a generic base for code validation. The fully tabulated experimental data for critical heat flux, pressure drop and sub-channel mixing are encompassed by ranges of pressure between 20 and 160 Bar, coolant flow between 150 and 3600 Kg/m 2 s, and coolant inlet temperature between 150 and 320 0 C. The results of the experiments are compared with predicted data based upon several established critical heat flux correlations. It is concluded that the extrapolation of some correlations to conditions beyond their intended range of application can lead to dangerous over estimates of critical heat flux, but the Winfrith WSC-2 and the EPRI NP-2609 correlations perform well over the whole data range and correlate all data with RMS errors of 9% and 6% respectively. (author)

  17. Numerical simulation of internal and near-nozzle flow of a gasoline direct injection fuel injector

    Science.gov (United States)

    Saha, Kaushik; Som, Sibendu; Battistoni, Michele; Li, Yanheng; Quan, Shaoping; Senecal, Peter Kelly

    2015-12-01

    A numerical study of two-phase flow inside the nozzle holes and the issuing spray jets for a multi-hole direct injection gasoline injector has been presented in this work. The injector geometry is representative of the Spray G nozzle, an eight-hole counterbore injector, from, the Engine Combustion Network (ECN). Simulations have been carried out for the fixed needle lift. Effects of turbulence, compressibility and, non-condensable gases have been considered in this work. Standard k—ɛ turbulence model has been used to model the turbulence. Homogeneous Relaxation Model (HRM) coupled with Volume of Fluid (VOF) approach has been utilized to capture the phase change phenomena inside and outside the injector nozzle. Three different boundary conditions for the outlet domain have been imposed to examine non-flashing and evaporative, non-flashing and non-evaporative, and flashing conditions. Inside the nozzle holes mild cavitation-like and in the near-nozzle region flash boiling phenomena have been predicted in this study when liquid fuel is subjected to superheated ambiance. Noticeable hole to hole variation has been also observed in terms of mass flow rates for all the holes under both flashing and non-flashing conditions.

  18. An initial study on modeling the global thermal and fast reactor fuel cycle mass flow using Vensim

    International Nuclear Information System (INIS)

    Brinton, Samuel

    2008-01-01

    This study concentrated on modeling the construction and decommissioning rates of five major facilities comprising the nuclear fuel cycle: (1) current LWRs with a 60-year service life, (2) new LWRs burning MOX fuel, (3) new LWRs to replace units in the current fleet, (4) new FRs to be added to the fleet, and (5) new spent fuel reprocessing facilities. This is a mass flow mode starting from uranium ore and following it to spent forms. The visual dynamic modeling program Vensim was used to create a system of equations and variables to track the mass flows from enrichment, fabrication, burn-up, and the back-end of the fuel cycle. The scenarios considered provide estimates of the uranium ore requirements, quantities of LLW and HLW production, and the number of reprocessing facilities necessary to reduce recently reported levels of spent fuel inventory. Preliminary results indicate that the entire national spent fuel inventory produced in the next 100 years can be reprocessed with a reprocessing plant built every 11 years (small capacity) or even as low as every 23 years (large capacity). (authors)

  19. Analytical and numerical study on cooling flow field designs performance of PEM fuel cell with variable heat flux

    Science.gov (United States)

    Afshari, Ebrahim; Ziaei-Rad, Masoud; Jahantigh, Nabi

    2016-06-01

    In PEM fuel cells, during electrochemical generation of electricity more than half of the chemical energy of hydrogen is converted to heat. This heat of reactions, if not exhausted properly, would impair the performance and durability of the cell. In general, large scale PEM fuel cells are cooled by liquid water that circulates through coolant flow channels formed in bipolar plates or in dedicated cooling plates. In this paper, a numerical method has been presented to study cooling and temperature distribution of a polymer membrane fuel cell stack. The heat flux on the cooling plate is variable. A three-dimensional model of fluid flow and heat transfer in cooling plates with 15 cm × 15 cm square area is considered and the performances of four different coolant flow field designs, parallel field and serpentine fields are compared in terms of maximum surface temperature, temperature uniformity and pressure drop characteristics. By comparing the results in two cases, the constant and variable heat flux, it is observed that applying constant heat flux instead of variable heat flux which is actually occurring in the fuel cells is not an accurate assumption. The numerical results indicated that the straight flow field model has temperature uniformity index and almost the same temperature difference with the serpentine models, while its pressure drop is less than all of the serpentine models. Another important advantage of this model is the much easier design and building than the spiral models.

  20. 1D + 3D two-phase flow numerical model of a proton exchange membrane fuel cell

    International Nuclear Information System (INIS)

    Ferreira, Rui B.; Falcão, D.S.; Oliveira, V.B.; Pinto, A.M.F.R.

    2017-01-01

    Highlights: •A 1D + 3D model of a PEM fuel cell is described and experimentally validated. •VOF method tracks the two-phase flow and electrochemical reactions are considered. •Water dynamics inside a serpentine channel is analyzed for different voltages. •Water content in different regions of channel is quantified. •Important issues on coupling of the VOF model with electrochemical reactions are addressed. -- Abstract: In this work, a numerical model of a proton exchange membrane (PEM) fuel cell is presented. The volume of fluid (VOF) method is employed to simulate the air-water two-phase flow in the cathode gas channel, at the same time that the cell electrochemical performance is predicted. The model is validated against an experimental polarization curve and through the visualization of water distribution inside a transparent fuel cell. The water dynamics inside a serpentine gas channel is numerically analyzed under different operating voltages. Moreover, water content in different regions of the channel is quantified. Current density and water generation rate spatial distributions are also displayed and it is shown how they affect the process of water emergence into the gas channel. Important issues on the simulation of the PEM fuel cells two-phase flow are addressed, especially concerning the coupling of the VOF technique with electrochemical reactions. Both the model and the numerical results aim to contribute to a better understanding of the two-phase flow phenomenon that occurs in these devices.

  1. Experimental study of water flow in nuclear fuel elements; Estudo experimental do escoamento de agua em elementos combustiveis nucleares

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Lorena Escriche, E-mail: ler@cdtn.br [Centro Federal de Educacao Tecnologica de Minas Gerais (CEFET), Belo Horizonte, MG (Brazil); Rezende, Hugo Cesar; Mattos, Joao Roberto Loureiro de; Barros Filho, Jose Afonso; Santos, Andre Augusto Campagnole dos, E-mail: hcr@cdtn.br, E-mail: jrmattos@cdtn.br, E-mail: jabf@cdtn.br, E-mail: aacs@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2013-07-01

    This work aims to develop an experimental methodology for investigating the water flow through rod bundles after spacer grids of nuclear fuel elements of PWR type reactors. Speed profiles, with the device LDV (Laser Doppler Velocimetry), and the pressure drop between two sockets located before and after the spacer grid, using pressure transducers were measured.

  2. Summary and evaluation: fuel dynamics loss-of-flow experiments (tests L2, L3, and L4)

    International Nuclear Information System (INIS)

    Barts, E.W.; Deitrich, L.W.; Eberhart, J.G.; Fischer, A.K.; Meek, C.C.

    1975-09-01

    Three similar experiments conducted to support the analyses of hypothetical LMFBR unprotected-loss-of-flow accidents are summarized and evaluated. The tests, designated L2, L3, and L4, provided experimental data against which accident-analysis codes could be compared, so as to guide further analysis and modeling of the initiating phases of the hypothetical accident. The tests were conducted using seven-pin bundles of mixed-oxide fuel pins in Mark-II flowing-sodium loops in the TREAT reactor. Test L2 used fresh fuel. Tests L3 and L4 used irradiated fuel pins having, respectively, ''intermediate-power'' (no central void) and ''high-power'' (fully developed central void) microstructure. 12 references

  3. Ruthenium cluster-like chalcogenide as a methanol tolerant cathode catalyst in air-breathing laminar flow fuel cells

    International Nuclear Information System (INIS)

    Whipple, Devin T.; Jayashree, Ranga S.; Egas, Daniela; Alonso-Vante, Nicolas; Kenis, Paul J.A.

    2009-01-01

    This paper reports the incorporation of a cluster-like Ru x Se y as a methanol tolerant cathode catalyst in a laminar flow fuel cell. The effect on cell performance of several concentrations of methanol in the cathode stream was investigated for the Ru x Se y catalyst and compared to a conventional platinum catalyst. While the Pt catalyst exhibited up to ∼80% drop in power density, the Ru x Se y catalyst showed no decrease in performance when the cathode was exposed to methanol. At several methanol concentrations the Ru x Se y catalyst performed better than the Pt catalyst. This demonstration of a methanol tolerant catalyst in a laminar flow fuel cell opens up the way for further miniaturization of the cell design and simplification of its operation as the need for an electrolyte stream to prevent fuel crossover has been eliminated.

  4. A small-scale flow alkaline fuel cell for on-site production of hydrogen peroxide

    International Nuclear Information System (INIS)

    Brillas, Enric; Alcaide, Francisco; Cabot, Pere-Lluis

    2002-01-01

    The behavior of a small-scale flow alkaline fuel cell (AFC) built-up for on-site production of HO 2 - using commercial gas-diffusion electrodes has been studied. It produces a spontaneous current due to the oxidation of H 2 to H 2 O at the H 2 -diffusion anode and the reduction of O 2 to HO 2 - at the O 2 -diffusion cathode, while a fresh 1.0-6.0 mol dm -3 KOH electrolyte at 15.0-45.0 deg. C is injected through it. Under circulation of HO 2 - +KOH solutions in open circuit, the flow AFC behaves as a two-electron reversible system. When it is shorted with an external load (R ext ), steady cell voltage-current density curves are found. The use of O 2 /N 2 mixtures to fed the cathode causes a loss of its performance, being required to supply pure O 2 to yield a maximum HO 2 - electrogeneration. The current density and HO 2 - productivity increase with raising OH - concentration, temperature and pressure of O 2 fed. At R ext =0.10 Ω, a current efficiency close to 100% is obtained, and current densities >100 mA cm -2 are achieved for 1.0 mol dm -3 KOH at 45.0 deg. C and for higher KOH concentrations at 25.0 deg. C. The flow AFC can work under optimum conditions up to 6.0 mol dm -3 KOH and 45.0 deg. C for possible industrial applications

  5. Three-dimensional analysis of the coolant flow characteristics in the fuel assemblies of VVER-1000 reactors

    International Nuclear Information System (INIS)

    Dinh Van Thin; Tran Thi Nhan

    2015-01-01

    Computational Fluid Dynamics (CFD) is a widely used method around the world for complex flow and heat industrial problems. In this paper, the coolant flow parameters were investigated in subchannels of VVER-1000 reactor’s fuel assemblies by ANSYS V14.5 programme. The different mesh solutions and turbulence models were carried out to deal with the water flow problems such as velocity distribution, streamline, temperature and pressure change as well as the hydraulic resistances of the spacer grids. The obtained results are good agreement with the measured values and the published reports from other authors. (author)

  6. Gradients estimation from random points with volumetric tensor in turbulence

    Science.gov (United States)

    Watanabe, Tomoaki; Nagata, Koji

    2017-12-01

    We present an estimation method of fully-resolved/coarse-grained gradients from randomly distributed points in turbulence. The method is based on a linear approximation of spatial gradients expressed with the volumetric tensor, which is a 3 × 3 matrix determined by a geometric distribution of the points. The coarse grained gradient can be considered as a low pass filtered gradient, whose cutoff is estimated with the eigenvalues of the volumetric tensor. The present method, the volumetric tensor approximation, is tested for velocity and passive scalar gradients in incompressible planar jet and mixing layer. Comparison with a finite difference approximation on a Cartesian grid shows that the volumetric tensor approximation computes the coarse grained gradients fairly well at a moderate computational cost under various conditions of spatial distributions of points. We also show that imposing the solenoidal condition improves the accuracy of the present method for solenoidal vectors, such as a velocity vector in incompressible flows, especially when the number of the points is not large. The volumetric tensor approximation with 4 points poorly estimates the gradient because of anisotropic distribution of the points. Increasing the number of points from 4 significantly improves the accuracy. Although the coarse grained gradient changes with the cutoff length, the volumetric tensor approximation yields the coarse grained gradient whose magnitude is close to the one obtained by the finite difference. We also show that the velocity gradient estimated with the present method well captures the turbulence characteristics such as local flow topology, amplification of enstrophy and strain, and energy transfer across scales.

  7. Effects of structure parameters on flow and cavitation characteristics within control valve of fuel injector for modern diesel engine

    International Nuclear Information System (INIS)

    Wang, Chao; Li, Guo-Xiu; Sun, Zuo-Yu; Wang, Lan; Sun, Shu-Ping; Gu, Jiao-Jiao; Wu, Xiao-Jun

    2016-01-01

    Highlights: • The Schnerr-Sauer model was used to calculate the cavitation source term. • The development process and influencing factors of cavitation were studied. • The flow process inside control valve during the ball valve opened were studied. • The effects of the structure parameters of the control valve on the cavitation and flow were studied. - Abstract: Cavitation is a common phenomenon in diesel injector and has a strong influence on the internal flow. However, studies so far have focused on cavitation characteristics inside the nozzle. Its influence on the flow during control valve opening remains still unclear. In the paper, a computational study focused on the flow and cavitation phenomena within control valve has been reported and the effects of control valve’s structure parameters (including rounded edge, seal cone angle and outflowing control-orifice structure) on the flow and cavitation characteristics have been investigated in detail. Firstly the 3D model has been validated in terms of single injection quantity and fuel injection duration, showing a good consistency. And then, the development from sheet cavitation to cloud cavitation and the relationship between cavitation, pressure and velocity has been discussed. Based on the numerical results obtained, it is shown that not only the variation of pressure but also the velocity is the important factor which affects cavitation. The increase of the flow velocity reduces the pressure within the flow field which can aggravate the development of cavitation. As cavitation region increases, the fuel flow is hindered and the flow velocity decreases. However, the decrease of flow velocity has suppressed the development of cavitation. All of those variations form a cyclical process.

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

    International Nuclear Information System (INIS)

    Burkholder, Michael B.; Litster, Shawn

    2016-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-05-15

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

  10. Design, fabrication and testing of an air-breathing micro direct methanol fuel cell with compound anode flow field

    International Nuclear Information System (INIS)

    Wang, Luwen; Zhang, Yufeng; Zhao, Youran; An, Zijiang; Zhou, Zhiping; Liu, Xiaowei

    2011-01-01

    An air-breathing micro direct methanol fuel cell (μDMFC) with a compound anode flow field structure (composed of the parallel flow field and the perforated flow field) is designed, fabricated and tested. To better analyze the effect of the compound anode flow field on the mass transfer of methanol, the compound flow field with different open ratios (ratio of exposure area to total area) and thicknesses of current collectors is modeled and simulated. Micro process technologies are employed to fabricate the end plates and current collectors. The performances of the μDMFC with a compound anode flow field are measured under various operating parameters. Both the modeled and the experimental results show that, comparing the conventional parallel flow field, the compound one can enhance the mass transfer resistance of methanol from the flow field to the anode diffusion layer. The results also indicate that the μDMFC with an anode open ratio of 40% and a thickness of 300 µm has the optimal performance under the 7 M methanol which is three to four times higher than conventional flow fields. Finally, a 2 h stability test of the μDMFC is performed with a methanol concentration of 7 M and a flow velocity of 0.1 ml min −1 . The results indicate that the μDMFC can work steadily with high methanol concentration.

  11. Impact of Flight Enthalpy, Fuel Simulant, and Chemical Reactions on the Mixing Characteristics of Several Injectors at Hypervelocity Flow Conditions

    Science.gov (United States)

    Drozda, Tomasz G.; Baurle, Robert A.; Drummond, J. Philip

    2016-01-01

    The high total temperatures or total enthalpies required to duplicate the high-speed flight conditions in ground experiments often place stringent requirements on the material selection and cooling needs for the test articles and intrusive flow diagnostic equipment. Furthermore, for internal flows, these conditions often complicate the use of nonintrusive diagnostics that need optical access to the test section and interior portions of the flowpath. Because of the technical challenges and increased costs associated with experimentation at high values of total enthalpy, an attempt is often made to reduce it. This is the case for the Enhanced Injection and Mixing Project (EIMP) currently underway in the Arc-Heated Scramjet Test Facility at the NASA Langley Research Center. The EIMP aims to investigate supersonic combustion ramjet (scramjet) fuel injection and mixing physics, improve the understanding of underlying physical processes, and develop enhancement strategies and functional relationships between mixing performance and losses relevant to flight Mach numbers greater than 8. The experiments will consider a "direct-connect" approach and utilize a Mach 6 nozzle to simulate the combustor entrance flow of a scramjet engine. However, while the value of the Mach number is matched to that expected at the combustor entrance in flight, the maximum value of the total enthalpy for these experiments is limited by the thermal-structural limits of the uncooled experimental hardware. Furthermore, the fuel simulant is helium, not hydrogen. The use of "cold" flows and non-reacting mixtures of fuel simulants for mixing experiments is not new and has been extensively utilized as a screening technique for scramjet fuel injectors. In this study, Reynolds-averaged simulations are utilized (RAS) to systematically verify the implicit assumptions used by the EIMP. This is accomplished by first performing RAS of mixing for two injector configurations at planned nominal experimental

  12. On the role of radiation and dimensionality in predicting flow opposed flame spread over thin fuels

    Science.gov (United States)

    Kumar, Chenthil; Kumar, Amit

    2012-06-01

    In this work a flame-spread model is formulated in three dimensions to simulate opposed flow flame spread over thin solid fuels. The flame-spread model is coupled to a three-dimensional gas radiation model. The experiments [1] on downward spread and zero gravity quiescent spread over finite width thin fuel are simulated by flame-spread models in both two and three dimensions to assess the role of radiation and effect of dimensionality on the prediction of the flame-spread phenomena. It is observed that while radiation plays only a minor role in normal gravity downward spread, in zero gravity quiescent spread surface radiation loss holds the key to correct prediction of low oxygen flame spread rate and quenching limit. The present three-dimensional simulations show that even in zero gravity gas radiation affects flame spread rate only moderately (as much as 20% at 100% oxygen) as the heat feedback effect exceeds the radiation loss effect only moderately. However, the two-dimensional model with the gas radiation model badly over-predicts the zero gravity flame spread rate due to under estimation of gas radiation loss to the ambient surrounding. The two-dimensional model was also found to be inadequate for predicting the zero gravity flame attributes, like the flame length and the flame width, correctly. The need for a three-dimensional model was found to be indispensable for consistently describing the zero gravity flame-spread experiments [1] (including flame spread rate and flame size) especially at high oxygen levels (>30%). On the other hand it was observed that for the normal gravity downward flame spread for oxygen levels up to 60%, the two-dimensional model was sufficient to predict flame spread rate and flame size reasonably well. Gas radiation is seen to increase the three-dimensional effect especially at elevated oxygen levels (>30% for zero gravity and >60% for normal gravity flames).

  13. Effect of removal of a central thimble on coolant flow distribution in a research reactor fuel element

    International Nuclear Information System (INIS)

    Green, W.J.

    1977-01-01

    Using two twice full-size models of a HIFAR research reactor fuel element, experiments have been performed to determine how the flow distribution of coolant gas through the element in a transfer flask is affected by removal of the central instrumentation thimble. With the thimble present, experimental flow results agree with theoretical predictions. Over the range of total flowrates considered, mass flow apportioning among the five annular channels was independent of annular channel Reynolds number (in the range 3500 to 10,500) and ranged between 13% and 27% of the total flowrate. For the case with the thimble removed, interesting experimental flow characteristics were obtained which could not have been predicted. Flow apportioning among the annular channels was found to be uniquely dependent upon total flowrate and ranged between 3% and 8% for the experimental conditions investigated (annular channel Reynolds numbers in the range 800 to 4000). (Author)

  14. System and method having multi-tube fuel nozzle with differential flow

    Science.gov (United States)

    Hughes, Michael John; Johnson, Thomas Edward; Berry, Jonathan Dwight; York, William David

    2017-01-03

    A system includes a multi-tube fuel nozzle with a fuel nozzle body and a plurality of tubes. The fuel nozzle body includes a nozzle wall surrounding a chamber. The plurality of tubes extend through the chamber, wherein each tube of the plurality of tubes includes an air intake portion, a fuel intake portion, and an air-fuel mixture outlet portion. The multi-tube fuel nozzle also includes a differential configuration of the air intake portions among the plurality of tubes.

  15. Computation fluid dynamic modelling of natural convection heat flow in unpumped molten salt fuel tubes

    International Nuclear Information System (INIS)

    Leefe, S.; Jackson-Laver, P.; Scott, I.R.

    2015-01-01

    Use of static molten salt nuclear fuel in simple tubes was discarded in 1949 without considering how convection could affect its utility. This poster describes CFD studies showing that such tubes are practical as fuel elements in essentially conventional fuel assemblies. They can achieve power densities above 250kW per liter of fuel salt (higher than PWR's) and do so without causing the tube wall to heat to dangerous levels. This discovery enables the achievement of the many benefits of molten salt fuel while utilizing the highly developed technology, regulatory, non proliferation and safety benefits of current fuel assembly technology. (author)

  16. Nuclear energy in Europe: uranium flow modeling and fuel cycle scenario trade-offs from a sustainability perspective.

    Science.gov (United States)

    Tendall, Danielle M; Binder, Claudia R

    2011-03-15

    The European nuclear fuel cycle (covering the EU-27, Switzerland and Ukraine) was modeled using material flow analysis (MFA).The analysis was based on publicly available data from nuclear energy agencies and industries, national trade offices, and nongovernmental organizations. Military uranium was not considered due to lack of accessible data. Nuclear fuel cycle scenarios varying spent fuel reprocessing, depleted uranium re-enrichment, enrichment assays, and use of fast neutron reactors, were established. They were then assessed according to environmental, economic and social criteria such as resource depletion, waste production, chemical and radiation emissions, costs, and proliferation risks. The most preferable scenario in the short term is a combination of reduced tails assay and enrichment grade, allowing a 17.9% reduction of uranium demand without significantly increasing environmental, economic, or social risks. In the long term, fast reactors could theoretically achieve a 99.4% decrease in uranium demand and nuclear waste production. However, this involves important costs and proliferation risks. Increasing material efficiency is not systematically correlated with the reduction of other risks. This suggests that an overall optimization of the nuclear fuel cycle is difficult to obtain. Therefore, criteria must be weighted according to stakeholder interests in order to determine the most sustainable solution. This paper models the flows of uranium and associated materials in Europe, and provides a decision support tool for identifying the trade-offs of the alternative nuclear fuel cycles considered.

  17. Effect of fuel temperature on the methanol spray and nozzle internal flow

    International Nuclear Information System (INIS)

    Chen, Zhifang; Yao, Anren; Yao, Chunde; Yin, Zenghui; Xu, Han; Geng, Peilin; Dou, Zhancheng; Hu, Jiangtao; Wu, Taoyang; Ma, Ming

    2017-01-01

    Highlights: • Cavitation region increases with the increasing of methanol temperature. • The nozzle exit velocity increases with the increasing of methanol temperature. • The discharge coefficient decreases with the increasing of methanol temperature. • Droplet SMD reduces when methanol temperature increases measured by PDPA system. • Droplet velocity has the maximum value when methanol temperature is 60 °C. - Abstract: The increasing of fuel temperature can reduce the droplet size and have an advantage of improving spray atomization, while investigations of the effect of temperature on the methanol injector internal flow and external spray is rare. Firstly, a detailed three dimensional numerical simulations of nozzle internal flow have been conducted to probe into the cavitation in methanol injector nozzles, and then an experimental study has been carried out to investigate the droplet size and velocity of methanol spray at various temperatures using the Phase Doppler Particle Analyzer (PDPA) detecting system. And results show that the region of cavitations in nozzle orifice enlarges as methanol temperature and injection pressure increases, and the temperature for 'super-cavitation' occurring decreases gradually with the increasing of injection pressure. Moreover, the nozzle exit velocity, discharge coefficient and cavitations number were also analyzed. However, the discharge coefficient reduces nearly equal under various pressure when the methanol temperature is higher than 60 °C. In addition, the Sauter Mean Diameter (SMD) and velocity of methanol droplet were also analyzed, and found that the droplet velocity reaches the maximum value when the methanol temperature is 60 °C.

  18. Local flow management/profile descent algorithm. Fuel-efficient, time-controlled profiles for the NASA TSRV airplane

    Science.gov (United States)

    Groce, J. L.; Izumi, K. H.; Markham, C. H.; Schwab, R. W.; Thompson, J. L.

    1986-01-01

    The Local Flow Management/Profile Descent (LFM/PD) algorithm designed for the NASA Transport System Research Vehicle program is described. The algorithm provides fuel-efficient altitude and airspeed profiles consistent with ATC restrictions in a time-based metering environment over a fixed ground track. The model design constraints include accommodation of both published profile descent procedures and unpublished profile descents, incorporation of fuel efficiency as a flight profile criterion, operation within the performance capabilities of the Boeing 737-100 airplane with JT8D-7 engines, and conformity to standard air traffic navigation and control procedures. Holding and path stretching capabilities are included for long delay situations.

  19. 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)

  20. Influence of cathode flow pulsation on performance of proton exchange membrane fuel cell with interdigitated gas distributors

    International Nuclear Information System (INIS)

    Ramiar, A.; Mahmoudi, A.H.; Esmaili, Q.; Abdollahzadeh, M.

    2016-01-01

    In this paper, a numerical study is conducted in order to investigate the effect of pulsation of air flow at the cathode side of Proton Exchange Membrane (PEM) fuel cell with interdigitated flow field. A two dimensional, isothermal, two-phase, unsteady multi-component transport model is used in order to simulate the transport phenomena. The obtained results are discussed in terms of the influence of flow pulsation on water management and cell performance. The results prove the effectiveness of flow pulsation on improving water removal from cell, enhancing reactants transports to the reaction sites, and increasing the cell performance expressed by increment in the cell limiting current density and maximum output power. The effects of pulsation frequency (f), amplitude (Amp), and mean inlet pressure (P_i_n) on the performance and the output power of the cell, are also investigated. The performance of the cell has no dependency on the frequency range considered in this study. However, as the pulsation amplitude increases the increment in the cell performance is more obvious. Moreover, applying flow pulsation at low flow rates leads to higher efficiency in water removal and performance enhancement. - Highlights: • Mechanism of water and oxygen transport under flow pulsation are discussed. • Pulsating cathode flow increases the limiting current density and output power. • The performance of cell has no significant dependency on pulsation frequency. • The performance and output power increase with the pulsation amplitude. • Using pulsating flow at lower average pressures leads to higher water removal rate.

  1. Performance of PEM fuel cells stack as affected by number of cell and gas flow-rate

    Science.gov (United States)

    Syampurwadi, A.; Onggo, H.; Indriyati; Yudianti, R.

    2017-03-01

    The proton exchange membrane fuel cell (PEMFC) is a promising technology as an alternative green energy due to its high power density, low operating temperatures, low local emissions, quiet operation and fast start up-shutdown. In order to apply fuel cell as portable power supply, the performance investigation of small number of cells is needed. In this study, PEMFC stacks consisting of 1, 3, 5 and 7-cells with an active area of 25 cm2 per cell have been designed and developed. Their was evaluated in variation of gas flow rate. The membrane electrode assembly (MEA) was prepared by hot-pressing commercial gas diffusion electrodes (Pt loading 0.5 mg/cm2) on pre-treated Nafion 117 membrane. The stacks were constructed using bipolar plates in serpentine pattern and Z-type gas flow configuration. The experimental results were presented as polarization and power output curves which show the effects of varying number of cells and H2/O2 flow-rates on the PEMFC performance. The experimental results showed that not only number of cells and gas flow-rates affected the fuel cells performance, but also the operating temperature as a result of electrochemistry reaction inside the cell.

  2. Cold flow testing of the Space Shuttle Main Engine alternate turbopump development high pressure fuel turbine model

    Science.gov (United States)

    Gaddis, Stephen W.; Hudson, Susan T.; Johnson, P. D.

    1992-01-01

    NASA's Marshall Space Flight Center has established a cold airflow turbine test program to experimentally determine the performance of liquid rocket engine turbopump drive turbines. Testing of the SSME alternate turbopump development (ATD) fuel turbine was conducted for back-to-back comparisons with the baseline SSME fuel turbine results obtained in the first quarter of 1991. Turbine performance, Reynolds number effects, and turbine diagnostics, such as stage reactions and exit swirl angles, were investigated at the turbine design point and at off-design conditions. The test data showed that the ATD fuel turbine test article was approximately 1.4 percent higher in efficiency and flowed 5.3 percent more than the baseline fuel turbine test article. This paper describes the method and results used to validate the ATD fuel turbine aerodynamic design. The results are being used to determine the ATD high pressure fuel turbopump (HPFTP) turbine performance over its operating range, anchor the SSME ATD steady-state performance model, and validate various prediction and design analyses.

  3. Effect of oxy-fuel combustion with steam addition on coal ignition and burnout in an entrained flow reactor

    International Nuclear Information System (INIS)

    Riaza, J.; Alvarez, L.; Gil, M.V.; Pevida, C.; Pis, J.J.; Rubiera, F.

    2011-01-01

    The ignition temperature and burnout of a semi-anthracite and a high-volatile bituminous coal were studied under oxy-fuel combustion conditions in an entrained flow reactor (EFR). The results obtained under oxy-fuel atmospheres (21%O 2 -79%CO 2 , 30%O 2 -70% O 2 and 35%O 2 -65%CO 2 ) were compared with those attained in air. The replacement of CO 2 by 5, 10 and 20% of steam in the oxy-fuel combustion atmospheres was also evaluated in order to study the wet recirculation of flue gas. For the 21%O 2 -79%CO 2 atmosphere, the results indicated that the ignition temperature was higher and the coal burnout was lower than in air. However, when the O 2 concentration was increased to 30 and 35% in the oxy-fuel combustion atmosphere, the ignition temperature was lower and coal burnout was improved in comparison with air conditions. On the other hand, an increase in ignition temperature and a worsening of the coal burnout was observed when steam was added to the oxy-fuel combustion atmospheres though no relevant differences between the different steam concentrations were detected. -- Highlights: → The ignition temperature and the burnout of two thermal coals under oxy-fuel combustion conditions were determined. → The effect of the wet recirculation of flue gas on combustion behaviour was evaluated. → Addition of steam caused a worsening of the ignition temperature and coal burnout.

  4. Numerical simulations of carbon monoxide poisoning in high temperature proton exchange membrane fuel cells with various flow channel designs

    International Nuclear Information System (INIS)

    Jiao, Kui; Zhou, Yibo; Du, Qing; Yin, Yan; Yu, Shuhai; Li, Xianguo

    2013-01-01

    Highlights: ► Simulations of CO poisoning in HT-PEMFC with different flow channels are conducted. ► Parallel and serpentine designs result in least and most CO effects, respectively. ► General CO distributions in CLs are similar with different flow channel designs. - Abstract: The performance of high temperature proton exchange membrane fuel cell (HT-PEMFC) is significantly affected by the carbon monoxide (CO) in hydrogen fuel, and the flow channel design may influence the CO poisoning characteristics by changing the reactant flow. In this study, three-dimensional non-isothermal simulations are carried out to investigate the comprehensive flow channel design and CO poisoning effects on the performance of HT-PEMFCs. The numerical results show that when pure hydrogen is supplied, the interdigitated design produces the highest power output, the power output with serpentine design is higher than the two parallel designs, and the parallel-Z and parallel-U designs have similar power outputs. The performance degradation caused by CO poisoning is the least significant with parallel flow channel design, but the most significant with serpentine and interdigitated designs because the cross flow through the electrode is stronger. At low cell voltages (high current densities), the highest power outputs are with interdigitated and parallel flow channel designs at low and high CO fractions in the supplied hydrogen, respectively. The general distributions of absorbed hydrogen and CO coverage fractions in anode catalyst layer (CL) are similar for the different flow channel designs. The hydrogen coverage fraction is higher under the channel than under the land, and is also higher on the gas diffusion layer (GDL) side than on the membrane side; and the CO coverage distribution is opposite to the hydrogen coverage distribution

  5. Flow Characteristics of Ground Vehicle Wake and Its Response to Flow Control

    Science.gov (United States)

    Sellappan, Prabu; McNally, Jonathan; Alvi, Farrukh

    2017-11-01

    Air pollution, fuel shortages, and cost savings are some of the many incentives for improving the aerodynamics of vehicles. Reducing wake-induced aerodynamic drag, which is dependent on flow topology, on modern passenger vehicles is important for improving fuel consumption rates which directly affect the environment. In this research, an active flow control technique is applied on a generic ground vehicle, a 25°Ahmed model, to investigate its effect on the flow topology in the near-wake. The flow field of this canonical bluff body is extremely rich, with complex and unsteady flow features such as trailing wake vortices and c-pillar vortices. The spatio-temporal response of these flow features to the application of steady microjet actuators is investigated. The responses are characterized independently through time-resolved and volumetric velocity field measurements. The accuracy and cost of volumetric measurements in this complex flow field through Stereoscopic- and Tomographic- Particle Image Velocimetry (PIV) will also be commented upon. National Science Foundation PIRE Program.

  6. The Effect of Fuel Mass Fraction on the Combustion and Fluid Flow in a Sulfur Recovery Unit Thermal Reactor

    Directory of Open Access Journals (Sweden)

    Chun-Lang Yeh

    2016-11-01

    Full Text Available Sulfur recovery unit (SRU thermal reactors are negatively affected by high temperature operation. In this paper, the effect of the fuel mass fraction on the combustion and fluid flow in a SRU thermal reactor is investigated numerically. Practical operating conditions for a petrochemical corporation in Taiwan are used as the design conditions for the discussion. The simulation results show that the present design condition is a fuel-rich (or air-lean condition and gives acceptable sulfur recovery, hydrogen sulfide (H2S destruction, sulfur dioxide (SO2 emissions and thermal reactor temperature for an oxygen-normal operation. However, for an oxygen-rich operation, the local maximum temperature exceeds the suggested maximum service temperature, although the average temperature is acceptable. The high temperature region must be inspected very carefully during the annual maintenance period if there are oxygen-rich operations. If the fuel mass fraction to the zone ahead of the choke ring (zone 1 is 0.0625 or 0.125, the average temperature in the zone behind the choke ring (zone 2 is higher than the zone 1 average temperature, which can damage the downstream heat exchanger tubes. If the zone 1 fuel mass fraction is reduced to ensure a lower zone 1 temperature, the temperature in zone 2 and the heat exchanger section must be monitored closely and the zone 2 wall and heat exchanger tubes must be inspected very carefully during the annual maintenance period. To determine a suitable fuel mass fraction for operation, a detailed numerical simulation should be performed first to find the stoichiometric fuel mass fraction which produces the most complete combustion and the highest temperature. This stoichiometric fuel mass fraction should be avoided because the high temperature could damage the zone 1 corner or the choke ring. A higher fuel mass fraction (i.e., fuel-rich or air-lean condition is more suitable because it can avoid deteriorations of both zone 1

  7. Entropy generation analysis of a proton exchange membrane fuel cell (PEMFC) with a fermat spiral as a flow distributor

    International Nuclear Information System (INIS)

    Rangel-Hernandez, V.H.; Damian-Ascencio, C.; Juarez-Robles, D.; Gallegos-Munoz, A.; Zaleta-Aguilar, A.; Plascencia-Mora, H.

    2011-01-01

    The present paper aims at investigating the main sources of irreversibility in a Proton Exchange Membrane Fuel Cell (PEMFC) using a Fermat spiral as flow distributor and also to direct possible improvements in its design. The numerical analysis is based on a finite volume technique with a SIMPLE algorithm as numerical procedure. In order to have a more complete and rigorous analysis a new dimensionless parameter is proposed here. The parameter represents the ratio of the entropy generation due to mass transfer to the total entropy generation is proposed here. Results demonstrate that the main sources of irreversibility in a fuel cell are the concentration losses for the most part of the operational domain, whereas the heat transfer effect is not dominant. -- Highlights: → PEM Fuel Cell with Fermat Spiral as distributor. → Causes of irreversibilities. → A new dimensionless parameter to determine contribution of mass transfer in entropy generation.

  8. Random hydrodynamic loads and the vibration of fuel elements in the turbulent coolant flow in WWER fuel assembly

    International Nuclear Information System (INIS)

    Perevezentsev, V.V.

    2012-01-01

    The generalizing empirical dependences of vibration movements on the random hydrodynamic loads have been obtained. Two characteristic regions of the influence of random hydrodynamic loads on the vibration movements have been discovered. With the values of random hydrodynamic loads more than 80 N/m, a considerable increase in the intensity of vibrations has been observed. It can be explained by the slippage of fuel element in the cell of the spacing lattice [ru

  9. On scaling laws for modelling the steam/water flow in a 'Dodewaard' fuel-assembly using Freon-12

    International Nuclear Information System (INIS)

    Graaf, R. van de; Mudde, R.F.; Hagen, T.H.J.J. van der.

    1991-09-01

    To stimulate the steam/water flow behaviour in a fuel assembly as present in the boiling water reactor at Dodewaard, Freon-12 is used as a modelling fluid. Scaling criteria are elaborated using dimensional analysis as a fluid-to-fluid modelling technique. When scaling is emphasized on void-fraction distribution and flow-regime transitions it is found that an approximately half-scale geometry for the Freon-model should be used. Together with the low latent heat of vaporization of Freon-12 this reduces the total required heat input significantly to be only 2% of the required heat input in a 'Dodewaard' fuel-assembly. Finally, working pressure (and saturation temperature) can also be brought to a convenient level. (author). 16 refs., 11 figs., 1 tab

  10. Multidimensional simulations of fuel rod appendage effects on pressure drop and heat transfer in an annulus flow

    International Nuclear Information System (INIS)

    Banas, A.O.; Carver, M.B.; Leung, J.C.H.; Bromley, B.P.

    1992-10-01

    The general purpose computational fluid dynamics code, Harwell-FLOW3D, has been used to simulate the effects of fuel rod obstructions on pressure drop and heat transfer in single phase turbulent flows in a concentric annular channel. The results of two and three dimensional simulations are reported for obstructions approximating the geometry of bearing pads used in 37 element CANDU fuel bundles. Pressure drop penalty and augmentation of heat transfer have been quantified and correlated with the obstruction geometrical parameters and the dimensionless numbers representing operating conditions. The predicted effects on pressure drop have been compared with several experimental correlations, yielding good agreement. The methodology presented offers results that can be used directly as input into thermalhydraulic analyses in subchannel and system codes. (Author) (23 figs., 15 refs.)

  11. Power and power-to-flow reactivity transfer functions in EBR-II [Experimental Breeder Reactor II] fuel

    International Nuclear Information System (INIS)

    Grimm, K.N.; Meneghetti, D.

    1989-01-01

    Reactivity transfer functions are important in determining the reactivity history during a power transient. Overall nodal transfer functions have been calculated for different subassembly types in the Experimental Breeder Reactor II (EBR-II). Steady-state calculations for temperature changes and, hence, reactivities for power changes have been separated into power and power-to-flow-dependent terms. Axial nodal transfer functions separated into power and power-to-flow-dependent components are reported in this paper for a typical EBR-II fuel pin. This provides an improved understanding of the time dependence of these components in transient situations

  12. Calculation of the heat flow peak in case of local defect of the fuel plate of a nuclear reactor

    International Nuclear Information System (INIS)

    Fabrega, Serge

    1965-11-01

    The author reports the calculation of the local thermal flow which exits a fuel plate in a nuclear reactor, where a fabrication defect creates a much localized peak of the power density released in the plate. He first reports the development of the problem equations: hypotheses and data, equation elaboration, simplification and resolution. He presents the results of a numeric application to actual cases, and describes how the conduction in the sheath is taken into account (study of the influence of peak width and shape), and gives a synthetic presentation of the formula for the approximate calculation of the heat flow in case of local defect [fr

  13. Experimental Comparison of Speed : Fuel-flow and Speed-area Controls on a Turbojet Engine for Small Step Disturbances

    Science.gov (United States)

    Wenzel, L M; Hart, C E; Craig, R T

    1957-01-01

    Optimum proportional-plus-integral control settings for speed - fuel-flow control, determined by minimization of integral criteria, correlated well with analytically predicted optimum settings. Engine response data are given for a range of control settings around the optimum. An inherent nonlinearity in the speed-area loop necessitated the use of nonlinear controls. Response data for two such nonlinear control schemes are presented.

  14. Bioelectrocatalytic NAD+/NADH inter-conversion: transformation of an enzymatic fuel cell into an enzymatic redox flow battery.

    Science.gov (United States)

    Quah, Timothy; Milton, Ross D; Abdellaoui, Sofiene; Minteer, Shelley D

    2017-07-25

    Diaphorase and a benzylpropylviologen redox polymer were combined to create a bioelectrode that can both oxidize NADH and reduce NAD + . We demonstrate how bioelectrocatalytic NAD + /NADH inter-conversion can transform a glucose/O 2 enzymatic fuel cell (EFC) with an open circuit potential (OCP) of 1.1 V into an enzymatic redox flow battery (ERFB), which can be rapidly recharged by operation as an EFC.

  15. Optimization of material flow in the nuclear fuel cycle using a cyclic multi-stage production-to-inventory model

    International Nuclear Information System (INIS)

    DePorter, E.L.

    1977-01-01

    The nuclear fuel cycle is modelled as a cyclic, multi-stage production-to-inventory system. The objective is to meet a known deterministic demand for energy while minimizing acquisition, production, and inventory holding costs for all stages of the fuel cycle. The model allows for cyclic flow (feedback) of materials, material flow conversion factors at each stage, production lag times at each stage, and for escalating costs of uranium ore. It does not allow shortages to occur in inventories. The model is optimized by the application of the calculus of variations and specifically through recently developed theorems on the solution of functionals constrained by inequalities. The solution is a set of optimal cumulative production trajectories which define the stagewise production rates. Analysis of these production rates reveals the optimal nuclear fuel cycle costs and that inventories (stockpiles) occur in uranium fields, enriched uranium hexafluoride, and fabricated fuel assemblies. An analysis of the sensitivity of the model to variation in three important parameters is performed

  16. Flow-Induced Vibration Measurement of an Inner Cladding Tube in a Simulated Dual-Cooled Fuel Rod

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kang Hee; Kim, Hyung Kyu; Yoon, Kyung Ho; Lee, Young Ho; Kim, Jae Yong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2009-05-15

    To create an internal coolant flow passage in a dual cooled fuel rod, an inner cladding tube cannot have intermediate supports enough to relieve its vibration. Thus it can be suffered from a flow-induced vibration (FIV) more severely than an outer cladding tube which will be supported by series of spacer grids. It may cause a fatigue failure at welding joints on the cladding's end plug or fluid elastic instability of long, slender inner cladding due to decrease of a critical flow velocity. This is one of the challenging technical issues when a dual cooled fuel assembly is to be realized into a conventional reactor core To study an actual vibration phenomenon of a dual cooled fuel rod, FIV tests using a small-scale test bundle are being carried out. Measurement results of inner cladding tube of two typically simulated rods are presented. Causes of the differences in the vibration amplitude and response spectrum of the inner cladding tube in terms of intermediate support condition and pellet stacking are discussed.

  17. Volumetric formulation of lattice Boltzmann models with energy conservation

    OpenAIRE

    Sbragaglia, M.; Sugiyama, K.

    2010-01-01

    We analyze a volumetric formulation of lattice Boltzmann for compressible thermal fluid flows. The velocity set is chosen with the desired accuracy, based on the Gauss-Hermite quadrature procedure, and tested against controlled problems in bounded and unbounded fluids. The method allows the simulation of thermohydrodyamical problems without the need to preserve the exact space-filling nature of the velocity set, but still ensuring the exact conservation laws for density, momentum and energy. ...

  18. Modeling solid-fuel dispersal during slow loss-of-flow-type transients

    International Nuclear Information System (INIS)

    DiMelfi, R.J.; Fenske, G.R.

    1981-01-01

    The dispersal, under certain accident conditions, of solid particles of fast-reactor fuel is examined in this paper. In particular, we explore the possibility that solid-fuel fragmentation and dispersal can be driven by expanding fission gas, during a slow LOF-type accident. The consequences of fragmentation are studied in terms of the size and speed of dispersed particles, and the overall quantity of fuel moved. (orig.)

  19. Measurement of current distribution in a proton exchange membrane fuel cell with various flow arrangements – A parametric study

    International Nuclear Information System (INIS)

    Alaefour, Ibrahim; Karimi, G.; Jiao, Kui; Li, X.

    2012-01-01

    Highlights: ► Spatial local current distributions in a single PEMFC are measured. ► Effects of key operating conditions on the local current density are investigated. ► Increasing air and hydrogen stoichiometries improves local current density distributions. ► Operating pressure and temperature have negligible impact on local current distribution. - Abstract: Understanding of current distributions in proton exchange membrane fuel cells (PEMFCs) is crucial for designing cell components such as the flow field plates and the membrane electrode assembly (MEA). In this study, the spatial current density distributions in a single PEMFC with three serpentine flow channels are measured using a segmented bipolar plate and printed circuit board technique. The effects of key operating conditions such as stoichiometry ratios, inlet humidity levels, cell pressure and temperature on the local current density distributions for co-, counter-, and cross-flow arrangements are examined. It is observed that the local current density distribution over the MEA is directly affected by the cell operating conditions along with the configuration of the flow arrangement. It is also found that among the different flow configurations tested under the various operating conditions, the counter flow arrangement provides the optimum average current density and the lowest variations in the local current densities along the flow channels.

  20. Thermal-Hydraulic Analysis of Coolant Flow Decrease in Fuel Channels of Smolensk-3 RBMK during GDH Blockage Event

    International Nuclear Information System (INIS)

    Costa, A. L.; Cherubini, M.; D'Auria, F.; Giannotti, W.; Moskalev, A.

    2007-01-01

    One of the transients that have received considerable attention in the safety evaluation of RBMK reactors is the partial break of a group distribution header (GDH). The coolant flow rate blockage in one GDH might lead to excessive heat-up of the pressure tubes and can result in multiple fuel channels (FC) ruptures. In this work, the GDH flow blockage transient has been studied considering the Smolensk-3 RBMK NPP (nuclear power plant). In the RBMK, each GDH distributes coolant to 40-43 FC. To investigate the behavior of each FC belonging to the damaged GDH and to have a more realistic trend, one (affected) GDH has been schematised with its forty-two FC, one by one. The calculations were performed using the 0-D NK (neutron kinetic) model of the RELAP5-3.3 stand-alone code. The results show that, during the event, the mass flow rate is disturbed differently according to the power distribution established for each FC in the schematization. The start time of the oscillations in mass flow rate depends strongly on the attributed power to each FC. It was also observed that, during the event, the fuel channels at higher thermal power values tend to undergo first cladding rupture leaving the reactor to scram and safeguarding all the other FCs connected to the affected GDH.

  1. Effects of duct configuration on flow and temperature structure in sodium-cooled 19-rod simulated LMFBR fuel bundles with helical wire-wrap spacers

    International Nuclear Information System (INIS)

    Wantland, J.L.; Fontana, M.H.; Gnadt, P.A.; Hanus, N.; MacPherson, R.E.; Smith, C.M.

    1976-01-01

    Thermal-hydrodynamic testing of sodium-cooled 19-rod simulated LMFBR fuel bundles is being conducted at the O ak Ridge National Laboratory in the Fuel Failure Mockup (FFM), an engineering-scale high-temperature sodium facility which provides prototypic flows, temperatures and power densities. Electrically heated bundles have been tested with two scalloped and two hexagonal duct configurations. Peripheral helical flows, attributed to the spacers, have been observed with strengths dependent upon the evenness and relative sizes of the peripheral flow areas. Diametral sodium temperature profiles are more uniform with smaller peripheral flow areas

  2. Modeling of atomization and distribution of drop-liquid fuel in unsteady swirling flows in a combustion chamber and free space

    Science.gov (United States)

    Sviridenkov, A. A.; Toktaliev, P. D.; Tretyakov, V. V.

    2018-03-01

    Numerical and experimental research of atomization and propagation of drop-liquid phase in swirling flow behind the frontal device of combustion chamber was performed. Numerical procedure was based on steady and unsteady Reynolds equations solution. It's shown that better agreement with experimental data could be obtained with unsteady approach. Fractional time step method was implemented to solve Reynolds equations. Models of primary and secondary breakup of liquid fuel jet in swirling flows are formulated and tested. Typical mean sizes of fuel droplets for base operational regime of swirling device and combustion chamber were calculated. Comparison of main features of internal swirling flow in combustion chamber with unbounded swirling flow was made.

  3. Analysis of fuel pin mechanics in case of flow blockage of a single RBMK channel

    International Nuclear Information System (INIS)

    Pierro, F.; Moretti, F.; Mazzini, D.; D'Auria, F.

    2005-01-01

    The evaluation of the consequences of the pressure tube rupture due to accidental overheating is one of the key elements for addressing an RBMK safety analysis, since it causes the lost of design boundaries against the fission products release. Several events are expected to take place: thermal hydraulic crisis (energy unbalance), fuel overheating, fuel rod damage, pressure tube overheating, pressure tube failure and graphite stack damage, Hydrogen and fission products release. The present work deals with the research activity carried out at ''Dipartimento di Ingegneria Meccanica, Nucleare e della Produzione'' (DIMNP) of the University of Pisa aimed at assessing numerical models for safety analysis of the RBMK-1000. The attention is focused on the modelling of (1) a single fuel channel and its surrounding graphite column for evaluating the transient conditions enabling the different damaging phenomena, (2) a single fuel rod for investigating fuel pin behaviour, (3) the ruptured fuel channel for figuring the magnitude of the hydrodynamic loads acting on fuel rods. Different codes were employed to cover the competences for the investigation of each field; in particular, RELAP5 code for thermal-hydraulics, FRAPCON-3 and FRAPTRAN1-2 codes for fuel pin mechanics, FLUENT-6 for fluid dynamics. The paper discusses the numerical models, the analysis capabilities of numerical models in comparison with available data about the Leningrad NPP 1992 accident. Furthermore, the possibility to draw a failure map identifying the range of the cladding safety respect to the transient condition is outlined. (author)

  4. Subchannel analysis program for boiling water reactor fuel bundles based on five conservation equations of two-phase flow

    International Nuclear Information System (INIS)

    Bessho, Y.; Uchikawa, S.

    1985-01-01

    A subchannel analysis program, MENUETT, is developed for evaluation of thermal-hydraulic characteristics in boiling water reactor fuel bundles. This program is based on five conservation equations of two-phase flow with the drift-flux correlation. The cross flows are calculated separately for liquid and vapor phases from the lateral momentum conservation equation. The effects of turbulent mixing and void drift are accounted for in the program. The conservation equations are implicitly differentiated with the convective terms by the donor-cell method, and are solved iteratively in the axial and lateral directions. Data of the 3 X 3 rod bundle experiments are used for program verification. The lateral distributions of equilibrium quality and mass flow rate at the bundle exit calculated by the program compare satisfactorily with the experimental results

  5. IR1 flow tube and In-Pile Test Section Pressure drop test for the 3-Pin Fuel Test Loop

    Energy Technology Data Exchange (ETDEWEB)

    Lee, H. H.; Park, K. N.; Chi, D. Y.; Sim, B. S.; Park, S. K.; Lee, J. M.; Lee, C. Y.; Kim, H. N

    2006-02-15

    The in-pile Section (IPS) of 3-pin Fuel Test Loop(FTL) shall be installed in the vertical hole call IR1 of HANARO reactor core. In order to verify the pressure drop and flow rate both the inside region of IPS at the annular region between IPS and IR1 flow tube, a pressure drop was measured by varing the flow rate on both regions. The measured pressure drop in the annular region is 209kpa at 14.9kg/s which meets the limiting condition of operation of 200kpa. The measured pressure drop in side the IPS becomes 260.25kpa which is lower than the designed value of 306.65kpa. As the pressure drop is lower than the design value, it is quite conservative from the safety and operating point of view.

  6. Computational comparison of the effect of mixing grids of 'swirler' and 'run-through' types on flow parameters and the behavior of steam phase in WWER fuel assemblies

    International Nuclear Information System (INIS)

    Shcherbakov, S.; Sergeev, V.

    2011-01-01

    The results obtained using the TURBOFLOW computer code are presented for the numerical calculations of space distributions of coolant flow, heating and boiling characteristics in WWER fuel assemblies with regard to the effect of mixing grids of 'Swirler' and 'Run-through' types installed in FA on the above processes. The nature of the effect of these grids on coolant flow was demonstrated to be different. Thus, the relaxation length of cross flows after passing a 'Run-through' grid is five times as compared to a 'Swirler'-type grid, which correlates well with the experimental data. At the same time, accelerations occurring in the flow downstream of a 'Swirler'-type grid are by an order of magnitude greater than those after a 'Run-through' grid. As a result, the efficiency of one-phase coolant mixing is much higher for the grids of 'Run-through' type, while the efficiency of steam removal from fuel surface is much higher for 'Swirler'-type grids. To achieve optimal removal of steam from fuel surface it has been proposed to install into fuel assemblies two 'Swirler'-type grids in tandem at a distance of about 10 cm from each other with flow swirling in opposite directions. 'Run-through' grids would be appropriate for use for mixing in fuel assemblies with a high non-uniformity of fuel-by-fuel power generation. (authors)

  7. Experimental study of two-phase flow in a proton exchange membrane fuel cell in short-term microgravity condition

    International Nuclear Information System (INIS)

    Guo, Hang; Liu, Xuan; Zhao, Jian Fu; Ye, Fang; Ma, Chong Fang

    2014-01-01

    Highlights: • Two-phase flow in PEMFC cathode channels is observed in different gravity environments. • The PEMFC shows different operating behavior in normal and microgravity conditions. • Water tends can be removed in microgravity conditions at high water production regime. • Liquid aggregation occurs in microgravity conditions at low water production regime. • Effect of gravity on performance and two-phase flow at two operating regimes is studied. - Abstract: Water management is important for improving the performance and stability of proton exchange membrane fuel cells (PEMFCs) for space applications. An in situ visual observation was conducted on the gas–liquid two-phase flow in the cathode channels of a PEMFC in short-term microgravity condition. The microgravity environment was supplied by a drop tower. A single serpentine flow channel with a depth of 2 mm and a width of 2 mm was applied as the cathode flow field. A membrane electrode assembly comprising of a Nafion 112 membrane sandwiched between gas diffusion layers was used. The anode and cathode were loaded with 1 mg cm −2 platinum. The PEMFC shows a distinct operating behavior in microgravity because of the effect of gravity on the two-phase flow. At a high water production regime, cell performance is enhanced by 4.6% and the accumulated liquid water in the flow channel tends can be removed in microgravity conditions to alleviate flooding. At a low water production regime, cell performance deteriorates by 6.6% and liquid aggregation occurs in the flow channel because of the coalescence of dispersed water droplets in microgravity conditions, thus squeezing the flow channel. The operating behavior of PEMFC in microgravity conditions is different from that in normal gravity conditions. Further studies are needed on PEMFC operating characteristics and liquid management for space applications

  8. CFD simulation of flow-pressure characteristics of a pressure control valve for automotive fuel supply system

    International Nuclear Information System (INIS)

    Wu, Dazhuan; Li, Shiyang; Wu, Peng

    2015-01-01

    Highlights: • Direct CFD method for flow-pressure characteristic of a pressure control valve. • Fitted and interpreted the constants of the spool hydraulic force equation. • Established a flow coefficient function of both valve opening and pressure drop. • Developed an indirect CFD method based on the valve-governing equations. - Abstract: This study aims to elaborate on specific computational fluid dynamics (CFD) simulation methods for fitting the flow-pressure curve of a pressure control valve, which is spring-load valve widely used in the automotive fuel supply system. Given that the couple mechanism exists between the flow field in the valve and the spring system, numerous researchers chose to fit the characteristic curve with experimental approaches but scarcely focused on CFD methods. A direct CFD method is introduced in this study to solve this problem. Two evaluation criteria are used to determine whether the internal flow is physically real. An experiment is conducted to verify the simulation results, and the accuracy of this CFD method is proved. However, it is designed to solve one operating condition with fixed spring parameters and the accuracy depends on the amount of operating conditions. Thus, an indirect CFD method is developed based on the well-elaborated valve-governing equations to improve the efficiency and broaden the application extension. This method aims to simulate the exact value of the equation constants to uncouple the flow by numerical method. It is capable of dealing with changed operating conditions and varied spring parameters, and the results are also verified. The visualization of the internal flow provides a better understanding of the flow fields in the valve. The valve gap directly influences the hydraulic force distribution on the spool and causes most pressure loss. The physical meaning of the function constants are explained based on the flow analysis

  9. KIVA3, Transient Multicomponent 2-D and 3-D Reactive Flows with Fuel Sprays

    International Nuclear Information System (INIS)

    Amsden, A.A.

    2001-01-01

    1 - Description of program or function: KIVA3VRELEASE2 is a computer program for the numerical calculation of transient, two and three-dimensional, chemically reactive flows with sprays. It is a newer version of the earlier KIVA3 (1993) that has now been extended to model vertical of canted valves in the cylinder head of a gasoline or diesel engine. KIVA3, in turn, was based on the earlier KIVA2 (1989) and uses the same numerical solution procedure and solves the same sort of equations. KIVA3VRELEASE2 uses a block-structured mesh with connectivity defined through indirect addressing. The departure from a single rectangular structure in logical space allows complex geometries to be modeled with significantly greater efficiency because large regions of deactivated cells are no longer necessary. Cell-face boundary conditions permit greater flexibility and simplification in the application of boundary conditions. KIVA3VRELEASE2 contains a number of significant changes. New features enhance the robustness, efficiency, and usefulness of the overall program for engine modeling. Automatic restart of the cycle with a reduced time-step in case of iteration limit or temperature overflow will reduce code crashes. A new option provides automatic deactivation of a port region when it is closed from the cylinder and reactivation when it communicates with the cylinder. Corrections in the code improve accuracy; extensions to the particle-based liquid wall film model makes the model more complete and a spli injection option has been added. A new subroutine monitors the liquid and gaseous fuel phases and energy balance data and emissions are monitored and printed. New features have been added to the grid generator K3PREP and the graphics post processor, K3POST. 2 - Method of solution: KIVA3VRELEASE2 solves the unsteady equations of motion of a turbulent, chemically reactive mixture of ideal gases, coupled to the equations for a single-component vaporizing fuel spray. The gas

  10. Pressure loss coefficient and flow rate of side hole in a lower end plug for dual-cooled annular nuclear fuel

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Chang-Hwan, E-mail: shinch@kaeri.re.kr; Park, Ju-Yong, E-mail: juyong@kaeri.re.kr; In, Wang-Kee, E-mail: wkin@kaeri.re.kr

    2013-12-15

    Highlights: • A lower end plug with side flow holes is suggested to provide alternative flow paths of the inner channel. • The inlet loss coefficient of the lower end plug is estimated from the experiment. • The flow rate through the side holes is estimated in a complete entrance blockage of inner channel. • The consequence in the reactor core condition is evaluated with a subchannel analysis code. - Abstract: Dual-cooled annular nuclear fuel for a pressurized water reactor (PWR) has been introduced for a significant increase in reactor power. KAERI has been developing a dual-cooled annular fuel for a power uprate of 20% in an optimized PWR in Korea, the OPR1000. This annular fuel can help decrease the fuel temperature substantially relative to conventional cylindrical fuel at a power uprate. Annular fuel has dual flow channels around itself; however, the inner flow channel has a weakness in that it is isolated unlike the outer flow channel, which is open to other neighbouring outer channels for a coolant exchange in the reactor core. If the entrance of the inner channel is, as a hypothetical event, completely blocked by debris, the inner channel will then experience a rapid increase in coolant temperature such that a departure from nucleate boiling (DNB) may occur. Therefore, a remedy to avoid such a postulated accident is indispensable for the safety of annular fuel. A lower end plug with side flow holes was suggested to provide alternative flow paths in addition to the central entrance of the inner channel. In this paper, the inlet loss coefficient of the lower end plug and the flow rate through the side holes were estimated from the experimental results even in a complete entrance blockage of the inner channel. An optimization for the side hole was also performed, and the results are applied to a subchannel analysis to evaluate the consequence in the reactor core condition.

  11. Chemical processing of HTR fuels applying either THOREX or PUREX flow sheets

    Energy Technology Data Exchange (ETDEWEB)

    Zimmer, E; Merz, E [Kernforschungsanlage, Juelich GmbH, Institut fuer Chemische Technologie der Nuklearen Entsorgung, Juelich (Germany)

    1985-07-01

    Two fuel cycles are considered for utilization in high temperature gas-cooled reactors (HTRs): the high-enriched thorium-uranium (HEU 93% U-235) and the low-enriched uranium (LEU 8-12% U-235) fuel concept. For both fuel compositions suitable reprocessing procedures are required which are capable to separate the actinides thorium, uranium and plutonium from fission products and from each other. In any case, the processes under consideration utilize Tri-n-butylphosphate (TBP) together with a straight-chain paraffinic diluent (C{sub 8}-C{sub 14}, to day usually dodecane) as extractant in an aqueous nitrate system; most commonly, the related processes are known by the acronyms PUREX and THOREX. The PUREX process has become the reprocessing procedure quite generally used for all fuel types containing natural, slightly or highly enriched uranium together with lower or higher contents of plutonium. The THOREX process on the other hand has been developed to separate thorium, uranium and fission products from thorium based irradiated fuel. Generally, the utilization of the thorium fuel cycle is most attractive for High Temperature Reactors. On the other hand, the strong recommendation of INFCE to abandon the use of high-enriched uranium for nuclear energy applications virtually rules out the thorium fuel cycle, since economic utilization of thorium as a fertile material requires the use of high-enriched U-235. Thus, it was decided in the Federal Republic of Germany to switch over, at least for the foreseeable future, to the low enrichment uranium-plutonium fuel cycle, well aware of its economic shortcomings. In this paper various THOREX flowsheets as well as a PUREX variant suitable for LEU fuel reprocessing are described. Both processes have in common that the main stream is always presented by the fertile material, that means thorium and U-238, respectively.

  12. Fluid flows due to leakproofness defects of nuclear fuel cans: application to sipping in PWR

    International Nuclear Information System (INIS)

    Parrat, D.

    1983-10-01

    This thesis establishes the theoritical laws describing fluid and gas transfers through channels representative of nuclear fuel can defects. These laws, applied to craks on fuel cans (samples) and on new or spent experimental rods, allow to know their size. A computerized modelling has been developed to analyse more particularly the examination by ''quantitative permeation testing'', giving the equivalent size of a channel from the observed signal. The utilization of this process to non-tight fuel assemblies of pressurized water reactors leads to the establishment of a classification of defects according to their importance [fr

  13. Analysis of reactor material experiments investigating oxide fuel crust stability and heat transfer in jet impingement flow

    International Nuclear Information System (INIS)

    Sienicki, J.J.; Spencer, B.W.

    1985-01-01

    An analysis is presented of the crust stability and heat transfer behavior in the CSTI-1, CSTI-3, and CWTI-11 reactor material experiments in which a jet of molten oxide fuel at approx. 160 0 K above its freezing temperature was impinged normally upon stainless steel plates initially at 300 and 385 K. The major issue is the existence of nonexistence of a stable solidified layer of fuel, or crust, interstitial to the flowing hot fuel and the steel substrate, tending to insulate the steel from the hot molten fuel. A computer model was developed to predict the heatup of thermocouples imbedded immediately beneath the surface of the plate for both of the cases in which a stable crust is assumed to be either present or absent during the impingement phase. Comparison of the model calculations with the measured thermocouple temperatures indicates that a protective crust was present over nearly all of the plate surface area throughout the impingement process precluding major melting of the plate steel. However, the experiments also show evidence for very localized and isolated steel melting as revealed by localized and isolated pitting of the steel surface and the response of thermocouples located within the pitted region

  14. The indicative effects of inefficient urban traffic flow on fuel cost and exhaust air pollutant emissions

    CSIR Research Space (South Africa)

    Moselakgomo, M

    2015-07-01

    Full Text Available Poor urban traffic management such as poor intersection controls, congestions, illegal roadway blockages and construction works causes “stop-go” driving conditions with excessive idling resulting in wasted fuel and increased air pollutant emissions...

  15. Three-Dimensional Transport Modeling for Proton Exchange Membrane(PEM Fuel Cell with Micro Parallel Flow Field

    Directory of Open Access Journals (Sweden)

    Sang Soon Hwang

    2008-03-01

    Full Text Available Modeling and simulation for heat and mass transport in micro channel are beingused extensively in researches and industrial applications to gain better understanding of thefundamental processes and to optimize fuel cell designs before building a prototype forengineering application. In this study, we used a single-phase, fully three dimensionalsimulation model for PEMFC that can deal with both anode and cathode flow field forexamining the micro flow channel with electrochemical reaction. The results show thathydrogen and oxygen were solely supplied to the membrane by diffusion mechanism ratherthan convection transport, and the higher pressure drop at cathode side is thought to becaused by higher flow rate of oxygen at cathode. And it is found that the amount of water incathode channel was determined by water formation due to electrochemical reaction pluselectro-osmotic mass flux directing toward the cathode side. And it is very important tomodel the back diffusion and electro-osmotic mass flux accurately since the two flux wasclosely correlated each other and greatly influenced for determination of ionic conductivityof the membrane which directly affects the performance of fuel cell.

  16. Three-Dimensional Transport Modeling for Proton Exchange Membrane(PEM) Fuel Cell with Micro Parallel Flow Field.

    Science.gov (United States)

    Lee, Pil Hyong; Han, Sang Seok; Hwang, Sang Soon

    2008-03-03

    Modeling and simulation for heat and mass transport in micro channel are beingused extensively in researches and industrial applications to gain better understanding of thefundamental processes and to optimize fuel cell designs before building a prototype forengineering application. In this study, we used a single-phase, fully three dimensionalsimulation model for PEMFC that can deal with both anode and cathode flow field forexamining the micro flow channel with electrochemical reaction. The results show thathydrogen and oxygen were solely supplied to the membrane by diffusion mechanism ratherthan convection transport, and the higher pressure drop at cathode side is thought to becaused by higher flow rate of oxygen at cathode. And it is found that the amount of water incathode channel was determined by water formation due to electrochemical reaction pluselectro-osmotic mass flux directing toward the cathode side. And it is very important tomodel the back diffusion and electro-osmotic mass flux accurately since the two flux wasclosely correlated each other and greatly influenced for determination of ionic conductivityof the membrane which directly affects the performance of fuel cell.

  17. A new continuous-flow process for catalytic conversion of glycerol to oxygenated fuel additive: Catalyst screening

    International Nuclear Information System (INIS)

    Nanda, Malaya R.; Yuan, Zhongshun; Qin, Wensheng; Ghaziaskar, Hassan S.; Poirier, Marc-Andre; Xu, Chunbao

    2014-01-01

    Highlights: • A continuous-flow process for catalytic synthesis of solketal from glycerol. • Six different heterogeneous acid catalysts were studied in the process. • Glycerol conversion and solketal yield of 90% and 88% respectively were achieved. • The process has the potential to be scaled-up for industrial applications. - Abstract: A new continuous-flow reactor was designed for the conversion of glycerol to solketal, an oxygenated fuel additive, through ketalization with acetone. Six heterogeneous catalysts were investigated with respect to their catalytic activity and stability in a flow reactor. The acidity of the catalysts positively influences the catalyst’s activity. Among all the solid acid catalysts tested, the maximum solketal yield from experiments at 40 °C, 600 psi and WHSV of 4 h −1 attained 73% and 88% at the acetone/glycerol molar ratio of 2.0 and 6.0, respectively, with Amberlyst Wet. Based on the solketal yield and glycerol conversion results, the activity of all catalysts tested follows the following order of sequence: Amberlyst Wet ≈ Zeolite ≈ Amberlyst Dry > Zirconium Sulfate > Montmorillonite > Polymax. An increase in acetone/glycerol molar ratio or a decrease in WHSV enhanced the glycerol conversion as expected. This process offers an attractive route for converting glycerol, the main by-product of biodiesel, to solketal – a value-added green product with potential industrial applications as a valuable fuel additive or combustion promoter for gasoline engines

  18. Current density and polarization curves for radial flow field patterns applied to PEMFCs (Proton Exchange Membrane Fuel Cells)

    International Nuclear Information System (INIS)

    Cano-Andrade, S.; Hernandez-Guerrero, A.; Spakovsky, M.R. von; Damian-Ascencio, C.E.; Rubio-Arana, J.C.

    2010-01-01

    A numerical solution of the current density and velocity fields of a 3-D PEM radial configuration fuel cell is presented. The energy, momentum and electrochemical equations are solved using a computational fluid dynamics (CFD) code based on a finite volume scheme. There are three cases of principal interest for this radial model: four channels, eight channels and twelve channels placed in a symmetrical path over the flow field plate. The figures for the current-voltage curves for the three models proposed are presented, and the main factors that affect the behavior of each of the curves are discussed. Velocity contours are presented for the three different models, showing how the fuel cell behavior is affected by the velocity variations in the radial configuration. All these results are presented for the case of high relative humidity. The favorable results obtained for this unconventional geometry seems to indicate that this geometry could replace the conventional commercial geometries currently in use.

  19. The study of flow and proton exchange interactions in the cylindrical solid oxide fuel cell

    International Nuclear Information System (INIS)

    Saievar-Iranizad, E.; Malekifar, A.

    2002-01-01

    The solid oxide fuel cell operates at high temperature of about 1000 deg C. In this temperature, some known materials such as Ni, ... which is abundant in the nature, can be used as a catalyst in the electrodes. The electrolytes of such cell solid oxide fuel cell can be made through non-porous solid ceramics such as Zircon's (ZrO 2 ). It can be stabilized using a doped Yttrium oxide. The importance of Yttria-stabilised Zirconia at high temperature belongs to the transport of oxygen ions through the electrolyte. Oxygen using in the hot cathode side causes a considerable reduction in the concentration of oxygen molecules. The oxygen ions exchange through the electrolyte relates to the molecular oxygen concentration gradient between the anode and cathode. Applying fuels such as hydrogen or natural gas in the anode and its chemical reaction with oxygen ions transfer from cathode through the electrolyte, produce electricity, water and heat. To study the ion exchange and its interaction into solid oxide fuel cell, a mathematical model had been considered in this article. This model simulates and illustrates the interaction, diffusion and oxygen ions exchange into fuel cell. The electrical power of fuel cell due to the ion exchange can be obtained using a simulation method. The ion exchange simulation, diffusion of molecules, their interactions and system development through the mathematical model has been discussed in this paper

  20. Design of a full scale model fuel assembly for full power production reactor flow excursion experiments

    International Nuclear Information System (INIS)

    Nash, C.A.; Blake, J.E.; Rush, G.C.

    1990-01-01

    A novel full scale production reactor fuel assembly model was designed and built to study thermal-hydraulic effects of postulated Savannah River Site (SRS) nuclear reactor accidents. The electrically heated model was constructed to simulate the unique annular concentric tube geometry of fuel assemblies in SRS nuclear production reactors. Several major design challenges were overcome in order to produce the prototypic geometry and thermal-hydraulic conditions. The two concentric heater tubes (total power over 6 MW and maximum heat flux of 3.5 MW/m 2 ) (1.1E+6 BTU/(ft 2 hr)) were designed to closely simulate the thermal characteristics of SRS uranium-aluminum nuclear fuel. The paper discusses the design of the model fuel assembly, which met requirements of maintaining prototypic geometric and hydraulic characteristics, and approximate thermal similarity. The model had a cosine axial power profile and the electrical resistance was compatible with the existing power supply. The model fuel assembly was equipped with a set of instruments useful for code analysis, and durable enough to survive a number of LOCA transients. These instruments were sufficiently responsive to record the response of the fuel assembly to the imposed transient

  1. Tracking of fuel particles after pin failure in nominal, loss-of-flow and shutdown conditions in the MYRRHA reactor

    Energy Technology Data Exchange (ETDEWEB)

    Buckingham, Sophia; Planquart, Philippe [von Karman Institute, Chaussée de Waterloo 72, B-1640 Rhode-St-Genèse (Belgium); Van Tichelen, Katrien [SCK- CEN, Boeretang 200, 2400 Mol (Belgium)

    2017-02-15

    Highlights: • Quantification of the design and safety of the MYRRHA reactor in the event of a pin failure. • Simulation of different accident scenarios in both forced and natural convection regime. • The accumulation areas at the free-surface in case of the least dense particles depend on the flow regime. • The densest particles form an important deposit at the bottom of the vessel. • Further study of the risk of core blockage requires a detailed model of the core. - Abstract: This work on fuel dispersion aims at quantifying the design and safety of the MYRRHA nuclear reactor. A number of accidents leading to the release of a secondary phase into the primary coolant loop are investigated. Among these scenarios, an incident leading to the failure of one or more of the fuel pins is simulated while the reactor is operating in nominal conditions, but also in natural convection regime either during accident transients such as loss-of-flow or during the normal shut-down of the reactor. Two single-phase CFD models of the MYRRHA reactor are constructed in ANSYS Fluent to represent the reactor in nominal and natural convection conditions. An Euler–Lagrange approach with one-way coupling is used for the flow and particle tracking. Firstly, a steady state RANS solution is obtained for each of the three conditions. Secondly, the particles are released downstream from the core outlet and particle distributions are provided over the coolant circuit. Their size and density are defined such that test cases represent potential extremes that may occur. Analysis of the results highlights different particle behaviors, depending essentially on gravity forces and kinematic effects. Statistical distributions highlight potential accumulation regions that may form at the free-surfaces, on top of the upper diaphragm plate or at the bottom of the vessel. These results help to localize regions of fuel accumulation in order to provide insight for development of strategies for

  2. Direct coupling of a liquid chromatograph to a continuous flow hydrogen nuclear magnetic resonance detector for analysis of petroleum and synthetic fuels

    International Nuclear Information System (INIS)

    Haw, J.F.; Glass, T.E.; Hausler, D.W.; Motell, E.; Dorn, H.C.

    1980-01-01

    Initial results obtained for a flow 1 H nuclear magnetic resonance (NMR) detector directly coupled to a liquid chromatography unit are described. Results achieved for a model mixture and several jet fuel samples are discussed. Chromatographic separation of alkanes, alkylbenzenes, and substituted naphthalenes present in the jet fuel samples are easily identified with the 1 H NMR detector. Results with our present flow 1 H NMR insert indicate that 5-Hz linewidths are readily obtainable for typical chromatographic flow rates. The limitations and advantages of this liquid chromatography detector are compared with more commonly employed detectors (e.g., refractive index detectors). 11 figures

  3. Determination of dissolution rates of spent fuel in carbonate solutions under different redox conditions with a flow-through experiment

    International Nuclear Information System (INIS)

    Roellin, S.; Spahiu, K.; Eklund, U.-B.

    2001-01-01

    Dissolution rates of spent UO 2 fuel have been investigated using flow-through experiments under oxidizing, anoxic and reducing conditions. For oxidizing conditions, approximately congruent dissolution rates were obtained in the pH range 3-9.3 for U, Np, Ba, Tc, Cs, Sr and Rb. For these elements, steady-state conditions were obtained in the flow rate range 0.02-0.3 ml min -1 . The dissolution rates were about 3 mg d -1 m -2 for pH>6. For pH 2 (g) saturated solutions dropped by up to four orders of magnitude as compared to oxidizing conditions. Because of the very low concentrations, only U, Pu, Am, Mo, Tc and Cs could be measured. For anoxic conditions, both the redox potential and dissolution rates increased approaching the same values as under oxidizing conditions

  4. Studies of fuel-bulk flows using charged-particle and neutron spectrometry on OMEGA and the NIF

    Science.gov (United States)

    Gatu Johnson, M.; Rinderknecht, H.; Rosenberg, M.; Sio, H.; Zylstra, A.; Frenje, J.; Li, C. K.; Seguin, F.; Petrasso, R.; Delettrez, J.; Glebov, V.; Knauer, J.; McKenty, P.; Sangster, T. C.; Appelbe, B.; Amendt, P.; Bellei, C.; Bionta, R.; Bleuel, D.; Caggiano, J.; Casey, D.; Edwards, J.; Hatarik, R.; Hatchett, S.; Landen, O.

    2013-10-01

    A. MACKINNON, J. MCNANEY, D. MUNRO, J. PINO, S. WILKS, C. YEAMANS, LLNL, J. KILKENNY, A. NIKROO, GA - Charged-particle and neutron spectra are used to study fuel-bulk flows, which are indicative of implosion asymmetries and inefficient conversion of kinetic energy to thermal energy. We distinguish between (i) collective, directional motion of the burn region, which manifests itself as a directional shift of the fusion-product spectrum, and (ii) radial flow, which appears as an additional broadening of the spectrum relative to expected based on Ti Doppler broadening. In this talk, we will present neutron and charged particle spectra from OMEGA and the NIF, which display the effect of these phenomena and their relation to implosion asymmetry. This work was supported in part by the U.S. DOE, LLNL and LLE.

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

    Directory of Open Access Journals (Sweden)

    Voytkov Ivan V.

    2016-01-01

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

  6. Calculation of mass flow and steam quality distribution on fuel elements of light-water cooled boiling water nuclear reactors

    International Nuclear Information System (INIS)

    Hermanns, H.J.

    1977-04-01

    By the example of light-water cooled nuclear reactors, the state of the calculation methods at disposal for calculating mass flow and steam quality distribution (sub-channel analysis) is indicated. Particular regard was paid to the transport phenomena occurring in reactor fuel elements in the range of two phase flow. Experimentally determined values were compared with recalculations of these experiments with the sub-channel code COBRA; from the results of these comparing calculations, conclusions could be drawn on the suitability of this code for defined applications. Limits of reliability could be determined to some extent. Based on the experience gained and the study of individual physical model concepts, recognized as being important, a sub-channel model was drawn up and the corresponding numerical computer code (SIEWAS) worked out. Experiments made at GE could be reproduced with the code SIEWAS with sufficient accuracy. (orig.) [de

  7. Multiphase Flow Dynamics 4 Turbulence, Gas Adsorption and Release, Diesel Fuel Properties

    CERN Document Server

    Kolev, Nikolay Ivanov

    2012-01-01

    The present Volume 4 of the successful monograh package “Multiphase Flow Dynamics”is devoted to selected Chapters of the multiphase fluid dynamics that are important for practical applications but did not find place in the previous volumes. The state of the art of the turbulence modeling in multiphase flows is presented. As introduction, some basics of the single phase boundary layer theory including some important scales and flow oscillation characteristics in pipes and rod bundles are presented. Then the scales characterizing the dispersed flow systems are presented. The description of the turbulence is provided at different level of complexity: simple algebraic models for eddy viscosity, simple algebraic models based on the Boussinesq hypothesis, modification of the boundary layer share due to modification of the bulk turbulence, modification of the boundary layer share due to nucleate boiling. The role of the following forces on the mathematical description of turbulent flows is discussed: the lift fo...

  8. Computational investigation of the flow field contribution to improve electricity generation in granular activated carbon-assisted microbial fuel cells

    Science.gov (United States)

    Zhao, Lei; Li, Jian; Battaglia, Francine; He, Zhen

    2016-11-01

    Microbial fuel cells (MFCs) offer an alternative approach to treat wastewater with less energy input and direct electricity generation. To optimize MFC anodic performance, adding granular activated carbon (GAC) has been proved to be an effective way, most likely due to the enlarged electrode surface for biomass attachment and improved mixing of the flow field. The impact of a flow field on the current enhancement within a porous anode medium (e.g., GAC) has not been well understood before, and thus is investigated in this study by using mathematical modeling of the multi-order Butler-Volmer equation with computational fluid dynamics (CFD) techniques. By comparing three different CFD cases (without GAC, with GAC as a nonreactive porous medium, and with GAC as a reactive porous medium), it is demonstrated that adding GAC contributes to a uniform flow field and a total current enhancement of 17%, a factor that cannot be neglected in MFC design. However, in an actual MFC operation, this percentage could be even higher because of the microbial competition and energy loss issues within a porous medium. The results of the present study are expected to help with formulating strategies to optimize MFC with a better flow pattern design.

  9. Behavior of EBR-II Mk-V-type fuel elements in simulated loss-of-flow tests

    International Nuclear Information System (INIS)

    Liu, Y.Y.; Tsai, H.; Billone, M.C.; Kramer, J.M.

    1992-01-01

    The next step in the development of metal fuels for the integral fast reactor (IFR) is the conversion of the Experimental Breeder Reactor II (EBR-II) core to one containing the ternary U-20 Pu-10 Zr alloy clad with HT-9 cladding, i.e., the Mk-V core. This paper presents results of three hot-cell furnace simulation tests on irradiated Mk-V-type fuel elements (U-19 Pu-10 Zr/HT-9), which were performed to support the safety case for the Mk-V core. These tests were designed to envelop an umbrella (bounding) unlikely loss-of-flow (LOF) event in EBR-II during which the calculated peak cladding temperature would reach 776 degree C for < 2 min. The principal objectives of these tests were (a) demonstration of the safety margin of the fuel element, (b) investigation of cladding breaching behavior, and (c) provision of data for validation of the FPIN2 and LIFE-METAL codes

  10. Numerical predictions of a PEM fuel cell performance enhancement by a rectangular cylinder installed transversely in the flow channel

    International Nuclear Information System (INIS)

    Perng, Shiang-Wuu; Wu, Horng-Wen; Jue, Tswen-Chyuan; Cheng, Kuo-Chih

    2009-01-01

    This paper numerically investigates the installation of the transverse rectangular cylinder along the gas diffusion layer (GDL) in the flow channel for the cell performance enhancement of a proton exchange membrane fuel cell (PEMFC). The effects of the blockage at various gap sizes and the width of the cylinder on the cell performance enhancement have been studied with changing the gap ratios λ = 0.05-0.3, for the same cylinder) and the width-to-height ratios (WR = 0.66-1.66, for the same cylinder height and gap ratio). The results show that the transverse installation of a rectangular cylinder in the fuel flow channel effectively enhances the cell performance of a PEMFC. In addition, the influence of the width of the cylinder on the cell performance is obvious, and the best cell performance enhancement occurs at the gap ratio 0.2 among the gap ratios of 0.05, 0.1, 0.2, and 0.3.

  11. The study of flow and proton exchange interactions in the cylindrical solid oxide fuel cell

    CERN Document Server

    Saievar-Iranizad, E

    2002-01-01

    The solid oxide fuel cell operates at high temperature of about 1000 deg C. In this temperature, some known materials such as Ni, ... which is abundant in the nature, can be used as a catalyst in the electrodes. The electrolytes of such cell solid oxide fuel cell can be made through non-porous solid ceramics such as Zircon's (ZrO sub 2). It can be stabilized using a doped Yttrium oxide. The importance of Yttria-stabilised Zirconia at high temperature belongs to the transport of oxygen ions through the electrolyte. Oxygen using in the hot cathode side causes a considerable reduction in the concentration of oxygen molecules. The oxygen ions exchange through the electrolyte relates to the molecular oxygen concentration gradient between the anode and cathode. Applying fuels such as hydrogen or natural gas in the anode and its chemical reaction with oxygen ions transfer from cathode through the electrolyte, produce electricity, water and heat. To study the ion exchange and its interaction into solid oxide fuel cel...

  12. Flow visualization studies of transverse fuel injection patterns in a nonreacting Mach 2 combustor

    Science.gov (United States)

    Mcdaniel, J. C.

    1987-01-01

    Planar visualization images are recorded of transverse jet mixing in a supersonic combustor flowfield, without chemical reaction, using laser-induced fluorescence from iodine molecules. Digital image processing and three-dimensional display enable complete representations of fuel penetration boundary and shock surfaces corresponding to several injection geometries and pressures.

  13. Fuel Effects on Nozzle Flow and Spray Using Fully Coupled Eulerian Simulations

    Science.gov (United States)

    2015-09-01

    extinction and auto - ignition for surrogates were in good agreements with jet fuel data. Note that Honnet et al. (9) also introduced a widely used......with a wide set of data from shock tubes, rapid compression machines, jet stirred reactors, burner stabilized premixed flames and freely

  14. Hologlyphics: volumetric image synthesis performance system

    Science.gov (United States)

    Funk, Walter

    2008-02-01

    This paper describes a novel volumetric image synthesis system and artistic technique, which generate moving volumetric images in real-time, integrated with music. The system, called the Hologlyphic Funkalizer, is performance based, wherein the images and sound are controlled by a live performer, for the purposes of entertaining a live audience and creating a performance art form unique to volumetric and autostereoscopic images. While currently configured for a specific parallax barrier display, the Hologlyphic Funkalizer's architecture is completely adaptable to various volumetric and autostereoscopic display technologies. Sound is distributed through a multi-channel audio system; currently a quadraphonic speaker setup is implemented. The system controls volumetric image synthesis, production of music and spatial sound via acoustic analysis and human gestural control, using a dedicated control panel, motion sensors, and multiple musical keyboards. Music can be produced by external acoustic instruments, pre-recorded sounds or custom audio synthesis integrated with the volumetric image synthesis. Aspects of the sound can control the evolution of images and visa versa. Sounds can be associated and interact with images, for example voice synthesis can be combined with an animated volumetric mouth, where nuances of generated speech modulate the mouth's expressiveness. Different images can be sent to up to 4 separate displays. The system applies many novel volumetric special effects, and extends several film and video special effects into the volumetric realm. Extensive and various content has been developed and shown to live audiences by a live performer. Real world applications will be explored, with feedback on the human factors.

  15. Modelling of thermally driven groundwater flow in a facility for disposal of spent nuclear fuel in deep boreholes

    Energy Technology Data Exchange (ETDEWEB)

    Marsic, Nico; Grundfelt, Bertil [Kemakta Konsult AB, Stockholm (Sweden)

    2013-09-15

    In this report calculations are presented of buoyancy driven groundwater flow caused by the emission of residual heat from spent nuclear fuel deposited in deep boreholes from the ground surface in combination with the natural geothermal gradient. This work has been conducted within SKB's programme for evaluation of alternative methods for final disposal of spent nuclear fuel. The basic safety feature of disposal of spent nuclear fuel in deep boreholes is that the groundwater at great depth has a higher salinity, and hence a higher density, than more superficial groundwater. The result of this is that the deep groundwater becomes virtually stagnant. The study comprises analyses of the effects of different inter-borehole distances as well as the effect of different permeabilities in the backfill and sealing materials in the borehole and of different shapes of the interface between fresh and saline groundwater. The study is an update of a previous study published in 2006. In the present study, the facility design proposed by Sandia National Laboratories has been studied. In this design, steel canisters containing two BWR elements or one PWR element are stacked on top of each other between 3 and 5 kilometres depth. In order to host all spent fuel from the current Swedish nuclear programme, about 80 such holes are needed. The model used in this study comprises nine boreholes spaced 100 metres alternatively 50 metres apart in a 3{Chi}3 matrix. In one set of calculations the salinity in the groundwater was assumed to increase from zero above 700 metres depth to 10% by weight at 1500 metres depth and below. In another set, a sharper salinity gradient was applied in which the salinity increased from 0 to 10% between 1400 and 1500 metres depth. A geothermal gradient of 16 deg C/km was applied. The heat output from the spent fuel was assumed to decrease by time in manner consistent with the radioactive decay in the fuel. When the inter-borehole distance decreased from

  16. Local flow blockage analysis with checkerboard configuration in a wire wrapped fuel subassembly using the ASFRE code

    International Nuclear Information System (INIS)

    Nishimura, Masahiro; Fukano, Yoshitaka

    2014-01-01

    Local fault (LF) has been historically considered as one of the possible causes of severe accidents in sodium-cooled fast reactors because fuel pins are generally densely arranged in the fuel subassemblies (FSAs) in this type of reactors. Local flow blockage (LB) has been one of the dominant initiators of LFs. Therefore evaluations were performed on LBs in the past safety licensing assuming a planar and impermeable blockage of 66% of the total flow area at an FSA for the Japanese prototype fast breeder reactor. A conservative evaluation revealed that fuel pin damage propagation would be limited within a restricted area of the reactor core, even assuming such a hypothetical initiating event. In the newly formulated regulatory requirements, however, after the accident at the Fukushima Dai-ichi nuclear power plant, best estimate (BE) safety analyses on the basis of state-of-the-art knowledge are being required for beyond design basis accidents. A deterministic and BE evaluation therefore based on the most-recent knowledge was newly performed in this study for revalidation of the above-mentioned historical background using the ASFRE code, whereas the LF accidents would not be identified as a representative accident sequence from a viewpoint of both its frequencies and consequences. Nominal power and flow rate without safety margins were assumed for the analyses in order to make the accidental conditions to be realistic. A most likely and realistic blockage configuration was newly proposed and employed based on the existing experimental data in accordance with the BE concept mentioned above. The aforementioned blockage configuration was excessively conservative on a state-of-the-art knowledge basis. The most-recent experimental studies clarified that LBs due to foreign substances would be formed by accumulating the steel fragments of certain sizes trapped along the wrapping wires. This leads to an LB in a checkerboard configuration for an FSA of wire spacer type, which

  17. Volumetric Visualization of Human Skin

    Science.gov (United States)

    Kawai, Toshiyuki; Kurioka, Yoshihiro

    We propose a modeling and rendering technique of human skin, which can provide realistic color, gloss and translucency for various applications in computer graphics. Our method is based on volumetric representation of the structure inside of the skin. Our model consists of the stratum corneum and three layers of pigments. The stratum corneum has also layered structure in which the incident light is reflected, refracted and diffused. Each layer of pigment has carotene, melanin or hemoglobin. The density distributions of pigments which define the color of each layer can be supplied as one of the voxel values. Surface normals of upper-side voxels are fluctuated to produce bumps and lines on the skin. We apply ray tracing approach to this model to obtain the rendered image. Multiple scattering in the stratum corneum, reflective and absorptive spectrum of pigments are considered. We also consider Fresnel term to calculate the specular component for glossy surface of skin. Some examples of rendered images are shown, which can successfully visualize a human skin.

  18. Investigation of the Link Between Macroscopic Traffic Flow Characteristics and Individual Vehicle Fuel Consumption

    Science.gov (United States)

    2017-10-01

    This project investigated the factors impacting individual vehicle energy consumption, including vehicle characteristics, ambient temperature, season, speed, driving behavior, and traffic flow. A fleet of 18 vehicles with a variety of ownership, size...

  19. Development of the loss coefficient correlation for cross flow between graphite fuel blocks in the core of prismatic very high temperature reactor-PMR200

    International Nuclear Information System (INIS)

    Lee, Jeong-Hun; Cho, Hyoung-Kyu; Park, Goon-Cherl

    2016-01-01

    Highlights: • Cross flow experimental data are produced with wedge-shaped and parallel gaps. • The results of a CFD analysis and experimental data are in good agreement. • Pressure loss coefficient for the cross gap between fuel blocks in PMR200 is found. • A new correlation of the cross flow loss coefficient for PMR200 is proposed. - Abstract: The core of the very high temperature reactor (VHTR) PMR200 (a prismatic modular reactor rated at 200 MW of thermal power) consists of hexagonal prismatic fuel blocks and reflector blocks made of graphite. If the core bypass flow ratio increases, the coolant channel flow is decreased and can then lower the heat removal efficiency, resulting in a locally increased fuel block temperature. The coolant channels in the fuel blocks are connected to bypass gaps by the cross gap, complicating flow distribution in the VHTR core. Therefore, reliable estimation of the bypass flow is highly important for the design and safety analysis of the VHTR core. Because of the complexity of the core geometry and gap configuration, it is challenging to predict the flow distribution in the VHTR core. To analyze this flow distribution accurately, it is necessary to determine the cross flow phenomena, and the loss coefficient across the cross gap has to be evaluated to determine the flow distribution in the VHTR core when a lumped parameter code or a flow network analysis code that uses the correlation of the loss coefficient is employed. The purpose of this paper is to develop a loss coefficient correlation applicable to the cross gap in the PMR200 core. The cross flow was evaluated experimentally using the difference between the measured inlet and outlet mass flow rates. Next, the applicability of a commercial computational fluid dynamics (CFD) code, CFX 15, was confirmed by comparing the experimental data and CFD analysis results. To understand the cross flow phenomena, the loss coefficient was evaluated; in the high Reynolds number region

  20. Development of the loss coefficient correlation for cross flow between graphite fuel blocks in the core of prismatic very high temperature reactor-PMR200

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeong-Hun, E-mail: huny12@snu.ac.kr; Cho, Hyoung-Kyu, E-mail: chohk@snu.ac.kr; Park, Goon-Cherl, E-mail: parkgc@snu.ac.kr

    2016-10-15

    Highlights: • Cross flow experimental data are produced with wedge-shaped and parallel gaps. • The results of a CFD analysis and experimental data are in good agreement. • Pressure loss coefficient for the cross gap between fuel blocks in PMR200 is found. • A new correlation of the cross flow loss coefficient for PMR200 is proposed. - Abstract: The core of the very high temperature reactor (VHTR) PMR200 (a prismatic modular reactor rated at 200 MW of thermal power) consists of hexagonal prismatic fuel blocks and reflector blocks made of graphite. If the core bypass flow ratio increases, the coolant channel flow is decreased and can then lower the heat removal efficiency, resulting in a locally increased fuel block temperature. The coolant channels in the fuel blocks are connected to bypass gaps by the cross gap, complicating flow distribution in the VHTR core. Therefore, reliable estimation of the bypass flow is highly important for the design and safety analysis of the VHTR core. Because of the complexity of the core geometry and gap configuration, it is challenging to predict the flow distribution in the VHTR core. To analyze this flow distribution accurately, it is necessary to determine the cross flow phenomena, and the loss coefficient across the cross gap has to be evaluated to determine the flow distribution in the VHTR core when a lumped parameter code or a flow network analysis code that uses the correlation of the loss coefficient is employed. The purpose of this paper is to develop a loss coefficient correlation applicable to the cross gap in the PMR200 core. The cross flow was evaluated experimentally using the difference between the measured inlet and outlet mass flow rates. Next, the applicability of a commercial computational fluid dynamics (CFD) code, CFX 15, was confirmed by comparing the experimental data and CFD analysis results. To understand the cross flow phenomena, the loss coefficient was evaluated; in the high Reynolds number region

  1. Investigations of flow and temperature field development in bare and wire-wrapped reactor fuel pin bundles cooled by sodium

    International Nuclear Information System (INIS)

    Govindha Rasu, N.; Velusamy, K.; Sundararajan, T.; Chellapandi, P.

    2013-01-01

    Highlights: ► We study sodium flow and temperature development in fuel pin bundles. ► Pin diameter, number of pins, wire wrap and ligament gap are varied as parameters. ► Flow development is achieved within ∼30–40 hydraulic diameters. ► Thermal development is attained only for small pin diameter and less number of pins. ► Wire wrap and ligament gap strongly influence Nusselt number. - Abstract: Simultaneous development of liquid sodium flow and temperature fields in the heat generating pin bundles of reactor has been investigated. Development characteristics are seen to be strongly influenced by pin diameter, number of pins, helical wire-wrap, ligament gap between the last row of pins and hexcan wall and Reynolds number. Flow development is achieved within an axial length of ∼125 hydraulic diameters, for all the pin bundle configurations considered. But temperature development is attained only if the pin diameter is small or the number of pins is less. In the case of large pin diameter with more pins, temperature development could not be achieved even after a length of ∼1000 hydraulic diameters. The reason for this behavior is traced to be the weak communication among sub-channels in tightly packed bundles. It is seen that the pin Nusselt number decreases from center to periphery in a bundle. Also, if the ligament gap is narrow, the Nusselt number is large and more uniform. Flow development length is short if the Reynolds number is large and the converse is true for thermal development length. Helical wire-wrap shortens the thermal entry length and significantly enhances the global Nusselt number. But, its influence on hydrodynamic entry length is not significant

  2. Performance analysis of a membrane humidifier containing porous metal foam as flow distributor in a PEM fuel cell system

    International Nuclear Information System (INIS)

    Afshari, Ebrahim; Baharlou Houreh, Nasser

    2014-01-01

    Highlights: • Three metal foam configurations for the membrane humidifier are introduced. • The performances of the humidifiers containing metal foam are investigated. • A 3D CFD model is developed to compare the introduced humidifiers with one another. • Using metal foam at dry side has no positive effect on the humidifier performance. - Abstract: Using metal foam as flow distributor in membrane humidifier for proton exchange membrane (PEM) fuel cell system has some unique characteristics like more water transfer, low manufacturing complexity and low cost compared to the conventional flow channel plate. Metal foam can be applied at wet side or dry side or both sides of a humidifier. The three-dimensional CFD models are developed to investigate the performance of the above mentioned meanwhile compare them with the conventional humidifier. This model consists of a set of coupled equations including conservations of mass, momentum, species and energy for all regions of the humidifier. The results indicate that with the metal foam installed at wet side and both sides, water recovery ratio and dew point at dry side outlet are more than that of the conventional humidifier, indicating a better humidifier performance; while using metal foam at dry side has no positive effect on humidifier performance. At dry side mass flow rates higher than 10 mgr/s pressure drop in humidifier containing metal foam at wet side is lower than that of the conventional humidifier. As the mass flow rate increases from 9 to 15 mgr/s humidifier containing metal foam at wet side has better performance, while at mass flow rates lower than 9 mgr/s, the humidifier containing metal foam at both sides has better performance. At dry side inlet temperatures lower than 303 K, humidifier containing metal foam at wet side has better performance and at temperatures higher than 303 K, humidifier containing metal foam at both sides has better performance

  3. Effect of humidity content and direction of the flow of reactant gases on water management in the 4-serpentine and 1-serpentine flow channel in a PEM (proton exchange membrane) fuel cell

    International Nuclear Information System (INIS)

    Khazaee, I.; Sabadbafan, H.

    2016-01-01

    The performance of a PEM (proton exchange membrane) fuel cell depends on design and operating parameters such as relative humidity, operation pressure, and number of channels and direction of the flow of reactant gases. In this study, a three-dimensional, two-phase model has been established to investigate the water management and performance of PEM fuel cell with rectangular geometry and 1-serpentine and 4-serpentine with parallel flow, counter flow and cross flow for hydrogen and oxygen. The numerical simulation was realized with a PEM fuel cell model based on the FLUENT. The active area of each cell is 24.8 cm 2 that its weight is 1300 gr. The material of the gas diffusion layer is carbon clothes, the membrane is nafion117 and the catalyst layer is a plane with 0.004 g cm −2 platinum. Pure hydrogen is used on the anode side and oxygen on the cathode side. Simulation results are obtained for voltage as a function of current density at different humidity. The simulation results are compared with the experimental data, and the agreement is found to be good. The results show that the cell performance at lower voltages increases with increasing humidity in cell with 4-Serpentine flow channel and also in cell with 1-Serpentine flow channel, cell performance at all voltages increases with increasing humidity. In cell with 4-Serpentine and parallel flow channel cell performance is better than counter and cross flow in low voltage and in cell with 1-Serpentine and parallel flow, performance is better than counter and cross flow in high voltage. - Highlights: • Investigation new geometries of a fuel cell. • The effect of geometry on current density, oxygen and water distribution. • The effect of humidity on current density, oxygen and water distribution. • Seeing the interacting and complex electrochemical phenomena.

  4. Numerical Research on Hybrid Fuel Locking Device for Upward Flow Core-Research Reactor

    International Nuclear Information System (INIS)

    Huh, Hyung; Cho, Yeong-Garp; Yoo, Yeon-Sik; Ryu, Jeong-Soo

    2016-01-01

    The assembly must be held firmly against these forces, but cannot be permanently attached to the support stand because periodic refueling of the reactor requires removal or relocation of each assembly. There are so many kinds of fuel locking device, but they are operated manually. As a part of a new project, we have investigated a hybrid fuel locking device (HFLD) for research reactor which is operated automatically. Prior method of holding down the fuel assembly includes a hybrid zero electromagnet consisting of an electromagnet and a permanent magnet. The role of an electromagnet is converged to zero power for overcoming the lifting power of a permanent magnet by controlling the coil current. At this time, a HFLD is an unlocking state. On the contrary, it is locking state that only a permanent magnet works when the power of an electromagnet is off. The results of a FEM in this work lead to the following conclusions: (1) It is possible that an electromagnet is converged to zero power for overcoming the lifting power of a permanent magnet by remote controlling the coil current. (2) At this time, it is able to detect remotely using proximity sensor whether a HFLD is latched or not

  5. Laminated exfoliated graphite composite-metal compositions for fuel cell flow field plate or bipolar plate applications

    Science.gov (United States)

    Zhamu, Aruna; Shi, Jinjun; Guo, Jiusheng; Jang, Bor Z

    2014-05-20

    An electrically conductive laminate composition for fuel cell flow field plate or bipolar plate applications. The laminate composition comprises at least a thin metal sheet having two opposed exterior surfaces and a first exfoliated graphite composite sheet bonded to the first of the two exterior surfaces of the metal sheet wherein the exfoliated graphite composite sheet comprises: (a) expanded or exfoliated graphite and (b) a binder or matrix material to bond the expanded graphite for forming a cohered sheet, wherein the binder or matrix material is between 3% and 60% by weight based on the total weight of the first exfoliated graphite composite sheet. Preferably, the first exfoliated graphite composite sheet further comprises particles of non-expandable graphite or carbon in the amount of between 3% and 60% by weight based on the total weight of the non-expandable particles and the expanded graphite. Further preferably, the laminate comprises a second exfoliated graphite composite sheet bonded to the second surface of the metal sheet to form a three-layer laminate. Surface flow channels and other desired geometric features can be built onto the exterior surfaces of the laminate to form a flow field plate or bipolar plate. The resulting laminate has an exceptionally high thickness-direction conductivity and excellent resistance to gas permeation.

  6. Efficient H2O2/CH3COOH oxidative desulfurization/denitrification of liquid fuels in sonochemical flow-reactors.

    Science.gov (United States)

    Calcio Gaudino, Emanuela; Carnaroglio, Diego; Boffa, Luisa; Cravotto, Giancarlo; Moreira, Elizabeth M; Nunes, Matheus A G; Dressler, Valderi L; Flores, Erico M M

    2014-01-01

    The oxidative desulfurization/denitrification of liquid fuels has been widely investigated as an alternative or complement to common catalytic hydrorefining. In this process, all oxidation reactions occur in the heterogeneous phase (the oil and the polar phase containing the oxidant) and therefore the optimization of mass and heat transfer is of crucial importance to enhancing the oxidation rate. This goal can be achieved by performing the reaction in suitable ultrasound (US) reactors. In fact, flow and loop US reactors stand out above classic batch US reactors thanks to their greater efficiency and flexibility as well as lower energy consumption. This paper describes an efficient sonochemical oxidation with H2O2/CH3COOH at flow rates ranging from 60 to 800 ml/min of both a model compound, dibenzotiophene (DBT), and of a mild hydro-treated diesel feedstock. Four different commercially available US loop reactors (single and multi-probe) were tested, two of which were developed in the authors' laboratory. Full DBT oxidation and efficient diesel feedstock desulfurization/denitrification were observed after the separation of the polar oxidized S/N-containing compounds (S≤5 ppmw, N≤1 ppmw). Our studies confirm that high-throughput US applications benefit greatly from flow-reactors. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Electrochemical study of multi-electrode microbial fuel cells under fed-batch and continuous flow conditions

    KAUST Repository

    Ren, Lijiao

    2014-07-01

    Power production of four hydraulically connected microbial fuel cells (MFCs) was compared with the reactors operated using individual electrical circuits (individual), and when four anodes were wired together and connected to four cathodes all wired together (combined), in fed-batch or continuous flow conditions. Power production under these different conditions could not be made based on a single resistance, but instead required polarization tests to assess individual performance relative to the combined MFCs. Based on the power curves, power produced by the combined MFCs (2.12 ± 0.03 mW, 200 ω) was the same as the summed power (2.13 mW, 50 ω) produced by the four individual reactors in fed-batch mode. With continuous flow through the four MFCs, the maximum power (0.59 ± 0.01 mW) produced by the combined MFCs was slightly lower than the summed maximum power of the four individual reactors (0.68 ± 0.02 mW). There was a small parasitic current flow from adjacent anodes and cathodes, but overall performance was relatively unaffected. These findings demonstrate that optimal power production by reactors hydraulically and electrically connected can be predicted from performance by individual reactors. © 2013 Elsevier B.V. All rights reserved.

  8. Experimental studies of the effect of functional spacers to annular flow in subchannels of a BWR fuel element

    Energy Technology Data Exchange (ETDEWEB)

    Damsohn, M., E-mail: damsohn@lke.mavt.ethz.c [ETH Zurich, Department of Mechanical and Process Engineering, Sonneggstrasse 3, 8092 Zuerich (Switzerland); Prasser, H.-M. [ETH Zurich, Department of Mechanical and Process Engineering, Sonneggstrasse 3, 8092 Zuerich (Switzerland)

    2010-10-15

    For the prediction of dryout in fuel elements of boiling water reactors, the dynamic behavior of the water film covering the fuel rod has to be understood. This paper provides high resolved experimental data of the liquid film and gives insight into the dynamic film behavior. The experiments of this work were conducted in a vertical channel representing a pair of neighboring subchannels of a BWR fuel rod bundle. Air and water at ambient pressure and temperature are used as model fluids, creating an annular flow in the test section. The influence of different functional spacer shapes on the liquid film has been studied. The heart of the instrumentation is a liquid film sensor (LFS), which measures the film thickness distribution around a half cylinder with a matrix of 64 x 16 measuring points with a time resolution of 10,000 frames per second and a spatial resolution of 2 mm x 2 mm. The high resolution allows for a visualization of the dynamic liquid film as a movie animation. Principals of the dynamic behavior of the liquid film are observed. The time-averaged film thickness distributions show that the spacers structure the liquid film significantly. The gaseous phase is accelerated due to the cross-section blockage caused by the spacer. This leads to a local thinning of the liquid film downstream of the spacer. Two statistical evaluation methods are presented to determine different dynamic wave properties: The wave velocity as function of the wave height, the traveling path of the waves and the location of wave separation and merge events. The first evaluation method shows that big waves move generally faster than small waves. The analysis further shows wave acceleration in close proximity of the spacer with subsequent deceleration further downstream. Analyzing the wave as a two-dimensional entity it can be seen that the wave paths are clearly structured by the spacer and hence do not travel circumferentially around the fuel rod. Wave separation and merge has a

  9. Experimental studies of the effect of functional spacers to annular flow in subchannels of a BWR fuel element

    International Nuclear Information System (INIS)

    Damsohn, M.; Prasser, H.-M.

    2010-01-01

    For the prediction of dryout in fuel elements of boiling water reactors, the dynamic behavior of the water film covering the fuel rod has to be understood. This paper provides high resolved experimental data of the liquid film and gives insight into the dynamic film behavior. The experiments of this work were conducted in a vertical channel representing a pair of neighboring subchannels of a BWR fuel rod bundle. Air and water at ambient pressure and temperature are used as model fluids, creating an annular flow in the test section. The influence of different functional spacer shapes on the liquid film has been studied. The heart of the instrumentation is a liquid film sensor (LFS), which measures the film thickness distribution around a half cylinder with a matrix of 64 x 16 measuring points with a time resolution of 10,000 frames per second and a spatial resolution of 2 mm x 2 mm. The high resolution allows for a visualization of the dynamic liquid film as a movie animation. Principals of the dynamic behavior of the liquid film are observed. The time-averaged film thickness distributions show that the spacers structure the liquid film significantly. The gaseous phase is accelerated due to the cross-section blockage caused by the spacer. This leads to a local thinning of the liquid film downstream of the spacer. Two statistical evaluation methods are presented to determine different dynamic wave properties: The wave velocity as function of the wave height, the traveling path of the waves and the location of wave separation and merge events. The first evaluation method shows that big waves move generally faster than small waves. The analysis further shows wave acceleration in close proximity of the spacer with subsequent deceleration further downstream. Analyzing the wave as a two-dimensional entity it can be seen that the wave paths are clearly structured by the spacer and hence do not travel circumferentially around the fuel rod. Wave separation and merge has a

  10. Redesigned Gas Mass Flow Sensors for Space Shuttle Pressure Control System and Fuel Cell System

    Science.gov (United States)

    1996-01-01

    A program was conducted to determine if a state of the art micro-machined silicon solid state flow sensor could be used to replace the existing space shuttle orbiter flow sensors. The rather aggressive goal was to obtain a new sensor which would also be a multi-gas sensor and operate over a much wider flow range and with a higher degree of accuracy than the existing sensors. Two types of sensors were tested. The first type was a venturi throat design and the second was a bypass design. The accuracy of venturi design was found to be marginally acceptable. The bypass sensor was much better although it still did not fully reach the accuracy goal. Two main problems were identified which would require further work.

  11. Multidimensional flow, thermal, and chemical behavior in solid-oxide fuel cell button cells

    Energy Technology Data Exchange (ETDEWEB)

    Goldin, Graham M. [Ansys Incorporated, 10 Cavendish Ct., Centerra Resource Park, Lebanon, NH 03766 (United States); Zhu, Huayang; Kee, Robert J. [Engineering Division, Colorado School of Mines, Golden, CO 80401 (United States); Bierschenk, David; Barnett, Scott A. [Materials Science, Northwestern University, Evanston, IL 60208 (United States)

    2009-02-01

    The quantitative analysis and interpretation of button-cell experiments usually depends upon assuming isothermal conditions together with uniform and known gas composition within the gas compartments. An objective of the present effort is to develop computational tools to study the validity of such assumptions. A three-dimensional computational fluid dynamics (CFD) model is developed and applied to a particular SOFC button cell, characterizing the fluid flow, chemistry, and thermal transport. Results show that when inlet flow rates are sufficiently high, button-cell data can be interpreted using the commonly used assumptions. However, when flow rates are not sufficient, the assumptions of uniform composition can be significantly violated. Additionally, depending on operating conditions there can be significant temperature variations within the gas compartments and the membrane-electrode assembly. (author)

  12. Investigation on the liquid water droplet instability in a simulated flow channel of PEM fuel cell

    International Nuclear Information System (INIS)

    Ha, Tae Hun; Kim, Bok Yung; Kim, Han Sang; Min, Kyoung Doug

    2008-01-01

    To investigate the characteristics of water droplets on the gas diffusion layer from both top-view and side-view of the flow channel, a rig test apparatus was designed and fabricated with prism attached plate. This experimental device was used to simulate the growth of a single liquid water droplet and its transport process with various air flow velocity and channel height. Not only dry condition but also fully humidified condition was also simulated by using a water absorbing sponge. The detachment height of the water droplet with dry and wet conditions was measured and analyzed. It was found that the droplet tends towards becoming unstable by decreased channel height, increased flow velocity or making a gas diffusion layer (GDL) dryer. Also, peculiar behavior of the water droplet in the channel was presented like attachment to hydrophilic wall or sudden breaking of droplet in case of fully hydrated condition. The simplified force balance model matches with experimental data as well

  13. Performance characteristics of axisymmetric venturi-like reverse-flow diverters. Consolidated Fuel Reprocessing Program

    International Nuclear Information System (INIS)

    Smith, G.V.; Counce, R.M.

    1984-01-01

    This paper presents experimental and model-predicted pressure-flow characteristics of axisymmetric venturi-like reverse-flow diverters (RFDs), the key component of fluid pumping systems utilized for the transport of hazardous fluids. The effects of several key geometric parameters, operating conditions, and fluid properties on the performance of the RFD are presented and compared to model predictions. The results indicate good agreement between data and theory over a large portion of the range of variables studied. Cavitation is observed to be the primary factor in limiting the performance of the RFD at small values of load impedances

  14. Comparison of Numerical and Experimental Studies for Flow-Field Optimization Based on Under-Rib Convection in Polymer Electrolyte Membrane Fuel Cells

    Directory of Open Access Journals (Sweden)

    Nguyen Duy Vinh

    2016-10-01

    Full Text Available The flow-field design based on under-rib convection plays an important role in enhancing the performance of polymer electrolyte membrane fuel cells (PEMFCs because it ensures the uniform distribution of the reacting gas and the facilitation of water. This research focused on developing suitable configurations of the anode and cathode bipolar plates to enhance the fuel cell performance based on under-rib convection. The work here evaluated the effects of flow-field designs, including a serpentine flow field with sub channel and by pass and a conventional serpentine flow-field on single-cell performance. Both the experiment and computer simulation indicated that the serpentine flow field with sub channel and by pass (SFFSB configuration enables more effective utilization of the electrocatalysts since it improves reactant transformation rate from the channel to the catalyst layer, thereby dramatically improving the fuel cell performance. The simulation and experimental results indicated that the power densities are increased by up to 16.74% and 18.21%, respectively, when applying suitable flow-field configurations to the anode and cathode bipolar plates. The findings in this are the foundation for enhancing efficient PEMFCs based on flow field design.

  15. Hydrodynamic Simulations of the Inner Accretion Flow of Sagittarius A* Fueled By Stellar Winds

    Science.gov (United States)

    Ressler, S. M.; Quataert, E.; Stone, J. M.

    2018-05-01

    We present Athena++ grid-based, hydrodynamic simulations of accretion onto Sagittarius A* via the stellar winds of the ˜30 Wolf-Rayet stars within the central parsec of the galactic center. These simulations span ˜ 4 orders of magnitude in radius, reaching all the way down to 300 gravitational radii of the black hole, ˜32 times further in than in previous work. We reproduce reasonably well the diffuse thermal X-ray emission observed by Chandra in the central parsec. The resulting accretion flow at small radii is a superposition of two components: 1) a moderately unbound, sub-Keplerian, thick, pressure-supported disc that is at most (but not all) times aligned with the clockwise stellar disc, and 2) a bound, low-angular momentum inflow that proceeds primarily along the southern pole of the disc. We interpret this structure as a natural consequence of a few of the innermost stellar winds dominating accretion, which produces a flow with a broad distribution of angular momentum. Including the star S2 in the simulation has a negligible effect on the flow structure. Extrapolating our results from simulations with different inner radii, we find an accretion rate of ˜ a few × 10-8M⊙/yr at the horizon scale, consistent with constraints based on modeling the observed emission of Sgr A*. The flow structure found here can be used as more realistic initial conditions for horizon scale simulations of Sgr A*.

  16. Spent Nuclear Fuel (SNF) Project Canister Storage Building (CSB) Process Flow Diagram Mass Balance Calculations

    International Nuclear Information System (INIS)

    KLEM, M.J.

    2000-01-01

    The purpose of these calculations is to develop the material balances for documentation of the Canister Storage Building (CSB) Process Flow Diagram (PFD) and future reference. The attached mass balances were prepared to support revision two of the PFD for the CSB. The calculations refer to diagram H-2-825869

  17. Spent Nuclear Fuel (SNF) Project Multi Canister Overpack (MCO) Process Flow Diagram Mass Balance Calculations

    International Nuclear Information System (INIS)

    KLEM, M.J.

    2000-01-01

    The purpose of this calculation document is to develop the bases for the material balances of the Multi-Canister Overpack (MCO) Level 1 Process Flow Diagram (PFD). The attached mass balances support revision two of the PFD for the MCO and provide future reference

  18. Fundamental Combustion Processes of Particle-Laden Shear Flows in Solid Fuel Ramjets

    Science.gov (United States)

    1990-05-17

    iclIs can be used together to generate better performances. A new Zec ,,nique has recently been developed in which boron particles are coated with...34 Final Rept., AEDC-R-76-158, July 1, 1975-Sept. 30, 1976. 6. Peters , C. E., Phares, W. J., "Analytical Model of Supersonic, Turbulent, Near-Wake Flows

  19. On groundwater flow modelling in safety analyses of spent fuel disposal. A comparative study with emphasis on boundary conditions

    Energy Technology Data Exchange (ETDEWEB)

    Jussila, P

    1999-11-01

    Modelling groundwater flow is an essential part of the safety assessment of spent fuel disposal because moving groundwater makes a physical connection between a geological repository and the biosphere. Some of the common approaches to model groundwater flow in bedrock are equivalent porous continuum (EC), stochastic continuum and various fracture network concepts. The actual flow system is complex and measuring data are limited. Multiple distinct approaches and models, alternative scenarios as well as calibration and sensitivity analyses are used to give confidence on the results of the calculations. The correctness and orders of magnitude of results of such complex research can be assessed by comparing them to the results of simplified and robust approaches. The first part of this study is a survey of the objects, contents and methods of the groundwater flow modelling performed in the safety assessment of the spent fuel disposal in Finland and Sweden. The most apparent difference of the Swedish studies compared to the Finnish ones is the approach of using more different models, which is enabled by the more resources available in Sweden. The results of more comprehensive approaches provided by international co-operation are very useful to give perspective to the results obtained in Finland. In the second part of this study, the influence of boundary conditions on the flow fields of a simple 2D model is examined. The assumptions and simplifications in this approach include e.g. the following: (1) the EC model is used, in which the 2-dimensional domain is considered a continuum of equivalent properties without fractures present, (2) the calculations are done for stationary fields, without sources or sinks present in the domain and with a constant density of the groundwater, (3) the repository is represented by an isotropic plate, the hydraulic conductivity of which is given fictitious values, (4) the hydraulic conductivity of rock is supposed to have an exponential

  20. In situ diagnostic of two-phase flow phenomena in polymer electrolyte fuel cells by neutron imaging

    International Nuclear Information System (INIS)

    Zhang Jianbo; Kramer, Denis; Shimoi, Ryoichi; Ono, Yoshitaka; Lehmann, Eberhard; Wokaun, Alexander; Shinohara, Kazuhiko; Scherer, Guenther G.

    2006-01-01

    The formation of liquid water in operating polymer electrolyte fuel cells (PEFC) of industrial and laboratory size has been investigated by in situ neutron imaging. The influence of the materials chosen for the structural components of the cell on droplet formation and transport in flow fields and on liquid formation in gas diffusion layers has been studied. The changing of the cathodic gas diffusion layer material allowed the relationship between materials, liquid accumulation, and electrochemical performance to be examined. It has been shown that material choice has considerable bearing on the presence of liquid inside the porous structures and the electrochemical characteristics. A simplified quasi one-dimensional cell with an active area of 25 cm 2 was used for materials comparison, and the results were related to technically relevant operating conditions - where inhomogeneities have to be considered - by subsequent examination of cells with an active area of 100 cm 2

  1. Formation of polycyclic aromatic hydrocarbons and soot in fuel-rich oxidation of methane in a laminar flow reactor

    DEFF Research Database (Denmark)

    Skjøth-Rasmussen, Martin Skov; Glarborg, Peter; Østberg, M.

    2004-01-01

    Conversion of methane to higher hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), and soot was investigated under fuel-rich conditions in a laminar flow reactor. The effects of stoichiometry, dilution, and water vapor addition were studied at temperatures between 1073 and 1823 K. A chemical...... kinetic mechanism was established for methane oxidation, with emphasis on formation of higher hydrocarbons and PAH. A submodel for soot formation was adopted from the work of Frenklach and co-workers without changes. Modeling predictions showed good agreement with experimental results. Reactants, stable...... decrease with increasing addition of water vapor. The effect is described qualitatively by the reaction mechanism. The enhanced oxidation of acetylene is attributed to higher levels of hydroxyl radicals, formed from the reaction between the water vapor and hydrogen atoms....

  2. Multiphase flow in the geosphere around a repository for spent nuclear fuels. Inventory of the present knowledge

    International Nuclear Information System (INIS)

    Aalen, Bengt

    2004-10-01

    Important quantities of gas can form in an underground repository for nuclear wastes. Gas can be formed through: corroding metals; water and certain organic substances that undergo radiolysis; organic material degrading through microbial activity. The last point is of concern mainly for intermediate-level wastes, which can hold large amounts of organic materials. The first point is the main process for high-level wastes. The gas could transport radioactive substances through the buffer and the geosphere into the biosphere, or affect the performance of the repository in a negative way. The present report gives a review of the knowledge about two-phase flow in connection with deep geologic repositories for spent nuclear fuel

  3. Breakdown voltage at the electric terminals of GCFR-core flow test loop fuel rod simulators in helium and air

    International Nuclear Information System (INIS)

    Huntley, W.R.; Conley, T.B.

    1979-12-01

    Tests were performed to determine the ac and dc breakdown voltage at the terminal ends of a fuel rod simulator (FRS) in helium and air atmospheres. The tests were performed at low pressures (1 to 2 atm) and at temperatures from 20 to 350 0 C (68 to 660 0 F). The area of concern was the 0.64-mm (0.025-in.) gap between the coaxial conductor of the FRS and the sheaths of the four internal thermocouples as they exit the FRS. The tests were prformed to ensure a sufficient safety margin during Core Flow Test Loop (CFTL) operations that require potentials up to 350 V ac at the FRS terminals. The primary conclusion from the test results is that the CFTL cannot be operated safely if the terminal ends of the FRSs are surrounded by a helium atmosphere but can be operated safely in air

  4. Experimental investigation of turbulent flow through spacer grids in fuel rod bundles

    International Nuclear Information System (INIS)

    Caraghiaur, Diana; Anglart, Henryk; Frid, Wiktor

    2009-01-01

    This paper contains experimental data of pressure, velocity and turbulence intensity in a 24-rod fuel bundle with spacer grids. Detailed pressure measurements inside the spacer grid have been obtained by use of a sliding pressure-sensing rod. Laser Doppler Velocimetry technique was used to measure the local axial velocity and its fluctuating component upstream and downstream of the spacer grid in sub-channels with different blockage ratios. The measurements show a changing pattern in function of radial position in the cross-section of the fuel bundle. For sub-channels close to the box wall, the turbulence intensity suddenly increases just downstream of the spacer and then gradually decays. In inner sub-channels, however, the turbulence intensity downstream of the spacer decreases below its upstream value and then gradually increases until it reaches the maximum value at approximately two spacer heights. The present study reveals that spacer effects, such as local pressure distribution and turbulence intensity enhancement, not only depend exclusively on the local geometry details, but also on the location in the cross-section of the rod bundle.

  5. Experimental investigation of turbulent flow through spacer grids in fuel rod bundles

    Energy Technology Data Exchange (ETDEWEB)

    Caraghiaur, Diana [Royal Institute of Technology, Division of Nuclear Reactor Technology, Department of Physics, School of Engineering Sciences, AlbaNova University Center, SE-106 91 Stockholm (Sweden)], E-mail: dianac@kth.se; Anglart, Henryk [Royal Institute of Technology, Division of Nuclear Reactor Technology, Department of Physics, School of Engineering Sciences, AlbaNova University Center, SE-106 91 Stockholm (Sweden); Frid, Wiktor [Swedish Radiation Safety Authority, Reactor Technology and Structural Integrity, SE-171 16 Stockholm (Sweden)

    2009-10-15

    This paper contains experimental data of pressure, velocity and turbulence intensity in a 24-rod fuel bundle with spacer grids. Detailed pressure measurements inside the spacer grid have been obtained by use of a sliding pressure-sensing rod. Laser Doppler Velocimetry technique was used to measure the local axial velocity and its fluctuating component upstream and downstream of the spacer grid in sub-channels with different blockage ratios. The measurements show a changing pattern in function of radial position in the cross-section of the fuel bundle. For sub-channels close to the box wall, the turbulence intensity suddenly increases just downstream of the spacer and then gradually decays. In inner sub-channels, however, the turbulence intensity downstream of the spacer decreases below its upstream value and then gradually increases until it reaches the maximum value at approximately two spacer heights. The present study reveals that spacer effects, such as local pressure distribution and turbulence intensity enhancement, not only depend exclusively on the local geometry details, but also on the location in the cross-section of the rod bundle.

  6. A two-phase flow and non-isothermal agglomerate model for a proton exchange membrane (PEM) fuel cell

    International Nuclear Information System (INIS)

    Xing, Lei; Liu, Xiaoteng; Alaje, Taiwo; Kumar, Ravi; Mamlouk, Mohamed; Scott, Keith

    2014-01-01

    A two dimensional, across the channel, steady-state model for a proton exchange membrane fuel cell (PEMFC) is presented in which the non-isothermal model for temperature distribution, the two-phase flow model for liquid water transport and the agglomerate model for oxygen reduction reaction are fully coupled. This model is used to investigate thermal transport within the membrane electrode assembly (MEA) associated with the combinational water phase-transfer and transport mechanisms. Effective temperature distribution strategies are established aim to enhance the cell performance. Agglomerate assumption is adopted in which the ionomer and liquid water in turn cover the agglomerate to form the ionomer and liquid water films. Ionomer swelling is associated with the non-uniform distribution of the water content. The modelling results show that heat accumulates within the cathode catalyst layer under the channel. Higher operating temperature improves the cell performance by increasing the kinetics, reducing the liquid water saturation on the cathode and increasing the water carrying capacity of the anode gas. Applying higher temperature on the anode and enlarging the width ratio of the channel/rib could improve the cell performance. Higher cathode temperature decreases the oxygen mole fraction, resulting in an insufficient oxygen supply and a limitation of the cell performance. - Highlights: • The two-phase flow and non-isothermal model couple with the agglomerate model. • Oxygen diffusivity and solubility in Nafion ® relate to water content and temperature. • Higher anode operating temperature improves the fuel cell performance. • Insufficient oxygen supply limits cell performance at higher current densities

  7. Numerical investigation of heat transfer in upward flows of supercritical water in circular tubes and tight fuel rod bundles

    International Nuclear Information System (INIS)

    Yang Jue; Oka, Yoshiaki; Ishiwatari, Yuki; Liu Jie; Yoo, Jaewoon

    2007-01-01

    Heat transfer in upward flows of supercritical water in circular tubes and in tight fuel rod bundles is numerically investigated by using the commercial CFD code STAR-CD 3.24. The objective is to have more understandings about the phenomena happening in supercritical water and for designs of supercritical water cooled reactors. Some turbulence models are selected to carry out numerical simulations and the results are compared with experimental data and other correlations to find suitable models to predict heat transfer in supercritical water. The comparisons are not only in the low bulk temperature region, but also in the high bulk temperature region. The two-layer model (Hassid and Poreh) gives a better prediction to the heat transfer than other models, and the standard k-ε high Re model with the standard wall function also shows an acceptable predicting capability. Three-dimensional simulations are carried out in sub-channels of tight square lattice and triangular lattice fuel rod bundles at supercritical pressure. Results show that there is a strong non-uniformity of the circumferential distribution of the cladding surface temperature, in the square lattice bundle with a small pitch-to-diameter ratio (P/D). However, it does not occur in the triangular lattice bundle with a small P/D. It is found that this phenomenon is caused by the large non-uniformity of the flow area in the cross-section of sub-channels. Some improved designs are numerically studied and proved to be effective to avoid the large circumferential temperature gradient at the cladding surface

  8. Feasibility Studies of Vortex Flow Impact On the Proliferation of Algae in Hydrogen Production for Fuel Cell Applications

    Science.gov (United States)

    Miskon, Azizi; A/L Thanakodi, Suresh; Shiema Moh Nazar, Nazatul; Kit Chong, Marcus Wai; Sobri Takriff, Mohd; Fakir Kamarudin, Kamrul; Aziz Norzali, Abdul; Nooraya Mohd Tawil, Siti

    2016-11-01

    The instability of crude oil price in global market as well as the sensitivity towards green energy increases, more research works being carried out to find alternative energy replacing the depleting of fossil fuels. Photobiological hydrogen production system using algae is one of the promising alternative energy source. However, the yield of hydrogen utilizing the current photobioreactor (PBR) is still low for commercial application due to restricted light penetration into the deeper regions of the reactor. Therefore, this paper studies the feasibility of vortex flow impact utilizing magnetic stirring in hydrogen production for fuel cell applications. For comparison of results, a magnetic stirrer is placed under a PBR of algae to stir the algae to obtain an even distribution of sunlight to the algae while the controlled PBR of algae kept in static. The produced hydrogen level was measured using hydrogen sensor circuit and the data collected were communicated to laptop using Arduino Uno. The results showed more cell counts and hydrogen produced in the PBR under the influence of magnetic stirring compared to static PBR by an average of 8 percent in 4 days.

  9. Effect of engine load and biogas flow rate to the performance of a compression ignition engine run in dual-fuel (dieselbiogas) mode

    Science.gov (United States)

    Ambarita, H.

    2018-02-01

    The Government of Indonesia (GoI) has released a target on reduction Green Houses Gases emissions (GHG) by 26% from level business-as-usual by 2020, and the target can be up to 41% by international supports. In the energy sector, this target can be reached effectively by promoting fossil fuel replacement or blending with biofuel. One of the potential solutions is operating compression ignition (CI) engine in dual-fuel (diesel-biogas) mode. In this study effects of engine load and biogas flow rate on the performance and exhaust gas emissions of a compression ignition engine run in dual-fuel mode are investigated. In the present study, the used biogas is refined with methane content 70% of volume. The objectives are to explore the optimum operating condition of the CI engine run in dual-fuel mode. The experiments are performed on a four-strokes CI engine with rated output power of 4.41 kW. The engine is tested at constant speed 1500 rpm. The engine load varied from 600W to 1500W and biogas flow rate varied from 0 L/min to 6 L/min. The results show brake thermal efficiency of the engine run in dual-fuel mode is better than pure diesel mode if the biogas flow rates are 2 L/min and 4 L/min. It is recommended to operate the present engine in a dual-fuel mode with biogas flow rate of 4 L/min. The consumption of diesel fuel can be replaced up to 50%.

  10. Modelling of pressurized water reactor fuel, rod time dependent radial heat flow with boundary element method; Modeliranje spremenljivega radijalnega toplotnega toka tlacnovodne gorivne palice z metodo robnih elementov

    Energy Technology Data Exchange (ETDEWEB)

    Sarler, B [Institut Jozef Stefan, Ljubljana (Yugoslavia)

    1987-07-01

    The basic principles of the boundary element method numerical treatment of the radial flow heat diffusion equation are presented. The algorithm copes the time dependent Dirichlet and Neumann boundary conditions, temperature dependent material properties and regions from different materials in thermal contact. It is verified on the several analytically obtained test cases. The developed method is used for the modelling of unsteady radial heat flow in pressurized water reactor fuel rod. (author)

  11. CFD study of liquid-cooled heat sinks with microchannel flow field configurations for electronics, fuel cells, and concentrated solar cells

    International Nuclear Information System (INIS)

    Ramos-Alvarado, Bladimir; Li Peiwen; Liu Hong; Hernandez-Guerrero, Abel

    2011-01-01

    A study of the heat transfer performance of liquid-cooled heat sinks with conventional and novel micro-channel flow field configurations for application in electronic devices, fuel cells, and concentrated solar cells is presented in this paper. The analyses were based on computations using the CFD software ANSYS FLUENT. The flow regime in heat sinks is constrained to laminar flow in the study. Details of the heat transfer performance, particularly, the uniformity of temperature distribution on the heating surface, as well as the pressure losses and pumping power in the operation of the studied heat sinks were obtained. Comparisons of the flow distribution uniformity in multiple flow channels, temperature uniformity on heating surfaces, and pumping power consumption of heat sinks with novel flow field configurations and conventional flow field configurations were conducted. It was concluded that the novel flow field configurations studied in this work exhibit appreciable benefits for application in heat sinks. - Highlights: → We present novel designs of flow channel configurations in liquid cooled heat sinks. → The flow and heat transfer in heat sinks were simulated using CFD tool. → The temperature and pressure loss in novel and conventional heat sinks were studied. → Figure of merit of heat sinks in different flow channel configurations was presented. → The heat sinks having our novel design of flow channel configurations are excellent.

  12. Improved coal grinding and fuel flow control in thermal power plants

    DEFF Research Database (Denmark)

    Niemczyk, Piotr; Bendtsen, Jan Dimon

    2011-01-01

    A novel controller for coal circulation and pulverized coal flow in a coal mill is proposed. The design is based on optimal control theory for bilinear systems with additional integral action. The states are estimated from the grinding power consumption and the amount of coal accumulated in the m......A novel controller for coal circulation and pulverized coal flow in a coal mill is proposed. The design is based on optimal control theory for bilinear systems with additional integral action. The states are estimated from the grinding power consumption and the amount of coal accumulated...... as well as when parameter uncertainties and noise are present. The proposed controller lowers the grinding power consumption while in most cases exhibiting superior performance in comparison with the PID controller....

  13. Local Limit Phenomena, Flow Compression, and Fuel Cracking Effects in High-Speed Turbulent Flames

    Science.gov (United States)

    2015-06-01

    e.g. local extinction and re- ignition , interactions between flow compression and fast-reaction induced dilatation (reaction compression ), and to...time as a function of initial temperature in constant-pressure auto - ignition , and (b) the S-curves of perfectly stirred reactors (PSRs), for n...mechanism. The reduction covered auto - ignition and perfectly stirred reactors for equivalence ratio range of 0.5~1.5, initial temperature higher than

  14. Fuel spacer

    International Nuclear Information System (INIS)

    Nishida, Koji; Yokomizo, Osamu; Kanazawa, Toru; Kashiwai, Shin-ichi; Orii, Akihito.

    1992-01-01

    The present invention concerns a fuel spacer for a fuel assembly of a BWR type reactor and a PTR type reactor. Springs each having a vane are disposed on the side surface of a circular cell which supports a fuel rods. A vortex streams having a vertical component are formed by the vanes in the flowing direction of a flowing channel between adjacent cylindrical cells. Liquid droplets carried by streams are deposited on liquid membrane streams flowing along the fuel rod at the downstream of the spacer by the vortex streams. In view of the above, the liquid droplets can be deposited to the fuel rod without increasing the amount of metal of the spacer. Accordingly, the thermal margin of the fuel assembly can be improved without losing neutron economy. (I.N.)

  15. Mass balances and energy flows, reference concept. (Spent Fuel - Copper-Iron - Bentonite - Granite)

    International Nuclear Information System (INIS)

    Nordman, H.; Lehikoinen, J.

    2008-12-01

    In this work, a semi-quantitative analysis of mass and energy flows and balances in a deep repository of the KBS-3V type subject to a glacial cycle has been carried out. The energy flows and temperatures show the maximum temperature at the canister surface not to exceed the design temperature of 100 deg C. If the measures taken to limit the water flow into the underground facilities are appropriate, the lifetime of the calcite buffer in the hydraulically conductive fracture zones was calculated to extend well beyond the operational phase of the repository. The results from hydrogeochemical model calculations in the backfill imply a long-term exchange of sodium for calcium in the clay component, if MX-80 bentonite is used. As this constitutes a potential threat to the swelling pressure of backfill in saline water environments, the physicochemical properties of a backfill should be carefully adjusted to meet its preplanned function. Despite short-lived episodes of oxygen-rich glacial water intrusion, the corrosion of the copper canister will likely be minor in the long term. (orig.)

  16. Determination of the vibration characteristics of nuclear fuel rods in a fluid flow using multiphysics computation

    International Nuclear Information System (INIS)

    Sbragio, Ricardo

    1999-01-01

    The determination of natural frequencies and displacement Power Spectrum Density (PSD) of fuel rods in a fluid using Computational Fluid Dynamics and Finite Element Methods is presented. The rods are modeled as slender beams subjected to small displacements in a fluid using three-dimensional mesh. The incompressible Navier-Stokes and linear momentum balance equations are solved simultaneously using Spectrum code. Two examples from literature are analyzed. The first consists in one rod in a fluid. The excitation is an impulse force at the rod central node. The second example is a two rod system in a fluid. In this case, the excitation force is random and is determined from a PSD. (author)

  17. 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

    A model, called THERMOSS, is developed to compute the duration of stagnation in a CANDU reactor fuel channel with subcooled, stagnant initial conditions. The model solves, in closed form, the one dimensional, two-fluid conservation equations. In the computation of the duration of stagnation, the channel water level is an important intermediate variable because it determines the amount of steam production. A feature of the model is that water level is determined by a momentum balance between frictional pressure drop in the steam phase and hydrostatic head in the liquid phase. This is in contrast to an ealier model in which the level was determined from mass balance considerations. A satisfactory agreement between the predicted and experimentally observed channel water level and duration of stagnation is obtained. (orig.)

  18. Studies on the separation and purification of strontium from the highly radioactive waste flow of fuel element reprocessing

    International Nuclear Information System (INIS)

    Tuerker, A.

    1989-10-01

    The quantity of spent fuel elements is increasing due to the extended peaceful uses of nuclear energy. Of the numerous fission products, strontium has an interesting application potential as a radiation or energy source for utilization in various industrial fields. A necessary condition for its use is its isolation in high radiochemical purity from the highly radioactive waste flow of the Purex process. In the present study, precipitation and coprecipitation reactions, and in particular ion exchange reactions, were chosen from among the various possible chemical and physical separation methods and examined with respect to their suitability for a selective separation of strontium from the other fission products. In selecting separation materials, particularly with respect to radiation resistance, thermal stability and selectivity, polyantimonic acid proved to be the best absorbent (even in a very acid medium) for strontium. Furthermore, the behaviour of the most important radionuclides was studied with respect to the denitration reaction from a 5 molar nitric acid solution. On the basis of the high demands made on the purity of the product, a method was developed by combining lead sulphate carrier precipitation with an ion exchange reaction on polyantimonic acid and is shown in a flow chart. (orig.) [de

  19. Bridging PIV spatial and temporal resolution using governing equations and development of the coaxial volumetric velocimeter

    NARCIS (Netherlands)

    Schneiders, J.F.G.

    2017-01-01

    A series of techniques is proposed for volumetric air flow measurements that are based upon the principles of particle image velocimetry (PIV). The proposed techniques fall in two categories; part 1 of this dissertation considers measurement data processing using constitutive laws and part 2 focuses

  20. Investigation on thermo-acoustic instability dynamic characteristics of hydrocarbon fuel flowing in scramjet cooling channel based on wavelet entropy method

    Science.gov (United States)

    Zan, Hao; Li, Haowei; Jiang, Yuguang; Wu, Meng; Zhou, Weixing; Bao, Wen

    2018-06-01

    As part of our efforts to find ways and means to further improve the regenerative cooling technology in scramjet, the experiments of thermo-acoustic instability dynamic characteristics of hydrocarbon fuel flowing have been conducted in horizontal circular tubes at different conditions. The experimental results indicate that there is a developing process from thermo-acoustic stability to instability. In order to have a deep understanding on the developing process of thermo-acoustic instability, the method of Multi-scale Shannon Wavelet Entropy (MSWE) based on Wavelet Transform Correlation Filter (WTCF) and Multi-Scale Shannon Entropy (MSE) is adopted in this paper. The results demonstrate that the developing process of thermo-acoustic instability from noise and weak signals is well detected by MSWE method and the differences among the stability, the developing process and the instability can be identified. These properties render the method particularly powerful for warning thermo-acoustic instability of hydrocarbon fuel flowing in scramjet cooling channels. The mass flow rate and the inlet pressure will make an influence on the developing process of the thermo-acoustic instability. The investigation on thermo-acoustic instability dynamic characteristics at supercritical pressure based on wavelet entropy method offers guidance on the control of scramjet fuel supply, which can secure stable fuel flowing in regenerative cooling system.

  1. Temperature and flow fluctuations under local boiling in a simulated fuel subassembly

    International Nuclear Information System (INIS)

    Inujima, H.; Ogino, T.; Uotani, M.; Yamaguchi, K.

    1980-08-01

    Out-of-pile experiments were carried out with the sodium test loop SIENA in O-arai Engineering Center of PNC, and the feasibility studies had been made on the local boiling detection by use of temperature and flow fluctuations. The studies showed that the temperature fluctuation transferred the information on local boiling toward the end of the bundle, but hardly to the outlet. In addition, it was proved that the anomaly detection method, which used the algorithm of whiteness test method to the residual time series data of autoregressive model, is an effective one for detecting anomaly such as local boiling. (author)

  2. Coupled-Flow Simulation of HP-LP Turbines Has Resulted in Significant Fuel Savings

    Science.gov (United States)

    Veres, Joseph P.

    2001-01-01

    Our objective was to create a high-fidelity Navier-Stokes computer simulation of the flow through the turbines of a modern high-bypass-ratio turbofan engine. The simulation would have to capture the aerodynamic interactions between closely coupled high- and low-pressure turbines. A computer simulation of the flow in the GE90 turbofan engine's high-pressure (HP) and low-pressure (LP) turbines was created at GE Aircraft Engines under contract with the NASA Glenn Research Center. The three-dimensional steady-state computer simulation was performed using Glenn's average-passage approach named APNASA. The areas upstream and downstream of each blade row mutually interact with each other during engine operation. The embedded blade row operating conditions are modeled since the average passage equations in APNASA actively include the effects of the adjacent blade rows. The turbine airfoils, platforms, and casing are actively cooled by compressor bleed air. Hot gas leaks around the tips of rotors through labyrinth seals. The flow exiting the high work HP turbines is partially transonic and, therefore, has a strong shock system in the transition region. The simulation was done using 121 processors of a Silicon Graphics Origin 2000 (NAS 02K) cluster at the NASA Ames Research Center, with a parallel efficiency of 87 percent in 15 hr. The typical average-passage analysis mesh size per blade row was 280 by 45 by 55, or approx.700,000 grid points. The total number of blade rows was 18 for a combined HP and LP turbine system including the struts in the transition duct and exit guide vane, which contain 12.6 million grid points. Design cycle turnaround time requirements ran typically from 24 to 48 hr of wall clock time. The number of iterations for convergence was 10,000 at 8.03x10(exp -5) sec/iteration/grid point (NAS O2K). Parallel processing by up to 40 processors is required to meet the design cycle time constraints. This is the first-ever flow simulation of an HP and LP

  3. CANFLEX fuel bundle cross-flow endurance test 2 (Test report)

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sung Deok; Chung, C. H.; Chang, S. K.; Kim, B. D. [Korea Atomic Energy Research Institute, Taejeon (Korea)

    2000-02-01

    This report describes cross-flow endurance test 2 that was conducted at the CANDU-Hot Test Loop. The test was completed on March 30, 1999 using a new CANFLEX bundle, built by KAERI. It was carried out for a total of 22 hours. After an initial period of ten hours, the test was stopped at the intervals of four hours for bundle inspection and inter-element gap measurement[7]. The test bundle end-plate to end-cap welds were inspected carefully for failure or crack propagation using liquid penetrant examination especially at the heat-affected zones. 12 refs., 4 figs., 10 tabs. (Author)

  4. Biodegradation of phenol in batch and continuous flow microbial fuel cells with rod and granular graphite electrodes.

    Science.gov (United States)

    Moreno, Lyman; Nemati, Mehdi; Predicala, Bernardo

    2018-01-01

    Phenol biodegradation was evaluated in batch and continuous flow microbial fuel cells (MFCs). In batch-operated MFCs, biodegradation of 100-1000 mg L -1 phenol was four to six times faster when graphite granules were used instead of rods (3.5-4.8 mg L -1  h -1 vs 0.5-0.9 mg L -1  h -1 ). Similarly maximum phenol biodegradation rates in continuous MFCs with granular and single-rod electrodes were 11.5 and 0.8 mg L -1  h -1 , respectively. This superior performance was also evident in terms of electrochemical outputs, whereby continuous flow MFCs with granular graphite electrodes achieved maximum current and power densities (3444.4 mA m -3 and 777.8 mW m -3 ) that were markedly higher than those with single-rod electrodes (37.3 mA m -3 and 0.8 mW m -3 ). Addition of neutral red enhanced the electrochemical outputs to 5714.3 mA m -3 and 1428.6 mW m -3 . Using the data generated in the continuous flow MFC, biokinetic parameters including μ m , K S , Y and K e were determined as 0.03 h -1 , 24.2 mg L -1 , 0.25 mg cell (mg phenol) -1 and 3.7 × 10 -4  h -1 , respectively. Access to detailed kinetic information generated in MFC environmental conditions is critical in the design, operation and control of large-scale treatment systems utilizing MFC technology.

  5. Natural convection in wavy enclosures with volumetric heat sources

    International Nuclear Information System (INIS)

    Oztop, H.F.; Varol, Y.; Abu-Nada, E.; Chamkha, A.

    2011-01-01

    In this paper, the effects of volumetric heat sources on natural convection heat transfer and flow structures in a wavy-walled enclosure are studied numerically. The governing differential equations are solved by an accurate finite-volume method. The vertical walls of enclosure are assumed to be heated differentially whereas the two wavy walls (top and bottom) are kept adiabatic. The effective governing parameters for this problem are the internal and external Rayleigh numbers and the amplitude of wavy walls. It is found that both the function of wavy wall and the ratio of internal Rayleigh number (Ra I ) to external Rayleigh number (Ra E ) affect the heat transfer and fluid flow significantly. The heat transfer is predicted to be a decreasing function of waviness of the top and bottom walls in case of (IRa/ERa)>1 and (IRa/ERa)<1. (authors)

  6. Investigation of flow blockage in a fuel channel with the ASSERT subchannel code

    International Nuclear Information System (INIS)

    Harvel, G.D.; Dam, R.; Soulard, M.

    1996-01-01

    On behalf of New Brunswick Power, a study was undertaken to determine if safe operation of a CANDU-6 reactor can be maintained at low reactor powers with the presence of debris in the fuel channels. In particular, the concern was to address if a small blockage due to the presence of debris would cause a significant reduction in dryout powers, and hence, to determine the safe operation power level to maintain dryout margins. In this work the NUCIRC(1,2), ASSERT-IV(3), and ASSERT-PV(3) computer codes are used in conjunction with a pool boiling model to determine the safe operation power level which maintains dryout safety margins. NUCIRC is used to provide channel boundary conditions for the ASSERTcodes and to select a representative channel for analysis. This pool boiling model is provided as a limiting lower bound analysis. As expected, the ASSERT results predict higher CHF ratios than the pool boiling model. In general, the ASSERT results show that as the model comes closer to modelling a complete blockage it reduces toward, but does not reach the pool boiling model. (author)

  7. Characterization of wastewater treatment by two microbial fuel cells in continuous flow operation.

    Science.gov (United States)

    Kubota, Keiichi; Watanabe, Tomohide; Yamaguchi, Takashi; Syutsubo, Kazuaki

    2016-01-01

    A two serially connected single-chamber microbial fuel cell (MFC) was applied to the treatment of diluted molasses wastewater in a continuous operation mode. In addition, the effect of series and parallel connection between the anodes and the cathode on power generation was investigated experimentally. The two serially connected MFC process achieved 79.8% of chemical oxygen demand removal and 11.6% of Coulombic efficiency when the hydraulic retention time of the whole process was 26 h. The power densities were 0.54, 0.34 and 0.40 W m(-3) when electrodes were in individual connection, serial connection and parallel connection modes, respectively. A high open circuit voltage was obtained in the serial connection. Power density decreased at low organic loading rates (OLR) due to the shortage of organic matter. Power generation efficiency tended to decrease as a result of enhancement of methane fermentation at high OLRs. Therefore, high power density and efficiency can be achieved by using a suitable OLR range.

  8. Method of producing exfoliated graphite composite compositions for fuel cell flow field plates

    Energy Technology Data Exchange (ETDEWEB)

    Zhamu, Aruna; Shi, Jinjun; Guo, Jiusheng; Jang, Bor Z

    2014-04-08

    A method of producing an electrically conductive composite composition, which is particularly useful for fuel cell bipolar plate applications. The method comprises: (a) providing a supply of expandable graphite powder; (b) providing a supply of a non-expandable powder component comprising a binder or matrix material; (c) blending the expandable graphite with the non-expandable powder component to form a powder mixture wherein the non-expandable powder component is in the amount of between 3% and 60% by weight based on the total weight of the powder mixture; (d) exposing the powder mixture to a temperature sufficient for exfoliating the expandable graphite to obtain a compressible mixture comprising expanded graphite worms and the non-expandable component; (e) compressing the compressible mixture at a pressure within the range of from about 5 psi to about 50,000 psi in predetermined directions into predetermined forms of cohered graphite composite compact; and (f) treating the so-formed cohered graphite composite to activate the binder or matrix material thereby promoting adhesion within the compact to produce the desired composite composition. Preferably, the non-expandable powder component further comprises an isotropy-promoting agent such as non-expandable graphite particles. Further preferably, step (e) comprises compressing the mixture in at least two directions. The method leads to composite plates with exceptionally high thickness-direction electrical conductivity.

  9. Volumetric composition in composites and historical data

    DEFF Research Database (Denmark)

    Lilholt, Hans; Madsen, Bo

    2013-01-01

    The obtainable volumetric composition in composites is of importance for the prediction of mechanical and physical properties, and in particular to assess the best possible (normally the highest) values for these properties. The volumetric model for the composition of (fibrous) composites gives...... guidance to the optimal combination of fibre content, matrix content and porosity content, in order to achieve the best obtainable properties. Several composite materials systems have been shown to be handleable with this model. An extensive series of experimental data for the system of cellulose fibres...... and polymer (resin) was produced in 1942 – 1944, and these data have been (re-)analysed by the volumetric composition model, and the property values for density, stiffness and strength have been evaluated. Good agreement has been obtained and some further observations have been extracted from the analysis....

  10. Process conditions and volumetric composition in composites

    DEFF Research Database (Denmark)

    Madsen, Bo

    2013-01-01

    The obtainable volumetric composition in composites is linked to the gravimetric composition, and it is influenced by the conditions of the manufacturing process. A model for the volumetric composition is presented, where the volume fractions of fibers, matrix and porosity are calculated...... as a function of the fiber weight fraction, and where parameters are included for the composite microstructure, and the fiber assembly compaction behavior. Based on experimental data of composites manufactured with different process conditions, together with model predictions, different types of process related...... effects are analyzed. The applied consolidation pressure is found to have a marked effect on the volumetric composition. A power-law relationship is found to well describe the found relations between the maximum obtainable fiber volume fraction and the consolidation pressure. The degree of fiber...

  11. An experimental study on the effects of swirling oxidizer flow and diameter of fuel nozzle on behaviour and light emittance of propane-oxygen non-premixed flame

    Directory of Open Access Journals (Sweden)

    Javareshkian Alireza

    2017-01-01

    Full Text Available In this study, the stability and the light emittance of non-premixed propane-oxygen flames have been experimentally evaluated with respect to swirling oxidizer flow and variations in fuel nozzle diameter. Hence, three types of the vanes with the swirl angles of 30°, 45°, and 60° have been chosen for producing the desired swirling flows. The main aims of this study are to determine the flame behaviour, light emittance, and also considering the effect of variation in fuel nozzle diameter on combustion phenomena such as flame length, flame shape, and soot free length parameter. The investigation into the flame phenomenology was comprised of variations of the oxidizer and fuel flow velocities (respective Reynolds numbers and the fuel nozzle diameter. The results showed that the swirl effect could change the flame luminosity and this way could reduce or increase the maximum value of the flame light emittance in the combustion zone. Therefore, investigation into the flame light emittance can give a good clue for studying the mixing quality of reactants, the flame phenomenology (blue flame or sooty flame, localized extinction, and the combustion intensity in non-premixed flames.

  12. Development and Assessment of CFD Models Including a Supplemental Program Code for Analyzing Buoyancy-Driven Flows Through BWR Fuel Assemblies in SFP Complete LOCA Scenarios

    Science.gov (United States)

    Artnak, Edward Joseph, III

    This work seeks to illustrate the potential benefits afforded by implementing aspects of fluid dynamics, especially the latest computational fluid dynamics (CFD) modeling approach, through numerical experimentation and the traditional discipline of physical experimentation to improve the calibration of the severe reactor accident analysis code, MELCOR, in one of several spent fuel pool (SFP) complete loss-ofcoolant accident (LOCA) scenarios. While the scope of experimental work performed by Sandia National Laboratories (SNL) extends well beyond that which is reasonably addressed by our allotted resources and computational time in accordance with initial project allocations to complete the report, these simulated case trials produced a significant array of supplementary high-fidelity solutions and hydraulic flow-field data in support of SNL research objectives. Results contained herein show FLUENT CFD model representations of a 9x9 BWR fuel assembly in conditions corresponding to a complete loss-of-coolant accident scenario. In addition to the CFD model developments, a MATLAB based controlvolume model was constructed to independently assess the 9x9 BWR fuel assembly under similar accident scenarios. The data produced from this work show that FLUENT CFD models are capable of resolving complex flow fields within a BWR fuel assembly in the realm of buoyancy-induced mass flow rates and that characteristic hydraulic parameters from such CFD simulations (or physical experiments) are reasonably employed in corresponding constitutive correlations for developing simplified numerical models of comparable solution accuracy.

  13. Investigation of a wire wrapped fuel assembly with the anisotropic Coarse-Grid-CFD (AP-CGCFD)

    Energy Technology Data Exchange (ETDEWEB)

    Viellieber, Mathias; Dietrich, Philipp; Class, Andreas [Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen (Germany). AREVA Nuclear Professional School (ANPS)

    2013-07-01

    Within this work we demonstrated the ability of the AP-CGCFD method to deal with complex geometries like wire wrapped spacer grid fuel assemblies. Both qualitative and quantitative values like the pressure profile and velocity structures could be reproduced from the detailed RANS CFD simulation. Furthermore we introduced a novel mathematical formulation of the method. Compared to state-of-the-art subchannel analyses, neither parameter tuning is needed, nor empirical or experimental input, to adjust the solvers for a specific geometry. Certainly, this method requires the user making educated decisions on the representative geometry segments and a suitable parameter space for the initial fine CFD simulations needed to extract the volumetric source terms. Since similar flow conditions repeat many times, the costs of the representative CFD simulations needed to extract the volumetric forces are much lower than a full simulation. Thus AP-CGCFD simulations are suitable for simulations of geometries where flow situations are repeating many times. (orig.)

  14. Exploring interaction with 3D volumetric displays

    Science.gov (United States)

    Grossman, Tovi; Wigdor, Daniel; Balakrishnan, Ravin

    2005-03-01

    Volumetric displays generate true volumetric 3D images by actually illuminating points in 3D space. As a result, viewing their contents is similar to viewing physical objects in the real world. These displays provide a 360 degree field of view, and do not require the user to wear hardware such as shutter glasses or head-trackers. These properties make them a promising alternative to traditional display systems for viewing imagery in 3D. Because these displays have only recently been made available commercially (e.g., www.actuality-systems.com), their current use tends to be limited to non-interactive output-only display devices. To take full advantage of the unique features of these displays, however, it would be desirable if the 3D data being displayed could be directly interacted with and manipulated. We investigate interaction techniques for volumetric display interfaces, through the development of an interactive 3D geometric model building application. While this application area itself presents many interesting challenges, our focus is on the interaction techniques that are likely generalizable to interactive applications for other domains. We explore a very direct style of interaction where the user interacts with the virtual data using direct finger manipulations on and around the enclosure surrounding the displayed 3D volumetric image.

  15. Volumetric, dashboard-mounted augmented display

    Science.gov (United States)

    Kessler, David; Grabowski, Christopher

    2017-11-01

    The optical design of a compact volumetric display for drivers is presented. The system displays a true volume image with realistic physical depth cues, such as focal accommodation, parallax and convergence. A large eyebox is achieved with a pupil expander. The windshield is used as the augmented reality combiner. A freeform windshield corrector is placed at the dashboard.

  16. Detailed pressure drop measurements in single-and two-phase adiabatic air-water turbulent flows in realistic BWR fuel assembly geometry with spacer grids

    International Nuclear Information System (INIS)

    Caraghiaur, Diana; Frid, Wiktor; Tillmark, Nils

    2004-01-01

    In recent years, advance numerical simulation tools based on CFD methods have been increasingly used in various multi-phase flow applications. One of these is two-phase flow in fuel assemblies of Boiling Water Reactors. The important and often missing aspect of this development is validation of CFD codes against proper experimental data. The purpose of the current paper is to present detailed pressure measurements over a spacer grid in low pressure adiabatic single- and bubbly two-phase flow, which will be used to further develop a CFD code for BWR fuel bundle analysis. The experiments have been carried out in a n asymmetric 24-rod sub-bundle, representing one quarter of a Westinghouse SVEA-96 nuclear reactor fuel assembly. Single-phase flow measurements have been performed at superficial velocities between 0.90-4.50 m/s and in the two-phase flow, which was simulated by air-water mixture, measurements have been performed at void fractions ranging from 4 to 12% and liquid superficial velocity of 4.50 m/s. In order to increase the number of measuring points, five pressure taps were drilled in one of the rods, which was easily moved vertically by a traversing system, covering most of the points in axial direction. Any of the rods in the bundle could be substitute by the pressure sensing rod and the measurements were made for five pressure taps facing-angles. A detailed pressure distribution comparison between single- and two-phase flows for different sub-channel positions and different flow conditions was performed over one of the spacers. In addition, single-phase pressure drop measurements in the upper part of the test section comprising two spacer grids have been carried out. (author)

  17. An analytical model for the prediction of fluid-elastic forces in a rod bundle subjected to axial flow: theory, experimental validation and application to PWR fuel assemblies

    International Nuclear Information System (INIS)

    Beaud, F.

    1997-01-01

    A model predicting the fluid-elastic forces in a bundle of circular cylinders subjected to axial flow is presented in this paper. Whereas previously published models were limited to circular flow channel, the present one allows to take a rectangular flow external boundary into account. For that purpose, an original approach is derived from the standard method of images. This model will eventually be used to predict the fluid-structure coupling between the flow of primary coolant and a fuel assemblies in PWR nuclear reactors. It is indeed of major importance since the flow is shown to induce quite high damping and could therefore mitigate the incidence of an external load like a seismic excitation on the dynamics of the assemblies. The proposed model is validated on two cases from the literature but still needs further comparisons with the experiments being currently carried out on the EDF set-up. The flow has been shown to induce an approximate 12% damping on a PWR fuel assembly, at nominal reactor conditions. The possible grid effect on the fluid-structure coupling has been neglected so far but will soon be investigated at EDF. (author)

  18. Volumetric B1 (+) mapping of the brain at 7T using DREAM.

    Science.gov (United States)

    Nehrke, Kay; Versluis, Maarten J; Webb, Andrew; Börnert, Peter

    2014-01-01

    To tailor and optimize the Dual Refocusing Echo Acquisition Mode (DREAM) approach for volumetric B1 (+) mapping of the brain at 7T. A new DREAM echo timing scheme based on the virtual stimulated echo was derived to minimize potential effects of transverse relaxation. Furthermore, the DREAM B1 (+) mapping performance was investigated in simulations and experimentally in phantoms and volunteers for volumetric applications, studying and optimizing the accuracy of the sequence with respect to saturation effects, slice profile imperfections, and T1 and T2 relaxation. Volumetric brain protocols were compiled for different isotropic resolutions (5-2.5 mm) and SENSE factors, and were studied in vivo for different RF drive modes (circular/linear polarization) and the application of dielectric pads. Volumetric B1 (+) maps with good SNR at 2.5 mm isotropic resolution were acquired in about 20 s or less. The specific absorption rate was well below the safety limits for all scans. Mild flow artefacts were observed in the large vessels. Moreover, a slight contrast in the ventricle was observed in the B1 (+) maps, which could be attributed to T1 and T2 relaxation effects. DREAM enables safe, very fast, and robust volumetric B1 (+) mapping of the brain at ultrahigh fields. Copyright © 2013 Wiley Periodicals, Inc.

  19. Effect of sulphuric acid concentration on electroosmotic flow through polymer electrolyte membranes in PEM fuel cells. Paper no. IGEC-1-061

    International Nuclear Information System (INIS)

    Karimi, G.; Li, X.

    2005-01-01

    Polymer electrolyte membrane (PEM) fuel cells are highly efficient and environmentally clean, and hence one of the most promising power sources for both stationary and mobile applications. The operations of PEM fuel cells are complicated by the electroosmotic flow of water from anode to cathode through the polymer electrolyte membrane leading to the membrane dehydration and fuel cell performance degradations. In this study, electro osmotic flow in polymer electrolyte membranes is modeled by incorporating the electro kinetic effects in the presence of euphoric acid. The governing Poisson-Boatman and the Nervier-Stokes equations were solved numerically for a single membrane pore to determine the electro osmotic flow distributions through the membrane over a wide range of acid concentrations. The presence of euphoric acid modifies the protons distribution in the membrane and hence alters the driving force for electroosmotic drag. Numerical results indicate that the electro osmotic flow increases steadily with acid concentration. The water transport due to electro osmosis is almost doubled at 2 M acid concentration compared with that of non-doped membrane. The value of electroosmotic drag coefficient however falls steadily with acid concentration due to the presence of a larger number of protons in the electrolyte. (author)

  20. Numerical and Experimental Investigation of a Supersonic Flow Field around Solid Fuel on an Inclined Flat Plate

    Directory of Open Access Journals (Sweden)

    Uzu-Kuei Hsu

    2009-01-01

    Full Text Available This research adopts a shock tube 16 meters long and with a 9 cm bore to create a supersonic, high-temperature, and high-pressure flowfield to observe the gasification and ignition of HTPB solid fuel under different environments. Also, full-scale 3D numerical simulation is executed to enhance the comprehension of this complex phenomenon. The CFD (Computational Fluid Dynamics code is based on the control volume method and the pre-conditioning method for solving the Navier-Stokes equations to simulate the compressible and incompressible coupling problem. In the tests, a HTPB slab is placed in the windowed-test section. Various test conditions generate different supersonic Mach numbers and environmental temperatures. In addition, the incident angles of the HTPB slab were changed relative to the incoming shock wave. Results show that as the Mach number around the slab section exceeded 1.25, the flowfield temperature achieved 1100 K, which is higher than the HTPB gasification temperature (930 K ~ 1090 K. Then, gasification occurred and a short-period ignition could be observed. In particular, when the slab angle was 7∘, the phenomenon became more visible. This is due to the flow field temperature increase when the slab angle was at 7∘.

  1. Long-term performance of a 20-L continuous flow microbial fuel cell for treatment of brewery wastewater

    Science.gov (United States)

    Lu, Mengqian; Chen, Shing; Babanova, Sofia; Phadke, Sujal; Salvacion, Michael; Mirhosseini, Auvid; Chan, Shirley; Carpenter, Kayla; Cortese, Rachel; Bretschger, Orianna

    2017-07-01

    Microbial fuel cells (MFCs) have been shown as a promising technology for wastewater treatment. Integration of MFCs into current wastewater treatment plant have potential to reduce the operational cost and improve the treatment performance, and scaling up MFCs will be essential. However, only a few studies have reported successful scale up attempts. Fabrication cost, treatment performance and operational lifetime are critical factors to optimize before commercialization of MFCs. To test these factors, we constructed a 20 L MFC system containing two 10 L MFC reactors and operated the system with brewery wastewater for nearly one year. Several operational conditions were tested, including different flowrates, applied external resistors, and poised anodic potentials. The condition resulting in the highest chemical oxygen demand (COD) removal efficiency (94.6 ± 1.0%) was a flow rate of 1 mL min-1 (HRT = 313 h) and an applied resistor of 10 Ω across each MFC circuit. Results from each of the eight stages of operation (325 days total) indicate that MFCs can sustain treatment rates over a long-term period and are robust enough to sustain performance even after system perturbations. possible ways to improve MFC performance were discussed for future studies.

  2. Fuel assembly

    International Nuclear Information System (INIS)

    Gjertsen, R.K.; Bassler, E.A.; Huckestein, E.A.; Salton, R.B.; Tower, S.N.

    1988-01-01

    A fuel assembly adapted for use with a pressurized water nuclear reactor having capabilities for fluid moderator spectral shift control is described comprising: parallel arranged elongated nuclear fuel elements; means for providing for axial support of the fuel elements and for arranging the fuel elements in a spaced array; thimbles interspersed among the fuel elements adapted for insertion of a rod control cluster therewithin; means for structurally joining the fuel elements and the guide thimbles; fluid moderator control means for providing a volume of low neutron absorbing fluid within the fuel assembly and for removing a substantially equivalent volume of reactor coolant water therefrom, a first flow manifold at one end of the fuel assembly sealingly connected to a first end of the moderator control tubes whereby the first ends are commonly flow connected; and a second flow manifold, having an inlet passage and an outlet passage therein, sealingly connected to a second end of the moderator control tubes at a second end of the fuel assembly

  3. A review of cell-scale multiphase flow modeling, including water management, in polymer electrolyte fuel cells

    International Nuclear Information System (INIS)

    Andersson, M.; Beale, S.B.; Espinoza, M.; Wu, Z.; Lehnert, W.

    2016-01-01

    Highlights: • The transport expressions inside PEFC GDLs are developed to describe significantly different systems. • Insight into the fundamental processes of liquid water evolution and transport in the GDL and GC is still lacking. • One important feature is the possibility to track the front between the liquid and the gas phases. • The two phase micro channels pressure drop correlations may not be applicable for GCs since one wall being porous. - Abstract: The PEFC has emerged as the most viable fuel cell type for automotive and some portable applications, and also has potential back-up power unit applications due to its low operating temperature, comparative simplicity of construction, high power density, and ease of operation. In spite of tremendous scientific advances, as well as engineering progress over the last few decades, the commercialization of PEFCs remains unrealized, owing primarily to economic viability associated with the high prices of materials and components and technical problems relating primarily to water management. The difficulty in addressing the water management issues lies mostly in the two-phase multi-component flow involving phase-change in porous media, coupled heat and mass transfer, interactions between the porous layers and gas channel (GC) and the complex relationship between water content and cell performance. Due to the low temperature of operation, water generated by the electrochemical reactions often condenses into liquid form, potentially flooding the gas diffusion layer (GDL), GC or other components. Insight into the fundamental processes of liquid water evolution and transport is still lacking, preventing further enhanced PEFC development. The aim of this paper is to give a comprehensive introduction to PEFC modeling inside GCs and GDLs, with a focus on two-phase flow and related phase-change and transport processes. Relevant momentum, mass and heat transport processes are introduced and the microstructural effects

  4. Development of a method for detecting nuclear fuel debris and water leaks at a nuclear reactor/containment vessel by flow visualization

    International Nuclear Information System (INIS)

    Umezawa, Shuichi; Tanaka, Katsuhiko

    2013-01-01

    It is the important issue to fill up each nuclear reactor/containment vessel with water and to take out debris of damaged fuel from them for decommissioning of Fukushima Daiichi nuclear power plants. It is necessary to detect the debris and water leaks at a nuclear reactor/containment vessel for the purpose. However, the method is not completely developed in the present stage. Accordingly, we have developed a method for detecting debris and water leaks at a nuclear reactor/containment vessel by flow visualization. Experiments of the flow visualization were conducted using two types of water tanks. An optical fiber and a collimator lens were employed for modifying a straight laser beam into a sheet projection. Some visualized images were obtained through the experiments. Particle Image Velocimetry, i.e. PIV, analysis was applied to the images for quantitative flow rate analysis. Consequently, it is considered that the flow visualization method has a possibility for the practical use. (author)

  5. Thermal-hydraulic analysis under partial loss of flow accident hypothesis of a plate-type fuel surrounded by two water channels using RELAP5 code

    Directory of Open Access Journals (Sweden)

    Itamar Iliuk

    2016-01-01

    Full Text Available Thermal-hydraulic analysis of plate-type fuel has great importance to the establishment of safety criteria, also to the licensing of the future nuclear reactor with the objective of propelling the Brazilian nuclear submarine. In this work, an analysis of a single plate-type fuel surrounding by two water channels was performed using the RELAP5 thermal-hydraulic code. To realize the simulations, a plate-type fuel with the meat of uranium dioxide sandwiched between two Zircaloy-4 plates was proposed. A partial loss of flow accident was simulated to show the behavior of the model under this type of accident. The results show that the critical heat flux was detected in the central region along the axial direction of the plate when the right water channel was blocked.

  6. Analytical solutions for the temperature field in a 2D incompressible inviscid flow through a channel with walls of solid fuel

    Directory of Open Access Journals (Sweden)

    Sorin BERBENTE

    2011-12-01

    Full Text Available A gas (oxidizer flows between two parallel walls of solid fuel. A combustion is initiated: the solid fuel is vaporized and a diffusive flame occurs. The hot combustion products are submitted both to thermal diffusion and convection. Analytical solutions can be obtained both for the velocity and temperature distributions by considering an equivalent mean temperature where the density and the thermal conductivity are evaluated. The main effects of heat transfer are due to heat convection at the flame. Because the detailed mechanism of the diffusion flame is not introduced the reference chemical reaction is the combustion of premixed fuel with oxidizer in excess. In exchange the analytical solution is used to define an ideal quasi-uniform combustion that could be realized by an n adequate control. The given analytical closed solutions prove themselves flexible enough to adjust the main data of some existing experiments and to suggest new approaches to the problem.

  7. Large-scale numerical simulations on two-phase flow behavior in a fuel bundle of RMWR with the earth simulator

    International Nuclear Information System (INIS)

    Kazuyuki, Takase; Hiroyuki, Yoshida; Hidesada, Tamai; Hajime, Akimoto; Yasuo, Ose

    2003-01-01

    Fluid flow characteristics in a fuel bundle of a reduced-moderation light water reactor (RMWR) with a tight-lattice core were analyzed numerically using a newly developed two-phase flow analysis code under the full bundle size condition. Conventional analysis methods such as sub-channel codes need composition equations based on the experimental data. In case that there are no experimental data regarding to the thermal-hydraulics in the tight-lattice core, therefore, it is difficult to obtain high prediction accuracy on the thermal design of the RMWR. Then the direct numerical simulations with the earth simulator were chosen. The axial velocity distribution in a fuel bundle changed sharply around a grid spacer and its quantitative evaluation was obtained from the present preliminary numerical study. The high prospect was acquired on the possibility of establishment of the thermal design procedure of the RMWR by large-scale direct simulations. (authors)

  8. Cold-neutron tomography of annular flow and functional spacer performance in a model of a boiling water reactor fuel rod bundle

    International Nuclear Information System (INIS)

    Zboray, Robert; Kickhofel, John; Damsohn, Manuel; Prasser, Horst-Michael

    2011-01-01

    Highlights: → Annular flows w/wo functional spacers are investigated by cold neutron imaging. → Liquid film thickness distribution on fuel pins and on spacer vanes is measured. → The influence of the spacers on the liquid film distributions has been quantified. → The cross-sectional averaged liquid hold-up significantly affected by the spacers. → The sapers affect the fraction of the entrained liquid hold up in the gas core. - Abstract: Dryout of the coolant liquid film at the upper part of the fuel pins of a boiling water reactor (BWR) core constitutes the type of heat transfer crisis relevant for the conditions of high void fractions. It is both a safety concern and a limiting factor in the thermal power and thus for the economy of BWRs. We have investigated adiabatic, air-water annular flows in a scaled-up model of two neighboring subchannels as found in BWR fuel assemblies using cold-neutron tomography. The imaging of the double suchannel has been performed at the ICON beamline at the neutron spallation source SINQ at the Paul Scherrer Institute, Switzerland. Cold-neutron tomography is shown here to be an excellent tool for investigating air-water annular flows and the influence of functional spacers of different geometries on such flows. The high-resolution, high-contrast measurements provide the spatial distributions of the coolant liquid film thickness on the fuel pin surfaces as well as on the surfaces of the spacer vanes. The axial variations of the cross-section averaged liquid hold-up and its fraction in the gas core shows the effect of the spacers on the redistribution of the two phases.

  9. Effects of temperature and wave conditions on chemical dispersion efficacy of heavy fuel oil in an experimental flow-through wave tank.

    Science.gov (United States)

    Li, Zhengkai; Lee, Kenneth; King, Thomas; Boufadel, Michel C; Venosa, Albert D

    2010-09-01

    The effectiveness of chemical dispersants (Corexit 9500 and SPC 1000) on heavy fuel oil (IFO180 as test oil) has been evaluated under different wave conditions in a flow-through wave tank. The dispersant effectiveness was determined by measuring oil concentrations and droplet size distributions. An analysis of covariance (ANCOVA) model indicated that wave type and temperature significantly (p or = 400 microm). Copyright 2010 Elsevier Ltd. All rights reserved.

  10. Some insights into the role of axial gas flow in fuel rod behaviour during the LOCA based on Halden tests and calculations with the FALCON-PSI code

    International Nuclear Information System (INIS)

    Khvostov, G.; Wiesenack, W.; Zimmermann, M.A.; Ledergerber, G.

    2011-01-01

    Highlights: → A model for the dynamics of axial gas redistribution in fuel rods during the LOCA is developed and coupled to the FALCON fuel behaviour code. → The first verification of the model is carried out using the data of the selected Halden LOCA tests. → According to calculation, the short rods used in the Halden tests show a small effect of the delayed gas redistribution during the clad ballooning. → The predicted effect is significant in the full length rods, eventually resulting in a considerable delay of the predicted moment of cladding rupture. → The predicted delay of cladding burst may be large enough to eventually affect the efficiency of the emergency core cooling system. - Abstract: A model for axial gas flow in a fuel rod during the LOCA is integrated into the FRELAX model that deals with the thermal behaviour and fuel relocation in the fuel rods of the Halden LOCA test series. The first verification was carried out using the experimental data for the inner pressure during the gas outflow after cladding rupture in tests 3, 4 and 5. Furthermore, the modified FRELAX model is implicitly coupled to the FALCON fuel behaviour code. The analysis with the new methodology shows that the dynamics of axial gas-flow along the rod and through the cladding rupture can have a strong influence on the fuel rod behaviour. Specifically, a delayed axial gas redistribution during the heat-up phase of the LOCA can result in a drop of local pressure in the ballooned area, which is eventually able to affect the cladding burst. The results of the new model seem to be useful when analysing some of the Halden LOCA tests (showing considerable fuel relocation) and selected cases of LOCA in full-length fuel rods. While the short rods used in the Halden tests only show a very small effect of the delayed gas redistribution during the clad ballooning, such an effect is predicted to be significant in the full-scale rods - with a power peak located sufficiently away from

  11. Volumetric dispenser for small particles from plural sources

    International Nuclear Information System (INIS)

    Bradley, R.A.; Miller, W.H.; Sease, J.D.

    1975-01-01

    Apparatus is described for rapidly and accurately dispensing measured volumes of small particles from a supply hopper. The apparatus includes an adjustable, vertically oriented measuring tube and orifice member defining the volume to be dispensed, a ball plug valve for selectively closing the bottom end of the orifice member, and a compression valve for selectively closing the top end of the measuring tube. A supply hopper is disposed above and in gravity flow communication with the measuring tube. Properly sequenced opening and closing of the two valves provides accurate volumetric discharge through the ball plug valve. A dispensing system is described wherein several appropriately sized measuring tubes, orifice members, and associated valves are arranged to operate contemporaneously to facilitate blending of different particles

  12. Stability and Volumetric Properties of Asphalt Mixture Containing Waste Plastic

    Directory of Open Access Journals (Sweden)

    Abd Kader Siti Aminah

    2017-01-01

    Full Text Available The objectives of this study are to determine the optimum bitumen content (OBC for every percentage added of waste plastics in asphalt mixtures and to investigate the stability properties of the asphalt mixtures containing waste plastic. Marshall stability and flow values along with density, air voids in total mix, voids in mineral aggregate, and voids filled with bitumen were determined to obtain OBC at different percentages of waste plastic, i.e., 4%, 6%, 8%, and 10% by weight of bitumen as additive. Results showed that the OBC for the plastic-modified asphalt mixtures at 4%, 6%, 8%, and 10% are 4.98, 5.44, 5.48, and 5.14, respectively. On the other hand, the controlled specimen’s shows better volumetric properties compared to plastic mixes. However, 4% additional of waste plastic indicated better stability than controlled specimen.

  13. Plant fibre composites - porosity and volumetric interaction

    DEFF Research Database (Denmark)

    Madsen, Bo; Thygesen, Anders; Lilholt, Hans

    2007-01-01

    the combination of a high fibre volume fraction, a low porosity and a high composite density is optimal. Experimental data from the literature on volumetric composition and density of four types of plant fibre composites are used to validate the model. It is demonstrated that the model provides a concept......Plant fibre composites contain typically a relative large amount of porosity, which considerably influences properties and performance of the composites. The large porosity must be integrated in the conversion of weight fractions into volume fractions of the fibre and matrix parts. A model...... is presented to predict the porosity as a function of the fibre weight fractions, and to calculate the related fibre and matrix volume fractions, as well as the density of the composite. The model predicts two cases of composite volumetric interaction separated by a transition fibre weight fraction, at which...

  14. Tracking Energy Flow Using a Volumetric Acoustic Intensity Imager (VAIM)

    Science.gov (United States)

    Klos, Jacob; Williams, Earl G.; Valdivia, Nicolas P.

    2006-01-01

    A new measurement device has been invented at the Naval Research Laboratory which images instantaneously the intensity vector throughout a three-dimensional volume nearly a meter on a side. The measurement device consists of a nearly transparent spherical array of 50 inexpensive microphones optimally positioned on an imaginary spherical surface of radius 0.2m. Front-end signal processing uses coherence analysis to produce multiple, phase-coherent holograms in the frequency domain each related to references located on suspect sound sources in an aircraft cabin. The analysis uses either SVD or Cholesky decomposition methods using ensemble averages of the cross-spectral density with the fixed references. The holograms are mathematically processed using spherical NAH (nearfield acoustical holography) to convert the measured pressure field into a vector intensity field in the volume of maximum radius 0.4 m centered on the sphere origin. The utility of this probe is evaluated in a detailed analysis of a recent in-flight experiment in cooperation with Boeing and NASA on NASA s Aries 757 aircraft. In this experiment the trim panels and insulation were removed over a section of the aircraft and the bare panels and windows were instrumented with accelerometers to use as references for the VAIM. Results show excellent success at locating and identifying the sources of interior noise in-flight in the frequency range of 0 to 1400 Hz. This work was supported by NASA and the Office of Naval Research.

  15. Environmental Consequences of Volumetric Traffic Flow in Calabar ...

    African Journals Online (AJOL)

    User

    2011-05-20

    May 20, 2011 ... a capitalist economy, goods can be allocated either by pricing (ability to pay) or by queueing ... accommodate the total demand for peak-hour vehicle travel (a supply-side solution) ... increase in taxes as a transportation mode in Calabar has generally increase .... electric equipment among others. Beside ...

  16. Combined surface and volumetric occlusion shading

    KAUST Repository

    Schott, Matthias O.; Martin, Tobias; Grosset, A. V Pascal; Brownlee, Carson; Hollt, Thomas; Brown, Benjamin P.; Smith, Sean T.; Hansen, Charles D.

    2012-01-01

    In this paper, a method for interactive direct volume rendering is proposed that computes ambient occlusion effects for visualizations that combine both volumetric and geometric primitives, specifically tube shaped geometric objects representing streamlines, magnetic field lines or DTI fiber tracts. The proposed algorithm extends the recently proposed Directional Occlusion Shading model to allow the rendering of those geometric shapes in combination with a context providing 3D volume, considering mutual occlusion between structures represented by a volume or geometry. © 2012 IEEE.

  17. Combined surface and volumetric occlusion shading

    KAUST Repository

    Schott, Matthias O.

    2012-02-01

    In this paper, a method for interactive direct volume rendering is proposed that computes ambient occlusion effects for visualizations that combine both volumetric and geometric primitives, specifically tube shaped geometric objects representing streamlines, magnetic field lines or DTI fiber tracts. The proposed algorithm extends the recently proposed Directional Occlusion Shading model to allow the rendering of those geometric shapes in combination with a context providing 3D volume, considering mutual occlusion between structures represented by a volume or geometry. © 2012 IEEE.

  18. Volumetric and superficial characterization of carbon activated

    International Nuclear Information System (INIS)

    Carrera G, L.M.; Garcia S, I.; Jimenez B, J.; Solache R, M.; Lopez M, B.; Bulbulian G, S.; Olguin G, M.T.

    2000-01-01

    The activated carbon is the resultant material of the calcination process of natural carbonated materials as coconut shells or olive little bones. It is an excellent adsorbent of diluted substances, so much in colloidal form, as in particles form. Those substances are attracted and retained by the carbon surface. In this work is make the volumetric and superficial characterization of activated carbon treated thermically (300 Centigrade) in function of the grain size average. (Author)

  19. Volumetric polymerization shrinkage of contemporary composite resins

    OpenAIRE

    Nagem Filho, Halim; Nagem, Haline Drumond; Francisconi, Paulo Afonso Silveira; Franco, Eduardo Batista; Mondelli, Rafael Francisco Lia; Coutinho, Kennedy Queiroz

    2007-01-01

    The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill ...

  20. A volumetric data system for environmental robotics

    International Nuclear Information System (INIS)

    Tourtellott, J.

    1994-01-01

    A three-dimensional, spatially organized or volumetric data system provides an effective means for integrating and presenting environmental sensor data to robotic systems and operators. Because of the unstructed nature of environmental restoration applications, new robotic control strategies are being developed that include environmental sensors and interactive data interpretation. The volumetric data system provides key features to facilitate these new control strategies including: integrated representation of surface, subsurface and above-surface data; differentiation of mapped and unmapped regions in space; sculpting of regions in space to best exploit data from line-of-sight sensors; integration of diverse sensor data (for example, dimensional, physical/geophysical, chemical, and radiological); incorporation of data provided at different spatial resolutions; efficient access for high-speed visualization and analysis; and geometric modeling tools to update a open-quotes world modelclose quotes of an environment. The applicability to underground storage tank remediation and buried waste site remediation are demonstrated in several examples. By integrating environmental sensor data into robotic control, the volumetric data system will lead to safer, faster, and more cost-effective environmental cleanup

  1. MR volumetric assessment of endolymphatic hydrops

    International Nuclear Information System (INIS)

    Guerkov, R.; Berman, A.; Jerin, C.; Krause, E.; Dietrich, O.; Flatz, W.; Ertl-Wagner, B.; Keeser, D.

    2015-01-01

    We aimed to volumetrically quantify endolymph and perilymph spaces of the inner ear in order to establish a methodological basis for further investigations into the pathophysiology and therapeutic monitoring of Meniere's disease. Sixteen patients (eight females, aged 38-71 years) with definite unilateral Meniere's disease were included in this study. Magnetic resonance (MR) cisternography with a T2-SPACE sequence was combined with a Real reconstruction inversion recovery (Real-IR) sequence for delineation of inner ear fluid spaces. Machine learning and automated local thresholding segmentation algorithms were applied for three-dimensional (3D) reconstruction and volumetric quantification of endolymphatic hydrops. Test-retest reliability was assessed by the intra-class coefficient; correlation of cochlear endolymph volume ratio with hearing function was assessed by the Pearson correlation coefficient. Endolymph volume ratios could be reliably measured in all patients, with a mean (range) value of 15 % (2-25) for the cochlea and 28 % (12-40) for the vestibulum. Test-retest reliability was excellent, with an intra-class coefficient of 0.99. Cochlear endolymphatic hydrops was significantly correlated with hearing loss (r = 0.747, p = 0.001). MR imaging after local contrast application and image processing, including machine learning and automated local thresholding, enable the volumetric quantification of endolymphatic hydrops. This allows for a quantitative assessment of the effect of therapeutic interventions on endolymphatic hydrops. (orig.)

  2. MR volumetric assessment of endolymphatic hydrops

    Energy Technology Data Exchange (ETDEWEB)

    Guerkov, R.; Berman, A.; Jerin, C.; Krause, E. [University of Munich, Department of Otorhinolaryngology Head and Neck Surgery, Grosshadern Medical Centre, Munich (Germany); University of Munich, German Centre for Vertigo and Balance Disorders, Grosshadern Medical Centre, Marchioninistr. 15, 81377, Munich (Germany); Dietrich, O.; Flatz, W.; Ertl-Wagner, B. [University of Munich, Institute of Clinical Radiology, Grosshadern Medical Centre, Munich (Germany); Keeser, D. [University of Munich, Institute of Clinical Radiology, Grosshadern Medical Centre, Munich (Germany); University of Munich, German Centre for Vertigo and Balance Disorders, Grosshadern Medical Centre, Marchioninistr. 15, 81377, Munich (Germany); University of Munich, Department of Psychiatry and Psychotherapy, Innenstadtkliniken Medical Centre, Munich (Germany)

    2014-10-16

    We aimed to volumetrically quantify endolymph and perilymph spaces of the inner ear in order to establish a methodological basis for further investigations into the pathophysiology and therapeutic monitoring of Meniere's disease. Sixteen patients (eight females, aged 38-71 years) with definite unilateral Meniere's disease were included in this study. Magnetic resonance (MR) cisternography with a T2-SPACE sequence was combined with a Real reconstruction inversion recovery (Real-IR) sequence for delineation of inner ear fluid spaces. Machine learning and automated local thresholding segmentation algorithms were applied for three-dimensional (3D) reconstruction and volumetric quantification of endolymphatic hydrops. Test-retest reliability was assessed by the intra-class coefficient; correlation of cochlear endolymph volume ratio with hearing function was assessed by the Pearson correlation coefficient. Endolymph volume ratios could be reliably measured in all patients, with a mean (range) value of 15 % (2-25) for the cochlea and 28 % (12-40) for the vestibulum. Test-retest reliability was excellent, with an intra-class coefficient of 0.99. Cochlear endolymphatic hydrops was significantly correlated with hearing loss (r = 0.747, p = 0.001). MR imaging after local contrast application and image processing, including machine learning and automated local thresholding, enable the volumetric quantification of endolymphatic hydrops. This allows for a quantitative assessment of the effect of therapeutic interventions on endolymphatic hydrops. (orig.)

  3. Volumetric velocity measurements in restricted geometries using spiral sampling: a phantom study.

    Science.gov (United States)

    Nilsson, Anders; Revstedt, Johan; Heiberg, Einar; Ståhlberg, Freddy; Bloch, Karin Markenroth

    2015-04-01

    The aim of this study was to evaluate the accuracy of maximum velocity measurements using volumetric phase-contrast imaging with spiral readouts in a stenotic flow phantom. In a phantom model, maximum velocity, flow, pressure gradient, and streamline visualizations were evaluated using volumetric phase-contrast magnetic resonance imaging (MRI) with velocity encoding in one (extending on current clinical practice) and three directions (for characterization of the flow field) using spiral readouts. Results of maximum velocity and pressure drop were compared to computational fluid dynamics (CFD) simulations, as well as corresponding low-echo-time (TE) Cartesian data. Flow was compared to 2D through-plane phase contrast (PC) upstream from the restriction. Results obtained with 3D through-plane PC as well as 4D PC at shortest TE using a spiral readout showed excellent agreements with the maximum velocity values obtained with CFD (spiral sequences were respectively 14 and 13 % overestimated compared to CFD. Identification of the maximum velocity location, as well as the accurate velocity quantification can be obtained in stenotic regions using short-TE spiral volumetric PC imaging.

  4. Fuel assembly

    International Nuclear Information System (INIS)

    Nakatsuka, Masafumi; Matsuzuka, Ryuji.

    1976-01-01

    Object: To provide a fuel assembly which can decrease pressure loss of coolant to uniform temperature. Structure: A sectional area of a flow passage in the vicinity of an inner peripheral surface of a wrapper tube is limited over the entire length to prevent the temperature of a fuel element in the outermost peripheral portion from being excessively decreased to thereby flatten temperature distribution. To this end, a plurality of pincture-frame-like sheet metals constituting a spacer for supporting a fuel assembly, which has a plurality of fuel elements planted lengthwise and in given spaced relation within the wrapper tube, is disposed in longitudinal grooves and in stacked fashion to form a substantially honeycomb-like space in cross section. The fuel elements are inserted and supported in the space to form a fuel assembly. (Kamimura, M.)

  5. Fuel assemblies

    International Nuclear Information System (INIS)

    Nagano, Mamoru; Yoshioka, Ritsuo

    1983-01-01

    Purpose: To effectively utilize nuclear fuels by increasing the reactivity of a fuel assembly and reduce the concentration at the central region thereof upon completion of the burning. Constitution: A fuel assembly is bisected into a central region and a peripheral region by disposing an inner channel box within a channel box. The flow rate of coolants passing through the central region is made greater than that in the peripheral region. The concentration of uranium 235 of the fuel rods in the central region is made higher. In such a structure, since the moderating effect in the central region is improved, the reactivity of the fuel assembly is increased and the uranium concentration in the central region upon completion of the burning can be reduced, fuel economy and effective utilization of uranium can be attained. (Kamimura, M.)

  6. Volumetric PIV behind mangrove-type root models

    Science.gov (United States)

    Kazemi, Amirkhosro; van de Riet, Keith; Curet, Oscar M.

    2017-11-01

    Mangrove trees form dense networks of prop roots in coastal intertidal zones. The interaction of mangroves with the tidal flow is fundamental in estuaries and shoreline by providing water filtration, protection against erosion and habitat for aquatic animals. In this work, we modeled the mangrove prop roots with a cluster of rigid circular cylinders (patch) to investigate its hydrodynamics. We conducted 2-D PIV and V3V in the near- and far-wake in the recirculating water channel. Two models were considered: (1) a rigid patch, and (2) a flexible patch modeled as rigid cylinders with a flexible hinge. We found that Strouhal number changes with porosity while the patch diameter is constant. Based on the wake signature, we defined an effective diameter length scale. The volumetric flow measurements revealed a regular shedding forming von Kármán vortices for the rigid patch while the flexible patch produced a less uniform wake where vortices were substantially distorted. We compare the wake structure between that 2-D PIV and V3V. This analysis of the hydrodynamics of mangrove-root like models can also be extended to understand other complex flows including bio-inspired coastal infrastructures, damping-wave systems, and energy harvesting devices.

  7. Combustion Chemistry of Fuels: Quantitative Speciation Data Obtained from an Atmospheric High-temperature Flow Reactor with Coupled Molecular-beam Mass Spectrometer.

    Science.gov (United States)

    Köhler, Markus; Oßwald, Patrick; Krueger, Dominik; Whitside, Ryan

    2018-02-19

    This manuscript describes a high-temperature flow reactor experiment coupled to the powerful molecular beam mass spectrometry (MBMS) technique. This flexible tool offers a detailed observation of chemical gas-phase kinetics in reacting flows under well-controlled conditions. The vast range of operating conditions available in a laminar flow reactor enables access to extraordinary combustion applications that are typically not achievable by flame experiments. These include rich conditions at high temperatures relevant for gasification processes, the peroxy chemistry governing the low temperature oxidation regime or investigations of complex technical fuels. The presented setup allows measurements of quantitative speciation data for reaction model validation of combustion, gasification and pyrolysis processes, while enabling a systematic general understanding of the reaction chemistry. Validation of kinetic reaction models is generally performed by investigating combustion processes of pure compounds. The flow reactor has been enhanced to be suitable for technical fuels (e.g. multi-component mixtures like Jet A-1) to allow for phenomenological analysis of occurring combustion intermediates like soot precursors or pollutants. The controlled and comparable boundary conditions provided by the experimental design allow for predictions of pollutant formation tendencies. Cold reactants are fed premixed into the reactor that are highly diluted (in around 99 vol% in Ar) in order to suppress self-sustaining combustion reactions. The laminar flowing reactant mixture passes through a known temperature field, while the gas composition is determined at the reactors exhaust as a function of the oven temperature. The flow reactor is operated at atmospheric pressures with temperatures up to 1,800 K. The measurements themselves are performed by decreasing the temperature monotonically at a rate of -200 K/h. With the sensitive MBMS technique, detailed speciation data is acquired and

  8. Fuel cell generator with fuel electrodes that control on-cell fuel reformation

    Science.gov (United States)

    Ruka, Roswell J [Pittsburgh, PA; Basel, Richard A [Pittsburgh, PA; Zhang, Gong [Murrysville, PA

    2011-10-25

    A fuel cell for a fuel cell generator including a housing including a gas flow path for receiving a fuel from a fuel source and directing the fuel across the fuel cell. The fuel cell includes an elongate member including opposing first and second ends and defining an interior cathode portion and an exterior anode portion. The interior cathode portion includes an electrode in contact with an oxidant flow path. The exterior anode portion includes an electrode in contact with the fuel in the gas flow path. The anode portion includes a catalyst material for effecting fuel reformation along the fuel cell between the opposing ends. A fuel reformation control layer is applied over the catalyst material for reducing a rate of fuel reformation on the fuel cell. The control layer effects a variable reformation rate along the length of the fuel cell.

  9. Effect of pH in a Pd-based ethanol membraneless air breathing nanofluidic fuel cell with flow-through electrodes

    Science.gov (United States)

    López-Rico, C. A.; Galindo-de-la-Rosa, J.; Ledesma-García, J.; Arriaga, L. G.; Guerra-Balcázar, M.; Arjona, N.

    2015-12-01

    In this work, a nanofluidic fuel cell (NFC) in which streams flow through electrodes was used to investigate the role of pH in the cell performance using ethanol as fuel and two Pd nanoparticles as electrocatalysts: one commercially available (Pd/C from ETEK) and other synthesized using ionic liquids (Pd/C IL). The cell performances for both electrocatalysts in acid/acid (anodic/cathodic) streams were of 18.05 and 9.55 mW cm-2 for Pd/C ETEK and Pd/C IL. In alkaline/alkaline streams, decrease to 15.94 mW cm-2 for Pd/C ETEK and increase to 15.37 mW cm-2 for Pd/C IL. In alkaline/acidic streams both electrocatalysts showed similar cell voltages (up to 1 V); meanwhile power densities were of 87.6 and 99.4 mW cm-2 for Pd/C ETEK and Pd/C IL. The raise in cell performance can be related to a decrease in activation losses, the combined used of alkaline and acidic streams and these high values compared with flow-over fuel cells can be related to the enhancement of the cathodic mass transport by using three dimensional porous electrodes and two sources of oxygen: from air and from a saturated solution.

  10. Effect of pH in a Pd-based ethanol membraneless air breathing nanofluidic fuel cell with flow-through electrodes

    International Nuclear Information System (INIS)

    López-Rico, C A; Arriaga, L G; Galindo-de-la-Rosa, J; Ledesma-García, J; Guerra-Balcázar, M; Arjona, N

    2015-01-01

    In this work, a nanofluidic fuel cell (NFC) in which streams flow through electrodes was used to investigate the role of pH in the cell performance using ethanol as fuel and two Pd nanoparticles as electrocatalysts: one commercially available (Pd/C from ETEK) and other synthesized using ionic liquids (Pd/C IL). The cell performances for both electrocatalysts in acid/acid (anodic/cathodic) streams were of 18.05 and 9.55 mW cm -2 for Pd/C ETEK and Pd/C IL. In alkaline/alkaline streams, decrease to 15.94 mW cm -2 for Pd/C ETEK and increase to 15.37 mW cm -2 for Pd/C IL. In alkaline/acidic streams both electrocatalysts showed similar cell voltages (up to 1 V); meanwhile power densities were of 87.6 and 99.4 mW cm -2 for Pd/C ETEK and Pd/C IL. The raise in cell performance can be related to a decrease in activation losses, the combined used of alkaline and acidic streams and these high values compared with flow-over fuel cells can be related to the enhancement of the cathodic mass transport by using three dimensional porous electrodes and two sources of oxygen: from air and from a saturated solution. (paper)

  11. On the application of the method of turbulent flow to transient and quasi-stationary flow calculations in high temperature reactors with spherical fuel elements

    International Nuclear Information System (INIS)

    Hoefer, I.

    1980-12-01

    For the calculation of flows in high-temperature reactors and of their temperature behavior the equations of the method of turbulent flow in the primitive form are derived for inhomogeneous regions. This system of equations is appropriate for the investigation of transient and quasi-stationary phenomena in pebble beds. By modification of the flow function in parallel arranged reflector channels a parallel flow can be simulated. For simplification the flow in region with a smaller pressure loss is assumed to be a potential flow. For the numerical solution of the time-dependent convective parts of the system of equations a number of explicit and implicit difference methods are compared. If the method using UP-WIND differences is taken to be an interpolation method the introduction of an extension becomes possible, which together with preliminary integration of the fictional terms allows to apply larger time steps. The algebraic system of equations for numerical calculation of a steady flow field also is established by formation of UP-WIND differences for the convective terms. By mathematical verification of some examples the applicability of the mathematical model for flow problems in pebble beds with forced or natural convection is shown. (orig.) [de

  12. Fuel assembly guide tube

    International Nuclear Information System (INIS)

    Jabsen, F.S.

    1979-01-01

    This invention is directed toward a nuclear fuel assembly guide tube arrangement which restrains spacer grid movement due to coolant flow and which offers secondary means for supporting a fuel assembly during handling and transfer operations

  13. Volumetric polymerization shrinkage of contemporary composite resins

    Directory of Open Access Journals (Sweden)

    Halim Nagem Filho

    2007-10-01

    Full Text Available The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill Magic, Alert, and Solitaire to determine whether there are differences among these materials. The tests were conducted with precision of 0.1 mg. The volumetric shrinkage was measured by hydrostatic weighing before and after polymerization and calculated by known mathematical equations. One-way ANOVA (a or = 0.05 was used to determine statistically significant differences in volumetric shrinkage among the tested composite resins. Suprafill (1.87±0.01 and Definite (1.89±0.01 shrank significantly less than the other composite resins. SureFil (2.01±0.06, Filtek Z250 (1.99±0.03, and Fill Magic (2.02±0.02 presented intermediate levels of polymerization shrinkage. Alert and Solitaire presented the highest degree of polymerization shrinkage. Knowing the polymerization shrinkage rates of the commercially available composite resins, the dentist would be able to choose between using composite resins with lower polymerization shrinkage rates or adopting technical or operational procedures to minimize the adverse effects deriving from resin contraction during light-activation.

  14. MARTINS: A foam/film flow model for molten material relocation in HWRs with U-Al-fueled multi-tube assemblies

    International Nuclear Information System (INIS)

    Kalimullah.

    1994-01-01

    Some special purpose heavy-water reactors (EM) are made of assemblies consisting of a number of coaxial aluminum-clad U-Al alloy fuel tubes and an outer Al sleeve surrounding the fuel tubes. The heavy water coolant flows in the annular gaps between the circular tubes. Analysis of severe accidents in such reactors requires a model for predicting the behavior of the fuel tubes as they melt and disrupt. This paper describes a detailed, mechanistic model for fuel tube heatup, melting, freezing, and molten material relocation, called MARTINS (Melting and Relocation of Tubes in Nuclear subassembly). The paper presents the modeling of the phenomena in MARTINS, and an application of the model to analysis of a reactivity insertion accident. Some models are being developed to compute gradual downward relocation of molten material at decay-heat power levels via candling along intact tubes, neglecting coolant vapor hydrodynamic forces on molten material. These models are inadequate for high power accident sequences involving significant hydrodynamic forces. These forces are included in MARTINS

  15. Enhance performance of micro direct methanol fuel cell by in situ CO2 removal using novel anode flow field with superhydrophobic degassing channels

    Science.gov (United States)

    Liang, Junsheng; Luo, Ying; Zheng, Sheng; Wang, Dazhi

    2017-05-01

    Capillary blocking caused by CO2 bubbles in anode flow field (AFF) is one of the bottlenecks for performance improvement of a micro direct methanol fuel cell (μDMFC). In this work, we present a novel AFF structure with nested layout of hydrophilic fuel channels and superhydrophobic degassing channels which can remove most of CO2 from AFF before it is released to the fuel channels. The new AFFs are fabricated on Ti substrates by using micro photochemical etching combined with anodization and fluorination treatments. Performance of the μDMFCs with and without superhydrophobic degassing channels in their AFF is comparatively studied. Results show that the superhydrophobic degassing channels can significantly speed up the exhaust of CO2 from the AFF. CO2 clogging is not observed in the new AFFs even when their comparison AFFs have been seriously blocked by CO2 slugs under the same operating conditions. 55% and 60% of total CO2 produced in μDMFCs with N-serpentine and N-spiral AFF can be respectively removed by the superhydrophobic degassing channels. The power densities of the μDMFCs equipped with new serpentine and spiral AFFs are respectively improved by 30% and 90% compared with those using conventional AFFs. This means that the new AFFs developed in this work can effectively prevent CO2-induced capillary blocking in the fuel channels, and finally significantly improve the performance of the μDMFCs.

  16. Energy flows modelling of a PEM electrolyzer-Photovoltaic generator-PEM fuel cell coupling dedicated to stationary applications

    International Nuclear Information System (INIS)

    Agbli, Krehi Serge

    2012-01-01

    A standalone multi-source system based on the coupling of photovoltaic energy and both a PEM electrolyzer and a PEMFC for stationary application is studied. The system gathers photovoltaic array as main energy source, ultra-capacitors and batteries packs in order to smooth respectively fast and medium dynamic by supplying the load or by absorbing photovoltaic source overproduction. Because of the necessity of fuel availability, especially for islanding application like this one, a PEM electrolyzer is integrated to the system for in situ hydrogen production. The relevance of PEMFC system powered by solar hydrogen is pointed out before examining hydrogen storage issue. Energetic and economic analyses have been performed leading to the choice of the pressurised hydrogen storage (in the bottle) rather than hydrogen storage both as liquid and within metal hydride. The main purpose being the proper management of the power flows in order to meet the energy requirement (the load) without power cut, a graphical modelling tool namely Energetic Macroscopic Representation (EMR) is used because of its analysis and control strengths. The EMR ability to describe multi-physics energetic tools is used to develop a PEM electrolyzer model. The multi-domain interaction between the electrical, the electrochemical, the thermodynamic and the fluidic domain is emphasised. Moreover, the temperature variation influence on the electrochemical parameters of the electrolyzer is taken into account by the developed EMR model. Afterwards, thanks to the modular feature of the EMR, the different models of each energetic entity of the system are performed before their assembling leading to the overall system EMR model. By using scale effect allowing extending the energetic tool power range from the experimental validation one to another one, the energetic system sizing is performed according to a household power profile. Then, by the help of the multi-level representation, the maximal control

  17. Modeling of cladding and fuel motion in a loss of flow situation for GCFR safety analysis. Technical progress report (annual), June 15, 1974--March 15, 1975

    International Nuclear Information System (INIS)

    Eggen, D.T.

    1975-01-01

    During the first nine months of the project, methods and apparatus were developed to study the freezeout of molten cladding in a cooler blanket region. Three tests were run in which a mass of molten material from a simulated core region of a GCFR flowed into a bundle of simulated blanket elements. In all cases plugging occurred in or before the first grid-spacer. Theories and preliminary models are in accord with these observations. These tests have been done with a 50/50-Pb/Sn alloy simulating the cladding and spacer grids and alumina simulating the fuel. Materials are being obtained for tests with stainless steel cladding and spacers. Development is progressing well on an electrically-heated fuel element which will be used to study the melting and motion of cladding in the core region for a loss of flow accident. Preliminary models is being developed to calculate the motion and freezeout of flowing cladding in the blanket region. The SAS-GAS and Argus codes are being adapted for uses in conjunction with model development on the project. A survey of fission gas effects in oxide during TOP cases was prepared and other codes (LIFE) were reviewed for possible value on the project. A set of reference physical parameters is being developed for the various materials used in the analysis and experiments. (U.S.)

  18. Analysis and effect of multi-fuel and practical constraints on economic load dispatch in the presence of Unified Power Flow Controller using UDTPSO

    Directory of Open Access Journals (Sweden)

    Chintalapudi V. Suresh

    2015-09-01

    Full Text Available This paper presents an attempt to analyze the effect of multi-fuel and practical constraints on economic load dispatch problem using a novel uniform distributed two-stage particle swarm optimization (UDTPSO algorithm without and with unified power flow controller (UPFC while satisfying equality, inequality, practical constraints such as ramp-rate and prohibited operating zone (POZ limits and device operating limits. A Novel severity function is formulated based on the transmission line overloads and bus voltage violations to identify an optimal location to install UPFC. A multi-objective optimization problem is solved for multi-fuel non-convex cost and transmission power loss objectives. Obtained results for considered standard test functions and electrical systems indicate the effectiveness of the proposed algorithm and can obtain efficient solution when compared to existing methods. Hence, the proposed method is a promising method and can be easily applied to optimize the power system objectives.

  19. Development of quantitative analytical procedures on two-phase flow in tight-lattice fuel bundles for reduced-moderation light-water reactors

    International Nuclear Information System (INIS)

    Ohnuki, A.; Kureta, M.; Takae, K.; Tamai, H.; Akimoto, H.; Yoshida, H.

    2004-01-01

    The research project to investigate thermal-hydraulic performance in tight-lattice rod bundles for Reduced-Moderation Water Reactor (RMWR) started at Japan Atomic Energy Research Institute (JAERI) in 2002. The RMWR is a light water reactor for which a higher conversion ratio more than one can be expected. In order to attain this higher conversion ratio, triangular tight-lattice fuel bundles whose gap spacing between each fuel rod is around 1 mm are required. As for the thermal design of the RMWR core, conventional analytical methods are no good because the conventional composition equations can not predict the RMWR core with high accuracy. Then, development of new quantitative analytical procedures was carried out. Those analytical procedures are constructed by model experiments and advanced two-phase flow analysis codes. This paper describes the results of the model experiments and analytical results with the developed analysis codes. (authors)

  20. Heaters to simulate fuel pins for heat transfer tests in single-phase liquid-metal-flow

    International Nuclear Information System (INIS)

    Casal, V.; Graf, E.; Hartmann, W.

    1976-09-01

    The development of heaters for thermal simulation of the fuel elements of liquid metal cooled fast breeder reactors (SNR) is reported. Beginning with the experimental demands various heating methods are discussed for thermodynamic investigations of the heat transfer in liquid metals. Then a preferred heater rod is derived to simulate the fuel pins of a SNR. Finally it is reported on the fabrication and the operation practice. (orig.) [de

  1. Volumetric expiratory high-resolution CT of the lung

    International Nuclear Information System (INIS)

    Nishino, Mizuki; Hatabu, Hiroto

    2004-01-01

    We developed a volumetric expiratory high-resolution CT (HRCT) protocol that provides combined inspiratory and expiratory volumetric imaging of the lung without increasing radiation exposure, and conducted a preliminary feasibility assessment of this protocol to evaluate diffuse lung disease with small airway abnormalities. The volumetric expiratory high-resolution CT increased the detectability of the conducting airway to the areas of air trapping (P<0.0001), and added significant information about extent and distribution of air trapping (P<0.0001)

  2. Fuel assembly

    International Nuclear Information System (INIS)

    Nomata, Terumitsu.

    1993-01-01

    Among fuel pellets to be loaded to fuel cans of a fuel assembly, fuel pellets having a small thermal power are charged in a region from the end of each of spacers up to about 50mm on the upstream of coolants that flow vertically at the periphery of fuel rods. Coolants at the periphery of fuel rods are heated by the heat generation, to result in voids. However, since cooling effect on the upstream of the spacers is low due to influences of the spacers. Further, since the fuel pellets disposed in the upstream region have small thermal power, a void coefficient is not increased. Even if a thermal power exceeding cooling performance should be generated, there is no worry of causing burnout in the upstream region. Even if burnout should be caused, safety margin and reliability relative to burnout are improved, to increase an allowable thermal power, thereby enabling to improve integrity and reliability of fuel rods and fuel assemblies. (N.H.)

  3. Post-irradiation examination of prototype Al-64 wt% U3Si2 fuel rods from NRU

    International Nuclear Information System (INIS)

    Sears, D.F.; Primeau, M.F.; Buchanan, C.; Rose, D.

    1997-01-01

    Three prototype fuel rods containing Al-64 wt% U 3 Si 2 (3.15 gU/cm 3 ) have been irradiated to their design burnup in the NRU reactor without incident. The fuel was fabricated using production-scale equipment and processes previously developed for Al-U 3 Si fuel fabrication at Chalk River Laboratories, and special equipment developed for U 3 Si 2 powder production and handling. The rods were irradiated in NRU up to 87 at% U-235 burnup under typical driver fuel conditions; i.e., nominal coolant inlet temperature 37 degrees C, inlet pressure 654 kPa, mass flow 12.4 L/s, and element linear power ratings up to 73 kW/m. Post-irradiation examinations showed that the fuel elements survived the irradiation without defects. Fuel core diametral increases and volumetric swelling were significantly lower than that of Al-61 wt% U 3 Si fuel irradiated under similar conditions. This irradiation demonstrated that the fabrication techniques are adequate for full-scale fuel manufacture, and qualified the fuel for use in AECL's research reactors

  4. Adaptive controller for volumetric display of neuroimaging studies

    Science.gov (United States)

    Bleiberg, Ben; Senseney, Justin; Caban, Jesus

    2014-03-01

    Volumetric display of medical images is an increasingly relevant method for examining an imaging acquisition as the prevalence of thin-slice imaging increases in clinical studies. Current mouse and keyboard implementations for volumetric control provide neither the sensitivity nor specificity required to manipulate a volumetric display for efficient reading in a clinical setting. Solutions to efficient volumetric manipulation provide more sensitivity by removing the binary nature of actions controlled by keyboard clicks, but specificity is lost because a single action may change display in several directions. When specificity is then further addressed by re-implementing hardware binary functions through the introduction of mode control, the result is a cumbersome interface that fails to achieve the revolutionary benefit required for adoption of a new technology. We address the specificity versus sensitivity problem of volumetric interfaces by providing adaptive positional awareness to the volumetric control device by manipulating communication between hardware driver and existing software methods for volumetric display of medical images. This creates a tethered effect for volumetric display, providing a smooth interface that improves on existing hardware approaches to volumetric scene manipulation.

  5. Control of Flow Structure and Ignition of Hydrocarbon Fuel in Cavity and Behind Wallstep of Supersonic Duct by Filamentary DC Discharge

    Science.gov (United States)

    2011-01-01

    Lindstrom , K.R. Jackson, S. Williams, R. Givens, W.F. Bailey, C.J. Tam, W.F. Terry, AIAA Journal 47, 2368 (2009). 13. S.T. Sanders, J.A. Baldwin, T.P...A. Kuthi, C. Jiang, P. Ronney, and Martin A. Gundersen, ―Transient Plasma Ignition of Quiescent and Flowing Air/Fuel Mixtures‖ IEEE Transactions on...applications at elevated temperature. JQSRT 103 (2007) 565–577. 17. C.D. Lindstrom , K.R. Jackson, S. Williams, R. Givens, W.F. Bailey, C.J. Tam, W.F

  6. A new laboratory-scale experimental facility for detailed aerothermal characterizations of volumetric absorbers

    Science.gov (United States)

    Gomez-Garcia, Fabrisio; Santiago, Sergio; Luque, Salvador; Romero, Manuel; Gonzalez-Aguilar, Jose

    2016-05-01

    This paper describes a new modular laboratory-scale experimental facility that was designed to conduct detailed aerothermal characterizations of volumetric absorbers for use in concentrating solar power plants. Absorbers are generally considered to be the element with the highest potential for efficiency gains in solar thermal energy systems. The configu-ration of volumetric absorbers enables concentrated solar radiation to penetrate deep into their solid structure, where it is progressively absorbed, prior to being transferred by convection to a working fluid flowing through the structure. Current design trends towards higher absorber outlet temperatures have led to the use of complex intricate geometries in novel ceramic and metallic elements to maximize the temperature deep inside the structure (thus reducing thermal emission losses at the front surface and increasing efficiency). Although numerical models simulate the conjugate heat transfer mechanisms along volumetric absorbers, they lack, in many cases, the accuracy that is required for precise aerothermal validations. The present work aims to aid this objective by the design, development, commissioning and operation of a new experimental facility which consists of a 7 kWe (1.2 kWth) high flux solar simulator, a radiation homogenizer, inlet and outlet collector modules and a working section that can accommodate volumetric absorbers up to 80 mm × 80 mm in cross-sectional area. Experimental measurements conducted in the facility include absorber solid temperature distributions along its depth, inlet and outlet air temperatures, air mass flow rate and pressure drop, incident radiative heat flux, and overall thermal efficiency. In addition, two windows allow for the direct visualization of the front and rear absorber surfaces, thus enabling full-coverage surface temperature measurements by thermal imaging cameras. This paper presents the results from the aerothermal characterization of a siliconized silicon

  7. Determination of maximum reactor power level consistent with the requirement that flow reversal occurs without fuel damage

    International Nuclear Information System (INIS)

    Rao, D.V.; Darby, J.L.; Ross, S.B.; Clark, R.A.

    1990-01-01

    The High Flux Beam Reactor (HFBR) operated by Brookhaven National Laboratory (BNL) employs forced downflow for heat removal during normal operation. In the event of total loss of forced flow, the reactor will shutdown and the flow reversal valves open. When the downward core flow becomes sufficiently small then the opposing thermal buoyancy induces flow reversal leading to decay heat removal by natural convection. There is some uncertainty as to whether the natural circulation is adequate for decay heat removal after 60 MW operation. BNL- staff carried out a series of calculations to establish the adequacy of flow reversal to remove decay heat. Their calculations are based on a natural convective CHF model. The primary purpose of the present calculations is to review the accuracy and applicability of Fauske's CHF model for the HFBR, and the assumptions and methodology employed by BNL-staff to determine the heat removal limit in the HFBR during a flow reversal and natural convection situation

  8. EPA flow reference method testing and analysis: Findings report

    International Nuclear Information System (INIS)

    1999-06-01

    This report describes an experimental program sponsored by the US Environmental Protection Agency (EPA) to evaluate potential improvements to the Agency's current reference method for measuring volumetric flow (Method 2, 40 CFR Part 60, Appendix B). Method 2 (Determination of Stack Gas Velocity and Volumetric Flow Rate (Type S Pitot Tube)) specifies measurements to determine volumetric flow, but does not prescribe specific procedures to account for yaw or pitch angles of flow when the flow in the stack is not axial. Method 2 also allows the use of only two probe types, the Type S and the Prandtl

  9. Experimental study on the effect of cathode flow humidity and temperature on the performance of PEM fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    El-Emam, R.S.; Awad, M.M.; Hamed, A.M.; Tolba, M. [Mansoura Univ., Mansoura (Egypt). Dept. of Mechanical Engineering

    2009-07-01

    The fuel cell is an electrochemical energy conversion device that produces electricity directly from chemical energy, and the by-products are only water and heat. The fuel cell could provide a solution to a whole range of environmental challenges, such as global warming and harmful levels of local pollutants. One of the most promising alternative power generation methods is the proton exchange membrane fuel cell (PEMFC) because of its low operating temperature, relative tolerance for impurities, and high power-density. This paper presented an experimental study on the performance characteristics of a single unit of a PEMFC with an active area of 25 square centimetres using two different cell configurations. The test system was designed to control the temperature and the relative humidity of the cathode feeding gas. Oxygen and air were used as oxidizers, while dry hydrogen was the cell fuel. Two different cell configurations were assembled and integrated into the test stand. The paper described the experimental work and presented the results of the study. It was concluded that low oxygen relative humidity with the dry hydrogen caused membrane drying and ultimately resulted in a degradation of fuel cell power output and cell performance. 17 refs., 17 figs.

  10. Gas-Phase Mass-Transfer Resistances at Polymeric Electrolyte Membrane Fuel Cells Electrodes: Theoretical Analysis on the Effectiveness of Interdigitated and Serpentine Flow Arrangements

    Directory of Open Access Journals (Sweden)

    Elisabetta Arato

    2016-03-01

    Full Text Available Mass transfer phenomena in polymeric electrolyte membrane fuel cells (PEMFC electrodes has already been analyzed in terms of the interactions between diffusive and forced flows. It was demonstrated that the whole phenomenon could be summarized by expressing the Sherwood number as a function of the Peclet number. The dependence of Sherwood number on Peclet one Sh(Pe function, which was initially deduced by determining three different flow regimes, has now been given a more accurate description. A comparison between the approximate and the accurate results for a reference condition of diluted reactant and limit current has shown that the former are useful for rapid, preliminary calculations. However, a more precise and reliable estimation of the Sherwood number is worth attention, as it provides a detailed description of the electrochemical kinetics and allows a reliable comparison of the various geometrical arrangements used for the distribution of the reactants.

  11. Finite element analysis of volumetrically heated fluids in an axisymmetric enclosure

    International Nuclear Information System (INIS)

    Gartling, D.K.

    1979-01-01

    A general purpose finite element computer code has been used to analyze the steady state and transient response of a confined fluid that is heated volumetrically. The numerical procedure is demonstrated to be capable of resolving flow fields of considerable complexity without undue computational expense. Results are discussed for a Grashof number range (4.0 x 10 4 to 4.0 x 10 6 ) in which the flow varies from a steady, single cell configuration to a multiple cell configuration that includes a periodic interaction

  12. Experimental and numerical investigation of water flow through spacer grids of nuclear fuel elements using the Open FOAM code

    International Nuclear Information System (INIS)

    Vidal, Guilherme A.M.; Vieira, Tiago A.S.; Castro, Higor F.P.

    2017-01-01

    With the advancement and development of computational tools, the studies of thermofluidodynamic behavior in nuclear fuel elements have been developed in recent years. Of the devices present in these elements, the spacing grids received more attention. They have kept the fuel rods equally spaced and have fins that aim to improve the heat transfer process between the water and the fuel element. Therefore, the grids present an important structural and thermal function. This work was carried out with the purpose of verifying and validating simulations of spacer grids using OpenFOAM (2017) software of Computational Fluid Dynamics (CFD). The simulations were validated using results obtained through the commercial CFD program, Ansys CFX, and experiments available in the literature and obtained in test sections assembled on the Water-Air Circuit (CCA) of the CDTN thermo-hydraulic laboratory

  13. Fuel Assembly Damping Summary

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kanghee; Kang, Heungseok; Oh, Dongseok; Yoon, Kyungho; Kim, Hyungkyu; Kim, Jaeyong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-10-15

    This paper summary the fuel assembly damping data in air/in still water/under flow, released from foreign fuel vendors, compared our data with the published data. Some technical issues in fuel assembly damping measurement testing are also briefly discussed. Understanding of each fuel assembly damping mechanisms according to the surrounding medium and flow velocity can support the fuel design improvement in fuel assembly dynamics and structural integrity aspect. Because the upgraded requirements of the newly-developed advanced reactor system will demands to minimize fuel design margin in integrity evaluation, reduction in conservatism of fuel assembly damping can contribute to alleviate the fuel design margin for sure. Damping is an energy dissipation mechanism in a vibrating mechanical structure and prevents a resonant structure from having infinite vibration amplitudes. The sources of fuel assembly damping are various from support friction to flow contribution, and it can be increased by the viscosity or drag of surrounding fluid medium or the average velocity of water flowing. Fuel licensing requires fuel design evaluation in transient or accidental condition. Dynamic response analysis of fuel assembly is to show fuel integrity and requires information on assembly-wise damping in dry condition and under wet or water flowing condition. However, damping measurement test for the full-scale fuel assembly prototype is not easy to carry out because of the scale (fuel prototype, test facility), unsteadiness of test data (scattering, random sampling and processing), instrumentation under water flowing (water-proof response measurement), and noise. LWR fuel technology division in KAERI is preparing the infra structure for damping measurement test of full-scale fuel assembly, to support fuel industries and related research activities. Here is a preliminary summary of fuel assembly damping, published in the literature. Some technical issues in fuel assembly damping

  14. Constant strength fuel-fuel cell

    International Nuclear Information System (INIS)

    Vaseen, V.A.

    1980-01-01

    A fuel cell is an electrochemical apparatus composed of both a nonconsumable anode and cathode; and electrolyte, fuel oxidant and controls. This invention guarantees the constant transfer of hydrogen atoms and their respective electrons, thus a constant flow of power by submergence of the negative electrode in a constant strength hydrogen furnishing fuel; when said fuel is an aqueous absorbed hydrocarbon, such as and similar to ethanol or methnol. The objective is accomplished by recirculation of the liquid fuel, as depleted in the cell through specific type membranes which pass water molecules and reject the fuel molecules; thus concentrating them for recycle use

  15. Volumetric visualization of anatomy for treatment planning

    International Nuclear Information System (INIS)

    Pelizzari, Charles A.; Grzeszczuk, Robert; Chen, George T. Y.; Heimann, Ruth; Haraf, Daniel J.; Vijayakumar, Srinivasan; Ryan, Martin J.

    1996-01-01

    Purpose: Delineation of volumes of interest for three-dimensional (3D) treatment planning is usually performed by contouring on two-dimensional sections. We explore the usage of segmentation-free volumetric rendering of the three-dimensional image data set for tumor and normal tissue visualization. Methods and Materials: Standard treatment planning computed tomography (CT) studies, with typically 5 to 10 mm slice thickness, and spiral CT studies with 3 mm slice thickness were used. The data were visualized using locally developed volume-rendering software. Similar to the method of Drebin et al., CT voxels are automatically assigned an opacity and other visual properties (e.g., color) based on a probabilistic classification into tissue types. Using volumetric compositing, a projection into the opacity-weighted volume is produced. Depth cueing, perspective, and gradient-based shading are incorporated to achieve realistic images. Unlike surface-rendered displays, no hand segmentation is required to produce detailed renditions of skin, muscle, or bony anatomy. By suitable manipulation of the opacity map, tissue classes can be made transparent, revealing muscle, vessels, or bone, for example. Manually supervised tissue masking allows irrelevant tissues overlying tumors or other structures of interest to be removed. Results: Very high-quality renditions are produced in from 5 s to 1 min on midrange computer workstations. In the pelvis, an anteroposterior (AP) volume rendered view from a typical planning CT scan clearly shows the skin and bony anatomy. A muscle opacity map permits clear visualization of the superficial thigh muscles, femoral veins, and arteries. Lymph nodes are seen in the femoral triangle. When overlying muscle and bone are cut away, the prostate, seminal vessels, bladder, and rectum are seen in 3D perspective. Similar results are obtained for thorax and for head and neck scans. Conclusion: Volumetric visualization of anatomy is useful in treatment

  16. Co-combustion of pulverized coal and solid recovered fuel in an entrained flow reactor- General combustion and ash behavior

    DEFF Research Database (Denmark)

    Wu, Hao; Glarborg, Peter; Frandsen, Flemming

    2011-01-01

    .9 wt.%, 14.8 wt.% and 25 wt.%, respectively. The effect of additives was evaluated by maintaining the share of secondary fuel (mixture of SRF and additive) at 14.8 wt.%. The experimental results showed that the fuel burnout, NO and SO2 emission in co-combustion of coal and SRF were decreased...... with increasing share of SRF. The majority of the additives inhibited the burnout, except for NaCl which seemed to have a promoting effect. The impact of additives on NO emission was mostly insignificant, except for ammonium sulphate which greatly reduced the NO emission. For SO2 emission, it was found that all...

  17. Development and testing of high-performance fuel pin simulators for boiling experiments in liquid metal flow

    International Nuclear Information System (INIS)

    Casal, V.

    1976-01-01

    There are unknown phenomena, about local and integral boiling events in the core of sodium cooled fast breeder reactors. Therefore at GfK depend out-of-pile boiling experiments have been performed using electrically heated dummies of fuel element bundles. The success of these tests and the amount of information derived from them depend exclusively on the successful simulation of the fuel pins by electrically heated rods as regards the essential physical properties. The report deals with the development and testing of heater rods for sodium boiling experiments in bundles including up to 91 heated pins

  18. A Solar Volumetric Receiver: Influence of Absorbing Cells Configuration on Device Thermal Performance

    Science.gov (United States)

    Yilbas, B. S.; Shuja, S. Z.

    2017-01-01

    Thermal performance of a solar volumetric receiver incorporating the different cell geometric configurations is investigated. Triangular, hexagonal, and rectangular absorbing cells are incorporated in the analysis. The fluid volume fraction, which is the ratio of the volume of the working fluid over the total volume of solar volumetric receiver, is introduced to assess the effect of cell size on the heat transfer rates in the receiver. In this case, reducing the fluid volume fraction corresponds to increasing cell size in the receiver. SiC is considered as the cell material, and air is used as the working fluid in the receiver. The Lambert's Beer law is incorporated to account for the solar absorption in the receiver. A finite element method is used to solve the governing equation of flow and heat transfer. It is found that the fluid volume fraction has significant effect on the flow field in the solar volumetric receiver, which also modifies thermal field in the working fluid. The triangular absorbing cell gives rise to improved effectiveness of the receiver and then follows the hexagonal and rectangular cells. The second law efficiency of the receiver remains high when hexagonal cells are used. This occurs for the fluid volume fraction ratio of 0.5.

  19. The Effect of Volumetric Porosity on Roughness Element Drag

    Science.gov (United States)

    Gillies, John; Nickling, William; Nikolich, George; Etyemezian, Vicken

    2016-04-01

    Much attention has been given to understanding how the porosity of two dimensional structures affects the drag force exerted by boundary-layer flow on these flow obstructions. Porous structures such as wind breaks and fences are typically used to control the sedimentation of sand and snow particles or create micro-habitats in their lee. Vegetation in drylands also exerts control on sediment transport by wind due to aerodynamic effects and interaction with particles in transport. Recent research has also demonstrated that large spatial arrays of solid three dimensional roughness elements can be used to reduce sand transport to specified targets for control of wind erosion through the effect of drag partitioning and interaction of the moving sand with the large (>0.3 m high) roughness elements, but porous elements may improve the effectiveness of this approach. A thorough understanding of the role porosity plays in affecting the drag force on three-dimensional forms is lacking. To provide basic understanding of the relationship between the porosity of roughness elements and the force of drag exerted on them by fluid flow, we undertook a wind tunnel study that systematically altered the porosity of roughness elements of defined geometry (cubes, rectangular cylinders, and round cylinders) and measured the associated change in the drag force on the elements under similar Reynolds number conditions. The elements tested were of four basic forms: 1) same sized cubes with tubes of known diameter milled through them creating three volumetric porosity values and increasing connectivity between the tubes, 2) cubes and rectangular cylinders constructed of brass screen that nested within each other, and 3) round cylinders constructed of brass screen that nested within each other. The two-dimensional porosity, defined as the ratio of total surface area of the empty space to the solid surface area of the side of the element presented to the fluid flow was conserved at 0.519 for

  20. Cavitation characteristics of multihole diesel-fuel nozzles in high-speed oil flows. Diesel kikan yo nenryo tako nozzle no abura cavitation tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Yokota, M. (Shimonoseki Univ. of Fisheris, Yamaguchi (Japan)); Ito, Y. (Hachinohe Inst. of Tech., Aomori (Japan)); Aoki, H. (Xexel-Gleason U.S.A. Inc., New York (U.S.A))

    1991-07-25

    Recently, since higher velocity and higher pressure are required for diesel injection systems, cavitation behaviors in high velocity oil flows are strongly interested in such as 100 to 500 m/s for oil flow velocity and less than the cavitation factor {sigma} of 0.01. In this paper, oil cavitation characteristics at the injection part of multihole nozzles, especially on the flow characteristics, were studied systematically using fuel injection multihole nozzles for an actual use. As a result, it was clarified that subcavitation area (sub C), transition area, and supercavitation area (SC) could be existing in C{sub d}-{sigma} relation, which was similar to that specified cavitation conditions could be exisiting in the actual working area of multihole nozzles. And it was also clarified that flow coefficient C{sub d} relied on Reynolds number R{sub e} in the transition of {sigma}{ge}{sigma}{sub cr} and in {sub C} area, and mainly relied on {sigma} in SC area of {sigma}<{sigma}{sub cr}. Moreover, it was also confirmed that such tendency was similar to the one of the two-dimensional contraction of an area. 22 refs., 10 figs., 1 tab.

  1. Numerical simulations of heat transfer in an annular fuel channel with three-dimensional spacer ribs set up periodically under a fully developed turbulent flow

    International Nuclear Information System (INIS)

    Takase, Kazuyuki; Akino, Norio

    1996-06-01

    Thermal-hydraulic characteristics of an annular fuel channel with spacer ribs for high temperature gas-cooled reactors were analyzed numerically by three-dimensional heat transfer computations under a fully developed turbulent flow. The two-equations κ-ε turbulence model was applied to the present turbulent analysis. In particular, the κ-ε turbulence model constants and the turbulent Prandtl number were improved from the previous standard values proposed by Jones and Launder in order to obtain heat transfer predictions with higher accuracy. Consequently, heat transfer coefficients and friction factors in the spacer-ribbed fuel channel were predicted with sufficient accuracy in the range of Reynolds number exceeding 3000. It was clarified quantitatively from the present study that main mechanism for the heat transfer augmentation in the spacer-ribbed fuel channel was combined effects of the turbulence promoter effect by the spacer ribs and the velocity acceleration effect by a reduction in the channel cross-section. (author)

  2. Groundwater flow modeling of periods with temperate climate conditions for use in a safety assessment of a repository for spent nuclear fuel - 59154

    International Nuclear Information System (INIS)

    Joyce, Steven; Hartley, Lee; Simpson, Trevor

    2012-01-01

    Document available in abstract form only. Full text of publication follows: As a part of the license application for a final repository for spent nuclear fuel, the Swedish Nuclear Fuel and Waste Management Company (SKB) has prepared a safety report (SR-Site) that assesses the long-term radiological safety after closure of a repository located at 500 m depth in the Forsmark area, c. 120 km north of Stockholm. The movement and composition of groundwater affect both the key pathways for radionuclide migration and the performance of engineered barriers, and hence are important issues that have to be considered and modelled as part of quantitative assessment calculations. This presentation describes the groundwater flow modelling studies that have been performed to represent the post-closure hydrogeological and hydrochemical situations during temperate climate conditions, and how these are used to support safety assessment calculations and arguments. The collation and implementation of onsite hydrogeological and hydrogeochemical data from the surface based site investigations at Forsmark are used as the basis for defining a reference case for the natural hydrogeological situation at the site (hydrogeological base case). Areas of uncertainty within the current site understanding and the engineered system are examined by a series of flow model variants

  3. Emission Studies in CI Engine using LPG and Palm Kernel Methyl Ester as Fuels and Di-ethyl Ether as an Additive

    Science.gov (United States)

    Dora, Nagaraju; Jothi, T. J. Sarvoththama

    2018-05-01

    The present study investigates the effectiveness of using di-ethyl ether (DEE) as the fuel additive in engine performance and emissions. Experiments are carried out in a single cylinder four stroke diesel engine at constant speed. Two different fuels namely liquefied petroleum gas (LPG) and palm kernel methyl ester (PKME) are used as primary fuels with DEE as the fuel additive. LPG flow rates of 0.6 and 0.8 kg/h are considered, and flow rate of DEE is varied to maintain the constant engine speed. In case of PKME fuel, it is blended with diesel in the latter to the former ratio of 80:20, and DEE is varied in the volumetric proportion of 1 and 2%. Results indicate that for the engine operating in LPG-DEE mode at 0.6 kg/h of LPG, the brake thermal efficiency is lowered by 26%; however, NOx is subsequently reduced by around 30% compared to the engine running with only diesel fuel at 70% load. Similarly, results of PKME blended fuel showed a drastic reduction in the NOx and CO emissions. In these two modes of operation, DEE is observed to be significant fuel additive regarding emissions reduction.

  4. Determination of Uncertainty for a One Milli Litre Volumetric Pipette

    International Nuclear Information System (INIS)

    Torowati; Asminar; Rahmiati; Arif-Sasongko-Adi

    2007-01-01

    An observation had been conducted to determine the uncertainty of volumetric pipette. The uncertainty was determined from data obtained from a determine process which used method of gravimetry. Calculation result from an uncertainty of volumetric pipette the confidence level of 95% and k=2. (author)

  5. CFD analysis of flow distribution of reactor core and temperature rise of coolant in fuel assembly for VVER reactor

    International Nuclear Information System (INIS)

    Du Daiquan; Zeng Xiaokang; Xiong Wanyu; Yang Xiaoqiang

    2015-01-01

    Flow field of VVER-1000 reactor core was investigated by using computational fluid dynamics code CFX, and the temperature rise of coolant in hot assembly was calculated. The results show that the maximum value of flow distribution factor is 1.12 and the minimum value is 0.92. The average value of flow distribution factor in hot assembly is 0.97. The temperature rise in hot assembly is higher than current warning limit value ΔT t under the deviated operation condition. The results can provide reference for setting ΔT t during the operation of nuclear power plant. (authors)

  6. Fuel assembly

    International Nuclear Information System (INIS)

    Abe, Hideaki; Sakai, Takao; Ishida, Tomio; Yokota, Norikatsu.

    1992-01-01

    The lower ends of a plurality of plate-like shape memory alloys are secured at the periphery of the upper inside of the handling head of a fuel assembly. As the shape memory alloy, a Cu-Zn alloy, a Ti-Pd alloy or a Fe-Ni alloy is used. When high temperature coolants flow out to the handling head, the shape memory alloy deforms by warping to the outer side more greatly toward the upper portion thereof with the temperature increase of the coolants. As the result, the shape of the flow channel of the coolants is changed so as to enlarge at the exit of the upper end of the fuel assembly. Then, the pressure loss of the coolants in the fuel assembly is decreased by the enlargement. Accordingly, the flow rate of the coolants in the fuel assembly is increased to lower the temperature of the coolants. Further, high temperature coolants and low temperature coolants are mixed sufficiently just above the fuel assembly. This can suppress the temperature fluctuation of the mixed coolants in the upper portion of the reactor core, thereby enabling to decrease a fatigue and failures of the structural components in the upper portion of the reactor core. (I.N.)

  7. Study of nonequilibrium dispersed two phase flow

    International Nuclear Information System (INIS)

    Reyes, J.N. Jr.

    1986-01-01

    Understanding the behavior of liquid droplets in a superheated steam environment is essential to the accurate prediction of nuclear fuel rod surface temperatures during the blowdown and reflood phase of a loss-of-coolant-accident (LOCA). In response to this need, this treatise presents several original and significant contributions to the field of thermofluid physics. The research contained herein presents a statistical derivation of the two-phase mass, momentum, and energy-conservation equations using a droplet continuity equation analogous to that used in the Kinetic Theory of Gases. Unlike the Eulerian volume and time-averaged conservation equations generally used to describe dispersed two-phase flow behavior, this statistical averaging approach results in an additional mass momentum or energy term in each of the respective conservation equations. Further, this study demonstrates that current definitions of the volumetric vapor generation rate used in the mass conservation equation are inappropriate results under certain circumstances. The mass conservation equation derived herein is used to obtain a new definition for the volumetric vapor-generation rate. Last, a simple two phase phenomenological model, based on the statistically averaged conservation equations, is presented and solved analytically. It is shown that the actual quality and vapor temperature, under these circumstances, depend on a single dimensionless group

  8. PERFORMANCE EVALUATION OF EXTERNAL MIXTURE FORMATION STRATEGY IN HYDROGEN-FUELED ENGINE

    Directory of Open Access Journals (Sweden)

    Mohammed Kamil

    2011-12-01

    Full Text Available Mohammed Kamil1, M. M. Rahman2 and Rosli A. Bakar2Hydrogen induction strategy in an internal combustion engine plays a vital role in increasing the power density and prohibiting combustion anomalies. This paper inspects the performance characteristics of cylinder hydrogen-fueled engine with port injection feeding strategy. To that end, a one-dimensional gas dynamic model has been built to represent the flow and heat transfer in the components of the engine. The governing equations are introduced followed by the performance parameters and model description. Air-fuel ratio was varied from a stoichiometric limit to a lean limit. The rotational speed of the engine was also changed from 1000 to 4500 RPM. The injector location was fixed in the mid-point of the intake port. The general behavior of the hydrogen engine was similar to that of a gasoline engine, apart from a reduction in the power density, which was due to a decrease in the volumetric efficiency. This emphasizes the ability of retrofitting traditional engines for hydrogen fuel with minor modifications. The decrease in the volumetric efficiency needs to be rectified.

  9. A road map for the realization of global-scale thorium breeding fuel cycle by single molten-fluoride flow

    International Nuclear Information System (INIS)

    Furukawa, K.; Arakawa, K.; Erbay, L. B.

    2007-01-01

    For global survival in this century, we urgently need to launch a completely new global nuclear fission industry. To get worldwide public acceptance of nuclear energy, improvements are essential not only on safety, radio-waste management and economy but also especially nuclear proliferation resistance and safeguards. However, such global fission industry cannot replace the present fossil fuel industry in the next 50 years, unless the doubling-time of nuclear energy is less than 10 years, preferably 5-7 years. Such a doubling-time cannot be established by any kind of classical 'Fission Breeding Power Station' concept. We need a symbiotic system which couples fission power reactors with a system which can convert fertile thorium to fissile U-233, such as a spallation or D/T fusion (if and when it becomes available). For such a purpose, THORIMS-NES [Thorium Molten-Salt Nuclear Energy Synergetic System] has been proposed, which is composed of simple thermal fission power stations (FUJI) and fissile producing Accelerator Molten-Salt Breeder (AMSB). Its system functions are very ambitious, delicate and complex, but can be realized in the form of simple hardware applying the multifunctional 'single-phase molten-fluoride' circulation system. This system has no difficulties relating with 'radiation-damage', 'heat-removal' and 'chemical processing' owing to the simple 'idealistic ionic liquid' character. FUJI is size-flexible (economical even in smaller sizes), fuel self-sustaining without any continuous chemical processing and without core-graphite replacement, and AMSB is based on a single-fluid molten-salt target/blanket concept, which solves most engineering difficulties such as radiation-damage, heat-removal etc., except high-current proton accelerator development. Several AMSBs are accommodated in the regional centers (several ten sites in the world) with batch chemical processing plants including radio-waste management. The integrated thorium breeding fuel cycle is

  10. Investigation of the Link Between Macroscopic Traffic Flow Characteristics and Individual Vehicle Fuel Consumption : Tech Transfer Summary

    Science.gov (United States)

    2017-10-01

    The objective of this project was to investigate the impacts of several factors, including vehicle characteristics, ambient temperature, season, speed, driving behavior, and traffic flow, on individual vehicle energy consumption.

  11. Electrochemical study of multi-electrode microbial fuel cells under fed-batch and continuous flow conditions

    KAUST Repository

    Ren, Lijiao; Ahn, Yongtae; Hou, Huijie; Zhang, Fang; Logan, Bruce E.

    2014-01-01

    together (combined), in fed-batch or continuous flow conditions. Power production under these different conditions could not be made based on a single resistance, but instead required polarization tests to assess individual performance relative

  12. Sustainable Power Generation in Continuous Flow Microbial Fuel Cell Treating Actual Wastewater: Influence of Biocatalyst Type on Electricity Production

    Directory of Open Access Journals (Sweden)

    Zainab Z. Ismail

    2013-01-01

    Full Text Available Microbial fuel cells (MFCs have the potential to simultaneously treat wastewater for reuse and to generate electricity. This study mainly considers the performance of an upflow dual-chambered MFC continuously fueled with actual domestic wastewater and alternatively biocatalyzed with aerobic activated sludge and strain of Bacillus Subtilis. The behavior of