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Sample records for baffles

  1. Baffle construction notes

    DEFF Research Database (Denmark)

    Jørgensen, John Leif

    1997-01-01

    The procedures for manufacturing CFRP based stray light suppresion structures are described. Examples from production ofthe baffle designed for the "Astrid 2" and "TEAMSAT" missions are given......The procedures for manufacturing CFRP based stray light suppresion structures are described. Examples from production ofthe baffle designed for the "Astrid 2" and "TEAMSAT" missions are given...

  2. Baffle construction notes

    DEFF Research Database (Denmark)

    Jørgensen, John Leif

    1998-01-01

    The design process for multi-stage high performance straylight suppression baffles for star trackers are described. Furthermore details for manufacturing are given......The design process for multi-stage high performance straylight suppression baffles for star trackers are described. Furthermore details for manufacturing are given...

  3. Scandinavian baffle boiler design revisited

    Directory of Open Access Journals (Sweden)

    Stepanov Borivoj Lj.

    2015-01-01

    Full Text Available The aim of this paper is to examine whether the use of baffles in a combustion chamber, one of the well-known low-cost methods for the boiler performance improvement, can be enhanced. Modern day tools like computational fluid dynamics were not present at the time when these measures were invented, developed and successfully applied. The objective of this study is to determine the influence of location and length of a baffle in a furnace, for different mass flows, on gas residence time. The numerical simulations have been performed of a simple Scandinavian stove like furnace. The isothermal model is used, while air is used as a medium and turbulence is modeled by realizable k-epsilon model. The Lagrange particle tracking is used for the residence time distribution determination. The statistical analysis yielded the average residence time. The results of the computational fluid dynamics studies for different baffle positions, dimensions and flow rates show from up to 17% decrease to up to 13 % increase of residence time. The conclusion is that vertical position of the baffle is the most important factor, followed by the length of the baffle, while the least important showed to be the mass flow. [Projekat Ministarstva nauke Republike Srbije, br. III 43008: Development of methods, sensors and systems for monitoring of quality of water, air and land

  4. Modelling of baffled stirred tanks

    Energy Technology Data Exchange (ETDEWEB)

    Ahlstedt, H.; Lahtinen, M. [Tampere Univ. of Technology (Finland). Energy and Process Engineering

    1996-12-31

    The three-dimensional flow field of a baffled stirred tank has been calculated using four different turbulence models. The tank is driven by a Rushton-type impeller. The boundary condition for the impeller region has been given as a source term or by calculating the impeller using the sliding mesh technique. Calculated values have been compared with measured data. (author)

  5. Mixed convection in a baffled grooved channel

    Indian Academy of Sciences (India)

    Aayush K Sharma; Pallab S Mahapatra; Nirmal K Manna; Koushik Ghosh

    2015-05-01

    In the present numerical work, flow structure and heat transfer characteristics are investigated in a baffled grooved channel, differentially heated from the sides. The baffle is placed vertically downward from the top wall of grooved channel geometry, with the motive of diverting outside forced flow towards the inside of the square cavity. In-house CFD code based on finite volume method has been used to solve the 2D equations of continuity, momentum and energy. The effect of change in baffle position and height is investigated in the range of Richardson numbers 0.1 to 10. For the present study, external flow from both left and right of the grooved channel are considered. A remarkable enhancement of heat transfer is observed in presence of baffle. The study has also pointed out that for optimal performance, the position and height of the baffle need to be adjusted depending on the direction of external flow.

  6. Comparison of heat transfer performances of helix baffled heat exchangers with different baffle configurations

    Institute of Scientific and Technical Information of China (English)

    Cong Dong; Yaping Chen; Jiafeng Wu

    2015-01-01

    Numerical simulations were performed on flow and heat transfer performances of heat exchangers having six helical baffles of different baffle shapes and assembly configurations, i.e., two trisection baffle schemes, two quadrant baffle schemes, and two continuous helical baffle schemes. The temperature contour or the pressure contour and velocity contour plots with superimposed velocity vectors on meridian, transverse and unfolded concentric hexagonal slices are presented to obtain a full angular view. For the six helix baffled heat exchangers, the different patterns of the single vortex secondary flow and the shortcut leakage flow were depicted as wel as the heat transfer properties were compared. The results show that the optimum scheme among the six configurations is a circumferential overlap trisection helix baffled heat exchanger with a baffle incline angle of 20° (20°TCO) scheme with an anti-shortcut baffle structure, which exhibits the second highest pressure dropΔpo, the highest overal heat transfer coefficient K, shel-side heat transfer coefficient ho and shel-side average comprehensive index ho/Δpo.

  7. Simulasi Performansi Heat Exchanger Type Shell And Tube Dengan Double Segmental Baffle Terhadap Helical Baffle

    Directory of Open Access Journals (Sweden)

    Anggareza Adhitiya

    2013-12-01

    Full Text Available Pada heat exchanger type shell and tube, selain pengunaan baffle yang bertujuan untuk mengarahkan aliran pada sisi shell juga bertujuan untuk meningkatkan laju perpindahan panas yang terjadi antara fluida kerja dengan cara menimbulkan olakan aliran di sisi shell. Olakan –olakan ini nantinya yang akan mempengaruhi besarnya perpindahan panas dalam sisi shell. Pada kondisi standart baffle yang digunakan pada tugas akhir ini adalah jenis double segmental. Double segmental baffle mempunyai tingkat pressure drop yang cukup besar. sehingga perlu di ganti dengan baffle jenis helical yang mempunyai pressure drop yang lebih kecil. Untuk mengetahui performansi heat exchanger maka perlu adanya penelitian lebih lanjut simulasi numerik pada baffle heat exchanger type shell and tube. agar didapat pengaruh jenis baffle yang di gunakan terhadap karakteristik aliran dan perpindahan panas dari suatu heat exchanger type shell and tube. Tugas Akhir ini menggunakan program GAMBIT 2.4.6 untuk penggambaran geometri secara tiga dimensi dan program FLUENT 6.3.26 untuk mensimulasi aliran yang terjadi di dalam shell and tube heat exchanger. Pada software FLUENT 6.3.26 digunakan permodelan 3D Steady Flow dengan  memilih k – Epsilon RNG sebagai turbulence modeling serta mengaktifkan persamaan energy. Penelitian dilakukan dengan menggunakan dua variasi heat exchanger dengan jenis baffle yang berbeda .Heat exchanger type shell and tube dengan jenis double segmental baffle mempunyai nilai koefisien konveksi rata-rata = 218.408 w/m2.K. Sedangkan untuk helical baffle sebesar = 171.122 w/m2.K. Temperature outflow pada heat exchanger type shell and tube dengan jenis double segmental baffle = 306.7450K. Di ikuti dengan pressure drop sebesar = 2100 pascal Sedangkan untuk helical baffle mempunyai temperatur outflow sebesar = 307.0220K dengan pressure drop sebesar = 500 pascal.

  8. PENGARUH PENGGUNAAN BAFFLE PADA SHELL-AND-TUBE HEAT EXCHANGER

    OpenAIRE

    Ekadewi Anggraini Handoyo

    2001-01-01

    Shell-and-tube heat exchanger is a device commonly used to transfer heat. To enhance the heat transfer occurred and to support the tubes inside the shell, baffles are installed. Better heat transfer is obviously expected in a heat exchanger. A research is done to find out the effect of baffle used toward the effectiveness and pressure drop in heat exchanger. The result is that the effectiveness increases when the baffles are installed. Effectiveness increases as the spacing between the baffle...

  9. Velocity profiles between two baffles in a horizontal circular tube

    Science.gov (United States)

    Chang, Tae-Hyun; Lee, Hae-Soo; Oh, Keon-Je; Doh, Doeg Hee; Lee, Chang-Hoan

    2014-12-01

    The shell and tube heat exchanger is an essential part of a power plant for recovering heat transfer between the feed water of a boiler and the wasted heat. The baffles are also an important element inside the heat exchanger. Internal materials influence the flow pattern in the bed. The influence of baffles in the velocity profiles was observed using a three-dimensional particle image velocimetry around baffles in a horizontal circular tube. The velocity of the particles was measured before the baffle and between them in the test tube. Results show that the flows near the front baffle flow were parallel to the vertical wall, and then concentrate on the upper opening of the front baffle. The flows circulate in the front and rear baffles. These flow profiles are related to the Reynolds number (Re) or the flow intensity. The velocity profiles at lower Re number showed a complicated mixing, concentrating on the lower opening of the rear baffle as front wall. Swirling flow was employed in this study, which was produced using tangential velocities at the inlet. At the entrance of the front baffle, the velocity vector profiles with swirl were much different from that without swirl. However, velocities between two baffles are not much different from those without swirl.

  10. Velocity Profiles between Two Baffles in a Horizontal Circular Tube

    Institute of Scientific and Technical Information of China (English)

    Tae-Hyun Chang; Hae-Soo Lee; Keon-Je Oh; Doeg Hee Doh; Chang-Hoan Lee

    2014-01-01

    The shell and tube heat exchanger is an essential part of a power plant for recovering heat transfer between the feed water of a boiler and the wasted heat.The baffles are also an important element inside the heat exchanger.Internal materials influence the flow pattern in the bed.The influence of baffles in the velocity profiles was observed using a three-dimensional particle image velocimetry around baffles in a horizontal circular tube.The velocity of the particles was measured before the baffle and between them in the test tube.Results show that the flows near the front baffle flow were parallel to the vertical wall,and then concentrate on the upper opening of the front baffle.The flows circulate in the front and rear baffles.These flow profiles are related to the Reynolds number (Re) or the flow intensity.The velocity profiles at lower Re number showed a complicated mixing,concentrating on the lower opening of the rear baffle as front wall.Swirling flow was employed in this study,which was produced using tangential velocities at the inlet.At the entrance of the front baffle,the velocity vector profiles with swirl were much different from that without swirl.However,velocities between two baffles are not much different from those without swirl.

  11. Design and manufacturing of WEST Baffle

    Energy Technology Data Exchange (ETDEWEB)

    Batal, Tristan, E-mail: tristan.batal@cea.fr [CEA, IRFM, F-13108 Saint-Paul-Lez-Durance (France); Firdaouss, Mehdi; Richou, Marianne; Ferlay, Fabien; Larroque, Sébastien; Gargiulo, Laurent [CEA, IRFM, F-13108 Saint-Paul-Lez-Durance (France); Dupas, Timothée [SODITECH Ingénierie SA, 1 bis allée des gabians, 06150 Cannes la Bocca (France); Verger, Jean-Marc; Doceul, Louis; Samaille, Franck; Bucalossi, Jérôme [CEA, IRFM, F-13108 Saint-Paul-Lez-Durance (France); Salami, Michael [AVANTIS groupe, 12 route de Saint Mathieu, 06130 Grasse (France)

    2015-10-15

    Highlights: • Disruption's torque in the PFC was simulated thanks to ANSYS. • The ANSYS thermal results comply with WEST project requirements. • The cycling analysis complies with WEST project requirements. • 316L components comply with A level RCC-MRx criteria. - Abstract: The Tore Supra tokamak is being transformed in an X-point divertor fusion device in the frame of the WEST project, launched in support to the Iter tungsten divertor strategy. The WEST Baffle aims to evacuate particles by creating a toroidal pumping throat. It also protects the lower divertor cooling pipes and the passive stabilization plate from heat fluxes. The Baffle is made of actively cooled plasma facing components (PFCs), with underneath a passive stabilization plate and a support beam. The Baffle design is presented in a first part. In a second time the different ANSYS simulations are described: electromagnetic, thermal and mechanical results are presented. The design choices are justified for the different results obtained thanks to the simulation. In a final part, some aspects of the PFC manufacturing are presented.

  12. Coupling and Shielding Properties of the Baffle in ICP System

    Directory of Open Access Journals (Sweden)

    Jozef Brcka

    2011-01-01

    Full Text Available This contribution is dealing with experimental and computational evaluation of the deposition baffle that is transparent to radio frequency (RF magnetic fields generated by an external antenna in an inductively coupled plasma (ICP source but opaque to the deposition of the metal onto a dielectric wall in ionized physical vapor deposition (IPVD system. Various engineering aspects related to the deposition baffle are discussed. Among the many requirements focus is on specific structure of the slots and analysis to minimize deposition on the baffle (we used a string model for simulating the profile evolution and deposition through the DB on dielectric components of the ICP source. Transparency of the baffle to RF magnetic fields is computed using a three-dimensional (3D electromagnetic field solver. A simple two-dimensional sheath model is used to understand plasma interactions with the DB slot structure. Performance and possible failure of device are briefly discussed.

  13. Enhancing mixing of particles by baffles in a rotating drum mixer

    Institute of Scientific and Technical Information of China (English)

    Maoqiang Jiang; Yongzhi Zhao; Gesi Liu; Jinyang Zheng

    2011-01-01

    Baffles with shape of “-” (single baffle), “+” (cross-baffles with four arms) and (baffles with 6 arms)are used to enhance the mixing of particles in a rotating drum mixer. A micro-dynamics study of mixing and segregation of a bi-disperse system of two particle sizes in the rotating drum with these three kinds of baffles is carried out using the discrete element method (DEM). The effect of the baffles on mixing, and the mechanisms of mixing enhancement by the baffles are discussed and analyzed. Simulation results show that in an unbaffled drum mixer, particle convection, particle diffusion, and size segregation of bidisperse particles, all play important roles in the mixing process; whereas size segregation will be largely restrained when the drum mixer has a baffle, regardless of its shape, and the degree of mixing is higher than that in an unbaffled drum mixer. The different mixing characteristics for “-” shaped baffle, “+” baffle,and baffle are revealed by the simulation results. For “+” or “*” style baffles, there is an optimal size of baffles for the mixing of particles, and the optimal mixing efficiency is higher than that for “-” baffle.

  14. Effects of Transverse Baffle Design on Reducing Liquid Sloshing in Partially Filled Tank Vehicles

    Directory of Open Access Journals (Sweden)

    Xue-lian Zheng

    2013-01-01

    Full Text Available Longitudinal liquid sloshing in partially filled clear-bore tanks causes extensive degradation of tankers braking performance. To reduce the negative effect of longitudinal liquid sloshing on tankers, three kinds of transverse baffles were designed, namely, the conventional baffle, the circular baffle, and the staggered baffle. Each kind of baffle took several forms to investigate the impact of baffle installation angle, the sizes of holes pierced on the baffle, and their arrangement on the antisloshing effect. FLUENT software was used to simulate liquid sloshing in tanks equipped with different kinds of transverse baffles and subject to constant braking deceleration. A time-series analysis of the forces act on tank walls and transverse baffles was carried out. It was drawn that the baffle shape and its installation angle have great impact on the antisloshing effect of baffles. The study on the antisloshing effect of different transverse baffles is of great significance for tank vehicle driving and braking safety, as well as for the design of optimal transverse baffles.

  15. Steady state modeling of large diameter crystal growth using baffles

    Science.gov (United States)

    Sahai, Vivek; Williamson, John; Overfelt, Tony

    1991-01-01

    Buoyancy driven flow in the crystal melt is one of the leading causes of segregation. Natural convection arises from the presence of thermal and/or solutal gradients in the melt and it is not possible to completely eliminate the convection even in the low gravity environment of space. This paper reports the results of computational modeling research that is being done in preparation for space-based experiments. The commercial finite element code FIDAP was used to simulate the steady convection of a gallium-doped germanium alloy in a Bridgman-Stockbarger furnace. In particular, the study examines the convection-suppressing benefits of inserting cylindrical baffles in the molten region to act as viscous dampers. These thin baffles are assumed to be inert and noncontaminating. The results from this study show the manner in which the streamlines, velocities, and temperature fields at various gravity levels are affected by the presence of baffles. The effects of changing both the number and position of the baffles are examined and the advantages and disadvantages of using baffles are considered.

  16. Seismic Response of Liquid-Filled Tank with Baffles

    Institute of Scientific and Technical Information of China (English)

    Mohammad Reza Shekari

    2014-01-01

    In thispaper, the effects of a rigid baffle on the seismic response of liquid in a rigid cylindrical tank are evaluated. A baffle is an annular plate which supplies a kind of passive control on the effects of ground excitation. The contained liquid is assumed incompressible, inviscid and has irrotational motion. To estimate the seismic response, the method of superposition of modes has been applied. To analyze the rigid tank response, Laplace's equation is considered as the governing equation of the fluid domain, in both time and frequency domains. The boundary element method (BEM) is employed to evaluate the natural modes of liquid in a cylindrical tank. To gain this goal, the fluid domain is divided into two upper and lower parts partitioned by the baffle. Linearized kinematic and dynamic boundary conditions of the free surface of the contained liquid have been considered.

  17. Energy Loss, Velocity Distribution, and Temperature Distribution for a Baffled Cylinder Model

    Science.gov (United States)

    Brevoort, Maurice J

    1937-01-01

    A study has been made of the important principles involved in the operation of a baffle for an engine cylinder and shows that cooling can be improved by 20 percent by using a correctly designed baffle. Such a gain is as effective as a 65 percent increase in pressure drop across the standard baffle, which had a 1/4 inch clearance between baffle and fin tips.

  18. A Waveguide Transverse Broad Wall Slot Radiating Between Baffles

    DEFF Research Database (Denmark)

    Dich, Mikael; Rengarajan, S.R.

    1997-01-01

    An analysis of the self impedance of waveguide-fed transverse slots radiating between baffles is presented. The region exterior to the slot is treated as a parallel plate (PP) waveguide which radiates into half space through an aperture in an infinite ground plane. The slot problem is analyzed...

  19. Array gain for a cylindrical array with baffle scatter effects.

    Science.gov (United States)

    Bertilone, Derek C; Killeen, Damien S; Bao, Chaoying

    2007-11-01

    Cylindrical arrays used in sonar for passive underwater surveillance often have sensors surrounding a cylindrical metal baffle. In some operational sonars, the phones in each stave (i.e., each line of phones aligned with the cylinder axis) are hardwired together so that the array is equivalent to a baffled circular array of directional elements, where each element corresponds to a line array of omnidirectional phones steered to broadside. In this paper a model is introduced for computing the array gain of such an array at high frequencies, which incorporates baffle scatter using infinite, rigid cylinder scattering theory, and with ambient noise described by an angular spectral density function. In practice the phones are often offset from the baffle surface, and the acoustic field sampled by the staves is distorted at high frequencies due to interference between the incident and scattered fields. Examples are given to illustrate the resulting array gain degradation, using three noise distributions that are frequently used in sonar performance modeling: three-dimensional isotropic, two-dimensional isotropic, and surface dipole noise.

  20. Spatial impulse responses from a flexible baffled circular piston

    NARCIS (Netherlands)

    Aarts, R.M.; Janssen, A.J.E.M.

    2011-01-01

    The theory of orthogonal polynomial (Zernike) expansions of functions on a disk, as used in the diffraction theory of optical aberrations, is applied to obtain (semi-) analytical expressions for the spatial impulse responses arising from a non-uniformly moving, baffled, circular piston. These expres

  1. Shock-induced turbulent flow in baffle systems

    Energy Technology Data Exchange (ETDEWEB)

    Kuhl, A.L. [Lawrence Livermore National Lab., CA (United States); Reichenbach, H. [Fraunhofer-Institut fuer Kurzzeitdynamik - Ernst-Mach-Institut (EMI), Freiburg im Breisgau (Germany)

    1993-07-01

    Experiments are described on shock propagation through 2-D aligned and staggered baffle systems. Flow visualization was provided by shadow and schlieren photography, recorded by the Cranz-Schardin camera. Also single-frame, infinite-fringe, color interferograms were used. Intuition suggests that this is a rather simple 2-D shock diffraction problem. However, flow visualization reveals that the flow rapidly evolved into a complex 3-D turbulent mixing problem. Mushroom-shaped mixing regions blocked the flow into the next baffle orifice. Thus energy was transferred from the directed kinetic energy (induced by the shock) to rotational energy of turbulent mixing, and then dissipated by molecular effects. These processes dramatically dissipate the strength of the shock wave. The experiments provide an excellent test case that could be used to assess the accuracy of computer code calculations of such problems.

  2. Relay telescope including baffle, and high power laser amplifier utilizing the same

    Science.gov (United States)

    Dane, C. Brent; Hackel, Lloyd; Harris, Fritz B.

    2006-09-19

    A laser system includes an optical path having an intracavity relay telescope with a telescope focal point for imaging an output of the gain medium between an image location at or near the gain medium and an image location at or near an output coupler for the laser system. A kinematic mount is provided within a vacuum chamber, and adapted to secure beam baffles near the telescope focal point. An access port on the vacuum chamber is adapted for allowing insertion and removal of the beam baffles. A first baffle formed using an alignment pinhole aperture is used during alignment of the laser system. A second tapered baffle replaces the alignment aperture during operation and acts as a far-field baffle in which off angle beams strike the baffle a grazing angle of incidence, reducing fluence levels at the impact areas.

  3. Experimental investigation of shell-and-tube heat exchanger with a new type of baffles

    Science.gov (United States)

    Wang, Yingshuang; Liu, Zhichun; Huang, Suyi; Liu, Wei; Li, Weiwei

    2011-07-01

    A shell-and-tube heat exchanger with new type of baffles, is designed, fabricated and tested. The experimental investigation for the proposed model and the original segmental baffle heat exchanger are conducted. The operation performances of the two heat exchangers are also compared. The results suggest that, under the same conditions, the overall performance of the new model is 20-30% more efficient than that of the segmental baffle heat exchanger.

  4. Particle contamination from Martin Optical Black. [in design of barrel baffle of Infrared Astronomical Satellite

    Science.gov (United States)

    Young, P. J.; Noll, R.; Andreozzi, L.; Hope, J.

    1981-01-01

    The design of the barrel baffle of the Infrared Astronomical Satellite (IRAS) Optical Subsystem to minimize production of particulate contamination is described. The configuration of the 50-inch long, 28.5-inch diameter baffle required pop-rivet assembly after coating with Martin Optical Black for stray light suppression. An experiment to determine the contamination produced at assembly led to the modification of the baffle construction to preclude such damage to the coated surfaces.

  5. Further analysis of the effects of baffles on combustion instability. [computer techniques

    Science.gov (United States)

    Oberg, C. L.; Schuman, M. D.

    1975-01-01

    A computerized analytical model, developed to predict the effects of baffles on combustion instability, was modified in an effort to improve the ability to properly predict stability effects. The model was modified: (1) to replace a single spatially-averaged response factor by separate values for each baffle compartment; (2) to calculate the axial component of the acoustic energy flux, and (3) to permit analysis of traveling waves in a thin annular chamber. Allowance for separate average response factors in each baffle compartment was found to significantly affect the predicted results. With this modification, an optimum baffle length was predicted which gave maximum stability.

  6. EFFECT OF VERTICAL BAFFLES ON PARTICLE MIXING AND DRYING IN FLUIDIZED BEDS OF GROUP D PARTICLES

    Institute of Scientific and Technical Information of China (English)

    Chung Lim Law; Siti Masrinda Tasirin; Wan Ramli Wan Daud; Derek Geldart

    2003-01-01

    This study reports the effect of vertical baffles on the group D powder mixing and drying characteristics in a batch fluidized bed dryer. Results obtained in this study showed that operating the fluidized bed dryer with vertical baffles gave better particle mixing. This is due to the fact that the vertical baffles acted to limit the growth of small bubbles into large bubbles and the small bubbles caused more vigorous mixing in the bed of particles before finally erupting at the bed surface. Thus, insertion of vertical baffles is a useful way to process group D particles in a fluidized bed, especially when the fluidized bed is large.

  7. Study of Baffle Boundary and System Parameters on Liquid-Solid Coupling Vibration of Rectangular Liquid-Storage Structure

    Directory of Open Access Journals (Sweden)

    Wei Jing

    2016-01-01

    Full Text Available In order to study the vibration problem of liquid-solid coupling of rectangular liquid-storage structure with horizontal elastic baffle, ignoring the influence of surface gravity wave, two different velocity potential functions corresponding to the liquid above and below the elastic baffle are assumed; based on the theory of mathematical equation and energy method, the formulas of basic frequency of liquid-solid coupling vibration system are derived, the baffle joined to the tank wall with 3 kinds of boundary conditions, namely, four edges simply supported, two opposite edges clamped and two opposite edges simply supported, and four edges clamped; the influence rules of baffle length-width ratio, the ratio of baffle height to liquid level, baffle elastic modulus, baffle density, baffle thickness, and liquid density on the coupling vibration performance are studied. The results show that the frequency of the clamped boundary is minimum; the influences of baffle length-width ratio and relative height on the basic frequency are much greater than that of the other system parameters; the relation between baffle length-width ratio and the frequency is exponential, while baffle relative height has a parabola relation with the frequency; the larger the baffle length-width ratio, the closer the baffle to the liquid level; the coupling frequency will be reduced more obviously.

  8. Treatment of domestic wastewater using conventional and baffled septic tanks.

    Science.gov (United States)

    Nasr, Fayza Aly; Mikhaeil, Basem

    2013-01-01

    The main theme of the study was a comparative study of domestic wastewater treatment using conventional and baffled septic tanks. The septic tanks were fed continuously with domestic wastewater at three different hydraulic retention times (HRTs). The HRTs chosen were 24, 48 and 72 h with corresponding organic loads of 0.321, 0.436 and 0.885 kg chemical oxygen demand (COD) per m3 per day, respectively. The performance of the septic tanks at the three HRTs gave satisfactory results. For the conventional septic tank, COD removal was 53.4%, 56% and 65.3%, at an HRT of 24, 48 and 72 h, respectively, with residual COD of 412, 380 and 334mg/l, respectively. At HRTs of 72, 48 and 24 h, the following percentages removals were realized for: biochemical oxygen demand (BOD), 68.4%, 57, 53.5%; total suspended solid (TSS), 65.3%, 58.3, 55%; phosphorus, 29.3%, 26.9, 25.6%; total Kjeldahl nitrogen 26.8%, 20.8, 17.7%, respectively. On the contrary, ammonia concentrations increased by 7.1%, 5.2 and 4.2% under the same conditions. Consequently, the results showed that the removal of fecal coliform at all HRTs was less than one log. The two baffled septic tanks exhibited superior results at HRTs of 72, 48 and 24 h. Comparing the treated domestic wastewater quality produced by the two types of septic tanks in terms of physico-chemical and biological characteristics, better results were obtained using the two baffles type.

  9. Velocity profiles between two baffles in a shell and tube heat exchanger

    Science.gov (United States)

    Chang, Tae-Hyun; Lee, Chang-Hoan; Lee, Hae-Soo; Lee, Kwon-Soo

    2015-06-01

    Heat exchangers are extensively utilized for waste heat recovery, oil refining, chemical processing, and steam generation. In this study, velocity profiles are measured using a 3D particle image velocimetry (PIV) system betweentwo baffles in a shell and tube heat exchanger for parallel and counter flows. The PIV and computational fluid dynamics results show the occurrence of some strong vectors near the bottom. These vectors are assumed due to the clearance between the inner tubes and the front baffle. Therefore, the major parts of the vectors are moved out through the bottom opening of the rear baffle, and other vectors produce a large circle between the two baffles. Numerical simulations are conducted to investigate the effects of the baffle on the heat exchanger using the Fluent software. The k-ɛ turbulence model is employed to calculate the flows along the heat exchanger

  10. NUMERICAL SIMULATION OF TURBULENT FLOW CHARACTERISTICS IN A CURVED PIPE WITH A BAFFLE

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A numerical study on the characteristics of developing turbulent flow in a curved pipe with a baffle was carried out in body-fitted coordinates with the k-ε model turbulence. A curved duct of square cross-section was examined first, and the results agree very well with the experimental data. Then two kinds of pipes, a normal curved pipe and that with a baffle were studied. The computational results are presented and compared with each other to illustrate the changes of the flow after adding the baffle. The longitudinal velocity in the pipe with a baffle was characterized by outer velocity bigger than the inner one. The secondary flow was characterized by four-vortex structure with the intensity reduced, which results in the equability of the flow field of the cross-section compared with that without a baffle, and has much more significant meaning in engineering.

  11. Thermal analysis of the baffle structure of the Solar Space Telescope

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The SST(Space Solar Telescope) is an astronomical telescope with a primary mirror of 1 m in diameter.It observes the sun with a small view field to ensure that its high spatial resolution imaging has 0.1″-0.15″ and high SNR(signal to noise ratio).Surrounding the small view field is still the sun,which is an intense source of both heat and stray light.The baffles(the main baffle,the aperture,and the outer baffle),which are used to eliminate the stray light,will change the thermal flux in the SST and will weaken the effect of the thermal control design.In this study,the compatibility analysis of the thermal effect of baffle structures in SST is performed.The GCF(Geometry Composing Function) and BRDF(Bidirectional Reflectance Distribution Function),which are two inherent related parameters in the compatibility analysis,are derived.The objective and method of the compatibility analysis are determined.With the thermal analysis software,the temperature fields are calculated for different lengths of the main baffle,different radii of apertures,different lengths of the outer baffle with a 3’ tilt angle and 16’ tilt angle,and different tilt angles of the outer baffle with a 200 mm length.A series of configurations and sizes of the baffles are studied with the goals of both thermal control and elimination of stray light.The design of the baffle structure of SST is achieved:the main baffle of length 4100 mm,the internal shield of radius 494 mm,the outer baffle of length 200 mm,and the outer baffle of tilt angle 3’ are successfully designed.This paper presents the relationship between the thermal control design and stray light elimination plan in the SST.The aims of the optimal design of the baffle structure of SST are reached.The thoughts and methods of the optimal analysis are also useful for similar optical telescopes designed for solar observation.

  12. Industrially Experimental Investigations and Development of the Curve-ROD Baffle Heat Exchanger

    Institute of Scientific and Technical Information of China (English)

    严良文; 吴金星; 王志文

    2004-01-01

    The conventional heat exchanger with segmental baffles is prone to bring forth fluid-induced vibration of heat transfer tubes and increase the pressure drop of shell-side greatly at higher fluid flow velocity. In order to avoid the above defects, the ROD-baffle heat exchanger has been developed. However, its collocation of heat transfer tubes is conventionally in square, which leads to fewer heat transfer area per unit volume. Based on the ROD-baffle heat exchanger, a new type curve-ROD baffle has been developed, and an industrial investigation of the curve-ROD baffle heat exchanger with normal triangular collocation has been carried into execution. In this paper, two equations using the Reynolds number were acquired to predict the heat transfer coefficients of the shell-side and tubeside. The experimental results show that the shell-side heat transfer and pressure drop characteristics of the curve-ROD baffle heat exchanger are superior to those of the segmental baffle one.

  13. Simultaneous nitrification and denitrification based on internal circulation baffled reactor

    Directory of Open Access Journals (Sweden)

    LU Xiaoya

    2014-06-01

    Full Text Available Nitrogen removal experiments were carried out by using an internal circulation baffled bioreactor (ICBBR. Nitrate, nitrite and ammonia were used as N source for nitrogen removal experiments. The ICBBR has high nitrogen removal capacity. The removal rates of total nitrogen, nitrate, and nitrite are almost the same. When nitrate and nitrite were used as N sources their kinetic orders were 0.88. When ammonia was used as N source simultaneous nitrification and denitrification (SND was realized in ICBBR and ammonia removal fitted also 0.88 order kinetics, but total nitrogen removal fitted third-order kinetics. Nitrate and nitrite removal rates were faster than ammonia removal rate under the same C/N ratio, and total nitrogen removal rate increased with increasing C/N ratio.

  14. Modal radiation patterns of baffled circular plates and membranes

    DEFF Research Database (Denmark)

    Christiansen, Thomas Lehrmann; Hansen, Ole; Thomsen, Erik Vilain;

    2014-01-01

    The far field velocity potential and radiation pattern of baffled circular plates and membranes are found analytically using the full set of modal velocity profiles derived from the corresponding equation of motion. The derivation is valid for a plate or membrane subjected to an external excitation...... force, which is used as a sound receiver in any medium or as a sound transmitter in a gaseous medium. A general, concise expression is given for the radiation pattern of any mode of the membrane and the plate with arbitrary boundary conditions. Specific solutions are given for the four special cases...... that of a monopole, while the non-axisymmetric modes exhibit multipole behavior. Numerical results are also given, demonstrating the implications of having non-axisymmetric excitation using both a point excitation with varying eccentricity and a homogeneous excitation acting on half of the circular radiator....

  15. Rapid production of biodiesel in mesoscale oscillatory baffled reactors

    Energy Technology Data Exchange (ETDEWEB)

    Phan, A.N.; Harvey, A.P.; Eze, V. [School of Chemical Engineering and Advanced Materials, Newcastle Upon Tyne (United Kingdom)

    2012-07-15

    Continuous alkali-catalyzed transesterification of rapeseed oil with methanol was carried out in three mesoreactor designs. The induction time decreased with oscillatory Reynolds number for all three reactors. Stable steady states were achieved within induction times of 1.5, 2.5, and 4.0 residence times for the integral, wire wool, and helical baffle designs, respectively. Both experimental and simulated results indicated that under the given conditions there is an optimal residence time for homogeneous transesterification. Higher residence times resulted in reduced fatty acid methyl ester content due to the saponification side reaction. The results demonstrate that biodiesel can be produced at an industrially acceptable level of conversion (> 95 %) in < 5 min residence time. This requires a combination of high catalyst concentration and good mixing. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Optimum design of the carbon fiber thin-walled baffle for the space-based camera

    Science.gov (United States)

    Yan, Yong; Song, Gu; Yuan, An; Jin, Guang

    2011-08-01

    The thin-walled baffle design of the space-based camera is an important job in the lightweight space camera research task for its stringent quality requirement and harsh mechanical environment especially for the thin-walled baffle of the carbon fiber design. In the paper, an especially thin-walled baffle of the carbon fiber design process was described and it is sound significant during the other thin-walled baffle design of the space camera. The designer obtained the design margin of the thin-walled baffle that structural stiffness and strength can tolerated belong to its development requirements through the appropriate use of the finite element analysis of the walled parameters influence sensitivity to its structural stiffness and strength. And the designer can determine the better optimization criterion of thin-walled baffle during the geometric parameter optimization process in such guiding principle. It sounds significant during the optimum design of the thin-walled baffle of the space camera. For structural stiffness and strength of the carbon fibers structure which can been designed, the effect of the optimization will be more remarkable though the optional design of the parameters chose. Combination of manufacture process and design requirements the paper completed the thin-walled baffle structure scheme selection and optimized the specific carbon fiber fabrication technology though the FEM optimization, and the processing cost and process cycle are retrenchment/saved effectively in the method. Meanwhile, the weight of the thin-walled baffle reduced significantly in meet the design requirements under the premise of the structure. The engineering prediction had been adopted, and the related result shows that the thin-walled baffle satisfied the space-based camera engineering practical needs very well, its quality reduced about 20%, the final assessment index of the thin-walled baffle were superior to the overall design requirements significantly. The design

  17. On the role of hanging baffle performance enhancement by using slotted Helmholtz resonator array

    Science.gov (United States)

    Hanina, R.; Yahya, I.; Harjana

    2016-11-01

    This paper emphasizes on the experimental investigation performance of hanging baffle with slotted Helmholtz resonator array inclusion. Laboratory test procedure refers to ATMS E-1050 was conducted for measuring the sound absorption coefficient of the Helmholtz resonator, while interrupted noise reverberation time measurement refers to ISO 3382-2 has been done for room acoustic performance test of the proposed design hanging baffle. The result shows that broadband absorption occurs when the Helmholtz resonator inserted to the hanging baffle. Sound energy dissipation increase both in resonance and viscous damping mechanism. It reduces the reverberation time significantly in all frequencies. The proposed design slotted resonator inclusion has brought opportunity for tuning the response and performance of the hanging baffle.

  18. Thermal Test Verification of Emission Control through Directional Baffles for the James Webb Space Telescope

    Science.gov (United States)

    Garrison, Matthew; Rashford, Robert; Switzer, Timothy; Shaw, David; White, Bryant; Lynch, Michael; Huber, Frank; Bachtell, Neal

    2009-01-01

    The thermal performance of NASA s planned James Webb Space Telescope is highly reliant on a collection of directional baffles that are part of the Integrated Science Instrument Module Electronics Compartment. In order to verify the performance of the baffle concept, two test assemblies were recently fabricated and tested at the Goddard Space Flight Center. The centerpiece of the testing was a fixture that used bolometers to measure the emission field through the baffles while the radiator panels and baffles ran a flight-like temperature. Although not all test goals were able to be met due to facility malfunctions, the test was able to prove the design viability enough to gain approval to begin manufacturing the flight article.

  19. A study of resonant-cavity and fiberglass-filled parallel baffles as duct silencers. [for wind tunnels

    Science.gov (United States)

    Soderman, P. T.

    1982-01-01

    Acoustical performance and pressure drop were measured for two types of splitters designed to attenuate sound propagating in ducts - resonant-cavity baffles and fiberglass-filled baffles. Arrays of four baffles were evaluated in the 7- by 10-foot wind tunnel number 1 at Ames Research Center at flow speeds from 0 to 41 m/sec. The baffles were 2.1 m high, 305 to 406 mm thick, and 3.1 to 4.4 m long. Emphasis was on measurements of silencer insertion loss as affected by variations of such parameters as baffle length, baffle thickness, perforated skin geometry, cavity size and shape, cavity damping, wind speed, and acoustic field directivity. An analytical method for predicting silencer performance is described and compared with measurements. With the addition of cavity damping in the form of 25-mm foam linings, the insertion loss above 250 Hz of the resonant-cavity baffles was improved 2 to 7 db compared with the undamped baffles; the loss became equal to or greater than the insertion loss of comparable size fiberglass baffles at frequencies above 250 Hz. Variations of cavity size and shape showed that a series of cavities with triangular cross-sections (i.e., variable depth) were superior to cavities with rectangular cross sections (i.e., constant depth). In wind, the undamped, resonant-cavity baffles generated loud cavity-resonance tones; the tones could be eliminated by cavity damping.

  20. 3D NUMERICAL STUDY ON LAMINAR FORCED CONVECTION IN V-BAFFLED SQUARE CHANNEL

    Directory of Open Access Journals (Sweden)

    Amnart Boonloi

    2013-01-01

    Full Text Available The article presents a mathematical study of fully developed periodic laminar flow visualization and heat transfer characteristics in an isothermal wall square-channel fitted with V-shaped baffles on one wall. The computations based on the finite volume method together with the SIMPLE algorithm have been performed. The investigation covers a range of Re based on the hydraulic diameter of the channel, Re = 100-1200. To create a pair of main streamwise vortex flows through the tested section, the V-baffles with the attack angle of 30° with the main flow direction are mounted in tandem and pointing downstream on the lower channel wall only. Effects of different baffle heights and pitches on heat transfer and pressure drop in the channel are examined and the results obtained are compared with smooth channel with no baffle. The numerical result shows that the presence of the V-baffle yields a significant heat transfer enhancement compared with the smooth channel. It is visible that the main vortex flows, a pair of streamwise twisted vortex (P-vortex can induce impingement flows on the walls leading to a drastic increase in heat transfer rate over the channel. In addition, the increase in the baffle height leads to the rise in the heat transfer and pressure loss while that in the baffle pitch provides the opposite trend. The predicted results expose that the maximum thermal enhancement factors for the V-baffles with BR = 0.3, 0.3 and 0.4; and PR = 1, 1.5 and 2 are, respectively, about 2.44, 2.29 and 2.37 at higher Re.

  1. Energy Loss, Velocity Distribution, and Temperature Distribution for a Baffled Cylinder Model, Special Report

    Science.gov (United States)

    Brevoort, Maurice J.

    1937-01-01

    In the design of a cowling a certain pressure drop across the cylinders of a radial air-cooled engine is made available. Baffles are designed to make use of this available pressure drop for cooling. The problem of cooling an air-cooled engine cylinder has been treated, for the most part, from considerations of a large heat-transfer coefficient. The knowledge of the precise cylinder characteristics that give a maximum heat-transfer coefficient should be the first consideration. The next problem is to distribute this ability to cool so that the cylinder cools uniformly. This report takes up the problem of the design of a baffle for a model cylinder. A study has been made of the important principles involved in the operation of a baffle for an engine cylinder and shows that the cooling can be improved 20% by using a correctly designed baffle. Such a gain is as effective in cooling the cylinder with the improved baffle as a 65% increase in pressure drop across the standard baffle and fin tips.

  2. Effects of baffles on separation of aqueous ethanol solution with hollow fibers

    Institute of Scientific and Technical Information of China (English)

    Zhihong YANG; Guoliang ZHANG; Lan LIN; Danping REN; Qin MENG; Hongzi ZHANG

    2009-01-01

    The effects of baffles on the operation and mass-transfer characteristics in novel hollow fiber membrane contactor used in distillation were investi-gated. Hollow fiber membranes, coated with a 7 μmpolydimethyl-siloxane, were operated as structural packing in the separation of ethanol-water solutions. The parallel flow mode was chosen for separation due to the stronger driving force of the concentration difference, in which liquid flows through the lumens of the fibers and vapor flows countercurrent-wise outside the fibers. Two baffles were installed on the shell side of the membrane contactors to enhance separation, which had a round shape with a semi-lunar hole. The results show that both baffled and unbaffled membrane contactors gave better, more produc-tive separations than traditional packing in distillation,such as the excellent Sulzer Gauze BX structured packing.The baffled membrane contactors performed better than unbaffled ones, especially at high vapor velocities. The minimal HTU of membrane contactor with baffles could reach as low as 4.5 cm, and almost all the contactors could work well above the limit where flooding normally occurs in conventional cases. Theoretical analysis predicted that baffles helped membrane module to obtain a higher mass-transfer coefficient and a smaller mass-transfer resistance.Finally, theoretical mass-transfer coefficient and experi-mental value were compared as well as the contribution of each individual mass-transfer coefficients among liquid,gas and membrane.

  3. Heat transfer and flow resistance performance of shutter baffle heat exchanger with triangle tube layout in shell side

    OpenAIRE

    Xin Gu; Bing Liu; Yongqing Wang; Ke Wang

    2016-01-01

    Effect of main structural parameters of shutter baffle heat exchanger with a triangle tube layout in the shell side on heat transfer and flow resistance performance is studied in the article. A periodic whole cross-sectional computation model is built for the heat exchanger in the numerical study. The effects of structural parameters are analyzed, including assembly mode of shutter baffles, shutter baffle pitch, strip inclination angles, and strip widths. The correctness and accuracy of numer...

  4. Biometanation of Distillery Wastewater in an Anaerobic Baffled Reactor System

    Directory of Open Access Journals (Sweden)

    Lalov I. G.

    2007-12-01

    Full Text Available Anaerobic digestion is an established technology for distillery effluent treatment witch seems to be a promising alternative for Bulgarian industry. In this study the methanogenic activity of two different naturally formed microbial consortiums was compared. The better one was used to start continuous anaerobic digestion of high-strength distillery wastewater (COD 85 520 mgO2 . l-1 in laboratory scale anaerobic baffled reactor system. The average applied organic loading rate and hydraulic retention time were 4.28 kg COD m-3 . d-1 and 20 d respectively. A COD reduction of about 98 % and specific methane production of 0.39 m3 . kg-1 CODremoved were reached. Effects of different inhibitory factors such as low pH and presence of oxygen were investigated. In spite of unfavorable factors were applied simultaneously after an adaptation period the reactor showed stable response. The results obtained show the feasibility of this anaerobic process for distillery effluent treatment, representing a valid option to up-grade the existing wastewater treatment processes.

  5. Steady-state modeling of large-diameter crystal growth using baffles

    Science.gov (United States)

    Sahai, Vivek; Williamson, John W.; Overfelt, Tony

    1991-12-01

    Buoyancy driven flow in the crystal melt is one of the leading causes of segregation. Natural convection arises from the presence of thermal and/or solutal gradients in the melt and it is not possible to completely eliminate the convection even in the low gravity environment of space. This paper reports the results of computational modeling research that is being done in preparation for space-based experiments. The commercial finite element code FIDAP was used to simulate the steady convection of a gallium-doped germanium alloy in a Bridgman- Stockbarger furnace. In particular, the study examines the convection-suppressing benefits of inserting cylindrical baffles in the molten region to act as viscous dampers. These thin baffles are assumed to be inert and noncontaminating. The results from this study show the manner in which the streamlines, velocities, and temperature fields at various gravity levels are affected by the presence of baffles. The effects of changing both the number and position of the baffles are examined and the advantages and disadvantages of using baffles are considered.

  6. Vibro-impact responses of a tube with tube--baffle interaction. [LMFBR

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Y S; Sass, D E; Jendrzejczyk, J A

    1978-01-01

    The relatively small, inherent tube-to-baffle hole clearances associated with manufacturing tolerances in heat exchangers affect the vibrational characteristics and the response of the tube. Numerical studies were made to predict the vibro-impact response of a tube with tube-baffle interaction. The finite element method has been employed with a non-linear elastic contact spring-dashpot to model the effect of the relative approach between the tube and the baffle plate. The coupled equations of motion are directly integrated with a proportional system damping represented by a linear combination of mass and stiffness. Lumped mass approach with explicit time integration scheme was found to be a suitable choice for tube-baffle impacting analysis. Fourier analyses indicate that the higher mode contributions to the tube response are significant for strong tube-baffle impacting. The contact damping forces are negligible compared with the contact spring forces. The numerical analysis results are in reasonably good agreement with those of the experiments.

  7. Oxygen mass transfer and scale-up studies in baffled roller bioreactors.

    Science.gov (United States)

    Nikakhtari, H; Song, W; Nemati, M; Hill, G A

    2014-02-01

    Oxygen mass transfer was studied in conventional, bead mill and baffled roller bioreactors. Using central composite rotational design, impacts of size, rotation speed and working volume on the oxygen mass transfer were evaluated. Baffled roller bioreactor outperformed its conventional and bead mill counterparts, with the highest k(L)a obtained in these configurations being 0.58, 0.19, 0.41 min(-1), respectively. Performances of the bead mill and baffled roller bioreactor were only comparable when a high bead loading (40%) was applied. Regardless of configuration increase in rotation speed and decrease in working volume improved the oxygen mass transfer rate. Increase in size led to enhanced mass transfer and higher k(L)a in baffled roller bioreactor (0.49 min(-1) for 2.2 L and 1.31 min(-1) for 55 L bioreactors). Finally, the experimentally determined k(L)a in the baffled roller bioreactors of different sizes fit reasonably well to an empirical correlation describing the k(L)a in terms of dimensionless numbers.

  8. Computational fluid dynamics (CFD) simulation of effect of baffles on separation in mixer settler

    Institute of Scientific and Technical Information of China (English)

    Mohsen Ostad Shabani; Ali Mazahery; Mehdi Alizadeh; Ali Asghar Tofigh; Mohammad Reza Rahimipour; Mansour Razavi; Alireza Kolahi

    2012-01-01

    The main ideas in the development of the solvent extraction mixer settler focused on achieving clean phase separation,minimizing the loss of the reagents and decreasing the surface area of the settlers.The role of baffles in a mechanically agitated vessel is to ensure even distribution,reduce settler turbulence,promote the stability of power drawn by the impeller and to prevent swirling and vortexing of liquid,thus,greatly improving the mixing of liquid.The insertion of the appropriate number of baffles clearly improves the extent of liquid mixing.However,excessive baffling would interrupt liquid mixing and lengthen the mixing time.Computational fluid dynamics (CFD) provides a tool for determining detailed information on fluid flow (hydrodynamics) which is necessary for modeling subprocesses in mixer settler.A total of 54 final CFD runs were carried out representing different combinations of variables like number of baffles,density and impeller speed.CFD data shows that amount of separation increases with increasing baffles number and decreasing impeller speed.

  9. Experimental Investigation on Noise Suppression in Supersonic Jets from Convergent-Divergent Nozzles with Baffles

    Institute of Scientific and Technical Information of China (English)

    Yoshiaki Miyazato; Yong-Hun Kweon; Toshiyuki Aoki; Mitsuharu Masuda; Kwon-Hee Lee; Heuy-Dong Kim; Toshiaki Setoguchi; Kazuyasu Matsuo

    2003-01-01

    The acoustic properties of supersonic jet noise from a convergent-divergent nozzle with a baffle have been studied experimentally over the range of nozzle pressure ratios from 2.0 to 8.0. Acoustic measurements were conducted in a carefully designed anechoic room providing a free-field environment. A new approach for screech noise suppression by a cross-wire is proposed. Schlieren photographs were taken to visualize the shock wave patterns in the supersonic jet with and without the cross-wire. The effects of the baffle and the cross-wire on acoustic properties are discussed. It is shown that the baffle has little effect on the screech frequency for the underexpanded supersonic jet without the cross-wire. Also, the cross-wire introduced in supersonic jets is found to lead to a significant reduction in overall sound pressure level.

  10. Thermal Performance Analysis and Empirical Correlations for Laminar Forced Convection over 30° V-Baffled Square Channel

    Directory of Open Access Journals (Sweden)

    Amnart Boonloi

    2014-09-01

    Full Text Available Thermal performance analysis for laminar forced convection in an isothermal wall square channel with 30° V-baffle is presented numerically. The parameters of the V-baffle, blockage ratio (b/H, BR, pitch ratio (P/H, PR, flow direction (V-Downstream and V-Upstream, and arrangement (in-line and staggered, are studied and compared with the previous works, 20° and 45° V-baffle. The Reynolds number based on the hydraulic diameter of the channel (Dh, Re = 100–2000, is used in range study. The results show that the flow configurations of 30° V-baffle are found similar as 20° and 45° V-baffle. The fully developed periodic flow and heat transfer are created around 7th-8th module, while the periodic flow and heat transfer profiles are found at 2nd module in all cases. Except for the periodic concept, the 30° V-baffle can help to reduce the pressure loss around 2.3 times in comparison with the 45° V-baffle at the maximum f/f0 value (BR = 0.3, PR = 1, V-Downstream. The optimum thermal enhancement factor for the 30° V-baffle is found around 4.25 at BR = 0.15, PR = 1, and Re = 2000 for V-Downstream case with in-line arrangement.

  11. Shell side numerical analysis of a shell and tube heat exchanger considering the effects of baffle inclination angle on fluid flow using CFD

    OpenAIRE

    Raj Karuppa Thundil R.; Ganne Srikanth

    2012-01-01

    In this present study, attempts were made to investigate the impacts of various baffle inclination angles on fluid flow and the heat transfer characteristics of a shell-and-tube heat exchanger for three different baffle inclination angles namely 0°,10° and 20°. The simulation results for various shell and tube heat exchangers, one with segmental baffles perpendicular to fluid flow and two with segmental baffles inclined to the direction of fluid flow are compared for their performance. ...

  12. Numerical and experimental investigations of heat transfer enhancement in circular tubes with transverse twisted-baffles

    Science.gov (United States)

    Nanan, K.; Piriyarungrod, N.; Thianpong, C.; Wongcharee, K.; Eiamsa-ard, S.

    2016-10-01

    Transverse twisted-baffles (T-TBs) and transverse baffles (TBs) were employed for heat transfer enhancement in circular tubes. The experimental and numerical studies were carried out to investigate heat transfer, friction loss and thermal performance factor associated with the use of the baffles (T-TBs/TBs). The studies encompass three different baffle width ratios ( w/ D = 0.1, 0.2 and 0.3, for TBs and T-TBs), three baffle twist ratios ( y/ w = 2.0, 3.0 and 4.0, for T-TBs) and Reynolds numbers from 6000 to 20,000. The experimental results reveal that at similar conditions, thermal performance factors of the tubes with the T-TBs are consistently higher than those of the ones with the TBs. This is attributed to the superior heat transfer enhancement with lower pressure drop penalty as the beneficial effects given by the T-TBs, as compared to those given by the TBs. For T-TBs, thermal performance factor increases as baffle width ratio ( w/ D) increases and twist ratio ( y/ w) decreases. The T-TBs with the smallest twist ratio ( y/ w = 2.0) give higher thermal performance factors than the ones with 3.0 and 4.0 by around 4.7-6.1 and 10.2-15 %, respectively. For the studied range, the T-TBs with the optimal geometric parameters, ( y/ w = 2.0 and w/ D = 0.3), give the thermal performance factors in a range of 1.46-1.69.

  13. Validation of High-Resolution CFD Method for Slosh Damping Extraction of Baffled Tanks

    Science.gov (United States)

    Yang, H. Q.; West, Jeff

    2016-01-01

    Determination of slosh damping is a very challenging task as there is no analytical solution. The damping physics involve the vorticity dissipation which requires the full solution of the nonlinear Navier-Stokes equations. As a result, previous investigations and knowledge were mainly carried out by extensive experimental studies. A Volume-Of-Fluid (VOF) based CFD program developed at NASA MSFC was applied to extract slosh damping in a baffled tank from the first principle. First, experimental data using water with subscale smooth wall tank were used as the baseline validation. CFD simulation was demonstrated to be capable of accurately predicting natural frequency and very low damping value from the smooth wall tank at different fill levels. The damping due to a ring baffle at different liquid fill levels from barrel section and into the upper dome was then investigated to understand the slosh damping physics due to the presence of a ring baffle. Based on this study, the Root-Mean-Square error of our CFD simulation in estimating slosh damping was less than 4.8%, and the maximum error was less than 8.5%. Scalability of subscale baffled tank test using water was investigated using the validated CFD tool, and it was found that unlike the smooth wall case, slosh damping with baffle is almost independent of the working fluid and it is reasonable to apply water test data to the full scale LOX tank when the damping from baffle is dominant. On the other hand, for the smooth wall, the damping value must be scaled according to the Reynolds number. Comparison of experimental data, CFD, with the classical and modified Miles equations for upper dome was made, and the limitations of these semi-empirical equations were identified.

  14. REVIEW OF HEAT TRANSFER ENHANCEMENT IN DIFFERENT TYPES OF BAFFLES AND THEIR ORIENTATIONS.

    Directory of Open Access Journals (Sweden)

    S.P.WALDE

    2012-04-01

    Full Text Available The use of baffles in channel is commonly used for passive heat transfer enhancement strategy in single phase internal flow. Considering the rapid increase in energy demand, effective heat transfer enhancement techniques have become important task worldwide. Some of the applications of passive heat transfer enhancement strategies are in process industries, thermal regenerator, Shell and tube type heat exchanger, Internal cooling system of gas turbine blades, radiators for space vehicles and automobiles, etc. Thepresent paper is a review of different types of baffles and its arrangement. According to recent studies these are known to be economic heat transfer augmentation tools.

  15. Heat transfer and flow resistance performance of shutter baffle heat exchanger with triangle tube layout in shell side

    Directory of Open Access Journals (Sweden)

    Xin Gu

    2016-03-01

    Full Text Available Effect of main structural parameters of shutter baffle heat exchanger with a triangle tube layout in the shell side on heat transfer and flow resistance performance is studied in the article. A periodic whole cross-sectional computation model is built for the heat exchanger in the numerical study. The effects of structural parameters are analyzed, including assembly mode of shutter baffles, shutter baffle pitch, strip inclination angles, and strip widths. The correctness and accuracy of numerical simulation method are confirmed with a laser Doppler velocimeter experiment. Based on the research results, correlations for heat transfer coefficient and pressure drop in shell side are presented. Using the field synergy principle, the heat transfer enhancement mechanisms of segmental baffle heat exchanger and shutter baffle heat exchanger in shell side are analyzed.

  16. Performance comparison for oil-water heat transfer of circumferential overlap trisection helical baffle heat exchanger

    Institute of Scientific and Technical Information of China (English)

    王伟晗; 程道来; 刘涛; 刘颖昊

    2016-01-01

    The performance tests were conducted on oil–water heat transfer in circumferential overlap trisection helical baffle heat exchangers with incline angles of 12°, 16°, 20°, 24° and 28°, and compared with a segmental baffle heat exchanger. The results show that the shell side heat transfer coefficientho and pressure dropΔpo both increase while the comprehensive indexho/Δpo decreases with the increase of the mass flow rate of all schemes. And the shell side heat transfer coefficient, pressure drop and the comprehensive indexho/Δpo decrease with the increase of the baffle incline angle at a certain mass flow rate. The average values of shell side heat transfer coefficient and the comprehensive indexho/Δpo of the 12° helical baffled scheme are above 50% higher than those of the segmental one correspondingly, while the pressure drop value is very close and the ratios of the average values are about 1.664 and 1.596, respectively. The shell-side Nusselt numberNuo and the comprehensive index Nuo·Euzo−1 increase with the increase of Reynolds number of the shell side axial in all schemes, and the results also demonstrate that the small incline angled helical scheme has better comprehensive performance.

  17. THE BAFFLED FLASK TEST FOR DISPERSANT EFFECTIVENESS: A ROUND ROBIN EVALUATION OF REPRODUCIBILITY AND REPEATABILITY

    Science.gov (United States)

    After two previous investigations demonstrated that the Baffled Flask Test (BFT) was an effective and reproducible method for screening the effectiveness of dispersant products in the laboratory, the USEPA decided that before the new protocol cold be considered for replacement of...

  18. Influence of baffle plate geometry on decay of shock waves propagating in a beamline

    Energy Technology Data Exchange (ETDEWEB)

    Takiya, Toshio; Terada, Yukihiro; Komura, Akio [Hitachi Zosen Corp., Osaka (Japan); Higashino, Fumio; Sugiyama, Hiroshi; Ando, Masami

    1998-06-01

    Dependency of geometries of baffle plates in a shock tube on the decay of shock waves was investigated to find an optimal design for acoustic delay lines (ADLs) in beamlines of a synchrotron radiation facility. Fabricating a thin orifice, a coned baffle plate, a diverging tube and a converging tube as a model of the ADL, we performed pressure measurement with piezo-pressure transducers by using a dedicated shock tube and two-dimensional flow visualization around the model by means of Schlieren photography. According to the results of pressure measurements, a theory of one-dimensional steady flow employed generally is not available for the coned baffle. The decay ratios defined by the strength of incident and transmitted shock waves clearly differ among the four types of the ADL models, although all of the models have the same aperture. These results suggest that non-steady phenomena observed by the Schlieren photography, such as shock wave reflection and diffraction, viscous flow behind shock waves, may be involved in shock wave decay through baffle plates. (author)

  19. Dispersant Effectiveness Of Heavy Fuel Oils Using The Baffled Flask Test

    Science.gov (United States)

    Dispersants have been widely used as a primary response measure for marine oil spills around the world. Recently, the U.S. Environmental Protection Agency (EPA) developed an improved laboratory dispersant testing protocol, called the Baffled Flask Test (BFT). The BFT protocol w...

  20. Removal of nutrients from septic tank effluent with baffle subsurface-flow constructed wetlands.

    Science.gov (United States)

    Cui, Lihua; Ouyang, Ying; Yang, Weizhi; Huang, Zhujian; Xu, Qiaoling; Yu, Guangwei

    2015-04-15

    Three new baffle flow constructed wetlands (CWs), namely the baffle horizontal flow CW (Z1), baffle vertical flow CW (Z2) and baffle hybrid flow CW (Z3), along with one traditional horizontal subsurface flow CW (Z4) were designed to test the removal efficiency of nitrogen (N) and phosphorus (P) from the septic tank effluent under varying hydraulic retention times (HRTs). Results showed that the optimal HRT was two days for maximal removal of N and P from the septic tank effluent among the four CWs. At this HRT, the Z1, Z2, Z3 and Z4 CWs removed, respectively, 49.93, 58.50, 46.01 and 44.44% of TN as well as 87.82, 93.23, 95.97 and 91.30% of TP. Our study further revealed that the Z3 CW was the best design for overall removal of N and P from the septic tank effluent due to its hybrid flow directions with better oxygen supply inside the CW system.

  1. Baffle puncture guided by transoesophageal echocardiography in a patient with dextrocardia and Mustard correction

    NARCIS (Netherlands)

    B. Schwagten (Bruno); L.J.L.M. Jordaens (Luc); E. Jessurun; M. Witsenburg (Maarten); M.G. Scheffer (Michael); T. Szili-Torok (Tamas)

    2009-01-01

    textabstractA baffle puncture is a challenging procedure but can be safely done using direct visualization of the region of interest. To our knowledge, however, it has never been performed in a patient with dextrocardia. We present a 62-year-old male with dextrocardia, right isomerism, congenitally

  2. Studi Numerik Pengaruh Baffle Inclination Pada Alat Penukar Kalor Tipe U – Tube Terhadap Aliran Fluida Dan Perpindahan Panas

    Directory of Open Access Journals (Sweden)

    Reza Hidayatullah

    2014-09-01

    Full Text Available Alat penukar kalor sangat berpengaruh dalam industri terhadap keberhasilan keseluruhan rangkaian proses, karena kegagalan operasi alat ini baik akibat kegagalan mekanikal maupun opersional dapat menyebabkan berhentinya operasi unit. Penelitian terhadap desain heat exchanger masih terus dilakukan untuk mencari kinerja dari heat exchanger yang paling optimal, baik pada bagian baffle cut dan baffles inclination maupun susunan dari tube dengan menggunakan heat exchanger ukuran kecil sebagai model. Berdasarkan pada permasalahan di atas, maka dilakukan penelitian terhadap kinerja heat exchanger tipe U-tube dengan memvariasikan baffle inclination. Penelitian ini dilakukan secara numerik dengan variasi baffle inclination sebesar 0o, 10o, 20o dan variasi laju aliran massa sebesar 0,5 kg/s, 1kg/s, dan 2 kg/s. Tube yang digunakan adalah tipe U-tube yang disusun secara persegi. Model viskous yang digunakan adalah turbulensi model yaitu k-ε standar, dimana fluida yang digunakan adalah air pada boundary condition. Hasil analisa numerik menunjukkan adanya pengaruh baffle inclination pada alat penukar kalor tipe U – tube terhadap aliran fluida dan perpindahan panas. Peningkatan laju aliran massa dapat meningkatkan pressure drop secara cepat, alat penukar kalor shell and tube tipe U – tube dengan baffle inclination 20o memiliki unjuk kerja yang terbaik dibandingkan dengan baffle inclination 0o dan 10o.

  3. Studi Numerik Pengaruh Baffle Inclination Pada Alat Penukar Kalor Tipe Shell And Tube Terhadap Aliran Fluida Dan Perpindahan Panas

    Directory of Open Access Journals (Sweden)

    Rezky Fadil Arnaw

    2014-09-01

    Full Text Available Heat exchanger atau alat penukar kalor merupakan suatu peralatan yang digunakan untuk memindahkan sejumlah energi dalam bentuk panas dari satu fluida ke fluida yang lain. Perpindahan panas tersebut terjadi dari suatu fluida yang suhunya lebih tinggi ke fluida lain yang suhunya lebih rendah. Pada tugas akhir ini akan dilakukan penelitian tentang pengaruh baffle inclination terhadap aliran fluida dan perpindahan panas pada alat penukar kalor tipe shell and tube. Dalam penelitian ini akan dilakukan tiga variasi sudut baffle inclination yaitu 0º, 10° dan 20° dengan besar laju aliran massa yang divariasikan yaitu sebesar 0.5 kg/s, 1 kg/s dan 2 kg/s. Tipe baffle yang digunakan adalah single segmental baffle dengan baffle cut sebesar 36% dan menggunakan arah aliran jenis parallel. Hasil analisa simulasi menunjukkan bahwa laju aliran massa yang meningkat akan menyebabkan kenaikan pressure drop yang cukup drastis dan penurunan temperatur outlet. Alat penukar kalor dengan baffle inclination 0° memiliki nilai perpindahan panas terbaik jika dibandingkan dengan baffle inclination 10° dan 20°.

  4. A Computational Fluid Dynamics Study of Swirling Flow Reduction by Using Anti-Vortex Baffle

    Science.gov (United States)

    Yang, H. Q.; Peugeot, John W.; West, Jeff S.

    2017-01-01

    An anti-vortex baffle is a liquid propellant management device placed adjacent to an outlet of the propellant tank. Its purpose is to substantially reduce or eliminate the formation of free surface dip and vortex, as well as prevent vapor ingestion into the outlet, as the liquid drains out through the flight. To design an effective anti-vortex baffle, Computational Fluid Dynamic (CFD) simulations were undertaken for the NASA Ares I vehicle LOX tank subjected to the simulated flight loads with and without the anti-vortex baffle. The Six Degree-Of-Freedom (6-DOF) dynamics experienced by the Crew Launch Vehicle (CLV) during ascent were modeled by modifying the momentum equations in a CFD code to accommodate the extra body forces from the maneuvering in a non-inertial frame. The present analysis found that due to large moments, the CLV maneuvering has a significant impact on the vortical flow generation inside the tank. Roll maneuvering and side loading due to pitch and yaw are shown to induce swirling flow. The vortical flow due to roll is symmetrical with respect to the tank centerline, while those induced by pitch and yaw maneuverings showed two vortices side by side. The study found that without the anti-vortex baffle, the swirling flow caused surface dip during the late stage of drainage and hence early vapor ingestion. The flow can also be non-uniform in the drainage pipe as the secondary swirling flow velocity component can be as high as 10% of the draining velocity. An analysis of the vortex dynamics shows that the swirling flow in the drainage pipe during the Upper Stage burn is mainly the result of residual vortices inside the tank due to the conservation of angular momentum. The study demonstrated that the swirling flow in the drainage pipe can be effectively suppressed by employing the anti-vortex baffle.

  5. On-line testing of a horizontally-baffled flotation column in an operating coal-cleaning plant

    Energy Technology Data Exchange (ETDEWEB)

    Eisele, T.C.; Kawatra, S.K. [Michigan Technological Univ., Houghton, MI (United States). Dept. of Metallurgical and Materials Engineering

    1995-10-01

    A horizontal-baffle arrangement has been developed to prevent excessive axial mixing in flotation columns. These baffles have been shown in previous work to improve the grade/recovery performance of both a laboratory-scale column and a pilot-scale column. In this paper, results are given for continuous on-line operation of the pilot-scale baffled column in a commercial coal-cleaning plant. These results show its ability to operate for extended periods without plugging, to produce a consistent-quality product even while the feed quality was fluctuating, and to remove much of the pyritic sulfur from the coal.

  6. Experimental Investigation on Heat Transfer and Frictional Characteristics of Shell-and-tube Heat exchangers with Different Baffles and Tubes

    Science.gov (United States)

    Wang, C.; Zhu, J. G.; Sang, Z. F.

    2010-03-01

    In this study, the heat transfer and tube frictional characteristics of the helixchangers (shell-and-tube heat exchanger with helical baffles) with spirally corrugated and smooth tubes and the conventional shell-and-tube heat exchanger with smooth tubes were experimentally obtained. The results show that the helixchangers with the spirally corrugated tube and the smooth tubes enhance the total heat transfer coefficient about 26% and 7% on the average than the segmental baffled heat exchanger. In the tube side, the spirally corrugated tube leads to about 28% average increase on convective heat transfer performance and about 24% average increase on pressure drop than the smooth tube, but its conversion efficiency is still higher. The helical baffle could enhance the shell-side condensation coefficient by 13%, and the spirally corrugated tube could help the helixchanger with it enhance remarkably the condensation performance by 53% than the segmental baffled heat exchanger.

  7. Free Vibration Sloshing Analysis in Axisymmetric Baffled Containers under Low-Gravity Condition

    Science.gov (United States)

    Ebrahimian, M.; Noorian, M. A.; Haddadpour, H.

    2015-03-01

    The free vibrations analysis of liquid sloshing is carried out for arbitrary axisymmetric containers under low-gravity condition using boundary element method. A potential flow theory is used to model the flow field and the free-surface Laplace-Young equation is used to model the surface tension effect. The obtained governing equations are solved using eigenanalysis techniques to determine the natural frequencies and mode shapes of the sloshing liquid. The results for a circular cylindrical container are compared to the analytical values and very good agreement is achieved for the slipping and anchored contact line assumptions. Furthermore, some baffled containers are also analysed and the effects of baffles on the sloshing frequencies under low and zero gravity conditions are investigated and some conclusions are outlined.

  8. Simulation of the influence of the baffle on flowing field in the anode baking ring furnace

    Institute of Scientific and Technical Information of China (English)

    周萍; 梅炽; 周孑民; 周乃君; 徐琼辉

    2002-01-01

    In an anode baking horizontal flue ring furnace, the temperature distribution is one of the key factors influencing the quality of baked anode and is closely correlated with the gas flow. To understand the gas flow distribution in the flue, Navier-Stokes equation with "k-ε" two-equation turbulence model was adopted and the simulation on the gas flow was performed. The numerical simulation results showed that the even direction of gas flow should be considered in the design of flue baffles and the gas flow distribution was really uneven in the flue in practical use. By adjusting the number and location of flue baffles rationally, the even distribution of gas flow can be improved obviously.

  9. Effects of Perforated Baffle on Reducing Sloshing in Rectangular Tank:Experimental and Numerical Study

    Institute of Scientific and Technical Information of China (English)

    薛米安; 林鹏智; 郑金海; 马玉祥; 苑晓丽; Viet-Thanh NGUYEN

    2013-01-01

    A liquid sloshing experimental rig driven by a wave-maker is designed and built to study liquid sloshing problems in a rectangular liquid tank with perforated baffle. A series of experiments are conducted in this experimental rig to estimate the free surface fluctuation and pressure distribution by changing external excitation frequency of the shaking table. An in-house CFD code is also used in this study to simulate the liquid sloshing in three-dimensional (3D) rectangular tank with perforated baffle. Good agreements of free surface elevation and pressure between the numerical results and the experimental data are obtained and presented. Spectral analysis of the time history of free surface elevation is conducted by using the fast Fourier transformation.

  10. Effects of perforated baffle on reducing sloshing in rectangular tank: Experimental and numerical study

    Science.gov (United States)

    Xue, Mi-an; Lin, Peng-zhi; Zheng, Jin-hai; Ma, Yu-xiang; Yuan, Xiao-li; Nguyen, Viet-Thanh

    2013-10-01

    A liquid sloshing experimental rig driven by a wave-maker is designed and built to study liquid sloshing problems in a rectangular liquid tank with perforated baffle. A series of experiments are conducted in this experimental rig to estimate the free surface fluctuation and pressure distribution by changing external excitation frequency of the shaking table. An in-house CFD code is also used in this study to simulate the liquid sloshing in three-dimensional (3D) rectangular tank with perforated baffle. Good agreements of free surface elevation and pressure between the numerical results and the experimental data are obtained and presented. Spectral analysis of the time history of free surface elevation is conducted by using the fast Fourier transformation.

  11. Validation of High-Resolution CFD Method for Slosh Damping Extraction of Baffled Cryogenic Propellant Tanks

    Science.gov (United States)

    Yang, H. Q.; West, Jeff

    2016-01-01

    Propellant slosh is a potential source of disturbance critical to the stability of space vehicles. The slosh dynamics are typically represented by a mechanical model of a spring-mass-damper. This mechanical model is then included in the equation of motion of the entire vehicle for Guidance, Navigation and Control analysis. A Volume-Of-Fluid (VOF) based Computational Fluid Dynamics (CFD) program developed at MSFC was applied to extract slosh damping in the baffled tank from the first principle. First the experimental data using water with sub-scale smooth wall tank were used as the baseline validation. It is demonstrated that CFD can indeed accurately predict low damping values from the smooth wall at different fill levels. The damping due to a ring baffles at different depths from the free surface was then simulated, and fairly good agreement with experimental measurement was observed. Comparison with an empirical correlation of Miles equation is also made.

  12. Coupling Frequency of the Liquid Sloshing in a Cylindrical Tank with a Flexible Baffle

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The coupling oscillation of a liquid in a cylindrical tank with an elastic slosh baffle is investigated. Free surface conditions are considered in the study. The complexity of the coupled boundary-value problem for the liquid and elastic damping spacer results in significant analytical difficulties. Two different velocity potential functions are respectively used in the liquid domain above, or below the damping spacer. A coupled frequency equation is obtained by using the pair of velocity potential functions. The numerical and theoretical analysis show that the natural frequency changes according to the location and stiffness of the spacer. Results indicate that the frequency coupling between damping spacer and sloshing liquid is obvious near the free liquid surface. It is shown that the coupling frequency increases with the increase of damping baffle rigidity.

  13. Influences of prolate spheroidal baffle of sound diffraction on spatial directivity of acoustic vector sensor

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The directivity of acoustic vector sensor (AVS) will be distorted by the sound diffraction of the AVS carrier. In this paper,the scattering of a plane acoustic wave from a prolate spheroid baffle is considered. At first,the sound diffraction of prolate spheroidal baffle is established,then the mathematical expressions of sound pressure field and particle vibration velocity field of sound diffraction are derived and the characteristic of the directivity of pressure and velocity of sound diffraction field at different frequencies and distances is analyzed. The directivity of AVS is determined by the amplitude and phase difference of diffraction wave and incident wave,which possesses a close relationship with frequency and incident angle. Finally,the calculated results are compared with the experimental results.

  14. Combustor having mixing tube bundle with baffle arrangement for directing fuel

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, Michael John; McConnaughhay, Johnie Franklin

    2016-08-23

    A combustor includes a tube bundle that extends radially across at least a portion of the combustor. The tube bundle includes an upstream surface axially separated from a downstream surface, and a plurality of tubes extend from the upstream surface through the downstream surface to provide fluid communication through the tube bundle. A barrier extends radially inside the tube bundle between the upstream and downstream surfaces, and a baffle extends axially inside the tube bundle between the upstream surface and the barrier.

  15. Computational Investigation on Fully Developed Periodic Laminar Flow Structure in Baffled Circular Tube with Various BR

    Directory of Open Access Journals (Sweden)

    Withada Jedsadaratanachai

    2014-01-01

    Full Text Available This paper presents a 3D numerical analysis of fully developed periodic laminar flow in a circular tube fitted with 45° inclined baffles with inline arrangement. The computations are based on a finite volume method, and the SIMPLE algorithm has been implemented. The characteristics of fluid flow are presented for Reynolds number, Re = 100–1000, based on the hydraulic diameter (D of the tube. The angled baffles were repeatedly inserted at the middle of the test tube with inline arrangement to generate vortex flows over the tested tube. Effects of different Reynolds numbers and blockage ratios (b/D, BR with a single pitch ratio of 1 on flow structure in the tested tube were emphasized. The flows in baffled tube show periodic flow at x/D ≈ 2-3, and become a fully developed periodic flow profiles at x/D ≈ 6-7, depending on Re, BR and transverse plane positions. The computational results reveal that the higher of BR and closer position of turbulators, the faster of fully developed periodic flow profiles.

  16. Design and evaluation of hydraulic baffled-channel PAC contactor for taste and odor removal from drinking water supplies.

    Science.gov (United States)

    Kim, Young-Il; Bae, Byung-Uk

    2007-05-01

    Based on the concept of hydraulic flocculator, a baffled-channel powdered activated carbon (PAC) contactor, placed before the rapid-mixing basin, was designed and evaluated for removal of taste and odor (T&O) in drinking water. PAC adsorption kinetic tests for raw water samples were conducted for selection of design parameters related to contact time and degree of mixing. Within the tested range of velocity gradient (G) from 18 to 83s(-1), mixing had a relatively minor effect on the adsorption kinetics of the PAC. The hydrodynamic characteristics of the pilot-scale horizontally and vertically baffled-channel PAC contactor were investigated by tracer tests. It was found that the plug flow fractions of vertically baffled-channel PAC contactor (vBPC) were higher than those of the horizontally baffled-channel PAC contactor (hBPC) for the same bend width or bend height. However, the hBPC seems to be more appropriate than the vBPC in terms of construction and maintenance. The geosmin and MIB removal rate increased with the number of baffles, PAC dose and contact time increased regardless of bend width in the pilot-scale hBPC. The pair of full-scale hBPCs at Pohang water treatment plant, having a design capacity of 6.5x10(4)m(3)/d with 20min of hydraulic retention time with a safety factor of 2, was designed based on lab- and pilot-scale experimental results. Under a velocity gradient of 20s(-1), the number of baffles to be installed was calculated to be 20 with a space of about 2m between each baffle, resulting in a hydraulic head loss through the contactor of about 0.056m. The successful application of hBPC for T&O removal from drinking water supplies should provide momentum for developing more effective treatment methods.

  17. Kinetic study of treatment of wastewater contains food preservative agent by anaerobic baffled reactor : An overview

    Science.gov (United States)

    Sumantri, Indro; Purwanto, Budiyono

    2015-12-01

    The characteristic of wastewater of food industries with preservative substances is high content of organic substances, degradable and high total suspended solid. High organic content in this waste forced the treatment is biologically and pointed out to anaerobic treatment. Anaerobic showed the better performance of degradation than aerobic for high content organic and also for toxic materials. During that day the treatment of food wastewater is aerobically which is high consume of energy required and high volume of sludge produced. The advantage of anaerobic is save high energy, less product of sludge, less requirement of nutrients of microorganism and high efficiency reduction of organic load. The high efficiency of reduction will reduce the load of further treatment, so that, the threshold limit based on the regulation would be easy to achieve. Research of treatment of wastewater of food industries would be utilized by both big scale industries and small industries using addition of preservative substances. The type reactor of anaerobic process is anaerobic baffled reactor that will give better contact between wastewater and microorganism in the sludge. The variables conducted in this research are the baffled configuration, sludge height, preservative agent contents, hydralic retention time and influence of micro nutrients. The respons of this research are the COD effluent, remaining preservative agent, pH, formation of volatile fatty acid and total suspended solid. The result of this research is kinetic model of the anaerobic baffled reactor, reaction kinetic of preservative agent degradation and technology of treatment wastewater contains preservative agent. The benefit of this research is to solve the treatment of wastewater of food industries with preservative substance in order to achieve wastewater limit regulation and also to prevent the environmental deterioration.

  18. Kinetic study of treatment of wastewater contains food preservative agent by anaerobic baffled reactor : An overview

    Energy Technology Data Exchange (ETDEWEB)

    Sumantri, Indro; Purwanto,; Budiyono [Chemical Engineering Department, Faculty of Engineering, Diponegoro University Jl. Prof. H. Soedarto, SH, Kampus Baru Tembalang, Semarang (Indonesia)

    2015-12-29

    The characteristic of wastewater of food industries with preservative substances is high content of organic substances, degradable and high total suspended solid. High organic content in this waste forced the treatment is biologically and pointed out to anaerobic treatment. Anaerobic showed the better performance of degradation than aerobic for high content organic and also for toxic materials. During that day the treatment of food wastewater is aerobically which is high consume of energy required and high volume of sludge produced. The advantage of anaerobic is save high energy, less product of sludge, less requirement of nutrients of microorganism and high efficiency reduction of organic load. The high efficiency of reduction will reduce the load of further treatment, so that, the threshold limit based on the regulation would be easy to achieve. Research of treatment of wastewater of food industries would be utilized by both big scale industries and small industries using addition of preservative substances. The type reactor of anaerobic process is anaerobic baffled reactor that will give better contact between wastewater and microorganism in the sludge. The variables conducted in this research are the baffled configuration, sludge height, preservative agent contents, hydralic retention time and influence of micro nutrients. The respons of this research are the COD effluent, remaining preservative agent, pH, formation of volatile fatty acid and total suspended solid. The result of this research is kinetic model of the anaerobic baffled reactor, reaction kinetic of preservative agent degradation and technology of treatment wastewater contains preservative agent. The benefit of this research is to solve the treatment of wastewater of food industries with preservative substance in order to achieve wastewater limit regulation and also to prevent the environmental deterioration.

  19. Post-Service Examination of PWR Baffle Bolts, Part I. Examination and Test Plan

    Energy Technology Data Exchange (ETDEWEB)

    Leonard, Keith J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Sokolov, Mikhail A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gussev, Maxim N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-04-30

    In support of extended service and current operations of the US nuclear reactor plants, the Oak Ridge National Laboratory (ORNL), through the Department of Energy (DOE), Light Water Reactor Sustainability (LWRS) Program, is coordinating with Ginna Nuclear Power Plant, The Westinghouse Electric Company, LLC, and ATI Consulting, the selective procurement of baffle bolts that were withdrawn from service in 2011 and currently stored on site at Ginna. The goal of this program is to perform detailed microstructural and mechanical property characterization of baffle former bolts following in-service exposures. This report outlines the selection criteria of the bolts and the techniques to be used in this study. The bolts available are the original alloy 347 steel fasteners used in holding the baffle plates to the baffle former structures within the lower portion of the pressurized water reactor vessel. Of the eleven possible bolts made available for this work, none were identified to have specific damage. The bolts, however, did show varying levels of breakaway torque required in their removal. The bolts available for this study varied in peak fluence (highest dose within the head of the bolt) between 9.9 and 27.8x1021 n/cm2 (E>1MeV). As no evidence for crack initiation was determined for the available bolts from preliminary visual examination, two bolts with the higher fluence values were selected for further post-irradiation examination. The two bolts showed different breakaway torque levels necessary in their removal. The information from these bolts will be integral to the LWRS program initiatives in evaluating end of life microstructure and properties. Furthermore, valuable data will be obtained that can be incorporated into model predictions of long-term irradiation behavior and compared to results obtained in high flux experimental reactor conditions. The two bolts selected for the ORNL study will be shipped to Westinghouse with bolts of

  20. Polyamide-6 Polymerization in the VK Tube Reactor with Baffle Structure

    Institute of Scientific and Technical Information of China (English)

    WANG Xia-qin; TANG Zhi-lian

    2002-01-01

    The melt flow mechanism of polyamide-6 (PA6) was simulated with the mathematical flow model and tested by Particle Image Velotrimitry (PIV). The complete mathematical model for PA6 polymerization while flowing through the VK tube reactor was established according to PA6 hydrolytic polymerization kinetics. The characteristic data such as residence time, caprolactam conversion and the degree of polymerization (D. P.), at every stage of polymerization reaction and at every point of the VK tube were presented for the melt flowing through ten alternate conical baffles in VK tube.

  1. Investigation of the effects of baffle orientation, baffle cut and fluid viscosity on shell side pressure drop and heat transfer coefficient in an e-type shell and tube heat exchanger

    OpenAIRE

    Mohammadi, Koorosh

    2011-01-01

    The commercial CFD code FLUENT is used to determine the effect of baffle orientation and baffle cut as well as viscosity of the working fluid on the shell-side heat transfer and pressure drop of a shell and tube heat exchanger. The shell and tube heat exchangers considered follow the TEMA standards. The investigation has been completed in three stages: 1. The shell and tube heat exchanger consists of 660 plain tubes with fixed outside diameter which are arranged in a triangular layout. Hor...

  2. Shell side numerical analysis of a shell and tube heat exchanger considering the effects of baffle inclination angle on fluid flow using CFD

    Directory of Open Access Journals (Sweden)

    Raj Karuppa Thundil R.

    2012-01-01

    Full Text Available In this present study, attempts were made to investigate the impacts of various baffle inclination angles on fluid flow and the heat transfer characteristics of a shell-and-tube heat exchanger for three different baffle inclination angles namely 0°,10° and 20°. The simulation results for various shell and tube heat exchangers, one with segmental baffles perpendicular to fluid flow and two with segmental baffles inclined to the direction of fluid flow are compared for their performance. The shell side design has been investigated numerically by modeling a small shell-and-tube heat exchanger. The study is concerned with a single shell and single side pass parallel flow heat exchanger. The flow and temperature fields inside the shell are studied using non-commercial CFD software tool ANSYS CFX 12.1. For a given baffle cut of 36 %, the heat exchanger performance is investigated by varying mass flow rate and baffle inclination angle. From the CFD simulation results, the shell side outlet temperature, pressure drop, recirculation near the baffles, optimal mass flow rate and the optimum baffle inclination angle for the given heat exchanger geometry are determined.

  3. Numerical Investigation on Double Shell-Pass Shell-and-Tube Heat Exchanger with Continuous Helical Baffles

    OpenAIRE

    Shui Ji; Wen-jing Du; Peng Wang; Lin Cheng

    2011-01-01

    A double shell-pass shell-and-tube heat exchanger with continuous helical baffles (STHXCH) has been invented to improve the shell-side performance of STHXCH. At the same flow area, the double shell-pass STHXCH is compared with a single shell-pass STHXCH and a conventional shell-and-tube heat exchanger with segmental baffles (STHXSG) by means of numerical method. The numerical results show that the shell-side heat transfer coefficients of the novel heat exchanger are 12–17% and 14–25% higher t...

  4. 3D numerical simulation and structural optimization of the rod baffle heat exchanger

    Institute of Scientific and Technical Information of China (English)

    YAN Liang-wen; PAN Lei; KAN Shu-lin

    2009-01-01

    Because of the complexities of fluid dynamics equations and the structure of heat exchangers, few theoretical solutions have been acquired to specify the shell side characteristics of the rod baffle heat exchanger (RBHE). Based on the platform of PHEONICS version 3.5.1, a three-dimensionai numerical method for predicting the turbulent fluid flow behavior in the shell side of the rod baffle heat exchangers is developed in this paper. With this method, modeling of the tube bundle is carried out based on the porous media concept using volumetric porosities and applicable flow resistance correlations. Turbulence effects are modeled using a standard κ-ε model. It is shown that the simulation results and experimental results are in good agreement in the shell side. The maximum absolute deviation value of pressure drops is less than 5%, and that of the heat transfer coefficients is less than 8%. Furthermore, the numerical model is used to optimize the structure of the RBHE and improves its performance.

  5. Hydrodynamic characteristics of a four-compartment periodic anaerobic baffled reactor

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Periodic anaerobic baffled reactor (PABR) is a novel reactor based on the design concept of anaerobic baffled reactor (ABR).Residence time distribution (RTD) studies on both clean and working reactors at the same hydraulic residence time (HRT) of 2 d were carried out to investigate the dead spaces and mixing patterns in PABRs at different organic loading rates (OLRs) in various switching manners and frequencies. The results showed that the fraction of dead space in PABR was similar to that in ABR, which was low in comparison with other reactor designs. Dead space may be divided into two categories, hydraulic and biological. In RTD studies without biomass, the hydraulic dead space in the PABR run in an "every second" switching manner with T = 2 d was the lowest whereas that in the PABR run in a T = ∞ (ABR) switching manner was the highest. The same trend was obtained with the total dead space in RTD studies with biomass no matter what the OLR was. Biological dead space was the major contributor to dead space but affected decreasingly at higher OLR whichever switching manner the PABR run in. The flow patterns within the PABRs were intermediate between plug-flow and perfectly mixed under all the conditions tested.

  6. Performance of Inclined Baffle Column for Pectin Continuous Extraction Process from Cocoa Peel (Theobromacacao

    Directory of Open Access Journals (Sweden)

    Soemargono

    2016-01-01

    Full Text Available Pectin from cocoa peel was successfully prepared by extraction method in the bubble column reactor. The process could be carried out in batch and continuous, with co-current or counter current flow. Bubble pipe reactor with inclined baffle is expected to reduce the problem from gas flow patterns, jagged sloping bulkhead serves as a bubble breaker that could replace mechanical stirrer. In this study the reactor column sloping bulkhead was used as extractor to recover pectin in the cocoa peel by citric acid (1 N solvent. Cocoa peel paste and citric acid were entered to the top of the column at 1 : 1 rate ratio by streamed using dosing pump. Nitrogen gas as a medium stirrer flowed counter current from the bottom of the column. Once extraction was completed, the liquid then precipitated by acid alcohol. Pectin solids were washed with alcohol (96%. The temperature of extraction process is maintained at 70° C. The residence time in the column material was determined by feed flow rate (cocoa paste and citric acid, and the volume of suspension that remains in the reactor (V. Residence time equation obtained is: t = (7045.86G-0.1275/L. The yield of yellowish white precipitate reached up to 5.2973% and methoxyl concentration reached 5,21% for 72 minutes. The experiment shows that the continuous extraction process of pectin in baffle columns is better than batch process.

  7. 球面弓形折流板换热器折流板曲率半径的优化研究%Optimization Research of Baffle Curvature Radius in Spherical Baffle Heat Exchanger

    Institute of Scientific and Technical Information of China (English)

    郭土; 马贵阳; 张一楠; 孙皓; 曹燕龙

    2013-01-01

    In order to research the influence of the spherical baffle heat exchanger’s baffle curvature radius to the shell side pressure drop and the coefficient of heat transfer, shell side fluid flow condition and heat exchanger performance of the spherical baffle heat exchangers with curvature radius of 0.75D,1D,1.25D or 1.5D and conventional segmental baffle heat exchangers were numerically analyzed and studied. The shell side fluid flow field distribution, shell side pressure drop and coefficient of heat transfer were obtained. The results indicate that, under the same inlet flow conditions, the smaller of the baffle curvature radius,the bigger of comprehensive performance index of the heat exchanger’s shell side heat transfer and flow resistance, the comprehensive performance index of the spherical baffle heat exchanger with curvature radius of 0.75D is higher by 8.5%than that of the conventional segmental baffle heat exchanger.%为了研究球面弓形折流板换热器折流板曲率半径对换热器壳程压降和换热系数的影响,对曲率半径分别为0.75D、1D、1.25D、1.5D 的球面弓形折流板换热器和普通弓形折流板换热器的壳侧流体流动与传热性能进行数值模拟与研究,得到了壳程流体流场分布以及壳程压降和传热系数。研究结果表明在相同入口流速下,曲率半径越小换热器壳程传热与流阻综合性能指标越大,0.75D 球面弓形折流板换热器可比普通弓形折流板换热器提高8.5%左右。

  8. Experimental investigation of effect of flow attack angle on thermohydraulic performance of air flow in a rectangular channel with discrete V-pattern baffle on the heated plate

    Directory of Open Access Journals (Sweden)

    Raj Kumar

    2016-05-01

    Full Text Available In this work, the effect of angle of attack ( α a of the discrete V-pattern baffle on thermohydraulic performance of rectangular channel has been studied experimentally. The baffle wall was constantly heated and the other three walls of the channel were kept insulated. The experimentations were conducted to collect the data on Nusselt number ( N u b and friction factor ( f b by varying the Reynolds number (Re = 3000–21,000 and angle of attack ( α a from 30° to 70°, for the kept values of relative baffle height ( H b / H = 0 . 50 , relative pitch ratio ( P b / H = 1 . 0 , relative discrete width ( g w / H b = 1 . 5 and relative discrete distance ( D d / L v = 0 . 67 . As compared to the smooth wall, the V-pattern baffle roughened channel enhances the Nusselt number ( N u b and friction factor ( f b by 4.2 and 5.9 times, respectively. The present discrete V-pattern baffle shapes with angle of attack ( α a of 60° equivalent to flow Reynolds number of 3000 yields the greatest thermohydraulic performance. Discrete V-pattern baffle has improved thermal performance as compared to other baffle shapes’ rectangular channel.

  9. Effect of segmental baffles on the shell-and-tube heat exchanger effectiveness

    Directory of Open Access Journals (Sweden)

    Vukić Mića V.

    2014-01-01

    Full Text Available In this paper, the results of the experimental investigations of fluid flow and heat transfer in laboratory experimental shell-and-tube heat exchanger are presented. Shell-and-tube heat exchanger is with one pass of warm water on the shell side and two passes of cool water in tube bundle. Shell-and-tube heat exchanger is with 24x2 tubes (U-tube in triangle layout. During each experimental run, the pressure drops and the fluid temperatures on shell side, along the shell-and-tube heat exchanger (at positions defined in advance have been measured. Special attention was made to the investigation of the segmental baffles number influence of the shell-and-tube heat exchanger effectiveness.

  10. Arc erosion of full metal plasma facing components at the inner baffle region of ASDEX Upgrade

    Directory of Open Access Journals (Sweden)

    V. Rohde

    2016-12-01

    Full Text Available At the inner baffle of the AUG divertor massive polished inserts of tungsten and P92 steel were installed to measure the erosion by arcing. For tungsten most of the traces are less than 0.4µm deep and a similar amount of tungsten is deposited close to the traces. Few craters up to 4µm resulting in an average erosion rate of 2×1013 at cm−2s−1 are observed. The behaviour for P92 steel is quite different: most of the traces are 4µm deep, up to 80µm were observed. An average erosion rate of 400×1013 at cm−2s−1, i.e. more than a factor of hundred higher compared to tungsten, is found. Therefore, erosion by arcing has to be taken into account to determine the optimal material mix for future fusion devices.

  11. Modified two-phase anaerobic baffled process for low-concentration wastewater treatment

    Institute of Scientific and Technical Information of China (English)

    LIN Ying-zi; HAN Xiang-kui; YIN Jun; SHAO Pi-hong; AI Sheng-shu

    2009-01-01

    In this study low-concentration wastewater was investigated in the integral two-phase anaerobic baf-fled reactor by determining the removal of COD at various HRT,reflex ratios,and temperatures.Results indi-cate that the removal efficiency of COD is more than 90%at 25℃and 10-h HRT with no wastewater recycled,and the removal efficiency is up to 88%at 8-h HRT and reflex ratio of 150%.The removal efficiency is de-creased with the decreasing temperature and HRT.The removal efficiency of COD is approximaleIy 60%at10℃,which proves that the temperature does not affect it apparently.This research has significance for reduc-ing the cost ot wastewater and sludge treatment in cold area.

  12. Performance study of solar air heater duct having absorber plate with V down perforated baffles

    Directory of Open Access Journals (Sweden)

    Sunil Chamoli

    2014-04-01

    Full Text Available This paper presents results of a study of the performance of solar air heaters with V down perforated baffles as roughness on the air flow side of the absorber plate. Investigations have been carried out using a mathematical model to study the effects of ambient conditions, operating and design parameters on effective efficiency of such air heaters. The thermal and effective efficiencies differ only marginally at lower flow rates. With an increase in the flow rate, the difference between the thermal and effective efficiencies increases because of the increase in the pumping power. The results of the study are presented in the form of plots to show the effect of ambient, design and operating conditions on thermal and effective efficiency.

  13. FLOW AND HEAT TRANSFER CHARACTERISTICS IN SHELL SIDE OF SHELL-AND-TUBE HEAT EXCHANGERS WITH SEPARATED BAFFLES PARALLEL TO SEGMENTAL BAFFLES%平行流分隔板管壳式换热器壳侧流场与传热性能

    Institute of Scientific and Technical Information of China (English)

    王杨君; 邓先和; 陈颖; 李志武

    2004-01-01

    A shell-and-tube heat exchanger with separated baffles parallel to segmental baffles was proposed, and an investigation on velocity distribution, heat transfer and flow resistance characteristics in the shell side of the proposed heat exchanger and traditional single segmental baffled shell-and-tube heat exchanger was reported. After the experiment, the empirical relations of heat transfer and flow resistance were obtained. The heat transfer enhancement comprehensive evaluation factor η was in the range from 1.15 to 1.20 for Reynolds number (1.25×104-3.35×104). The resuhs indicated that flow field uniformization was enhanced in the shell side of shell-and-tube heat exchangers by two separated baffles parallel to segmental baffles and the performance of heat transfer was improved by controlling the dimension of vortices. The results could be used as reference in further research.

  14. Preservation of Thermal Control Specular Gold Baffle Surface on the James Webb Space Telescope (JWST) Integrated Science Instrument Module (ISIM) Electronics Compartment (IEC)

    Science.gov (United States)

    MonteedeGarcia, Kristina; Patel, Jignasha; Perry, Radford, III

    2010-01-01

    Extremely tight thermal control property degradation allowances on the vapor-deposited, gold-coated IEC baffle surface, made necessary by the cryogenic JWST Observatory operations, dictate tight contamination requirements on adjacent surfaces. Theoretical degradation in emittance with contaminant thickness was calculated. Maximum allowable source outgassing rates were calculated using worst case view factors from source to baffle surface. Tight requirements pushed the team to change the design of the adjacent surfaces to minimize the outgassing sources

  15. Simulation of the Effect of a Baffle Structure on Membrane Efficiency Using Computational Fluid Dynamics during the Clarification of Pomegranate Juice

    Directory of Open Access Journals (Sweden)

    Reza Sharifanfar

    2016-10-01

    Full Text Available Background and Objectives: Pomegranate juice (PJ contains large particles that stick to evaporator walls causing off flavors in the concentrate due to burning. Microfiltration is used to clarify PJ. Fouling is a limiting phenomenon that can prevent the industrialization of membrane clarification. Changes in the geometry of the membrane module such as using baffles are useful to decrease this problem. Computational fluid dynamics (CFD is a powerful numerical tool used in modeling membrane processing. Materials and Methods: The effect of baffle geometry on the efficiency of membrane clarification of pomegranate juice in a flat-sheet module was simulated using computational fluid dynamics (CFD. The geometry of the membrane unit was plotted and meshed with Gambit software, and was solved using FLUENT software. A two-dimensional double-precision method at steady state was selected to simulate the membrane process. The convective terms were discretized with a standard first-order upwind scheme in computational solution. The RNG k-  model was used due to its high accuracy in eddy flows with a low Reynolds number. The effects on the process performance of the number of baffles, their angle and the distance between the baffles and the membrane surface were evaluated. Results: The results showed that the configuration with the feed-channel height of 2 cm, the baffle angle of 90o and the distance between the membrane surface and baffles of 2 mm had maximum permeate flux. Conclusions: Reducing the distance between the baffles and the membrane surface increased the permeate flux due to create an eddy flow near the membrane surface in the flat-sheet module and reduced the total and cake-layer resistances. Keywords: Baffle, Computational fluid dynamics, Juice, Membrane, Pomegranate

  16. Performance of an Anaerobic Baffled Filter Reactor in the Treatment of Algae-Laden Water and the Contribution of Granular Sludge

    OpenAIRE

    Yaqin Yu; Xiwu Lu; Yifeng Wu

    2014-01-01

    This study investigated the performance and stability of an anaerobic baffled filter reactor in the treatment of algae-laden water from Taihu Lake at several organic loading rates. The study also evaluated the capability of soft filler to train granule sludge and improve the anaerobic environment and sludge activity in the anaerobic baffled reactor (ABR), thereby enhancing the treatment efficiency. The ABR consisted of five rectangular compartments, each of which was 120 cm long, 80 cm wide, ...

  17. Effect of baffles and a louvered bypass on the airflow and the convective patterns of contaminant inside a fume hood.

    Science.gov (United States)

    Hu, P; Ingham, D B; Wen, X

    1998-05-01

    Various numerical predictions are given for the containment testing of fume hoods with internal baffles of different size and at different locations and with a louvered bypass. The numerical predictions were compared with experimental data and a fairly good agreement for the air velocity was found, although there was only qualitative agreement for the concentration of the contaminant. It was found that the level of contaminant leakage at the working aperture depended not only on the size of the recirculating airflow behind the fume hood sash but also on the blockage caused by the baffles inside the fume hood near the exhaust duct. Finally, some new suggestions for the design of the fume hood have been proposed. However, before implementing these suggestions it is essential that either experimental testing be performed, or the cost-effective alternative of using numerical predictions for containment testing, to determine accurately the level of contaminant leakage from the working aperture.

  18. Analysis of the Effect of Variation of Baffle Height on the Liquid Sloshing In the Tank with CFD Approach

    Directory of Open Access Journals (Sweden)

    Suresh Patil. G. L,

    2015-12-01

    Full Text Available Sloshing is a common physical phenomenon which occurs in moving tanks with contained liquid masses, such as liquid cargo carriers, rockets, aircrafts, and the seismically excited storage tanks, dams, reactors, and nuclear vessels. The sloshing frequencies of contained liquid are essential in the analysis and design of the liquid tanks and the associated structures. In this paper an attempt made with the VOF model and considered with immiscible fluids by solving a single set of momentum equations and tracking the volume fraction of each of the fluids throughout the domain. Further investigated the effect of the vertical baffle heights on the liquid sloshing in a three-dimensional (3D rectangular tank. studied dynamic analysis of sloshing in rectangular tanks with multiple vertical baffles. ANSYS-CFX software was used to study this dynamic analysis subjected to random excitations including earthquake induced motions. analytically estimated hydrodynamic damping ratio for liquid sloshing phenomenon in a partially filled rectangular tank for baffles. They used the velocity potential formulation and linear wave theory for analytic calculations.

  19. Investigations of the Gas-Liquid Multiphase System Involving Macro-Instability in a Baffled Stirred Tank Reactor

    Directory of Open Access Journals (Sweden)

    Shuo Zhang

    2016-01-01

    Full Text Available Bubble Sauter Mean Diameter (SMD in gas-liquid multiphase system is of particular interest and the quantification of gas characteristics is still a challenge today. In this contribution, multiphase Computational Fluid Dynamic (CFD simulations are combined with Population Balance Model (PBM to investigate the bubble SMD in baffled stirred tank reactor (STR. Hereby, special attention is given to the phenomenon known as the fluid macro-instability (MI, which is a large-scale low-frequency fluid velocity variation in baffled STRs, since the fluid MIs have a dominating influence on the bubble breakage and coalescence processes. The simulations, regarding the fluid velocity, are validated with Laser Doppler Anemometry (LDA experiments, in which the instant radial velocity is analyzed through Fast Fourier Transform (FFT spectrum. The frequency peaks of the fluid MIs are found both in the simulation and in the experiment with a high degree of accuracy. After the validation, quantitative predictions of overall bubble SMD with and without MIs are carried out. Due to the accurate prediction of the fluid field, the influence of the fluid MI to bubble SMD is presented. This result provides more adequate information for engineers working in the field of estimating bubble SMDs in baffled STRs.

  20. Large Scale Finite Element Thermal Analysis of the Bolts of a French PWR Core Internal Baffle Structure

    Energy Technology Data Exchange (ETDEWEB)

    Rupp, Isabelle; Christophe, Peniguel [EDF R and D, Paris (France); Tommy, Martin Michel [1 av du General de Gaulle, Paris (France)

    2009-11-15

    The internal core baffle structure of a French Pressurized Water Reactor (PWR) consists of a collection of baffles and formers that are attached to the barrel. The connections are done thanks to a large number of bolts (about 1500). After inspection, some of the bolts have been found cracked. This has been attributed to the Irradiation Assisted Stress Corrosion Cracking (IASCC). The Electricite De France (EDF) has set up a research program to gain better knowledge of the temperature distribution, which may affect the bolts and the whole structure. The temperature distribution in the structure was calculated thanks to the thermal code SYRTHES that used a finite element approach. The heat transfer between the by-pass flow inside the cavities of the core baffle and the structure was accounted for thanks to a strong thermal coupling between the thermal code SYRTHES and the CFD code named Code{sub S}aturne. The results for the CP0 plant design show that both the high temperature and strong temperature gradients could potentially induce mechanical stresses. The CPY design, where each bolt is individually cooled, had led to a reduction of temperatures inside the structures. A new parallel version of SYRTHES, for calculations on very large meshes and based on MPI, has been developed. A demonstration test on the complete structure that has led to about 1.1 billion linear tetraedra has been calculated on 2048 processors of the EDF Blue Gene computer

  1. Removal of Organic Load in Communal Wastewater by using the Six Stage Anaerobic Baffle Reactor (ABR

    Directory of Open Access Journals (Sweden)

    Trilita Minarni Nur

    2016-01-01

    Full Text Available The reduction of water quality in the urban drainage is a crucial problem to overcome because it can affect the health of community. This fact encouraged the researcher to conduct the research in efforts to increase the water quality in the drainage. One of the solutions to increase the water quality in the drainage is that the domestic wastewater must be treated at first before it is flown through the drainage. Furthermore, the wastewater treatment was conducted by employing the communal wastewater processor. The research was aimed at knowing the capability of Anaerobic Baffle Reactor with the six-stage design in communal wastewater processor in efforts to decrease the organic load. This research was conducted in a laboratory scale. Meanwhile, the sort of waste used was taken from the domestic wastewater of settlement by varying its discharge and waste concentration flowing into the waste processor. Finally, the research result showed that the reduction of organic load of COD was reaching up to 92%, N was 85% and Phosphate was 50%.

  2. Treatment of nitrate-rich water in a baffled membrane bioreactor (BMBR) employing waste derived materials.

    Science.gov (United States)

    Basu, Subhankar; Singh, Saurabh K; Tewari, Prahlad K; Batra, Vidya S; Balakrishnan, Malini

    2014-12-15

    Nitrate removal in submerged membrane bioreactors (MBRs) is limited as intensive aeration (for maintaining adequate dissolved oxygen levels and for membrane scouring) deters the formation of anoxic zones essential for biological denitrification. The present study employs baffled membrane bioreactor (BMBR) to overcome this constraint. Treatment of nitrate rich water (synthetic and real groundwater) was investigated. Sludge separation was achieved using ceramic membrane filters prepared from waste sugarcane bagasse ash. A complex external carbon source (leachate from anaerobic digestion of food waste) was used to maintain an appropriate C/N ratio. Over 90% COD and 95% NO3-N reduction was obtained. The bagasse ash filters produced a clear permeate, free of suspended solids. Sludge aggregates were observed in the reactor and were linked to the high extracellular polymeric substances (EPS) content. Lower sludge volume index (40 mL/g compared to 150 mL/g for seed sludge), higher settling velocity (47 m/h compared to 10 m/h for seed sludge) and sludge aggregates (0.7 mm aggregates compared to filters in water treatment.

  3. The anaerobic baffled reactor (ABR) treating communal wastewater under mesophilic conditions: a review.

    Science.gov (United States)

    Reynaud, N; Buckley, C A

    2016-01-01

    A review concerning the anaerobic baffled reactor (ABR) treating communal wastewater under mesophilic conditions is presented. Existing studies indicate strong resilience of the reactor towards loading variations and shock-loads. The compartmentalisation of the ABR is a strongly stabilising factor with feed fluctuations being evened out across reactor chambers. Significant chemical oxygen demand (COD) reduction occurs almost exclusively in the first three chambers. The hydraulic rather than the organic loading rate is treatment limiting. Laboratory-scale studies show high treatment efficiencies of above 80% COD removal. It was found that most laboratory-scale studies do not factor in important aspects of field operation, such as diurnal fluctuations of feed characteristics, adequate start-up periods and periods of constant loading and optimised chamber outlet design, and never studied the effect of loading on sludge digestion. Performance data on full-scale ABR implementations, however, are extremely scarce, and existing studies are without exception affected by site-specific treatment-limiting factors hindering the extrapolation of generally valid conclusions. In view of a large-scale roll-out, communal ABRs are not sufficiently understood. Current challenges concerning the optimisation of reactor design require numerous well-monitored long-term full-scale reactor investigations. Existing ABR investigations yield encouraging results, supporting that the ABR may be one of the solutions answering the global call for low-maintenance, robust treatment systems.

  4. Anaerobic baffled reactor coupled with chemical precipitation for treatment and toxicity reduction of industrial wastewater.

    Science.gov (United States)

    Laohaprapanona, Sawanya; Marquesa, Marcia; Hogland, William

    2014-01-01

    This study describes the reduction of soluble chemical oxygen demand (CODs) and the removal of dissolved organic carbon (DOC), formaldehyde (FA) and nitrogen from highly polluted wastewater generated during cleaning procedures in wood floor manufacturing using a laboratory-scale biological anaerobic baffled reactor followed by chemical precipitation using MgCI2 .6H20 + Na2HPO4. By increasing the hydraulic retention time from 2.5 to 3.7 and 5 days, the reduction rates of FA, DOC and CODs of nearly 100%, 90% and 83%, respectively, were achieved. When the Mg:N:P molar ratio in the chemical treatment was changed from 1:1:1 to 1.3:1:1.3 at pH 8, the NH4+ removal rate increased from 80% to 98%. Biologically and chemically treated wastewater had no toxic effects on Vibrio fischeri and Artemia salina whereas chemically treated wastewater inhibited germination of Lactuca sativa owing to a high salt content. Regardless of the high conductivity of the treated wastewater, combined biological and chemical treatment was found to be effective for the removal of the organic load and nitrogen, and to be simple to operate and to maintain. A combined process such as that investigated could be useful for on-site treatment of low volumes of highly polluted wastewater generated by the wood floor and wood furniture industries, for which there is no suitable on-site treatment option available today.

  5. Biologic treatment of wastewater from cassava flour production using vertical anaerobic baffled reactor (VABR

    Directory of Open Access Journals (Sweden)

    Gleyce T Correia

    2008-08-01

    Full Text Available The estimate cassava production in Brazil in 2007 was of 25 million tons (= 15% of the world production and most of it is used in the production of flour. During its processing, waste that can cause environmental inequality is generated, if discharged inappropriately. One of the liquid waste generated, manipueira, is characterized by its high level of organic matter. The anaerobic treatment that uses a vertical anaerobic baffled reactor (VABR inoculated with granulated sludge, is one of the ways of treating this effluent. The anaerobic biodigestion phases are separated in this kind of reactor, allowing greater stability and resistance to load shocks. The VABR was built with a width/height rate of 1:2. The pH, acidity, alkalinity, turbidity and COD removal were analyzed in 6 different regions of the reactor, which was operated with an increasing feeding from ? 2000 to ? 10000 mg COD L?¹ and HRT between 6.0 and 2.5 days. The VABR showed decreasing acidity and turbidity, an increase in alkalinity and pH, and 96% efficiency in COD removal with 3-day HRT and feeding of 3800 mg COD L?¹.

  6. Experimental study of hydrodynamic and operation start of a baffled anaerobic reactor treating sewage

    Directory of Open Access Journals (Sweden)

    Ana Carolina Silveira Perico

    2009-12-01

    Full Text Available It is important to provide individual sanitation systems for sewage peri-urban communities or rural areas to minimize impacts on the environment and human health caused by sewage discharge in natura into water resources. In this context, the anaerobic digestion of effluent has been one of the main considered technologies due to easy implementation, material minimization and reduction in waste production. The objective of this work was to study a Baffled Anaerobic Reactor (BAR including its hydrodynamic characteristics, percentile of inoculum to be applied and reactor operation start. It was concluded that the flow is dispersed with 3.84% of dead spaces and that 20% of the cow manure provided best results; however, due to the high fiber content of the manure, its use is not recommended as inoculum. The BAR system, composed of four chambers, presented good performance for sewage treatment of a rural community in terms of organic substance removal (COD, turbidity and solids meeting effluent disposal standards of these parameters considering the Federal and Minas Gerais State legislation, in Brazil, even in a transient phase of operation, at temperatures below 20°C. However, the effluents from the BAR can’t be released into water bodies without other parameters such as nitrogen, phosphorus, fecal coliforms, and others are investigated to be conforming to those standards.

  7. Two stage anaerobic baffled reactors for bio-hydrogen production from municipal food waste.

    Science.gov (United States)

    Tawfik, A; Salem, A; El-Qelish, M

    2011-09-01

    A two-step anaerobic baffled reactor (ABR-1 and ABR-2) for H2 production from municipal food waste (MFW) was investigated at a temperature of 26 °C. In ABR-1, the average yield of H2 at an HRT of 26 h and OLR of 58 kg COD/m3 d was 250 ml H2/g VS removed. As unexpected; the H2 production in the ABR-2 was further increased up to 370 ml H2/gVS removed at a HRT of 26 h and OLR of 35 kg COD/m3 d. The total H2 yield in the two-step process was estimated to be 4.9 mol H2/mol hexose. The major part of H2 production in the ABR-1 was due to the conversion of COD(particulate) (36%). In the ABR-2 the H2 yield was mainly due to the conversion of COD in the soluble form (76%). Based on these results MFW could be ideal substrate for H2 production in a two-step ABR processes.

  8. Effects of baffle on combustion acoustic characteristics of liquid rocket engine%隔板对燃烧室声学特性的影响

    Institute of Scientific and Technical Information of China (English)

    李丹琳; 田原; 孙纪国

    2012-01-01

    为了研究液体火箭发动机燃烧室出现的横向一阶切向燃烧不稳定,通过冷态声学试验和理论算例的计算,研究了不同参数的隔板装置对一阶切向声学频率及阻尼特性的影响,结果表明:增加轴向隔板长度和径向隔板数目均会降低一阶切向声学频率,同时增强声阻尼效果;喷嘴式隔板产生的声阻尼效果,比典型直板形状的隔板要好得多,隔板喷嘴最佳间隙在0.1-0.4mm,采用最佳隔板喷嘴间隙能够在较短的轴向隔板长度上得到较高的阻尼能力,从而改善冷却问题.%Cold acoustic tests have been performed to elucidate the effect of baffle on the damping characteristics of the first-tangential acoustic mode in a liquid rocket engine. Differ- ent kinds of baffle parameters were researched by acoustic tests. The results agree well with the theory typical example and show that when increasing the axial baffle length and the ra- dial baffle number, the acoustic frequency of the first-tangential acoustic mode decreases and the acoustic damping capacity increases. Injector-forming baffles have some advantages over the typical straight baffles in acoustic damping capability; an optimal acoustic damping ca- pacitance has been achieved in 0.1-0. 4mm; axial baffle length can be reduced by using the optimal baffle gap, providing a possible solution of thermal cooling problems.

  9. Numerical Investigation on Double Shell-Pass Shell-and-Tube Heat Exchanger with Continuous Helical Baffles

    Directory of Open Access Journals (Sweden)

    Shui Ji

    2011-01-01

    Full Text Available A double shell-pass shell-and-tube heat exchanger with continuous helical baffles (STHXCH has been invented to improve the shell-side performance of STHXCH. At the same flow area, the double shell-pass STHXCH is compared with a single shell-pass STHXCH and a conventional shell-and-tube heat exchanger with segmental baffles (STHXSG by means of numerical method. The numerical results show that the shell-side heat transfer coefficients of the novel heat exchanger are 12–17% and 14–25% higher than those of STHXSG and single shell-pass STHXCH, respectively; the shell-side pressure drop of the novel heat exchanger is slightly lower than that of STHXSG and 29–35% higher than that of single shell-pass STHXCH. Analyses of shell-side flow field show that, under the same flow rate, double shell-pass STHXCH has the largest shell-side volume average velocity and the most uniform velocity distribution of the three STHXs. The shell-side helical flow pattern of double shell-pass STHXCH is more similar to longitudinal flow than that of single shell-pass STHXCH. Its distribution of fluid mechanical energy dissipation is also uniform. The double shell-pass STHXCH might be used to replace the STHXSG in industrial applications to save energy, reduce cost, and prolong the service life.

  10. Investigation of the baffle effects on reactor of fluidized beds with circulating flow along with ozone decomposition

    Directory of Open Access Journals (Sweden)

    E. Zohrabi

    2016-09-01

    Full Text Available Fluidized beds with circulating flow, as the gas-solid contactors, are widely used in physical and chemical processes such as drying of solids, pharmaceutical industries, coating solids, granulation, and water and wastewater treatment industry. In this study, numerical simulation using FLUENT software was conducted to investigate the distribution of solid particles of fluidized beds with circulating flow. To conduct simulation, Eulerian-Eulerian with the help of kinetic theory of granular flow was used. Various values of particle-wall elastic modulus were studied. After selecting the appropriate model to predict the particles flow behavior, ozone decomposition reaction was carried out in fluidized beds with circulating flow and they were solved by FLUENT software. The results showed that the location of ring baffles has the greatest impact on fluctuation of system pressure drop, and adverse mix of gas and increase of solid materials are tangible by baffles, resulting from regulation of bed and accumulation of circulating particles beside the wall.

  11. 波形折流杆换热器的开发和工业化实验研究%Industrially Experimental Investigations and Development of the Curve-ROD Baffle Heat Exchanger

    Institute of Scientific and Technical Information of China (English)

    严良文; 吴金星; 王志文

    2004-01-01

    The conventional heat exchanger with segmental baffles is prone to bring forth fluid-induced vibration of heat transfer tubes and increase the pressure drop of shell-side greatly at higher fluid flow velocity. In order to avoid the above defects, the ROD-baffle heat exchanger has been developed. However, its collocation of heat transfer tubes is conventionally in square, which leads to fewer heat transfer area per unit volume. Based on the ROD-baffle heat exchanger, a new type curve-ROD baffle has been developed, and an industrial investigation of the curve-ROD baffle heat exchanger with normal triangular collocation has been carried into execution. In this paper, two equations using the Reynolds number were acquired to predict the heat transfer coefficients of the shell-side and tubeside. The experimental results show that the shell-side heat transfer and pressure drop characteristics of the curve-ROD baffle heat exchanger are superior to those of the segmental baffle one.

  12. Seismic design optimization of IHP cooling baffle in nuclear power plant%核电厂IHP通风围板的抗震设计优化

    Institute of Scientific and Technical Information of China (English)

    徐峰

    2012-01-01

    核电厂一体化堆顶组件(IHP)通风围板为驱动机构磁轭线圈的冷却提供了间隙均匀的通道.为了优化IHP通风围板的设计,根据ANSI/AISC N690分析了当前设计的通风围板的关键结构件在D级使用限制下的应力和变形并对关键结构件进行了初步设计优化,然后对IHP通风围板进行了有限元分析并对通风围板进行了最终设计改进.经过抗震设计优化通风围板的最大应力值分布趋于均匀.本文对抗震类设备的设计优化具有一定的参考价值.%Integrated head package (IHP) cooling baffle supplies uniform gap cooling channel for control rod drive mechanism coil stack. For optimizing design of IHP cooling baffle, stress and deformation of cooling baffle key parts were analyzed at Level D service limit according to ANSI/AISC 690, and primary optimization of key parts was processed. Then the cooling baffle was analyzed using finite element method, and final design improvement of baffle was made. The result shows better maximum stress distribution is obtained after optimization. This paper could be referenced for design optimization of seismic components.

  13. Experimental study on heat transfer enhancement of a helically baffled heat exchanger combined with three-dimensional finned tubes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Zhnegguo; Xu Tao; Fang Xiaoming [South China University of Technology, Guangzhou (China). Ministry of Education

    2004-10-01

    Heat transfer and pressure drop of helically baffled heat exchanger combined with petal-shaped finned tubes for oil (ISO VG-32) cooling with water as coolant was experimentally studied. The tube side heat transfer coefficient was obtained by a modified Wilson plot technique. Results were presented as plots of the shell side heat transfer coefficient based on the actual outside surface area of tube bundle and pressure drop against volumetric flow rate of oil. Under experimental conditions, the maximum shell side heat transfer coefficient is 2265 W/m{sup 2} K, the corresponding shell side pressure drop is 91 kPa. The preliminary heat transfer enhancement mechanisms were discussed for oil flow helically on outside surface of petal-shaped finned tubes. (author)

  14. Laboratory evaluation of a reactive baffle approach to NOx control. Final technical report, February-April 1993

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, S.G.; Van Stone, D.A.; Little, R.C.; Peterson, R.A.

    1993-09-01

    Vermiculite, vermiculite coated with magnesia, and activated carbon sorbents have successfully removed NOx (and carbon monoxide and particles) from combustion exhausts in a subscale drone jet engine test cell (JETC), but back pressure so generated elevated the temperature of the JETC and of the engine. The objective of this effort was to explore the feasibility of locating the sorbents in the face of the duct or of baffles parallel to the direction of flow within the ducts. Jet engine test cells (JETCs) are stationary sources of oxides of nitrogen (NOx), soot, and unburned or partially oxidized carbon compounds that form as byproducts of imperfect combustion. Regulation of NOx emissions is being considered for implementation under the Clean Air Act Amendments of 1990. Several principles have been examined as candidate methods to control NOx emissions from JETCs.

  15. Passage and behaviour of cultured Lake Sturgeon in a prototype side-baffle fish ladder: I. Ladder hydraulics and fish ascent

    Science.gov (United States)

    Kynard, B.; Pugh, D.; Parker, T.

    2011-01-01

    Research and development of a fish ladder for sturgeons requires understanding ladder hydraulics and sturgeon behaviour in the ladder to insure the ladder is safe and provides effective passage. After years of research and development, we designed and constructed a full-scale prototype side-baffle ladder inside a spiral flume (38.3m long??1m wide??1m high) on a 6% (1:16.5) slope with a 1.92-m rise in elevation (bottom to top) to test use by sturgeons. Twenty-eight triangular side baffles, each extending part way across the flume, alternated from inside wall to outside wall down the ladder creating two major flow habitats: a continuous, sinusoidal flow down the ladder through the vertical openings of side-baffles and an eddy below each side baffle. Ascent and behaviour was observed on 22 cultured Lake Sturgeon=LS (Acipenser fulvescens) repeatedly tested in groups as juveniles (as small as 105.1cm TL, mean) or as adults (mean TL, 118cm) during four periods (fall 2002 and 2003; spring 2003 and 2007). Percent of juveniles entering the ladder that ascended to the top was greater in spring (72.7%) than in fall (40.9-45.5%) and 90.9% of 11 adults, which ascended as juveniles, ascended to the top. Six LS (27.3%) never swam to the top and seven (31.8%) swam to the top in all tests, indicating great variability among individuals for ascent drive. Some LS swam directly to the top in mean velocity, 1.2ms-1) swam at 1.8-2.2body lengthss-1 and 3.2-3.3tail beatss-1, either at or approaching prolonged swimming speed. The side-baffle ladder was stream-like and provided key factors for a sturgeon ladder: a continuous flow and no full cross-channel walls, abundant eddies for resting, an acceptable water depth, and a water velocity fish could ascend swimming 2bls-1. A side-baffle ladder passes LS and other moderate-swimming fishes. ?? 2011 Blackwell Verlag, Berlin.

  16. 3D simulation on the unit duct in the shell side of the ROD baffle heat exchanger%杆支撑换热器壳侧单元流道的三维模拟

    Institute of Scientific and Technical Information of China (English)

    吴金星; 董其伍; 刘敏珊; 魏新利

    2006-01-01

    The ROD baffle heat exchanger can slightly enhance the shell side heat transfer coefficient with the significant reduction of pressure loss due to the shell side fluid flowing longitudinally through tube bundle, which leads to the reduction of the manufacture and running cost and in some cases to the dimensions reduction of the heat exchangers. Because of the complexities of fluid dynamics equations and the structure of heat exchangers, few theoretical researches have been accomplished to specify the shell side characteristics of the ROD baffle heat exchanger. A unit duct model in the shell side of the longitudinal flow type heat exchanger has been developed based on suitable simplification. A numerical analysis on shell side of the ROD baffle heat exchanger has been carried out at constant wall temperature to obtain the characteristics of heat transfer and pressure drop. The numerical results show that the ROD baffles placed vertically and horizontally in the unit duct continue to shear and comminute the streamline flow when the fluid crosses over the ROD-baffles, and change the fluid flow directions, and then the continuity and stability of the fluid are destroyed. The effect of disturbing flow can promote fluid turbulent intensity and effectively enhance heat transfer. The numerical analyses can provide the theoretical bases for optimizing the structure of ROD baffle heat exchanger and improving its performance.

  17. A study of the various baffles used in the Marcoule chimneys and the search for a new model (1961); Etude des differents deflecteurs utilises pour les cheminees de Marcoule et recherche d'un nouveau type de deflecteur (1961)

    Energy Technology Data Exchange (ETDEWEB)

    Chassany, J. [Commissariat a l' Energie Atomique, Centre de Production de Plutonium, Marcoule (France). Centre d' Etudes Nucleaires; Parigi, H. [Institut de Mecanique des Fluides de Marseille, 13 (France); Salaun-Penquer, G. [Centre National de la Recherche Scientifique (CNRS), 75 - Paris (France)

    1961-07-01

    The baffle placed at the top of a chimney determines the shape of the smoke pall for low exit-velocities. The G. 1 type baffle was studied taking into account the characteristics of its collar: totally hollow - partially hollow - solid; on a ribbed chimney or on a plain chimney. The Pu type baffle was also tested. The search for a new type of baffle was limited to variants of the blade - type baffle: - a porous envelope device; - a cone - shaped device and - a deflector of the cupel type. Only the blade-type baffle was rejected, efficient solutions are proposed using the other types or their combinations. (authors) [French] Le deflecteur place au sommet d'une cheminee conditionne l'allure du panache pour les rejets a faible vitesse de sortie. Le deflecteur type Gl a ete etudie en tenant compte de son embase: totalement evidee - partiellement evidee - pleine; sur une cheminee striee et sur une cheminee lisse. Le deflecteur type Pu a ete egalement teste. La recherche d'un nouveau type de deflecteur a porte sur les deflecteurs a aubage: - un dispositif a enveloppe poreuse; - un dispositif en ogive et - le deflecteur en coupelle. Seul le deflecteur a aubage a ete rejete, des solutions efficaces sont proposees avec les autres types ou leur combinaison. (auteurs)

  18. Ultrasonic testing of core baffle former bolts of the core tanks of pressurised water reactors; Ultraschallpruefung von Kernumfassungsschrauben der Kernbehaelter von Druckwasserreaktoren

    Energy Technology Data Exchange (ETDEWEB)

    Bies, Christian M.; Alaerts, Louis; Bonitz, Frank W. [Westinghouse Electric Germany GmbH, Mannheim (Germany); Devlin, Russell S.; Minogue, Patrick [WesDyne International, Madison, PA (United States)

    2013-07-01

    This article presents the MIDAS VI testing robot used by Westinghouse / WesDyne. This is a remotely operated underwater vehicle which positions ultrasonic probes under camera control. This vehicle makes it possible to substantially reduce the time required for setting up and preparing ultrasonic tests on core baffle former bolts. It has also accelerated the test procedure itself. Test methods have also been developed for bolt types which were hitherto considered incapable of being tested. One of these methods is based on a phased array probe. The article also reports on experiences gained over the course of years in testing core baffle former bolts in European nuclear power plants using the SUPREEM testing robot.

  19. Magnetically insulated baffled probe for real-time monitoring of equilibrium and fluctuating values of space potentials, electron and ion temperatures, and densities.

    Science.gov (United States)

    Demidov, V I; Koepke, M E; Raitses, Y

    2010-10-01

    By restricting the electron-collection area of a cold Langmuir probe compared to the ion-collection area, the probe floating potential can become equal to the space potential, and thus conveniently monitored, rather than to a value shifted from the space potential by an electron-temperature-dependent offset, i.e., the case with an equal-collection-area probe. This design goal is achieved by combining an ambient magnetic field in the plasma with baffles, or shields, on the probe, resulting in species-selective magnetic insulation of the probe collection area. This permits the elimination of electron current to the probe by further adjustment of magnetic insulation which results in an ion-temperature-dependent offset when the probe is electrically floating. Subtracting the floating potential of two magnetically insulated baffled probes, each with a different degree of magnetic insulation, enables the electron or ion temperature to be measured in real time.

  20. 螺旋折流板与弓型折流板强化管换热器的传热性能对比%Comparison on Heat Transfer Performance of Helically Baffled Heat Exchanger with Segmentally Baffled Heat Exchanger Combined with Enhanced Tubes

    Institute of Scientific and Technical Information of China (English)

    刘建; 张正国; 高学农; 王真勇

    2011-01-01

    Experiments were performed to compare the shell - side heat transfer coefficient and pressure drop of a helically baffled heat exchanger to those of a segmentally baffled heat exchanger combined with three - dimensional finned tubes for oil cooling using water as a coolant. The experimental results showed that Nusselt numbers and pressure drops increase with increasing Reynolds numbers in the shell sides for the tested heat exchangers, but the variations of Nusselt numbers were more sharp for the helically baffled heat exchanger than those of the segmentally baffled heat exchanger. The shell - side Nusselt numbers of the helically baffled heat exchanger were 1.2 -1.5 times as large as those of the segmentally baffled heat exchanger, and pressure drops were reduced by 5% ~ 12%at the same Reynolds numbers. It was proved that there was very high heat transfer enhancement performance for the helically baffled heat exchanger combined with three - dimensional finned tubes.%以油-水换热为对象,比较了螺旋折流板与弓型折流板三维翅片管换热器的壳程传热与压降性能.试验结果表明,2台实验换热器的壳程努塞尔特常数和压降都随雷诺常数的增加而增加,但螺旋折流板三维翅片管换热器的努塞尔特常数随雷诺常数的变化更明显.在相同雷诺常数下,螺旋折流板换热器的努塞尔特常数是弓型折流板换热器的1.2~1.5倍,而压降却降低5%~12%,证明螺旋折流板三维翅片管换热器具有很高的传热强化性能.

  1. Performance of an Anaerobic Baffled Filter Reactor in the Treatment of Algae-Laden Water and the Contribution of Granular Sludge

    Directory of Open Access Journals (Sweden)

    Yaqin Yu

    2014-01-01

    Full Text Available This study investigated the performance and stability of an anaerobic baffled filter reactor in the treatment of algae-laden water from Taihu Lake at several organic loading rates. The study also evaluated the capability of soft filler to train granule sludge and improve the anaerobic environment and sludge activity in the anaerobic baffled reactor (ABR, thereby enhancing the treatment efficiency. The ABR consisted of five rectangular compartments, each of which was 120 cm long, 80 cm wide, 80 cm high, and packed with soft filler. The anaerobic baffled filter reactor was found to be an efficient reactor configuration for the treatment of algae-laden water. The reactor was operated at an organic loading rate of 1.5 kg chemical oxygen demand (COD/(m3d and an ambient temperature of 30 °C; under these conditions, the COD removal efficiency was 80% and the biogas production rate was 293 mL/(Ld. Moreover, the soft filler increased the biomass retention time and decreased the rate at which solids were washed out from the reactor, promoting an improved spatial distribution of the microbial communities within the compartments. Methanoregula, Methanobacteriaceae, Methanosaeta, Methanoculleu, and Thermogymnomonas were the dominant archaeal species in each compartment during an operational period of approximately 100 days. The protease activity in the reactor decreased longitudinally down the reactor from Compartments 1 to 5, whereas the activity of coenzyme F420 increased. The soft filler played a key role in successfully treating algae-laden water with the anaerobic baffled filter reactor.

  2. Wastewater treatment using integrated anaerobic baffled reactor and Bio-rack wetland planted with Phragmites sp. and Typha sp.

    Science.gov (United States)

    Jamshidi, Shervin; Akbarzadeh, Abbas; Woo, Kwang-Sung; Valipour, Alireza

    2014-01-01

    The purpose of this study is to examine the potential use of anaerobic baffled reactor (ABR) followed by Bio-rack wetland planted with Phragmites sp. and Typha sp. for treating domestic wastewater generated by small communities (751 mg COD/L, 500 SCOD mg/L, 348 mg BOD5/L). Two parallel laboratory-scale models showed that the process planted with Phragmites sp. and Typha sp. are capable of removing COD by 87% & 86%, SCOD by 90% & 88%, BOD5 by 93% & 92%, TSS by 88% & 86%, TN by 79% & 77%, PO4-P by 21% & 14% at an overall HRT of 21 (843 g COD/m(3)/day & 392 g BOD5/m(3)/day) and 27 (622 g COD/m(3)/day & 302 g BOD5/m(3)/day) hours, respectively. Microbial analysis indicated a high reduction in the MPN of total coliform and TVC as high as 99% at the outlet end of the processes. The vegetated system using Phragmites sp. showed significantly greater (p Phragmites sp. indicated a higher relative growth rate (3.92%) than Typha sp. (0.90%). Microorganisms immobilized on the surface of the Bio-rack media (mean TVC: 2.33 × 10(7) cfu/cm(2)) were isolated, identified and observed using scanning electron microscopy (SEM). This study illustrated that the present integrated processes could be an ideal approach for promoting a sustainable decentralization, however, Phragmites sp. would be more efficient rather than Typha sp.

  3. Effects of Temperature and Hydraulic Residence Time (HRT) on Treatment of Dilute Wastewater in a Carrier Anaerobic Baffled Reactor

    Institute of Scientific and Technical Information of China (English)

    HUA-JUN FENG; LI-FANG HU; DAN SHAN; CHENG-RAN FANG; DONG-SHENG SHEN

    2008-01-01

    To examine the effect of hydraulic residence time (HRT) on the performance and stability,to treat dilute wastewater at different operational temperatures in a carrier anaerobic baffled reactor (CABR),and hence to gain a deeper insight into microbial responses to hydraulic shocks on the base of the relationships among macroscopic performance,catabolic intermediate,and microcosmic alternation.Methods COD,VFAs,and microbial activity were detected with constant feed strength (300 mg/L) at different HRTs (9-18 h) and temperatures (10℃-28℃) in a CABR.Results The removal efficiencies declined with the decreases of HRTs and temperatures.However,the COD removal load was still higher at short HRT than at long HRT.Devastating reactor performance happened at temperature of 10℃ and at HRT of 9 h.HRTs had effect on the VFAs in the reactor slightly both at high and low temperatures,but the reasons differed from each other.Microbial activity was sensitive to indicate changes of environmental and operational parameters in the reactor.Conclusion The CABR offers to certain extent an application to treat dilute wastewater under a hydraulic-shock at temperatures from 10℃ to 28℃.

  4. HEAT TRANSFER COEFFICIENT AND FRICTION FACTOR CHARACTERISTICS OF A GRAVITY ASSISTED BAFFLED SHELL AND HEAT-PIPE HEAT EXCHANGER

    Directory of Open Access Journals (Sweden)

    P. Raveendiran

    2015-06-01

    Full Text Available The heat transfer coefficients and friction factors of a baffled shell and heat pipe heat exchanger with various inclination angles were determined experimentally; using methanol as working fluid and water as heat transport fluid were reported. Heat pipe heat exchanger reported in this investigation have inclination angles varied between 15o and 60o for different mass flow rates and temperature at the shell side of the heat exchanger. All the required parameters like outlet temperature of both hot and cold side of heat exchanger and mass flow rate of fluids were measured using an appropriate instrument. Different tests were performed from which condenser side heat transfer coefficient and friction factor were calculated. In all operating conditions it has been found that the heat transfer coefficient increases by increasing the mass flow rate and angle of inclination. The reduction in friction factor occurs when the Reynolds number is increased. The overall optimum experimental effectiveness of GABSHPHE has found to be 42% in all operating conditioning at ψ = 45o.

  5. Influences of finite-sized non-uniform air-backed baffle on transducer directivity%有限非均匀空腔障板对换能器指向性的影响

    Institute of Scientific and Technical Information of China (English)

    尹义龙; 李俊宝; 夏金东; 邢建新; 吕可佳

    2011-01-01

    声障板可以改善换能器的灵敏度和指向性,是换能器及基阵设计中必不可少的声学结构.本文建立了有限空腔障板和非均匀空腔障板的模型.利用射线声学的理论,研究了以上两种障板对换能器指向性的影响,结果表明障板的边缘和障板的厚度变化都会影响换能器的指向性.文章最后给出了部分实验结果,理论结果与实验结果基本相符.%Sound baffle which improves the sensitivity and the directivity of a transducer is a useful structure for the transducer design.In the paper, models of the finite air-backed baffle and the non-uniform air-backed baffle are presented.Based on ray theory, the influence of the two kinds of air-backed baffles on the directivity of the transducer is studied.Results show that the edge of the baffle and the changes of the baffie's thickness affect the directivity of the transducer.The comparisons between the theoretical and the experimental results are given.

  6. Comparison of two mathematical models for correlating the organic matter removal efficiency with hydraulic retention time in a hybrid anaerobic baffled reactor treating molasses

    OpenAIRE

    Ghaniyari-Benis, Saeid; Martín, Antonio; Borja Padilla, Rafael; M. A. Martín; Hedayat, N.

    2012-01-01

    A modelling of the anaerobic digestion process of molasses was conducted in a 70-L multistage anaerobic biofilm reactor or hybrid anaerobic baffled reactor with six compartments at an operating temperature of 26 °C. Five hydraulic retention times (6, 16, 24, 72 and 120 h) were studied at a constant influent COD concentration of 10,000 mg/L. Two different kinetic models (one was based on a dispersion model with first-order kinetics for substrate consumption and the other based on a modificati...

  7. Effective Increase of Crystal Area during Sublimation Growth of 6H-SiC by Using the Cone-shaped Baffle

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A novel design of crucible is proposed in this paper for the growth of SiC crystals. The relation between grown crystal shape and temperature distribution in a growth chamber was discussed. It is pointed out that the crystal shape had a close relationship with temperature distribution. The calculations suggested that the radial temperature field of the growing crystal became homogenous by setting up the cone-shaped baffle in the growth chamber. By modifying the crucible design and temperature distribution in the growth chamber, it is possible to enhance the enlargement of crystal, and also possible to keep grown surface flat.

  8. Shell-side fluid flow and heat transfer in curved baffle heat exchanger%曲面弓形折流板换热器壳程流体流动与传热

    Institute of Scientific and Technical Information of China (English)

    钱才富; 高宏宇; 孙海阳

    2011-01-01

    提出一种新型折流板-曲面弓形折流板,并构造曲面弓形折流板换热器,采用数值模拟和实验相结合的方法研究其壳程传热和流动阻力性能.在实验方面,设计了实验用曲面弓形折流板和普通弓形折流板换热器试样,其中换热器管束采用可拆连接形式,以考察不同折流板结构和板间距的影响.通过改变管程及壳程流量和管程流体进口温度,获得了大量对应于不同折流板结构的壳程压力降和传热系数实验数据.在模拟方面,利用Fluent软件建立了曲面弓形折流板换热器和普通弓形折流板换热器流体数值分析模型,得到了壳程流体流场分布及壳程压力降和传热系数.结果发现,在相同结构参数和流动条件下,曲面弓形折流板换热器壳程压力降比普通弓形折流板换热器降低9 %~24%,而壳程传热系数比普通弓形折流板换热器提高3%~11%.%With reliable structure, mature design methodology and wide applications, shell-and-tube heat exchanger is the major form of heat exchange equipment and widely used in chemical, oil refining, power,food, medicine, aerospace and many other industries. In this study, a new type of baffle, namely curved baffle, is proposed and used to construct a shell-and-tube heat exchanger. Heat transfer and flow resistance of fluid in the shell side were studied numerically and experimentally. For the experiments, heat exchangers with curved baffles were designed and constructed, and the traditional heat exchanger with plane baffles was also made for comparison. Tube bundles in these heat exchangers are detachable for investigation of the effects of baffle structure and distance between them. By changing volumetric flow in the tube or shell-side and the inlet temperature of tube-side fluid, a large amount of experimental data about the pressure drop and heat transfer coefficient in the shell side were obtained for different baffle structures. For the simulation

  9. 垂直内挡板对流态化流体动力学及谷物干燥特性之影响%The Effect of Vertical Internal Baffles on Fluidization Hydrodynamics and Grain Drying Characteristics

    Institute of Scientific and Technical Information of China (English)

    LAW Chung Lim; Siti Masrinda TASIRIN; Wan Ramli Wan DAUD; NG Pin Pin

    2004-01-01

    The effect of vertical internal baffles on the particle mixing and grain drying characteristics in a batch fluidized bed column is investigated. Experimental work was carried out in a 3 m high rectangular fluidized bed dryer of cross sectional area of 0.15 m×0.61 m at different operating conditions using paddy, a group D particle, as the fluidizing material. The results of the study showed that the fluidized bed dryer system with vertical internal baffles gave better particle mixing effect in the bed of particles than that without vertical internal baffles. This is due to the fact that the vertical internal baffle act as gas bubble breakers by breaking up the large gas bubbles into smaller ones. The smaller bubbles cause a more vigorous mixing in the bed of particles before finally erupting at the bed surface. This improves the contacting efficiency and enhanced the heat and mass transfer of the fluidized bed system. Thus a higher drying rate was obtained in the falling rate period because the higher contacting efficiency increases the evaporation rate at the particle surface. However, the drying rate in the diffusion region shows little improvement because the moisture diffusivity does not depend on the contacting efficiency. The fluidized bed dryer with vertical internal baffles could therefore be used in the initial rapid drying stage in a two stage drying strategy for paddy. The insertion of vertical internal baffles into a fluidiz ed bed system improves the processing of Group D particles in a fluidized bed system especially if the system is large in scale.

  10. Effect of Baffle Opening on the Performance of Shell-and-T ube Heat Exchanger%折流板开孔对管壳式换热器性能的影响

    Institute of Scientific and Technical Information of China (English)

    郭土; 马贵阳; 石龙; 黄腾龙

    2013-01-01

    The traditional baffle heat exchanger is widely used for its simple structure ,safety and reliability and adaptability advantages ,but the traditional baffle heat exchanger has many weaknesses :its thermal efficiency is low ,shell side pressure loss is bigger and easy scaling .It is a very important engineering significance through improving the vertical baffles'structure to ameliorate the shell and tube heat exchanger's flow and heat transfer condition of shell side and reduce its energy dissipation . Baffle opening to improve the structure of a gap 0 .2D height was studied by numerical simulation method .The velocity field and temperature field numerically simulated ordinary baffles heat exchanger and baffle opening heat exchanger . Under the condition of the same entering velocity of shell side ,the thermal effect of baffle opening heat exchanger is better than ordinary vertical baffle plate heat exchanger .And when the entering velocity of shell side is slow ,the effect is better .%传统的弓形折流板换热器因其结构简单、安全可靠及适应性强等优点应用非常广泛,但是传统的弓形折流板换热器换热效率较低,壳程压力损失较大,容易结垢。因此,通过对弓形折流板结构进行改进以改善管壳式换热器的壳程流动传热状况,减小其能耗损失具有十分重大的工程意义。采用数值模拟的方法,对缺口高度为0.2D的折流板进行开孔优化研究,对不同壳程进口流速下的普通弓形折流板换热器和折流板开孔换热器的壳程流场及温度场分别进行了数值模拟。在壳程进口流速相等的条件下,折流板开孔的换热器比普通弓形折流板换热器的换热效果好;壳程进口速度较低时,效果最明显。

  11. Harvey Cushing and pituitary Case Number 3 (Mary D.): the origin of this most baffling problem in neurosurgery.

    Science.gov (United States)

    Pascual, José María; Prieto, Ruth

    2016-07-01

    From the very beginning of his career, Harvey Williams Cushing (1869-1939) harbored a deep interest in a complex group of neoplasms that usually developed at the infundibulum. These were initially known as "interpeduncular" or "suprasellar" cysts. Cushing introduced the term "craniopharyngioma" for these lesions, which he believed represented one of the most baffling problems faced by neurosurgeons. The patient who most influenced Cushing's thinking was a 16-year-old seamstress named "Mary D.," whom he attended in December 1901, exactly the same month that Alfred Fröhlich published his seminal article describing an adiposogenital syndrome in a young boy with a pituitary cyst. Both Cushing's and Fröhlich's patients showed similar symptoms caused by the same type of tumor. Notably, Cushing and Fröhlich had met one another and became good friends in Liverpool the summer before these events took place. Their fortunate relationship led Cushing to realize that Fröhlich's syndrome represented a state of hypopituitarism and provided a useful method of diagnosing interpeduncular cysts. It is noteworthy that Cushing's very first neurosurgical procedure on a pituitary tumor was performed in the case of Mary D.'s "interpeduncular cyst," on February 21, 1902. Cushing failed to remove this lesion, which was later found during the patient's autopsy. This case was documented as Pituitary Case Number 3 in Cushing's masterpiece, The Pituitary Body and Its Disorders, published in 1912. This tumor was considered "a teratoma"; however, multiple sources of evidence suggest that this lesion actually corresponded to an adamantinomatous craniopharyngioma. Unfortunately, the pathological specimens of this lesion were misplaced, and this prompted Cushing's decision to retain all specimens and documents of the cases he would operate on throughout his career. Accordingly, Mary D.'s case crystallized the genesis of the Cushing Brain Tumor Registry, one of Cushing's major legacies to

  12. Experimental and Numerical Investigation on Non-Newtonian Nanofluids Flowing in Shell Side of Helical Baffled Heat Exchanger Combined with Elliptic Tubes

    Directory of Open Access Journals (Sweden)

    Ziye Ling

    2017-01-01

    Full Text Available In this paper, an aqueous solution of xanthan gum (XG at a weight fraction as high as 0.2% was elected as the non-Newtonian base liquid, the multi-walled carbon nanotubes (MWCNTs dispersed into non-Newtonian XG aqueous at different weight factions of MWCNTs was prepared. Convection heat transfer of non-Newtonian nanofluids in the shell side of helical baffled heat exchanger combined with elliptic tubes has been investigated experimentally and numerically using single-phase flow model. Results showed that the enhancement of the convective heat transfer coefficient increases with an increase in the Reynolds number and the nanoparticle concentration. For nanofluids with 0.2 wt %, 0.5 wt % and 1.0 wt % MWCNTs, the Nusselt number, respectively, increases by 11%, 21% and 35% on average at the same Reynolds number, while the comprehensive thermal performance factors are 3%–5%, 15%–17% and 24%–26% higher than that of base fluid at the same volume rate. A remarkable heat transfer enhancement can be obtained by adding MWCNTs into XG aqueous solution based on thermal resistance analysis. Correlations have been suggested for the shell-side Nusselt number and friction factor of non-Newtonian nanofluids in the helical baffled heat exchanger with elliptic tubes. Good agreements existed between corrections and experimental data.

  13. Optimization of Mechanical Process of PWR Reactor Internals Baffle%压水堆堆内构件的围板机械加工工艺优化

    Institute of Scientific and Technical Information of China (English)

    青辉

    2013-01-01

    The structure characteristics and functions of baffles in the reactor internals in PWR were briefly introduced.The mechanical processing characteristic of baffle were described,which includes technique characters of milling and planing,processing difficulties of austenitic stainless steels,factors effecting the quality of mechanical processing,causes of residual stress produced in mechanical processing and their effects on products,etc.A preferable process was obtained through process optimization which increased the processing quality and pass rate of product and made the products meet the design and engineering requirements.%对压水堆堆内构件的围板的结构特点和功能进行了简述,介绍围板的机械加工工艺特点,包括铣削和刨削加工工艺的特点、奥氏体不锈钢加工难点、影响机加工质量的因素、机械加工残余应力产生的原因及其对产品的影响等.围板通过适宜的工艺优化方案提高其产品机加工质量和合格率,使产品达到其设计要求和满足其用途.

  14. Calculation of baffle effect and mutual interaction between elements for an underwater acoustic conformal array with application to the optimization of projecting beampattern

    Institute of Scientific and Technical Information of China (English)

    HE ZhengYao; MA YuanLiang

    2007-01-01

    The boundary element theory together with the optimization method is used to calculate the driving voltage weighting vector of a conformal array of underwater acoustic projecting transducers to obtain a low-sidelobe beampattern. At first, the relationship between the acoustic radiated field and the vibration velocity of the array is formulated from the boundary element equation when the boundary impedance of the array baffle is specified. Then, the mutual impedance matrix of the array is calculated, and the relationship between the driving voltage and the vibration velocity of the transducers is presented based on the equivalent circuit principle. At last, the driving voltage weighting vector of the array is calculated through an optimization method to obtain a low-sidelobe projecting beampattern. Computer simulation is conducted for a 14-element conformal array. An experiment has been carried out to measure the radiation directivity of the array in an anechoic water tank. The calculated and the experimental results show that the proposed method accounts for the acoustic effect of the baffle and the mutual interactions among transducers successfully and obtain a low-sidelobe projecting beampattern, and at the same time provide the largest amplitude of pressure in the axial direction when the maximum amplitude of the driving voltage weighting vectors keeps unchanged.

  15. Heat Flow Characteristics of a Newly-Designed Cooling System with Multi-Fans and Thermal Baffle in the Wheel Loader

    Directory of Open Access Journals (Sweden)

    Yidai Liao

    2017-03-01

    Full Text Available In the traditional cooling case, there is usually one fan in charge of heat transfer and airflow for all radiators. However, this seems to be inappropriate, or even insufficient, for modern construction machinery, as its overall heat flow density is increasing but thermal distribution is becoming uneven. In order to ensure that the machine works in a better condition, this paper employs a new cooling system with multiple fans and an independent cooling region. Based on the thermal flow and performance requirements, seven fans are divided into three groups. The independent cooling region is segregated from the engine region by a thermal baffle to avoid heat flowing into the engine region and inducing an overheat phenomenon. The experiment validates the efficiency of the new cooling system and accuracy of simulation. After validation, the simulation then analyzes heat transfer and flow characteristics of the cooling system, changing with different cross-sections in different axis directions, as well as different distances of the fan central axes. Finally, thermal baffles are set among the fan groups and provided a better cooling effect. The research realizes a multi-fan scheme with an independent cooling region in a wheel loader, which is a new, but high-efficiency, cooling system and will lead to a new change of various configurations and project designs in future construction machinery.

  16. 周向重叠三分螺旋折流板换热器性能比较%Performance comparison of circumferential overlap trisection helical baffle heat exchanger

    Institute of Scientific and Technical Information of China (English)

    董聪; 陈亚平; 吴嘉峰; 操瑞兵

    2013-01-01

    Numerical simulation of flow and heat transfer performances were conducted in respect for four helical baffle heat exchangers with identical equilateral triangle tube layout and approximate spiral pitch but different baffle shapes and assembly configurations,i.e.,a trisection circumferential overlap baffle scheme with the baffle incline angle of 20° (20°TCO),a quadrant circumferential overlap baffle scheme with the baffle incline angle of 18° (18°QCO),a quadrant end-to-end baffle scheme with the baffle incline angle of 18° (18°QEE),and a continuous helical baffle scheme with the baffle helix angle of 18.4° (18.4°CH).The velocity-vector superimposed pressure or velocity nephograms meridian slices and the unfolded concentric hexagonal slices and the curves of local average heat fluxes on nine heat transfer tubes within a 60° sector region and on the four concentric heat transfer tube layers were presented.The results show that each baffle chamber contains secondary flow and there exists reverse leakage at the V-notch region,but the leakage of 20°TCO scheme is the least of the four schemes.Among the four schemes,the 20°TCO scheme has the highest shell-side heat transfer factor jo,friction coefficient fo and average comprehensive index (jo/fo) ; the 18°QCO scheme has the second highest values of both shell-side heat transfer factor joand friction coefficient fo; although,the 18.4°CH scheme has the lowest shell-side friction coefficient fo,its shell-side heat transfer factor jo and average comprehensive index (jo/fo) are the lowest.%对采用正三角形布管且螺距相同的4种螺旋折流板换热器方案,即倾斜角为20°三分周向重叠(20°TCO)、倾斜角为18°四分周向重叠(18°QCO)、倾斜角为18°首尾相连(18°QEE)以及螺旋角为18.4°的连续(18.4°CH)螺旋折流板换热器的流动和传热性能进行数值模拟.给出了子午切面、同心正六边形切面上速度矢量叠加压力或速度云图分布以及60

  17. 不同挡流板形式紫外线消毒仪杀菌效果模拟%Numerical simulation of sterilizing efficiency of ultraviolet disinfection reactors with different flow baffle types

    Institute of Scientific and Technical Information of China (English)

    牛培平; 丁日升; 宋卫堂; 王媛

    2015-01-01

    Nutrient solution recycling has become one of the essential techniques of soilless cultivation. But nutrient solutions are susceptible to be polluted by infectious diseases during the recycling process, so it is needed to disinfect nutrient solutions before recycling use. Compared to other disinfection methods of common nutrient solutions, ultraviolet (UV) disinfection has many advantages, such as high efficiency, low cost, not changing the physical and chemical properties of nutrient solutions, so UV disinfection is an environment-friendly technology of nutrient solution treatment.In general, experimental research and numerical simulation are the most common methods of UV disinfection. Although experimental results of the performance of UV disinfection reactor are credible, direct measurement is difficult and costly and thus seldom done. On the other hand, one can use numerical simulation techniques to model the UV disinfection. Computational fluid dynamics (CFD) has been widely used for simulating the UV disinfection. In previous studies, some researchers analyzed the performance of small-scale horizontal UV disinfection reactors with different flow baffle numbers and flow areas. They designed an alternately arranged flat-type flow baffle and analyzed the performance of the UV disinfection device for nutrient solutions using the CFD simulations and the measurements of biological bacterial disinfection. However, the effects of different flow baffle types on the performance of the UV disinfection reactor have seldom been investigated. In this study, we designed 5 different flow baffle types of the UV disinfection reactor. The main objectives were to increase disinfection efficiency by optimizing the flow baffle arrangement and to test the performance of the UV disinfection reactor with different flow baffle types. The 5 different flow baffle types were proposed: 2 circular channels and annulus alternation, 2 circular channels, 4 circular channels and annulus

  18. 3-D numerical study of the effect of Reynolds number and baffle angle on heat transfer and pressure drop of turbulent flow of air through rectangular duct of very small height

    Directory of Open Access Journals (Sweden)

    Abhijit Paul

    2016-09-01

    Full Text Available Present article illustrates a computational study of three-dimensional steady state heat transfer and high turbulent flow characteristics through a rectangular duct with constant heat fluxed upper wall and single rectangular cross-sectioned baffle insertion at different angles. RNG k–ɛ model along with standard wall function based computations has been accomplished applying the finite volume method, and SIMPLE algorithm has been executed for solving the governing equations. For a Reynolds number, Re of 10,000 to 50,000, Prandtl Number, Pr of 0.707 and baffle angle, α of 30°, 60°, 90°, 120°, 150°, computational studies are executed, centred onto the hydraulic diameter, Dh, test section and hydrodynamic entry length of the duct. Flow field has been solved using Ansys Fluent 14.0 software. Study exposes that baffled rectangular duct has a higher average Nusselt number, Nu and Darcy friction factor, f compared to a smooth rectangular duct. Nu as well as f are found to be maximum at 90° baffle angle. Results illustrate that both α and Re play a significant role in heat transfer as well as flow characteristics and also effects TEF. The correctness of the results attained in this study is corroborated by comparing the results with those existing in the literature for smooth rectangular duct within a precision of ±2% for f and ±4% for Nu.

  19. Study on a Flat Plate Solar Air Collector with Baffles%扰流板型太阳能平板空气集热器集热性能

    Institute of Scientific and Technical Information of China (English)

    夏佰林; 赵东亮; 代彦军; 李勇

    2011-01-01

    对一种扰流板型太阳能平板空气集热器的集热性能进行了研究,并对各种影响集热器热性能的因素进行了分析,揭示了总热损失系数、扰流板肋片效率、流道内空气流速和扰流板的间距对效率因子和热迁移因子的影响机理.获得了扰流板型太阳能平板空气集热器的集热效率理论表达式,为此类太阳能空气集热器的设计及应用提供了参考.%A flat plate solar air collector with baffles was studied. Several factors that have influence on the thermal performance of the solar collectors were analyzed. The paper investigated the relations between the efficiency factor, the heat-removal factor of the solar air collector and the total heat loss coefficient, baffles fin efficiency, air velocity inside the flow channel, the space between baffles, and the height of baffles. Also, the time constant of the collectors was studied. The theoretical formula of the collector's thermal efficiency was obtained, which can be used for design and application of such kind of collectors.

  20. 遮光罩对GEO对地激光通信系统可通率影响%The Influence of Baffle for Available Probability of GEO Laser Communication System

    Institute of Scientific and Technical Information of China (English)

    周鑫弘; 李小明; 韩成; 张立中; 康一丁

    2015-01-01

    地球同步卫星(GEO)对地激光通信系统具有通信速率高、保密性好等优势.但系统的光学天线暴露在星体外部,太阳照射对可通率影响严重.针对某GEO对地激光通信系统,不同长度遮光罩对太阳规避造成的可通率及比刚度影响的分析,证明增加遮光罩长度系统可通率提升效果明显.对现有遮光罩形式进行了分析与总结,简述工程中遮光罩长度的确定与限定条件,为优化设计GEO激光通信系统遮光罩及提高系统可通率提供技术基础.%GEO to ground laser communication is characterized by high speed,security. The optical antenna of GEO la-ser communication system exposes outside of satellite. Solar radiation unable to avoid,it affects the optical system seri-ously, reduces available probability. Analyze the effect of these factors for available probability and emphasize analysis the effect of baffle's length. The results show that, increase the length of baffle can increase the available probability. The paper hood length determination and in the engineering qualification.Then in order to optimize the design of baffle GEO laser communication systems summarizes the baffle structure form,provide support for increase the performance of baffle.

  1. 大管孔导流板管壳式换热器及其计算%Big Hole Baffle Tube and Shell Heat Exchanger Calculation

    Institute of Scientific and Technical Information of China (English)

    刘炳福

    2016-01-01

    管壳式换热器的折流板有圆缺形、碟环形等,使气体折流横过换热管流动,有其缺点。大管孔导流板是将这种板制作成一块整版,板上的管孔开大,叫大管孔导流板,即管孔直径比换热管直径大10%以上,让管隙流体全部导流从换热管外壁与大管孔的环隙间流过,使流体更趋向于紧贴换热管壁内外逆流传热。实践证明传热效果很好。还介绍了这种换热器传热系数和压力降的计算公式,很有实用价值。%shell and tube heat exchanger baffles have a moon-shaped,annular plate,so that the gas flow deflector across the heat exchange tubes,has its drawbacks.Big hole baffle plate is to make this into a full-page,open a large hole board,called the big hole deflector that pore diameter than the diameter of the heat transfer tubes more than 10% larger,so that tube gap all heat exchange fluid diversion from the outer ring with the big hole interstitial flow through the fluid tend to close the inner and outer countercurrent heat exchange tube has proved very good heat transfer effect.This also describes the formula coefficient of heat transfer and pressure drop, very practical value.

  2. On the Uplift Forces of Waves on the Piled Baffle Permeable Breakwater%桩基挡板式透空堤底板波浪的上托力

    Institute of Scientific and Technical Information of China (English)

    茆福文; 陈德春; 董霞

    2013-01-01

    The uplift forces of waves acting on the plate are the important parameters for designing the piled baffle permeable breakwater.Based on the wave model test,the wave steepness and superelevation are analyszd which are the main factors that influence the uplift forces of the impact pressure on the plate.Through the dimensional analysis and linear regression method,the empirical formula of calculating the uplift forces of the impact pressure on the plate of piled baffle permeable breakwater is derived when 1.67 < d/H < 3.2,0.03 < H/L < 0.1and-0.16 < △h/H < 0.48.Finnaly,compared with the former results,the experimental data show that the expirical formula is consistent with the experiment.%波浪对底板的上托力是桩基挡板式透空堤设计的重要参数.通过波浪模型试验,分析波陡、超高等因素对其底板波浪上托力冲击压强的影响,采用因次分析和线性回归方法,得到1.67<∥H< 3.23,0.03 <H/L <0.1,-0.16<△h/H<0.48波浪条件下,桩基挡板式透空堤底板波浪上托力冲击压强的计算公式,并与以往公式进行比较.试验资料表明,该公式与试验值有较好的一致性.

  3. 热镀锌过程挡板对镀层均匀性影响的模拟研究%Computational studies on coating uniformity influenced by baffle in hot dip galvanizing process

    Institute of Scientific and Technical Information of China (English)

    富聿晶; 张红梅; 李培兴; 赵红阳

    2015-01-01

    为解决热镀锌过程中常出现的边部过镀锌缺陷,利用数值模拟方法对热镀锌气刀射流喷吹过程进行仿真研究,分析了挡板厚度对带钢边部压力场的影响;并借助镀层厚度计算模型,计算挡板厚度和边部角度对镀层厚度的作用关系;同时通过不同拉钢速度、气刀狭缝总压等工况,对挡板的厚度及边部角度进行优化。结果表明:随挡板厚度减小,带钢边部作用力增大并逐渐接近中心处;带钢边部镀层厚度随挡板厚度的减小而变薄,随挡板边部角度的增加而先减小后增大;挡板厚度2 mm、边部角度90°时,能有效提高带钢横向作用力和镀层分布的均匀性。%Numerical simulation of the gas⁃jet wiping in hot dip galvanizing process was conducted, aiming to reduce the possible of edge over coating ( EOC) . The effects of baffle thickness and edge angle on pressure fields of strip edge were studied. By using the analytic model of film thickness, the correlation betweent the coating thickness and baffle thickness and edge angle was revealed. Considering different conditions of steel moving speed and total gas knife pressure, the baffle thickness and edge angle were optimized .The results show that the coating thickness of strip edge increases with the decrease of baffle thickness. In addition, with the increase of baffle edge angle, the coating thickness decreases firstly and then increases. When the baffle thickness is 2 mm and the angle is 90°, uniformity distribution of the pressure and coating on the strip is achieved.

  4. Manufacturing Technique of U Rod Baffle Heat Exchanger under High Temperature and Pressure%高温高压U型折流杆换热器的制造技术

    Institute of Scientific and Technical Information of China (English)

    赵洪勇

    2015-01-01

    Rod baffle heat exchanger is a kind of shell-and-tube heat exchanger made up with a series of small baffle rods.It is designed for the purpose of reducing the flow-induced tube vibration in normal plate baffle heat exchanger.Coordinate precision between rod baffles and heat exchange tube determines wheth-er the bundles in heat exchanger meet the certain design requirements.The technique of manufacturing U rod baffle heat exchanger under high temperature and pressure shall overcome the difficulties of baffle ring assembly,heat exchange tube bending,stress relief treatment and high assembly precision.Making break-throughs on above difficulties,our company tackles the processing and manufacturing problems in fabrica-ting a petrochemical company second converter waste heat boiler(E -8).%折流杆式换热器是一种壳体内的折流元件由一系列细小的折流杆组成的管壳式换热器,是为了改善常规的板式折流板换热器的流体诱导振动而设计的。折流杆与换热管之间的配合是否精密,决定了换热器管束是否能够满足设计技术要求。而对于高温高压工况下的 U 型折流杆换热器,在制造技术上需克服折流圈的装配、换热管消应力处理、装配精度高等相应难题。在某石化公司第二转换炉废热锅炉(E -8)制造过程中,针对以上制造难点进行了攻关,通过提高换热管的精度要求、采用模具组装法保证折流圈组对间隙、对每个规格的 U 型管在弯制中进行预估,并采用整体入炉热处理方法控制变形量,解决了制造过程中的加工工艺以及制造上的难题。

  5. Effects of baffle on acoustic attenuation performance of micro-perforated tube muffler%隔板对汽车微穿孔管消声器声学特性的影响

    Institute of Scientific and Technical Information of China (English)

    左曙光; 龙国; 吴旭东; 张孟浩; 相龙洋; 张珺

    2014-01-01

    为分析隔板对微穿孔管消声器声学特性的影响,该文首先通过试验验证微穿孔管消声器传递损失数值计算方法,然后建立带隔板微穿孔管消声器传递损失的理论模型并利用数值方法进行验证,最后基于理论模型分析了隔板对微穿孔管消声器传递损失的影响。分析发现,隔板位置影响主消声频带及传递损失大小,隔板越靠近中间位置,第一拱形衰减域向高频扩大,且传递损失越大;隔板数目增加,传递损失相应增大,但当隔板数目达到一定值时传递损失不再显著增大;在简单微穿孔管消声器内加隔板后,可以适当缩短膨胀腔长度,而不会明显降低该消声器消声性能,此方法可大大降低消声器的轴向长度,对微穿孔管消声器的优化设计具有指导意义。%The correctness of the numerical finite element method to calculate transmission loss (TL) of the micro-perforated tube muffler is validated through the measurement of the transmission loss of a micro-perforated tube muffler sample. The transmission loss is measured by a two-load technique that is usually applied to measure the acoustic impedance of micro-perforated panel (MPP) and the transmission loss of various mufflers. A theoretical calculation model of the transmission loss of the micro-perforated tube muffler with a baffle is then established and afterwards verified by the finite element method that has been previously validated. The theoretical model is based on the analysis of a simple pass-through micro-perforated muffler and the plane wave theory. The transfer matrix method is applied to connect the sound pressure and particle velocity of the inlet and the outlet of the muffler. Additionally, boundary conditions and continuity requirements are considered in the theoretical modeling process. Finally, several analyses of the effect of the baffle on the transmission loss of the micro-perforated tube muffler

  6. 螺旋折流板换热器局部流场和温度场的数值研究%Numerical Study on Local Flow Field and Temperature Field of Helical Baffles Heat Exchanger

    Institute of Scientific and Technical Information of China (English)

    许伟峰; 王珂; 靳遵龙; 刘敏珊

    2015-01-01

    建立连续螺旋折流板换热器和四分螺旋折流板换热器模型,采用大型CFD分析软件FLUENT借助数值模拟的方法,研究螺旋折流板换热器局部流场和温度场的分布规律,并采用(火积)耗散原理对两种折流板结构下换热器的综合性能进行对比研究.结果表明,以(火积)耗散分析为指标的评价标准同以换热器综合性能为指标的评价标准具有一致性.相同的壳程流量下,同四分螺旋折流板换热器相比,连续螺旋折流板换热器(火积)耗散值较小.两种折流板类型的换热器局部流场和温度场分布均呈现出相同的规律,壳程中心部位,换热管壁面传热系数最高,沿壳体径向,流体螺旋流动状态和换热管壁面传热系数均呈现先减小后增加的现象.同连续折流板相比,折流板的不连续性在小流量下能够促进壳程中心部位的局部传热,当流量增大到一定程度则表现为减弱壳程中心部位的局部传热.计算结果为改进螺旋折流板结构形式提供了理论依据.%Models of continuous helical baffles and quarter helical baffles heat exchangers are established. With large CFD analysis software FLUENT, the distribution characteristics of local flow field and temperature field of helical baffles heat exchangers are investigated through numerical simulation. And comprehensive performances of both heat exchangers are compared and studied with entransy dissipation. The results show:In the research of heat exchanger, the evaluation standard of entransy dissipation is consistent with that of comprehensive performances. When the flow of shell side is the same, the entransy dissipation value of continuous helical baffles heat exchanger is less than that of quarter helical baffles heat exchanger. The distribution characteristics of local flow field and temperature field of both heat exchangers present the same rules, in the central part of shell side, heat transfer coefficient of tubes is

  7. Numerical Analysis on Enhanced Heat Transfer of the Segmental Baffle in the Shell Side of the Heat Exchanger%弓形折流板强化换热器壳程传热数值分析

    Institute of Scientific and Technical Information of China (English)

    张江勇; 苏慧; 孟强

    2012-01-01

    为了分析弓形折流板强化换热器壳程传热机制,在原换热器模型的基础上增设了折流板.利用FLUENT软件建立弓形折流板换热器的三维模型,模拟得到不同工况下的换热器温度场、流场分布图及传热量、总传热系数等相关数据.将上述数据与原模型数值模拟结果进行对比,结果表明:弓形折流板强化换热器壳程传热效果明显,验证了换热器结构优化的合理性和必要性.%In order to analyze the enhanced heat transfer mechanism of segmental baffle in the shell side of the heat exchanger, segmental baffles were added to optimize the design of the original model of shell-and-tube heat exchanger. The three-dimension models of the segmental baffle heat exchangers were set up using FLUENT software, and distribution maps of temperature field and flow field, relevant datas including the capacity of heat transmission and the total heat transfer coefficient in different conditions were gotten. Comparing the numerical simulation results with the original model data, it is shown that the enhanced heat exchanger effect of segmental baffles in the shell side of the heat exchanger is obvious. So the structure optimization of heat exchanger is' necessary and rational.

  8. On the effect of added impurity on crystal purity of urea in an oscillatory baffled crystallizer and a stirred tank crystallizer

    Science.gov (United States)

    McLachlan, Hannah; Ni, Xiong-Wei

    2016-05-01

    Previous work has indicated that crystals produced in oscillatory baffled crystallisers (OBC) from a relatively 'pure' starting environment gave statistically higher purities than that in stirred tank crystallisers (STC) under comparable conditions. In this work, a known amount of biuret (the impurity) was added to the 'pure' urea system and the results show that the OBC still produced higher purity crystals than the STC, although these purity values were statistically lower than from the 'pure' environment in both vessels. By evaluating crystallisation rates of both urea and biuret, we noticed that these rates are higher in the STC than in the OBC, which would have led to small crystals in the former vessel. The CSD data however gave the opposite result where the CSD is wider with more, large crystals in the STC than in the OBC, in particular in the presence of added impurity. These larger crystals are likely formed due to agglomeration coupled with incorporation of impurity, which leads to a lower purity.

  9. Physical-chemical and operational performance of an anaerobic baffled reactor (ABR treating swine wastewater - 10.4025/actascitechnol.v32i4.7203

    Directory of Open Access Journals (Sweden)

    Erlon Lopes Pereira

    2010-12-01

    Full Text Available Since hog raising concentrates a huge amount of swine manure in small areas, it is considered by the environmental government organizations to be one of the most potentially pollutant activities. Therefore the main objective of this research was to evaluate by operational criteria and removal efficiency, the performance of a Anaerobic Baffled Reactor (ABR, working as a biological pre-treatment of swine culture effluents. The physical-chemical analyses carried out were: total COD, BOD5, total solids (TS, fix (TFS and volatiles (TVS, temperature, pH, total Kjeldahl nitrogen, phosphorus, total acidity and alkalinity. The ABR unit worked with an average efficiency of 65.2 and 76.2%, respectively, concerning total COD and BOD5, with a hydraulic retention time (HRT about 15 hours. The results for volumetric organic loading rate (VOLR, organic loading rate (OLR and hydraulic loading rate (HLR were: 4.46 kg BOD m-3 day-1; 1.81 kg BOD5 kg TVS-1 day-1 and 1.57 m3 m-3 day-1, respectively. The average efficiency of the whole treatment system for total COD and BOD5 removal were 66.5 and 77.8%, showing an adequate performance in removing the organic matter from swine wastewater.

  10. Performance of a novel baffled osmotic membrane bioreactor-microfiltration hybrid system under continuous operation for simultaneous nutrient removal and mitigation of brine discharge

    KAUST Repository

    Pathak, Nirenkumar

    2017-03-14

    The present study investigated the performance of an integrated osmotic and microfiltration membrane bioreactor system for wastewater treatment employing baffles in the reactor. Thus, this reactor design enables both aerobic and anoxic processes in an attempt to reduce the process footprint and energy costs associated with continuous aeration. The process performance was evaluated in terms of water flux, salinity build up in the bioreactor, organic and nutrient removal and microbial activity using synthetic reverse osmosis (RO) brine as draw solution (DS). The incorporation of MF membrane was effective in maintaining a reasonable salinity level (612-1434 mg/L) in the reactor which resulted in a much lower flux decline (i.e. 11.48 to 6.98 LMH) as compared to previous studies. The stable operation of the osmotic membrane bioreactor–forward osmosis (OMBR-FO) process resulted in an effective removal of both organic matter (97.84%) and nutrient (phosphate 87.36% and total nitrogen 94.28%), respectively.

  11. Evaluation of A Novel Split-Feeding Anaerobic/Oxic Baffled Reactor (A/OBR) For Foodwaste Anaerobic Digestate: Performance, Modeling and Bacterial Community

    Science.gov (United States)

    Wang, Shaojie; Peng, Liyu; Jiang, Yixin; Gikas, Petros; Zhu, Baoning; Su, Haijia

    2016-10-01

    To enhance the treatment efficiency from an anaerobic digester, a novel six-compartment anaerobic/oxic baffled reactor (A/OBR) was employed. Two kinds of split-feeding A/OBRs R2 and R3, with influent fed in the 1st, 3rd and 5th compartment of the reactor simultaneously at the respective ratios of 6:3:1 and 6:2:2, were compared with the regular-feeding reactor R1 when all influent was fed in the 1st compartment (control). Three aspects, the COD removal, the hydraulic characteristics and the bacterial community, were systematically investigated, compared and evaluated. The results indicated that R2 and R3 had similar tolerance to loading shock, but the R2 had the highest COD removal of 91.6% with a final effluent of 345 mg/L. The mixing patterns in both split-feeding reactors were intermediate between plug-flow and completely-mixed, with dead spaces between 8.17% and 8.35% compared with a 31.9% dead space in R1. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis revealed that the split-feeding strategy provided a higher bacterial diversity and more stable bacterial community than that in the regular-feeding strategy. Further analysis indicated that Firmicutes, Bacteroidetes, and Proteobacteria were the dominant bacteria, among which Firmicutes and Bacteroidetes might be responsible for organic matter degradation and Proteobacteria for nitrification and denitrification.

  12. Reduction of COD and Turbidity of Effluent in the Swine Productions Unit Employing Anaerobic Baffled Reactor (ABR Followed by Biological Filters and Sand Filter

    Directory of Open Access Journals (Sweden)

    Euzebio Beli

    2010-04-01

    Full Text Available The growing swine production is constantly in conflict with the environment due to the lack of environmental management directed to the cycle of animal production and the industrial sector, mainly due to the mishandling of slurry produced. In association with large concentrations of confined animals appear huge dumps of organic matter, inorganic nutrients and gaseous emissions, which require special care for its disposal to the environment. The aim of this study was to evaluate the use of an anaerobic baffled reactor (ABR in series with two downflow biological filters, followed by a sand filter as a polishing treatment. It were analyzed the reduction of COD and turbidity, and the behavior of pH in all phases of treatment. The removal of COD in the conjugated system, which occurred during treatment ranged from 74.55% to 94.41% with an average removal of 84.24%. In turn, the removal of turbidity from the period ranged from 53.07% to 96.11% with an average removal of 85.49%. In the studied period the pH changed from 5,6 to 8,4. This system was efficient in the removal of COD and turbidity of swine wastewater.

  13. Effect of thermal pre-treatment on inoculum sludge to enhance bio-hydrogen production from alkali hydrolysed rice straw in a mesophilic anaerobic baffled reactor.

    Science.gov (United States)

    El-Bery, Haitham; Tawfik, Ahmed; Kumari, Sheena; Bux, Faizal

    2013-01-01

    The effect of thermal pre-treatment on inoculum sludge for continuous H2 production from alkali hydrolysed rice straw using anaerobic baffled reactor (ABR) was investigated. Two reactors, ABR1 and ABR2, were inoculated with untreated and thermally pre-treated sludge, respectively. Both reactors were operated in parallel at a constant hydraulic retention time of 20 h and organic loading rate ranged from 0.5 to 2.16 g COD/L d. The results obtained indicated that ABR2 achieved a better hydrogen conversion rate and hydrogen yield as compared with ABR1. The hydrogen conversion rates were 30% and 24%, while the hydrogen yields were 1.19 and 0.97 mol H2/mol glucose for ABR2 and ABR1, respectively. Similar trend was observed for chemical oxygen demand (COD) and carbohydrate removal, where ABR2 provided a removal efficiency of 53 +/- 2.3% for COD and 46 +/- 2% for carbohydrate. The microbial community analysis using 16S rRNA phylogeny revealed the presence of different species of bacteria, namely Clostridium, Prevotella, Paludibacter, Ensifer, and Petrimonas within the reactors. Volatile fatty acids generated from ABR1 and ABR2 were mainly in the form of acetate and butyrate and a relatively low fraction ofpropionate was detected in ABR1. Based on these results, thermal pre-treatment ofinoculum sludge is preferable for hydrogen production from hydrolysed rice straw.

  14. Studies on Flow Characteristic of Heat Exchangers With Helical Baffles%螺旋折流板换热器流动特性研究

    Institute of Scientific and Technical Information of China (English)

    王素华; 王树立; 赵志勇

    2001-01-01

    The flow field in shell-and-tube heat exchan gers with helical baffles was measured using LDV, The influence on the velocity distribution , impulsive speed by helix inclination angle and flow rate was inve stigated. The influence on heat-exchanging capability and flow resistance of vel ocity distribution was also investigated. The dimension of heat-exchanger used i n experiments is 200 mm×6 mm×3 000 mm(outer diameter ×wall thickness×lengt h) and is made of organic glass. The tube bundle was consists of 52 tubes with externa l diameter 15 mm. There are four kinds of baffle inclination angles designed in double helix style, namely 30,35,40,42°. The actuating medium working unde r normal temperature is service water. The rotator flowmeter is chosen to measur e the volume of flow varying from 3 to 20 m3/h. Generally, the line spe ed and impulsive speed will increase with helix inclination angle decreasing correspon dingly, which promotes the heat-exchanging capability. The flow volume increasin g makes velocity distribute along diameter uniformly. But flow loss will increas correspondingly with helix inclination angle decreasing , especially when helix inclination angle is less than 35°, the loss increases sharply.With a comprehe nsive consideration, it is proposed that the helix inclination angle be 35°.%用激光测速仪详细测量了螺旋折流板换热器的流场特性 ,着重研究了旋流角对速度分布和对脉动速度的影响及其与流量的偶合关系,并对速度分布 对换热性能及阻力的影响做了详细的分析和讨论。模型换热器采用有机玻璃制作,壳体尺寸 为200 mm×6 mm×3 000 mm(外径×壁厚×长度),换热管外径为15 mm,共52根,均匀布置 。折流板倾斜角度取30,35,40,42°四种,双头布置。实验介质为常温下自来水, 流量测量采用转子流量计,流量范围为3~20 m3/h。一般情况下, 随着旋流角的减小, 切 向速度分量增大, 脉动速

  15. Relationships between chemical oxygen demand (COD) components and toxicity in a sequential anaerobic baffled reactor/aerobic completely stirred reactor system treating Kemicetine.

    Science.gov (United States)

    Sponza, Delia Teresa; Demirden, Pinar

    2010-04-15

    In this study the interactions between toxicity removals and Kemicetine, COD removals, intermediate products of Kemicetine and COD components (CODs originating from slowly degradable organics, readily degradable organics, inert microbial products and from the inert compounds) were investigated in a sequential anaerobic baffled reactor (ABR)/aerobic completely stirred tank reactor (CSTR) system with a real pharmaceutical wastewater. The total COD and Kemicetine removal efficiencies were 98% and 100%, respectively, in the sequential ABR/CSTR systems. 2-Amino-1 (p-nitrophenil)-1,3 propanediol, l-p-amino phenyl, p-amino phenol and phenol were detected in the ABR as the main readily degradable inter-metabolites. In the anaerobic ABR reactor, the Kemicetin was converted to corresponding inter-metabolites and a substantial part of the COD was removed. In the aerobic CSTR reactor the inter-metabolites produced in the anaerobic reactor were completely removed and the COD remaining from the anerobic reactor was biodegraded. It was found that the COD originating from the readily degradable organics did not limit the anaerobic degradation process, while the CODs originating from the slowly degradable organics and from the inert microbial products significantly decreased the anaerobic ABR reactor performance. The acute toxicity test results indicated that the toxicity decreased from the influent to the effluent of the aerobic CSTR reactor. The ANOVA test statistics showed that there was a strong linear correlation between acute toxicity, CODs originating from the slowly degradable organics and inert microbial products. A weak correlation between acute toxicity and CODs originating from the inert compounds was detected.

  16. Effects of nitrobenzene concentration and hydraulic retention time on the treatment of nitrobenzene in sequential anaerobic baffled reactor (ABR)/continuously stirred tank reactor (CSTR) system.

    Science.gov (United States)

    Kuscu, Ozlem Selcuk; Sponza, Delia Teresa

    2009-04-01

    The effects of increasing nitrobenzene (NB) concentrations and hydraulic retention times (HRT) on the treatment of NB were investigated in a sequential anaerobic baffled reactor (ABR)/aerobic completely stirred tank reactor (CSTR) system. In the first step of the study, the maximum COD removal efficiencies were found as 88% and 92% at NB concentrations varying between 30 mg L(-1) and 210 mg L(-1) in ABR. The minimum COD removal efficiency was 79% at a NB concentration of 700 mg L(-1). The removal efficiency of NB was nearly 100% for all NB concentrations in the ABR reactor. The methane gas production and the methane gas percentage remained stable (1500 mL day(-1) and 48-50%, respectively) as the NB concentration was increased from 30 to 210 mg L(-1). In the second step of the study it was found that as the HRT decreased from 10.38 days to 2.5 days the COD removal efficiencies decreased slightly from 94% to 92% in the ABR. For maximum COD and NB removal efficiencies the optimum HRT was found as 2.5 days in the ABR. The total COD removal efficiency was 95% in sequential anaerobic (ABR)/aerobic (CSTR) reactor system at a minimum HRT of 1 day. When the HRT was decreased from 10.38 days to 1 day, the methane percentage decreased from 42% to 29% in an ABR reactor treating 100 mg L(-1) NB. Nitrobenzene was reduced to aniline under anaerobic conditions while aniline was mineralized to catechol with meta cleavage under aerobic conditions.

  17. Structure Optimization for Heat Exchanger Baffle Based on Computational Fluid Dynamics Simulation of Thermal-Fluid-Structure Coupling%基于计算流体力学热流固耦合仿真的换热器折流板结构优化

    Institute of Scientific and Technical Information of China (English)

    张仂; 谷芳

    2012-01-01

    采用多物理场耦合方法,建立了管壳式换热器的计算流体力学(CFD)热流固耦合仿真分析模型,对20种不同折流板结构参数的管壳式换热器进行了流动与传热的数值模拟.CFD仿真计算结果显示,换热器的折流板间距和折流板缺口高度对流动和传热的影响相互关联,不能进行单目标优化设计.以JF因子作为换热器综合性能的评价准则,对管壳式换热器的折流板间距和折流板缺口高度进行了结构优化设计,提出在换热器内径(d)200 mm、换热管长1140 mm、并流条件下,该换热器的最佳折流板间距为80 mm(折流板数目为10),最佳折流板缺口高度为0.3d(即60 mm).%A thermal-fluid-structure coupling simulation model for shell-and-tube heat exchangers was established based on computational fluid dynamics(CFD) by a multi-physical field coupling method. The flow and heat transfer in 20 different types of shell-and-tube heat exchangers with different baffle structural parameters were simulated by the model. The CFD simulation results showed that the effects of the baffle spacing and baffle gap height on the flow and heat transfer interconnected, which showed that the single-objective optimization could not be achieved. With JF factors as the evaluation criteria of the heat exchanger performances, the baffle spacings and baffle gap heights in the shell-and-tube heat exchangers were optimized. It was put forward that under the conditions of parallel flow, inside diameter of the heat exchanger(d)200 mm and heat exchange tube length 1 140 mm, the baffle space and baffle gap height were 80 mm(the baffle number 10) and 0.3d(60 mm), respectively.

  18. Characteristics and hydrogen production efficiency in anaerobic baffled reactor (ABR) system%ABR发酵系统运行特性及产氢效能研究

    Institute of Scientific and Technical Information of China (English)

    郑国臣; 李建政; 昌盛; 张照韩; 官涤; 金羽; 郭静波; 卢海凤

    2013-01-01

    To solve the continuous-flow stirred tank reactor (CSTR) hydrogen system has low efficient and waste energy,a 3-compartment anaerobic baffled reactor (ABR), with an effective volume of 27.8L, was adapted and its performing characteristics and hydrogen production efficiency were investigated,using diluted molasses as the material. ABR had higher efficiency and lower energy consumption comparing with CSTR. ABR achieved stable ethanol type fermentation within 26d with 35℃ and initial COD of 5000mg/L, and the specific hydrogen production rate was 0.13L/(gMLVSSd) while that of CSTR under the same conditions was 0.06L/g MLVSS-d. Results showed that ABR was an ideal facility for hydrogen production from organic wastewater fermentation.%为解决连续流搅拌槽式反应器(CSTR)发酵制氢系统存在的不足,如单位基质氢气转化率低、因搅拌带来的耗能,抗负荷冲击能力不强等问题,开展了厌氧折流板反应器(ABR)发酵产氢的研究.结果表明,在35℃和进水COD 5000mg/L等条件下,ABR系统可在26d达到乙醇型发酵,其比产氢速率为0.13L/(gMLVSS.d),而在同样条件下,CSTR达到乙醇型发酵后,比产氢速率仅为0.06L/(gMLVSS.d).ABR通过生物相的分离,使产氢系统梯级利用有机物并达到深度产氢的目的.与CSTR相比,ABR具有较高的产氢活性、较低能源消耗等优点,是一种较为理想的有机废水发酵制氢反应设备.

  19. 多组螺旋叶片折流板换热器性能试验研究%Experiment Research on Heat Transfer Performance in Multiple Sets of Shell and Tube Heat Exchangers With Spiral Blade Baffles

    Institute of Scientific and Technical Information of China (English)

    李林; 高磊; 张莹莹; 黄伟

    2013-01-01

    The test of heat transfer performance was carried out in five the spiral blade baffles heat exchangers, and their shell heat transfer and pressure drop were compared. Through analysis and regression calculation of experimental data, experience formulas of shell-side heat transfer coefficient and pressure drop were obtained. This result could provide a reference for numerical simulation and design of spiral blade baffles heat exchangers.%  进行了5组参数下螺旋叶片折流板换热器传热性能试验,对比壳程传热和压降性能,并对试验数据进行回归计算,获得其壳程传热系数和压力降的经验计算公式。结果可为螺旋叶片折流板换热器系统模拟和设计计算提供参考。

  20. 波形隔板对平板式生物反应器传质及混合性能的影响%Effect of Waved Baffle Panel on Mass Transfer and Mixing Performance of Flat Plate Photobioreactor

    Institute of Scientific and Technical Information of China (English)

    王淋淋; 尤学一

    2012-01-01

    The computational fluid dynamics was applied to simulate the flow field of a flat plate photobioreactor (PBR) with waved baffle panel. After the reliability of model was validated, the effects of two structural parameters of waved baffles, i.e. the ratio of waved baffles height to wave length (L/λX) and ratio of wave amplitude to wave length (A/λ) on the mass transfer and mixing performance were systematically analyzed. The results showed that when L/λ=12, better mass transfer and mixing performance were obtained and those related parameters such as the liquid volumetric mass transfer coefficient (kLa), ratio of cycle time of the downcomer to that of PBR (ff) and averaged turbulence kinetic energy (Em) were higher. Besides, the obtained liquid velocity was close to the optimum value being most favorable to microalgal growth. When L/λ12 and A/λ=0.8, the mass transfer performance was the best and the value of kLa was increased by about 10% compared with that of bioreactor with flat baffles. As L//b=l2 and A/λ0.4, the mixing performance of the reactor was the best and the value of Em was increased by 14.7% compared with that of bioreactor with flat baffles.%对带波纹隔板的平板式生物反应器,利用计算流体动力学进行流场模拟,验证模型可靠性后,系统分析波纹隔板高/波长(L/λ)和波幅/波长(A/λ)两个波纹隔板结构参数对反应器传质及流动混合特性的影响.结果表明,当L/λ=12时,传质及流动混合性能较好,液相体积传质系数(kLa)、平均湍动能(Em)、下降区停留时间占循环一周时间之比(θ)等表征传质及混合的参数值均较大,得到的液体流速在微藻生长的最佳流速附近.当A/λ=0.8时,反应器的传质性能最优,kLa比采用平直隔板时增加了约10%;当A/λ=0.4时,反应器的混合效果最佳,Em比采用平直隔板时增加14.7%.

  1. Parameters optimization of solar air collector with holes on baffles%开孔型折流板太阳能空气集热器参数优化

    Institute of Scientific and Technical Information of China (English)

    胡建军; 马龙; 刘凯彤; 孙喜山

    2016-01-01

    The introduction of baffles can effectively improve the efficiency of flat plate solar air collector. But at the same time, it is found that the flow separation on the back side of the baffle leads to the generation of local vortex, which causes the airflow to be heated in the corresponding position. The local temperature is higher and the heat loss is serious. This has become an important factor affecting the further improvement of the efficiency of solar air collector. Based on the aerodynamics of wind wall, the author is aim to open holes on the baffles without changing the whole structure of collector. Thus, we can use the hole jets to enhance the turbulence and mixing of the flow at the back side of the baffle, suppress the local vortex and reduce the heat loss; Also, the hole jets can enhance the convection heat transfer of air and heat absorber plate, which can make more heat into the air, and then achieve the purpose of improving the efficiency of solar air collector. The paper studies the impact of different parameters on solar air collector with holes on the internal baffles by using orthogonal numerical simulation test method. Considering the interaction between aperture factors, an L27(313) orthogonal experiment is designed with four factors and three values including hole size, location, quantity and mass flow rate. 27 solar air collector models with holes on the internal baffles are designed, and the three-dimensional numerical simulation of the designed condition is carried out. The efficiencies of the 27 designed collector models are obtained. The simulation results by variance analysis method are analyzed. The variance analysis is used to determine the significant level of the factors by F test. If the ratio of the F ratio and the critical value is greater than 1, it is considered that the factor has a significant effect on the collector efficiency. The results show that the interaction between the hole factors is not obvious. The effect of inlet

  2. 倾斜角对周向重叠三分螺旋折流板换热器性能的影响%Impacts of incline angle on performances of circumferential overlap trisection helical baffle heat exchangers

    Institute of Scientific and Technical Information of China (English)

    董聪; 陈亚平; 吴嘉峰

    2016-01-01

    对倾斜角为16°,20°,24°,28°,32°单头(即16°CO,20°CO,24°CO,28°CO和32°CO)和32°双头(即2-32°CO)6种周向重叠三分螺旋折流板换热器(cothSTHXs)以及作为对比的弓形折流板换热器的进行数值模拟,并与已有的实验数据进行比较。采用速度矢量图和压力云图叠加速度矢量的方式分析特殊剖面上局部参数。研究结果表明:数值模拟结果与实际吻合良好。螺旋折流板方案壳侧通道存在迪恩涡二次流,相邻折流板重叠区内的管排可抑制缺口泄漏,周向重叠结构有利于强化传热;在相同流量下,壳侧换热系数随倾斜角的增大而减小。20°CO倾斜角方案的性能最优,在相同压降下,其壳侧换热系数比其他方案的系数高,且流道内的迪恩涡二次流明显较强。弓形折流板方案的性能最差,其流道中存在流动死区,且壳侧压降远高于所有螺旋折流板方案;在相同压降下,其壳侧换热系数最低,但在相同流量下的壳侧换热系数在所有方案中位列第3,紧随16°CO和20°CO方案之后。%The six circumferential overlap trisection helical baffle shell-and-tube heat exchangers (cothSTHXs) with single thread but baffle incline angles of 16°, 20°, 24°, 28°, 32° (16°CO, 20°CO, 24°CO, 28°CO, 32°CO) as well as double thread and baffle incline angle of 32° (2-32°CO), as opposed to a segment baffle heat exchanger, were numerically simulated and compared with the available experimental data. Local parameter distributions of the velocity vectors or pressure contours plus velocity vectors on special sections were plotted and analyzed. The results show that the simulation results are satisfactory and in agreement with tests. The Dean Vortex secondary flow and bypass leakage between adjacent baffles in the spiral channel play essential roles in the heat transfer enhancement of the cothSTHXs. The shell-side heat transfer coefficient

  3. Influence of Overlap Size on Shell-side Performance of Heat Exchangers With Helical Baffles%搭接量对螺旋折流板换热器壳程性能的影响

    Institute of Scientific and Technical Information of China (English)

    曹兴; 杜文静; 汲水; 程林

    2012-01-01

    对螺旋折流板换热器进行数值模拟,研究相同螺旋角时搭接量对壳程对流传热充分发展段流动与传热性能的影响。结果表明,随搭接量的增大,同流量下壳程传热系数与压降均增大,而同压降下的传热系数降低。连续搭接时,轴向速度沿壳体径向逐渐降低;交错搭接后,轴向速度在搭接点前后变化趋势不同,分布均匀性变差。三角区漏流的切向速度方向与主流相反,强化了中心区域传热;而搭接区漏流的切向速度方向与主流相同,会增大螺旋旁流,不利于传热。搭接量越大,换热管表面换热量沿径向的不均匀性越强。%Numerical simulation of heat exchangers with helical baffles was carried out.The study focused on the effects of overlap size on shell-side flow and heat transfer characteristics under the same helix angle in fully developed regions.The results show that,with the increase of overlap size,both the heat transfer coefficient and pressure drop increase at identical mass flow rate,whereas the heat transfer coefficient decreases at identical pressure drop.When the adjacent baffles are arranged in a continuous manner,the axial velocities gradually decrease along the radial direction.When the baffles are connected in an overlapped manner,the variation trends of axial velocities are different before and after the overlap point,and the distributions get non-uniform.The direction of leakage's tangential velocities in triangle zone is opposite to that of the bulk flow's,which will enhance the heat transfer in central region.The direction of leakage's tangential velocities in overlapped zone is the same with that of the bulk flow's,which will increase the spiral-flow leakage and make against with the heat transfer.The bigger overlap size is,the more non-uniform radial distributions of heat transfer on tubes are.

  4. 面向工程的气动带挡板节流孔音速流导计算方法%Engineering Calculation Method of Sonic Conductance for Pneumatic Orifice with Baffle

    Institute of Scientific and Technical Information of China (English)

    刘文丰; 李刚炎; 杨凡

    2016-01-01

    目前,节流孔的音速流导计算一般只考虑与节流孔直径和长度的关系,没考虑节流孔挡板间隙.该文面向工程需要,针对气动带挡板节流孔音速流导计算问题,建立理论解析的数学模型,在Simulink中构建模型对音速流导进行计算,将计算得到的临界压力比数据,通过拟合的方式得到临界压力比计算式,进而得到带挡板节流孔的音速流导计算式.结合实验,确定音速流导计算式中的参数,将计算式简化成能在工程中使用的简易计算式;利用Fluent对带挡板节流孔模型进行仿真,通过仿真数据确定计算式的有效性与使用范围.%When sonic conductance of orifices is calculated, the diameter and length of the orifice are generally taken into accountbut the gap between the orifice and baffle at present. In this paper, based on the engineering needs, the mathematical model of the theoretical analy-sis and calculation model in Simulink is established for the calculation of the sonic conductance of pneumatic orifice with baffle.Based on the data of critical pressure ratio obtained by Simulink,a formula for calculating the critical pressure ratio is proposed. Then a formula for calculating the sonic conductance of orifice with baffle is proposed.The parameters in the calculation formula can be determined by the com-bination of experiment data. Therefor the formula can be simplified. The effectiveness and scope of the formula is verified by Fluent simula-tion data.

  5. Effect of baffle orientation on heat transfer performance of shell-and-tube heat exchangers%折流板切口方向对管壳式换热器传热性能影响

    Institute of Scientific and Technical Information of China (English)

    文宏刚; 周帼彦; 朱冬生; 覃新川

    2012-01-01

    为了研究单弓形折流板的切口方向对管壳式换热器传热与流动性能的影响,文中通过建立3个不同折流板切口方向的管壳式换热器简化实体模型,运用CFD软件Fluent对管壳式换热器壳程传热与流动状态进行了三维数值模拟.以水为壳程流体介质,在不断改变壳程进口流速,使得壳程进口雷诺数Re在10000到70000范围内变化时,得到了不同状态下的壳程流场与温度场.根据数值模拟结果,以总传热系数α,壳程总压降△p以及单位压降下的传热系数α/△P作为综合衡量标准,分析不同折流板切口方向时的管壳式换热器壳程流场与温度场.数值模拟分析结果表明:折流板为垂直切口方向时,管壳式换热器总传热系数最大,压降最小,综合性能最好,另外2种折流板切口方向的管壳式换热器综合性能差不多.%In order to study the effect of baffle orientation on the heat transfer and pressure drop in a shell-and-tube heat exchanger, three simplified physical models of shell-and-tube heat exchanger with different baffle orientation were built for three dimensional numerical simulation. The shellside turbulent flow and heat transfer characteristics of shell-and-tube heat exchanger were studied by using computational fluid dynamics (CFD) software Fluent. With water as fluid medium, the pressure fields and temperature fields of shellside at different shellside flow rates were gained by constantly changing the shellside inlet flow rates to keep Reynolds numbers ranging from 10 000 to 7 000. According to the numerical simulation results, the performance of three shell and tube heat exchanger models was compared and assessed by using heat transfer coefficient a, pressure drop △p, and the comprehensive performance factor a/△p. The results show that when the baffle orientation is in vertical, the total heat transfer coefficient of shell-and-tube heat exchanger is the maximum, pressure drop is the

  6. 三叶孔板换热器热力性能及其影响因素分析%Investigation of the effects of structural parameters on the thermal performance of heat exchangers with trefoil-baffles

    Institute of Scientific and Technical Information of China (English)

    朱凌云; 杨锦春; 周帼彦; 谭祥辉; 郭震; 朱辉; 郎红方; 朱冬生

    2014-01-01

    建立了三叶孔板换热器壳程周期性全截面模型,利用商用软件Fluent14.0及RNG k-ε湍流模型对8种不同结构参数的换热器壳程流体流动及传热性能进行数值模拟。分析了支撑板间距、三叶孔孔高、导流筒结构形式等结构参数对三叶孔板换热器传热及阻力性能的影响,并对比不同结构换热器的综合换热性能。结果表明:壳程传热系数与压力梯度都分别随着支撑板间距和开孔高度的增加而减小,且支撑板间距和三叶孔孔高对三叶孔板换热器壳程压降的影响大于其对传热的影响;六边形结构的导流筒换热器换热性能优于圆形导流筒换热器;8种换热器模型中,支撑板间距400mm、三叶孔高3.3mm(模型4-2)的换热器综合性能最好,支撑板间距400mm、三叶孔高1.8mm(模型2-2)的换热器综合性能最差。%This research established a simplified periodic model for the flow and heat transfer on shell side of heat exchangers with trefoil-baffles. Based on the RNG k-εturbulence model,the flow and heat transfer characteristics on shell side were investigated by using commercial CFD software Fluent14.0 for 8 heat exchanger samples with different structural parameters. Effects of the structural parameters,including baffle pitch,trefoil-hole height and draft tube structure,on the performance of heat transfer and friction were analyzed. The results showed that the heat transfer coefficient and pressure gradient decreased when baffle pitch,as well as trefoil-hole height, increased. Baffle pitch and trefoil-hole height had larger influence on pressure drop than that on heat transfer coefficient. The heat exchanger with hexagon draft tube had better heat transfer performance than that with circle draft tube. The comprehensive performances were also evaluated. The Case 4-2 (Lb=400mm,H=3.3mm)was best and case 2-2(Lb=400mm,H=1.8mm)was worst among all heat exchangers with different structural

  7. Selection and Application of 600MW unit Rod Baffle Closed cold%600MW机组首台折流杆闭冷器的选型及应用

    Institute of Scientific and Technical Information of China (English)

    陈延波; 吕圣杰

    2013-01-01

      关于外导流折流杆闭冷器首次在600 MW超临界燃煤发电机组行运情况的分析总结,该技术闭冷器具有换热效高、流动阻力小、结构紧凑、防振性强、不易结垢等优点,具重要应用价值。%About guide baffle rod outside the closed cycle cooling water heat exchanger in 600 MW supercritical coal-fired power generating units for the first time operation condition analysis summary , The technology of closed cycle cooling water heat exchange equipment has a high heat transfer efficiency, small flow resistance, compact structure, strong vibration resistance, not easy to scale advantages, has the important application value.

  8. 网状孔板纵向流换热器壳程流体流动及换热特性的数值模拟%Numerical Studies on Fluid Flow and Heat Transfer in the Shell Side of Reticulation Orifice-baffle Longitudinal Flow Type Heat Exchanger

    Institute of Scientific and Technical Information of China (English)

    王翠华; 戴玉龙; 吴剑华; 战洪仁

    2011-01-01

    应用 CFD软件对网状孔板换热器壳程流体流动及换热特性进行了数值模拟研究,揭示了网状孔板强化传热的机理,分析了孔板间距及开孔率对其换热、压降性能的影响,推导出网状孔板纵向流换热器壳程换热与流动的准数关系式.结果表明,流体流过网状孔板产生射流及二次流现象,强化了壳程流体的传热;在Re=2300~6300范围内,网状孔板换热器比弓形折流板换热器的Nu数增大约50%,但压降比弓形折流板换热器高约2 5倍;在研究范围内,孔板间距减小、开孔率减小均能使壳程流体的Nu数及压降增大,且Re数越大,开孔率、折流板间距对Nu数及压降的影响越大;但随开孔率、折流板间距减小,流体压降增加的速度明显比Nu数快.%Numerical simulation of fluid flow and heat transfer in the shell side of reticulation orifice-baffle longitudinal flow type heat exchanger is carried out with CFD software. Heat transfer enhancement principle of the reticulation orifice-baffle is summarized, and the influences of space between baffles (L), and open area ratio (ψ) on its heat transfer and pressure drop Sp analyzed, and correlations are developed for the models. The results indicate that jet flow and second flow appear after fluid leaves the reticulation orifice-baffle, which enhance heat transfer of fluid in the shell side. Compared with plate baffle heat exchangers within Reynolds number Re=2 300-6 300, Nusselt number (Nu) of the reticulation orifice-baffle heat exchanger is about 50% higher than that of the plate baffle heat exchanger, while its shell side pressure drop is about 2.5 times higher than that of the plate baffle heat exchanger. In the range of study, both Nu and pressure drop rise with L or ψ decreasing, and the influences of L or ψ on Nu and △p increase with the increase of Re, but with L or ψ decreasing, increasing speed of Ap is obviously bigger than that of Nu.

  9. Reator compartimentado anaeróbio/aeróbio: sistema de baixo custo para tratamento de esgotos de pequenas comunidades Anaerobic/aerobic baffled reactor: low cost system for sewage treatment in small communities

    Directory of Open Access Journals (Sweden)

    Gustavo H. R. da Silva

    2005-06-01

    Full Text Available No Brasil são conhecidas e usadas várias técnicas de tratamento de esgoto, desde os mais sofisticados sistemas de tratamento aos mais simples processos. Uma alternativa economicamente viável aos sistemas de tratamento de esgotos sanitários é o processo anaeróbio, o qual tem recebido especial atenção nas pesquisas desenvolvidas no País, notadamente os reatores anaeróbios de alta taxa, unidades compactas e com boa eficiência de tratamento. Dentre as alternativas tecnológicas capazes de proporcionar as referidas variações das condições ambientais necessárias à ocorrência dos processos, está o uso de reatores compartimentados anaeróbio/aeróbio. Este trabalho apresenta, como alternativa, um reator compartimentado anaeróbio/aeróbio, tratando esgoto sanitário, como possibilidade de ser utilizado em pequenas comunidades urbanas e rurais. O desempenho do sistema foi avaliado em diversos tempos de detenção hidráulica (TDH, nos quais os melhores valores de Demanda Química de Oxigênio Total (DQOtotal - 73,7% e Sólidos em Suspensão Totais (SST - 78,8%, foram obtidos com TDHtotal de 8 horas (4 horas para a fase anaeróbia e 4 horas para a fase aeróbia. O reator compartimentado apresentou a característica de estabilidade operacional necessária aos sistemas de baixo custo.Several techniques of sewage treatment, from the most sophisticated to the simplest processes, are known in Brazil. An economically viable alternative for the systems of treatment of sanitary sewage is the anaerobic process, which has been given special attention in Brazilian research programs, mainly in the field of high rate anaerobic reactors as they are compact units and have high efficiency. The use of baffled anaerobic/aerobic reactors is one technological solution to provide the necessary variations in environmental conditions to foster the processes mentioned. In this paper an alternative is presented in the form of a baffled anaerobic

  10. 连续螺旋折流板换热器流动与传热性能及熵产分析%Analyses on flow and heat transfer performance and entropy generation of heat exchanger with continuous helical baffles

    Institute of Scientific and Technical Information of China (English)

    曹兴; 杜文静; 程林

    2012-01-01

    采用数值模拟的方法,研究了螺旋角对连续螺旋折流板换热器流动与传热性能的影响,并以熵产数为指标对换热器性能进行了基于热力学第二定律的分析评价.结果表明,相同质量流量时壳程传热系数和压降均随螺旋角的增大而降低,且后者降低的幅度大于前者.连续螺旋折流板换热器壳程横截面上切向速度分布较弓形折流板换热器更加均匀.在靠近中心假管的内层区域,同一径向位置的轴向速度随螺旋角的增大而降低,而在靠近壳体壁面的外层区域则相反.螺旋角越大,不同径向位置的换热管间的换热量分布均匀性越好.壳程质量流量相等时,换热器中传热引起的熵产占总熵产的比重随着螺旋角的增大而增加,熵产数随着螺旋角的增大而降低.%A numerical simulation for heat exchanger with continuous helical baffles was carried out by using commercial codes of ANSYS CFX 12. 0. The study focuses on the effects of helix angle on flow and heat transfer characteristics, and heat exchanger performance is evaluated by entropy generation number based on the analysis of the second law of thermodynamics. The results show that both the shell-side heat transfer coefficient and pressure drop decrease with the increase of the helix angle at certain mass flow rate. The latter decreases more quickly than the former. The tangential velocity distribution on shell-side cross section is more uniform with continuous helical baffles than with segmental baffles. The axial velocity at certain radial position decreases as the helix angle increases in the inner region near the central dummy tube, whereas it increases as the helix angle increases in the outer region near the shell. The heat exchange quantity distribution in tubes at different radial positions is more uniform at larger helix angle. The proportion of the entropy generation contributed by heat transfer in total entropy generation increases and the

  11. 带弹性隔板圆柱形储液罐的流一固耦合特性研究%STUDY ON COUPLED VIBRATION CHARACTERISTICS OF A CYLINDRICAL TANK WITH A FLEXIBLE ANNUAL BAFFLE

    Institute of Scientific and Technical Information of China (English)

    王佳栋; 周叮; 刘伟庆

    2012-01-01

    该文研究带有环形弹性隔板的部分充液刚性圆柱罐中液体与隔板的耦合振动特性。将液体域分割成两个圆柱子域和两个圆环柱子域,利用分离变量法和叠加原理求得各子域内液体运动势函数的解。将环形薄板的湿模态用干模态展开以求解环形薄板与液体耦合振动的微分方程。对液体子域间的界面连续条件作Fourier展开并对表面波方程作Bessel展开,得到环形薄板与液体耦合振动的频率和对应模态。数值结果与流.固耦合专用软件ADINA的结果进行了比较,显示出很好的一致性。%The coupled vibration characteristics of liquid and a flexural annular baffle in a cylindrical rigid tank were studied. The complicated fluid domain is separated into four simple sub-domains composed of two circular columns and two annular columns, respectively. The velocity potential functions corresponding to every fluid sub-domain were analytically solved by using the separation variable method and the decomposition method. The dry-modal functions were used to expand the wet modes in order to solve the differential equation of coupled vibration of the baffle and liquid. Based on the consistent conditions of liquid movement between the sub-domain interfaces and the surface wave equation of fluid, the unknown coefficients in the solutions were determined by using the Fourier series expansions and the Bessel series expansions. Finally, the eigenvalue equation was obtained. The coupled frequencies were numerically calculated by using the searching root method for non-linear equations. The convergence study shows high accuracy of the present method. The numerical results were compared with those obtained from the ADINA finite element software.An excellent agreement has been achieved.

  12. Enhanced decolorization of azo dye in a small pilot-scale anaerobic baffled reactor coupled with biocatalyzed electrolysis system (ABR-BES): a design suitable for scaling-up.

    Science.gov (United States)

    Cui, Dan; Guo, Yu-Qi; Lee, Hyung-Sool; Wu, Wei-Min; Liang, Bin; Wang, Ai-Jie; Cheng, Hao-Yi

    2014-07-01

    A four-compartment anaerobic baffled reactor (ABR) incorporated with membrane-less biocatalyzed electrolysis system (BES) was tested for the treatment of azo dye (alizarin yellow R, AYR) wastewater (AYR, 200 mg L(-1); glucose, 1000 mg L(-1)). The ABR-BES was operated without and with external power supply to examine AYR reduction process and reductive intermediates with different external voltages (0.3, 0.5 and 0.7 V) and hydraulic retention times (HRT: 8, 6 and 4h). The decolorization efficiency in the ABR-BES (8h HRT, 0.5 V) was higher than that in ABR-BES without electrolysis, i.e. 95.1 ± 1.5% versus 86.9 ± 6.3%. Incorporation of BES with ABR accelerated the consumption of VFAs (mainly acetate) and attenuated biogas (methane) production. Higher power supply (0.7 V) enhanced AYR decolorization efficiency (96.4 ± 1.8%), VFAs removal, and current density (24.1 Am(-3) TCV). Shorter HRT increased volumetric AYR decolorization rates, but decreased AYR decolorization efficiency.

  13. 挡板式水解酸化法处理印染废水的中试试验研究%Study on treatment of printing and dyeing wastewater by anaerobic baffled reactor in a pilot plant

    Institute of Scientific and Technical Information of China (English)

    贾洪斌; 王力民; 赵大传

    2001-01-01

    Treatment of printing and dyeing wastewater by anaerobic baffledreactor in a pilot plant has been studied. As the influent pH is 10.0, MLSS 20 g/L, and HRT 9~10 h, the removal rates of COD could reach average 36.8%, and the BOD/COD ratio of influent to effluent could increase from 0.285 to 0.447, and the biodegradability of wastewater is improved obviously. As a pretreatment method before aerobic biological treatment of printing and dyeing wastewater, anaerobic baffled reactor is feasible both technically and economically.%对印染废水进行了挡板式水解酸化中试试验。结果表明,调节原水pH值为10左右,污泥质量浓度为20g/L,水力停留时间为9~10h的条件下,处理后的废水COD去除率平均为38.6%,进出水的BOD/COD比值由0.285升高至0.447,废水可生化性得到明显改善。挡板式水解酸化法作为印染废水好氧生物处理的前处理在技术上和经济上都是可行的。

  14. Farklı Hidrolik Bekletme Sürelerinin Anaerobik Perdeli Reaktörde Sülfat İndirgenmesi Üzerine Etkisi / Effect of Different Hydraulic Retention Time (HRT on Sulfate Reduction in Anaerobic Baffled Reactor

    Directory of Open Access Journals (Sweden)

    Şebnem ÖZDEMİR

    2012-12-01

    üresinin 2 gün olduğu çalışma koşullarında çıkış suyundaki KOİ ve SO4-2 verimleri %84 ile %88 olarak gözlemlenirken bekleme süresinin 0,5 gün olduğu çalışma koşullarında ise bu değer %80 ve %75 olarak gözlemlenmiştir. Ayrıca bekleme süresinin 2 gün olduğu çalışma koşullarında son bölmedeki sülfür oluşum verimi % 75 iken, bekleme süresi 0,5 güne indirildiğinde aynı bölmedeki sülfür oluşum veriminin %96’a çıktığı gözlemlenmiştir. Çıkarımlar ve Özgün Değer: Yapılan bu çalışma ile yüksek sülfat konsantrasyona sahip atıksuların arıtımında anaerobik perdeli reaktörün iyi bir alternatif olabileceği kanıtlanmıştır. Ayrıca çıkış sülfat ve sülfür konsantrasyonlarının değişen HBS’den etkilenmediği gözlenmiştir. Effect of Different Hydraulic Retention Time (HRT on Sulfate Reduction in Anaerobic Baffled Reactor Design and Method: The anaerobic baffled reactor (ABR is a modification of up-flow anaerobic sludge blanket (UASB reactor. A laboratory scale ABR was inoculated with an effluent of a full scale anaerobic digester located in Kayseri Wastewater Treatment Plant, Turkey. Before inoculation, the sludge was sieved to remove coarse materials. The ABR was 20 cm wide, 80 cm long, 20 cm deep and constructed from glass, with a working volume of 19 L. Reactor was divided into four equal 4.75 L compartments by vertical baffles, each compartment having down-comer and riser regions created by further vertical baffle. The lower parts of down-comer baffles were angled at 450 in order to direct the flow evenly through the riser. Ethanol and sulfate are consumed as electron donor and electron acceptor, respectively. Sulfate, dissolved sulfide, pH, alkalinity and chemical oxygen demand (COD have measured three times a week. Aim: There are varying structures and concentrations of sulfate compounds in natural waters. In addition, the amount of sulfate is higher in some industrial wastewaters In addition, some

  15. ABR处理大豆蛋白废水产氢效能的研究%Performance of hydrogen production in anaerobic baffled reactor (ABR) treating soy protein wastewater

    Institute of Scientific and Technical Information of China (English)

    王帅; 李博; 赵倩; 姜力行; 曹莉; 李永峰

    2011-01-01

    Anaerobic Baffled Reactor (ABR) is a class derived from multi-phase anaerobic reactor stages (Staged Multi -Phase Anaerobic Reactor, SMPA) theory of the third generation of a new anaerobic reactor. To study of anaerobic baffled reactor (ABR) soy protein wastewater treatment efficiency and operating characteristics of the 4 cell room operation of the system of ABR control measures were studied using the effective volume of 42 L four -room frame ABR, MLVSS in the sludge inoculum for the 18.0 g/ L, influent COD concentration of 2 000 mg/L , HRT 48 h, (35 ± 1) ℃ and other conditions (ie OLR1. 0 kg/( m3 · d) ) , running through a period of 80 d of the study based on the influent COD concentration was increased organic load ( OLR) to change the impact of its processing power, can successfully started in 31 d and reached the initial ABR and stable operation. In addition, rate of 96% , studied different organic load, ABR reactor COD removal efficiency and gas production. On this basis, for the efficient development of ABR equipment, and successfully applied to fermentation technology and bio-hydrogen production of soy protein wastewater treatment under study was provided.%厌氧折流板反应器(ABR)是一类源于分阶段多相厌氧反应器(Staged Multi -Phase Anaerobic Reactor,SMPA)理论的第三代新型厌氧反应器.为考察厌氧折流板反应器(ABR)处理大豆蛋白生产废水的效能及其运行特征,对4格室ABR反应系统的运行控制对策进行了研究,采用有效容积为42L的四格室ABR,在污泥接种量MLVSS为18.0 g/L、进水COD质量浓度2 000 mg/L、HRT 48 h、(35±1)℃等条件下(即OLR 1.0 kg/(m3·d)),通过为期80 d的运行,研究了基于进水COD质量浓度提高的有机负荷(OLR)改变对其处理效能的影响,可在31 d内成功启动ABR并达到初步稳定运行,研究不同有机负荷下,ABR反应器的COD去除效率及产气量.为在此基础上研发高效的ABR反应设备,并成功将其应用到发

  16. 厌氧折流板反应器处理PTA废水及其相分离特性%Terephthalic acid(PTA) wastewater treated by anaerobic baffled reactor and its phase separation characteristics

    Institute of Scientific and Technical Information of China (English)

    杨忠林; 钟中; 韩萍芳; 吕效平

    2012-01-01

    The start-up and phase separation characteristics of the anaerobic baffled reactor (ABR) treating purified terephthalic acid (PTA) wastewater were investigated. Results showed that under these conditions the temperature was (35 ± 1) ℃ , hydraulic retention time was 40 h and volumetric loading rate was 3.60 kg/(m3·d) , the ABR started up successfully and the maximum removal efficiency of COD reached 80% after 62 d operation. The concentration of volatile fatty acids ( VFA) in the different compartments of ABR decreased along the flow direction, In contrast, the content of CH4 , the volatile suspended solid (VSS) , the ratio of VSS and the total suspended solid (TSS) , the specific methane production activities and the coenzyme F420 increased, the significant phase separation characteristics.%对厌氧折流板反应器(ABR)处理精对苯二甲酸(PTA)生产废水的启动及相分离过程进行研究.结果表明:经过62 d的运行,反应器在(35±1)℃、水力停留时间40 h、容积负荷3.60 kg/(m3·d)的条件下,最大COD去除率达到80%以上,ABR启动成功.沿着水流方向,不同格室中挥发性脂肪酸(VFA)浓度依次减小,CH4含量不断增加,且污泥中挥发性悬浮固体浓度(VSS)及其与总悬浮固体浓度(TSS)之比、产甲烷活性和辅酶F420不断增大,ABR中显示出显著的厌氧微生物相分离特性.

  17. 异形孔隔板换热器壳侧传热与阻力性能的试验研究%Experimental study on shell-side heat transfer and flow resistance performance of heat exchangers with non-round orifice baffles

    Institute of Scientific and Technical Information of China (English)

    盛艳军; 陈亚平; 操瑞兵; 董聪; 吴嘉峰

    2012-01-01

    The shell-side heat transfer and flow resistance performances of shell-and-tube heat exchangers with different non-round orifice baffle (square, fillet triangle, mesh and cinquefoil) and a segment baffle heat exchanger were tested. A common heat exchanger shell and replaceable tube bundles were adopted. The shell-side axial Reynolds number is used as the independent variable versus the characteristics of the testing heat exchangers. The integrated index of the shell-side Nusselt number over the axial Euler number is suggested for evaluation of the heat exchanger performance of different schemes. The experimental results show that the mesh orifice baffle has the equivalent heat transfer coefficient as the segment baffle. But the pressure drop of the former is lower, and in the experimental range the average value of the relative comprehensive performance of the shell-side Nusselt number over the axial Euler number is about 1. 274. Both the heat transfer coefficients and the comprehensive performance indexes of the heat exchangers with cinquefoil, fillet triangle and square orifice are lower than those of the segment baffle heat exchanger. The heat transfer performance of the heat exchangers with non-round orifice baffles is related to the shape and the number of the orifices, and the flow resistance is related to the total area and hydraulic perimeter of the flow orifices.%对正方形孔、三角圆头孔、网状孔、六角梅花孔隔板换热器及弓形折流板换热器的传热性能和压降性能进行了测试试验.试验件采用公用管壳可拆卸芯体管束结构,针对其特点将壳侧轴向雷诺数作为自变量,利用单位壳侧轴向欧拉数的壳侧努谢尔特数指标来反映换热器的综合性能.试验结果表明,网状孔隔板换热器的壳侧换热系数与弓形折流板换热器相当,但该换热器的压降较低,在试验范围内综合性能指标的相对值为1.274;六角梅花孔、三角圆头孔和正方形孔隔

  18. Numerical simulation of heat transfer enhancement by strip-coil-baffles in tube-bundle for a tube-shell heat exchanger%螺旋折流片强化管壳式换热器内管束传热数值模拟

    Institute of Scientific and Technical Information of China (English)

    陈亚平; 梅娜; 施明恒

    2007-01-01

    介绍了一种用于强化管壳式换热器壳侧传热和支撑管束的螺旋折流片新型结构,该结构是对换热器管子相间地套上螺旋折流片以产生旋涡流动.研究模型是在正方形布置的4个管子中的2个对角管子套上螺旋折流片后形成的通道,利用FLUENT软件对该上述四管通道模型的流场和温度分布情况进行了数值模拟;分析了四管通道模型中螺旋折流片对强化传热和流动阻力随雷诺数的变化关系的影响.算例结果显示该新型结构可比相同尺寸的光管通道中的情形传热系数提高约40%~55%,同时也将伴随较高的流动阻力.可以相信螺旋折流片式换热器将会在许多工业领域有良好的应用前景.%A novel strip-coil-baffle structure used to enhance heat transfer and support the tube bundle for a tube-shell heat exchanger is proposed.The new structure can sleeve the tubes in bundle alternatively to create a vortex flow in a heat exchanger.The numerical simulation on the flow and heat transfer characteristics for this new structure heat exchanger is conducted.The computational domain consists of two strip-coil sleeved tubes and two bare tubes oppositely placed at each corner of a square.The velocity and temperature fields in such strip-coil-baffled channel are simulated using FLUENT software.The effects of the strip-coil-baffles on heat transfer enhancement and flow resistance in relation to the Reynolds number are analyzed.The results show that this new structure bundle can enhance the heat transfer coefficient up to a range of 40% to 55% in comparison with a bare tube bundle;meanwhile,higher flow resistance is also accompanied.It is believe that the strip-coil-baffled heat exchanger should have promising applications in many industry fields.

  19. Granulation of Anaerobic Sludge in Anaerobic Baffled Reactor Treating Livestock Wastewater%ABR反应器处理畜禽养殖废水中厌氧污泥颗粒化的研究

    Institute of Scientific and Technical Information of China (English)

    赵金安; 雷英春

    2015-01-01

    为了研究厌氧污泥颗粒形成过程中各因素的影响规律,本文采用厌氧折流板反应器(ABR)-改良序批式反应器(MSBR)联合工艺处理畜禽污水,通过单因素研究了影响规律,并对污泥形貌进行了表征.结果表明:有机负荷、有机底物浓度、pH 值等因素的合理控制可以促进污泥颗粒化,进而加快系统的启动. CODCr浓度为10000 mg/L 时,颗粒污泥的粒径分布为0.2~4.5 mm,显微镜低倍镜下观察到边缘非常整齐的菌团,主要菌种符合丝状产甲烷菌特征;扫描电镜清晰显示出颗粒污泥的形貌,呈球形、椭球形,表面有孔隙.启动达到设计负荷后,获得72%的CODCr去除率,产甲烷活性达到0.36 m3 CH4/kgVS.%In order to study the influence law of various factors at the formation process of anaerobic sludge granules,the anaerobic sludge granulation in anaerobic unit of the livestock wastewater was trea-ted by the combined process of anaerobic baffled reactor(ABR)and modified sequencing batch reactor (MSBR),and single factor was studied,and sludge morphology was characterized.The results show that,the granulation can be promoted by control the factors of organic loading rate(OLR),chemical ox-ygen demand(COD)concentration in the influent and pH value,and accelerate to start the ABR system. On the basis of high CODCr strength of 10 000 mg/L,the granules comprising of predominant filamen-tous methanogens present outstanding CODCr removal rate of 72% with size ranging of 0.2~4.5 mm and near spherical and ellipsoidal shape,surface porosity,and the methanogens exhibit methane yielding property of 0.36 m3 CH4/kgVS at designed organic loading rate.

  20. 布管方式对折流杆换热器壳程性能的影响%Impact of tube-layout on performance of rod baffle heat exchanger shell side

    Institute of Scientific and Technical Information of China (English)

    郭崇志; 胡崇举

    2013-01-01

    传统折流杆换热器的性能分析与设计计算多是针对方形布管的换热器形式进行的,三角形布管的折流杆换热器的性能评估与计算没有现成的资料.应用CFD软件进行分段模型研究,将不同布管方式的换热器局部流动与传热数据综合整理成整体法关联式,并与实验数据和C.C.Gentry提出的实验关联式进行对比研究,结果发现方形布管的模拟结果与C.C.Gentry关联式符合良好,传热预测平均偏差小于5%,压力降预测平均偏差小于9%;三角形布管的模拟结果与新提出的改进C.C.Gentry关联式比较,传热预测平均偏差小于7%,压力降预测平均偏差小于13%.从综合性能指标看,三角形布管折流杆换热器的综合性能优于方形布管的换热器,相同条件下,综合性能提高32%.%The analysis and design calculations of conventional rod baffle heat exchanger ( RBHE) performance are mainly for RBHE with square tube layout. Therefore, there is no information available for the performance evaluation and calculation of RBHE with triangular tube layout. The integer correlations are obtained with subsection model built with CFD software Fluent. The study and comparison with the experimental results and with correlations proposed by C. C. Gentry has found that the results of square tube layout simulation are well consistent with the results of correlation of C. C. Gentry. The average deviation of predicted heat transfer and predicted pressure drop is less than 5% and 9% respectively. It is also found by comparing simulation results of triangular tube layout model with improved correlations of C. C. Gentry that the average deviation of predicted heat transfer and predicted pressure drop is less than 7% and 13% respectively. In general, the comprehensive performances of RBHE are superior over those of heat exchangers with triangle-layout by 32%.

  1. Fluid mixing performance of bubble column reactor enhanced by tilted porous baffle%斜插穿流式挡板强化鼓泡塔内流体混合的研究

    Institute of Scientific and Technical Information of China (English)

    刘作华; 孙瑞祥; 宁伟征; 刘仁龙; 陶长元; 王运东

    2013-01-01

    乙炔二聚反应制备乙烯基乙炔是氯丁橡胶生产等工艺中的重要操作单元,通常在全混式鼓泡塔反应器中进行.但塔内流体混合模式单一、流场对称性强、液相轴向返混较高,乙烯基乙炔容易滞留在催化剂中,并与乙炔进一步反应生成二乙烯基乙炔和高聚物.强化乙炔二聚鼓泡塔内的反应,提高乙炔单程转化率和选择性,有助于氯丁橡胶生产实现节能减排.应用FLUENT软件模拟,计算了鼓泡塔内流场结构及变化规律,发现斜插穿流式挡板可有效地调控乙炔二聚鼓泡塔内流场结构,减小漩涡尺寸,降低液相湍流流速,减小液相返混区域,强化鼓泡塔内乙炔二聚反应.%Acetylene dimerization for preparation of monovinyl-acetylene is the key process for production of neoprene, which is usually operated in a full mixed bubble column reactor. But it has disadvantages of single mixing mode, symmetric flow field structure, serious liquid axial back mixing, and long residue time for monovinyl-acetylene in the catalyst leads to further reaction with acetylene, which results in formation of the divinyl-acetylene and byproduct polymers. Increasing conversion rate and selectivity contributes to energy saving and consumption reduction by the enhancement of bubble column reaction. The FLUENT software was used to simulate the flow field in the bubble column reactor. It shows that the tilted porous baffle can change the flow field structure effectively, reduce the vortex size. It can also reduce liquid back-mixing area and the turbulence intensity in the whole bubble column reactor, which can enhance the dimerization reaction of acetylene.

  2. Model and simulink of anaerobic baffled reactor treating sulfate organic wastewater based on back-propagation neural network%ABR处理硫酸盐有机废水的BP神经网络建模

    Institute of Scientific and Technical Information of China (English)

    韦添尹; 蒋永荣; 刘可慧; 刘成良; 张威

    2013-01-01

    The back-propagation neural network (BPNN) trained with the data from the sulfate organic wastewater treatment of anaerobic baffled reactor(ABR) and a network model was buih.The better training function and times were ‘ traingda' and 1 900,respectively.Partition connection weights (PCW) was adopted to analyze the dominant factors of effluent COD and SO42-.The results showed that all of the factors (feed COD,SO42-,pH,COD/SO42-and HRT) had an influence on effluent COD and SO42-.Nevertheless,the feed pH was the dominant factor,which relative importance (RI) were 30.79% and 23.44%,respectively.The model and simulink on restrictive factors for COD and SO42-removal were built respectively,which can be used for prediction on sulfate organic wastewater treatment.%通过厌氧折流板反应器(ABR)处理硫酸盐有机废水的实验数据对BP神经网络进行训练,建立了ABR处理硫酸盐有机废水的BPNN模型,通过测试对比,找出了较优训练函数为traingda,较优训练次数为1 900.利用分割连接权值法(PCW)对影响出水SO42-和COD的主要因素进行分析,结果显示进水COD、SO42-、pH、COD/SO42-和HRT对出水SO42-和COD均产生一定影响,其中进水pH对出水SO42-和COD的影响最大,相对重要性(RI)指数分别为30.79%和23.44%;并通过样本试验数据分别建立了对SO42-和COD去除率的限制因子仿真模型,为预测硫酸盐有机废水的厌氧处理过程提供指导.

  3. Start-up and Acclimation of Anaerobic Baffled Reactor for Treatment of Diseased Animal Wastewater%ABR处理疫病动物废水的启动驯化研究

    Institute of Scientific and Technical Information of China (English)

    卢韬; 李平; 吴锦华; 王向德

    2013-01-01

    采用厌氧折流板反应器(ABR)处理疫病动物废水,对其启动驯化过程进行了研究.结果表明,在逐级提高进水浓度的条件下,历经58 d成功启动反应器,当进水COD平均为8 120mg/L时,出水COD平均为491 mg/L,对COD的去除率可达94%,总产气量达到21.15 L/d,平均产气率为0.55 m3/kgCOD,疫病动物废水在ABR中可以得到高效降解.在启动过程中,随着进水浓度的提升,挥发性脂肪酸(VFA)在第1格室中不断积累,但同时废水在厌氧生物降解过程中可以产生大量碱度,保证了反应器内的中性环境条件,反应器未发生酸败现象.启动成功后,反应器各格室内的活性污泥主要以颗粒形态存在,且颗粒粒径沿水流方向逐渐减小,呈现明显的分级现象.%The start-up and acclimation of anaerobic baffled reactor (ABR) for treatment of diseased animal wastewater were investigated. The results showed that the reactor started up successfully after 58 d by gradually increasing influent concentration. When the mean influent COD was 8 120 mg/L, the mean effluent COD was 491 mg/L, and 94% COD removal rate was achieved. Besides, total biogas production and mean biogas production rate were 21. 15 L/d and 0. 55 mVkgCOD, respectively. VFA accumulation mainly occurred in compartment 1 because of the increasing COD in the influent. Since a-bundant alkalinity was generated in the anaerobic process, reactor acidification was avoided. After the successful start-up, the activated sludge in each compartment was mainly granular sludge. The particle size of the granular sludge decreased along the flow direction, which presented an obvious classification phenomenon in the reactor.

  4. 网状孔板纵向流换热器壳程流体流动及换热的三维数值模拟%Three-dimensional numerical simulation for shell side fluid flow and heat transfer characteristics in reticulated orifice-baffle longitudinal flow type heat exchangers

    Institute of Scientific and Technical Information of China (English)

    王翠华; 张平; 吴剑华; 张先珍

    2011-01-01

    利用Fluent软件对网状孔板纵向流换热器壳程流体流动及换热进行了三维数值模拟,得到了壳程流体温度场、速度场及压力场等细观信息。根据模拟的结果,揭示了网状孔板强化壳程流体换热的机理,分析了壳程流体沿轴向流动及换热的性能,总结了近壁区流场及温度场的特点。%The fluid flow and heat transfer for shell side in reticulated orifice-baffle longitudinal flow type heat exchanger was simulated with Fluent software.The temperature field,velocity field,and pressure field in shell side were obtained.The enhancement mechanism of heat transfer due to the structure of reticulated orifice-baffle was discussed and the axial flow and heat transfer were analyzed for shell side according to the simulation results.Finally,an analysis of the flow field and temperature field close to the wall was given.

  5. 微量元素对ABR发酵产氢产甲烷的影响%Effect of Trace Elements on Fermentative Co-production of Hydrogen and Methane in Anaerobic Baffled Reactor

    Institute of Scientific and Technical Information of China (English)

    郑国臣; 赵峰; 李建政; 张照韩; 昌盛; 闫志成; AJAYKumarJha

    2012-01-01

    In order to achieve fermentative co-production of hydrogen and methane in a 4-compart-ment anaerobic baffled reactor ( ABR) , the effects of trace elements on fermentative production of hydrogen in the front compartment and fermentative production of methane in the rear compartment were investigated. Under the conditions of influent COD of 6 000 mg/L and ALK of 1 900 mg/L, before addition of trace elements, the COD removal rate was 51% , the hydrogen production capacity was 0.46 m /(m ? D) , and the methane production capacity was 0.68 mV( m3 ? D), with low dehydrogenase activity of anaerobic sludge. While under the same conditions, after addition of trace elements, the COD removal rate increased to above 62% , the hydrogen production capacity decreased to 0. 37 m /( m ? D), and themethane production capacity increased to 1. 66 m /( m ? D). As a result, the addition of trace elements could effectively stimulate the activity of anaerobic sludge in fermentative co-production of hydrogen and methane in the ABR. The increase in the activity of hydrogen-consuming bacteria like methanogenic bacteria leaded to inhibition of the hydrogen production, but enhanced the methanogenic activity, which significantly improved the treatment efficient.%为构建厌氧折流板反应器(ABR)发酵联合产氢产甲烷系统,考察了微量元素对ABR系统前端格室发酵产氢、后端格室发酵产甲烷的影响.在进水COD为6 000 mg/L、碱度为1 900 mg/L的条件下,当未投加微量元素时,系统对COD的去除率为51%,产氢能力为0.46 m3/(m3·d),产甲烷能力为0.68 m3/(m3·d),四格室的厌氧污泥脱氢酶活性均较低;而在相同运行条件下,当投加微量元素后,系统对COD的去除率提高到62%以上,产氢能力为0.37 m3/(m3·d),产甲烷能力达到1.66 m3/( m3·d)..研究表明,投加微量元素可有效刺激ABR发酵联合产氢产甲烷系统中厌氧污泥的活性,由于ABR中产甲烷菌等耗氢菌群活性的增强导致发

  6. Uso de leitos cultivados de fluxo vertical por batelada no pós-tratamento de efluente de reator anaeróbio compartimentado Post-treatment of effluent of anaerobic baffled reactor using batchwise vertical flow constructed wetland beds

    Directory of Open Access Journals (Sweden)

    Marcelo Mazzola

    2005-06-01

    Full Text Available Neste trabalho avaliou-se o desempenho de um Reator Anaeróbio Compartimentado (RAC de duas câmaras em série, seguido de três leitos cultivados (constructed wetlands de fluxo vertical por batelada. A unidade experimental, em escala piloto, foi instalada na Faculdade de Engenharia Agrícola - UNICAMP, Campinas, SP, Brasil. O volume total do reator era de 2,3 m³ (TDH de 12 h. O efluente do RAC foi tratado em três leitos, dois cultivados com macrófitas (gêneros Typha sp. e Eleocharis sp. e um utilizado como controle (não cultivado. Os leitos, com 2,0 m³ cada um e brita #2 (24 - 35 mm como meio suporte, operaram com fluxo vertical por batelada (com tempos de reação de 24, 48, 72 e 96 h. Na avaliação do RAC, observou-se tendência de estabilização dos parâmetros pH, alcalinidade, ácidos voláteis, sólidos sedimentáveis e suspensos totais, porém a remoção de DQO revelou-se limitada (50%. Nos leitos cultivados o aumento do tempo de reação (até 72 h foi acompanhado pelo aumento de remoção de turbidez, DQO, fósforo e nitrato. O melhor desempenho de remoção de fósforo total foi obtido no leito vegetado com Typha sp para os tempos de 72 e 96 h, respectivamente, de 30 e 25%.This study evaluated the performance of vertical constructed wetlands treating effluent of anaerobic baffled reactor. The anaerobic reactor volume was 2.3 m³; it was operated with daily flow of 4.6 m³ (12 hours Hydraulic Retention Time. The reactor effluent was split into three wetlands beds, two of them cultivated with macrophytes (Typha sp. and Eleocharis sp., and one control. The wetlands were operated as a batch reactor. The medium utilized was gravel, the size ranging from 7 to 12 mm. The reaction time for each cycle (filling - reaction - drainage was 24, 48, 72, and 96 h. The anaerobic reactor achieved the following removal rates: settable solids, 93%; suspended solids, 80%; and COD 39%. The increase in reaction time (up to 72 h for the constructed

  7. Effect of pH and Alkalinity on Operation of Anaerobic Baffled Reactor%pH值和碱度对厌氧折流板反应器运行的影响

    Institute of Scientific and Technical Information of China (English)

    刘宇红; 曲颖; 宋虹苇; 于晓英

    2012-01-01

    为考察pH值和碱度对厌氧折流板反应器(ABR)高效、稳定运行的影响,采用一个有效容积为28 L的4格室ABR反应器处理豆制品废水.ABR反应器运行72 d的结果表明:在启动阶段的前期外加碱液调节进水pH值,使pH值和碱度分别基本稳定在6.0 ~7.0和1 000~1 300mg/L,运行效果良好.启动45 d时,停止外加碱液对进水pH值进行调节,系统仍稳定运行,但启动阶段出现丙酸浓度缓慢上升现象.在反应器稳定运行阶段,各格室的pH值分别为(4.5 ~6.0)、(5.5 ~6.8)、(6.8 ~7.2)、(7.1 ~7.3),碱度基本处在1 000 ~1 400 mg/L,反应器出水的发酵产物含量< 100 mg/L(乙酸占90%以上),对COD的去除率保持在90%以上.%A 4-compartment anaerobic baffled reactor (ABR) with an effective volume of 28 L was used to treat soybean processing wastewater. The influence of pH and alkalinity on the operation of ABR was investigated. The operation results for 72 d indicated that the reactor attained good operation effect in the early stage of start-up by adding alkaline to the influent. pH and alkalinity were controlled at 6.0 to 7.0 and 1 000 to 1 300 mg/L, respectively. After 45 d of startup without adding alkalinity to control pH of the influent, the reactor could also run well. However, slow increase of propionic acid in the start-up stage was observed. In continuous operation stage of ABR, the pH of each compartment was 4.5 to 6.0, 5.5 to 6.8, 6.8 to 7.2, and 7.1 to 7.3, and the alkalinity was 1 000 mg/L to 1 400 mg/L. The fermentation product in the effluent was less than 100 mg/L (acetic acid was more than 90% ) , and the removal rate of COD was above 90%.

  8. Study on the Influence of Baffle-tube Clearance on the Fluid Flow and Heat Transfer of Shell and Tube Heat Exchanger%管板间隙对管壳式换热器流动与传热的影响研究

    Institute of Scientific and Technical Information of China (English)

    耿伟轩; 张红; 陶汉中; 冯志伟

    2012-01-01

    In shell and tube heat exchanger,leakage flow caused by baffle -tube clearance is disadvantageous to the heat transfer of heat exchanger. By using a new method of grid generation, a three - dimensional numerical model is established and meshed,and the numerical simulations are carried out by using CFD code Fluent software to study the characteristics of fluid flow and heat transfer in shell side and tube pass under different conditions. The standard k梕 turbulent model and SIMPLEC method were used in calculations, and the pressure equation is of standard format. The simulated results are imported to the e-valuation indicator of heat exchanger to analyze, in an all - round way, the influence of baffle - tube clearance on the fluid flow and heat transfer of shell and tube heat exchanger.%管壳式换热器中,由管板间隙引起的漏流不利于换热器的传热.通过一种新型网格生成方法,对所建立的三维实体模型进行网格划分,并利用CFD软件Fluent进行数值模拟,研究不同情况下壳程与管程的流动与传热特性.计算中采用标准k-ε模型,SIMPLE算法,压力方程为标准格式.将模拟结果引入换热器评价指标,全面分析管板间隙对管壳式换热器流动与传热的影响.

  9. 螺旋折流板管壳式换热器内LNG混合介质流动冷凝特性仿真平台开发及影响因素分析%Simulation Platform Development and Influence Factor Analysis for Flow Condensation Characteristics of LNG Mixture in Shell-tube Heat Exchanger with Helical Baffles

    Institute of Scientific and Technical Information of China (English)

    黄庆楠; 陈杰; 杨文刚; 罗婷婷; 丁国良; 胡海涛

    2015-01-01

    螺旋折流板管壳式换热器用于冷凝混合烃类介质时,会产生冷凝不均导致设备效率降低等问题;但是由于换热器体积和能耗巨大,难以通过大量的实验测试得出换热器性能的规律。为了了解管壳式换热器内LNG混合介质流动冷凝特性,本文建立了一种用于螺旋折流板管壳式换热器内LNG混合介质流动冷凝的仿真模型。该模型考虑了流动过程中的传热传质及气相分率的变化,体现了换热器结构、螺旋折流板参数及工质物性等各种因素对流动和传热的影响,同时保证仿真的计算速度。此外,采用该模型开发的仿真平台具有友好的用户界面,方便用户输入仿真参数,准确快捷地对换热器性能进行仿真,并以形象直观的方式输出仿真结果。基于开发的仿真平台,对螺旋折流板管壳式换热器内 LNG 混合介质流动冷凝特性的结构影响因素进行了分析,给出了最佳螺旋角的推荐值。%When the shell-tube heat exchanger with helical baffles is used for cooling mixed hydrocarbons, it may cause the unbalance of condensation and reduce the equipment efficiency. But due to huge volume and energy consumption of the heat exchanger, it is difficult to study the performance rule by a large number of experimental tests. In order to understand the flow condensation characteristics of LNG mixture in the shell side, a simulation model of the seawater heat exchanger with helical baffles is developed in this paper. The heat and mass transfer and the change of the gas fraction along the flow process are considered in the model. And it reflects the influence of the heat exchanger structure, helical baffle parameters, flow process and fluid properties on flowing and heat exchanging. The simulation speed can be guaranteed by segmentation parameters method as well. In addition, the friendly graphic user interface has also been developed in this simulation platform

  10. 3D simulation for the influence of a feed baffle on the density current behaviors caused by temperature in a radial sedimentation tank%辐流式沉淀池挡板尺寸对温差异重流水力特性影响的三维模拟

    Institute of Scientific and Technical Information of China (English)

    魏文礼; 白朝伟; 刘玉玲

    2016-01-01

    在冬季或夏季,沉淀池内进水与池内水的温差将导致异重流现象,从而影响池内流态及流速.本文选取Realizable k-ε湍流模型,通过设置池内水与进水的不同温度,对进口处两种不同挡板形式的辐流式沉淀池冬季与夏季工况下异重流的演变规律进行三维数值模拟.结果表明:夏季低温水进入池内产生下异重流,而冬季高温水进入池内产生上异重流;夏季高流速水流在沉淀池底部,产生逆时针旋流,冬季高流速水流在沉淀池上部,产生较大的顺时针旋流.长挡板形式下的辐流式沉淀池对冬季产生的上异重流的影响更为明显,使得池内速度场更加均匀.%In summer or winter,temperature differences between the inflow water and the water in a pool will cause density flow phenomenon,whereby affecting flow pattern and flow speed in a Radial Sedimentation Tank.The Realizable k-εmodel is used to carry out 3D numerical simula-tion of density current evolution regulation under the operational conditions by setting different temperatures between the inflow water and the water in the tank with two different forms of feed baffles near the inlet in summer or winter.The results show that:low-temperature inflow water can produce gravity flow in bottom region in summer while high-temperature inflow water pro-duces the gravity flow in top region in winter;the higher velocity water is in bottom region of sedimentation pond,and counterclockwise vortex is obviously formed in summer,while higher ve-locity water is in top region of sedimentation pond ,clockwise vortex is obviously formed in win-ter.The impact of the longer baffle on the density currents in winter is more obvious,and make velocity field more uniform in the tank.

  11. 三分螺旋折流板换热器内二次流分布与强化传热关系分析%Analysis of the relationship between distribution of secondary flow and enhancement of heat transfer in shell-side channel of trisection helical baffled heat exchangers

    Institute of Scientific and Technical Information of China (English)

    王伟晗; 王清成; 陈亚平

    2013-01-01

    通过对倾斜角35°首尾相连的三分螺旋折流板换热器的数值模拟,展示了其壳侧通道内流体在典型切面上的流场和流线分布,以及典型切面上典型直线的流动和换热参数分布,并与性能测试结果进行了对比。结果表明,数值模拟结果与实验结果是吻合的。螺旋折流板形成的近似螺旋通道,使换热器壳侧流体受离心力和向心力共同作用形成了迪恩涡二次流,且在每个螺旋周期内都存在;二次流增强了主流区域流体与靠近壁面流体的掺混,使得壳侧典型切面上中心线和折流板外缘直线的轴向速度较大;除主流中心区域外,壳侧流体在二次流的作用下具有均匀的湍流动能;二次流所在区域内,壳侧同心柱面内典型直线上换热系数相差不大,但由于二次流能使其附近区域传热面上的流体得到不断卷吸掺混,由此强化传热。%Using the numerical simulation of end to end tube-and-shell heat exchangers with trisection helical baffles with 35°inclined angle, this research demonstrated the distribution of the flow field and streamline on the typical sections of fluid in the shell side channel, as well as the distribution of flow and heat transfer parameters of typical straight lines on the typical sections. The results showed that the approximate spiral channel composed by helical baffles impelled the Dean vortex secondary flow formed by the combined effect of centrifugal and centripetal force, and the Dean vortex secondary flow existed in each spiral cycle. the secondary flow enhanced the mixing of fluid in mainstream region and fluid near the wall, resulting a larger axial velocity of the centerline and the outer edge straight line on the typical sections. Other than the mainstream center region, the shell side fluid had uniform turbulent kinetic energy in the role of secondary flow. The heat transfer coefficient on the concentric cylindrical surface

  12. 单弓折流板管壳式换热器壳程局部传热及流阻研究%Study on shell-side local heat transfer and flow resistance of shell-and-tube heat exchanger with arc baffles

    Institute of Scientific and Technical Information of China (English)

    黄阔

    2012-01-01

    The local heat transfer performance, local flow velocity and resistance of shell-and-tube heat exchanger with arc baffles are studied. The measurement result indicates that the change rules of the local heat transfer coefficient of tube bundle and velocity of gas flow in shell-side are consistent. The twenty-four measuring positions are selected suitably, and can reflect the change rules of the local heat transfer and velocity of gas flow. The relevance equations between the average Nu and Re number, and the flow resistance coefficient f and Re number in shell-side of the heat exchanger are summarized, so it provide the reference for designing this kind of heat exchangers.%对半圆形单弓折流板管壳式换热器壳侧局部传热性能、局部流速及阻力进行了实验研究,测量结果表明,其壳侧局部传热膜系数的变化规律与相应点速率变化规律相一致.所取24个测量位置点分布较为合理,基本上反映了换热器局部相应换热及流场分布规律.同时归纳出换热器壳侧的平均努塞尔准数Nu与雷诺准数Re的关联式及流动阻力系数f与雷诺准数Re的关联式,为换热器的实际运用提供了参考依据.

  13. 螺旋折流板换热器的协同角分布特性及局部换热特征%Field synergy angle distribution and local heat transfer characteristic in shell and tube heat exchanger with helical baffles

    Institute of Scientific and Technical Information of China (English)

    张剑飞; 陶文铨; 何雅玲

    2013-01-01

    Three dimensional numerical simulation and field synergy principle analysis were conducted with simplified periodic models for shell and tube heat exchangers with helical baffles at three helix angles (30°,40°and 50°),and commercial codes of GAMBIT 2.3 and FLUENT 6.3 were adopted in the simulation.It is found that Nusselt number from the model with 40° angle is the largest and the predicted average field synergy intersection angle is the smallest,which is consistent with the field synergy principle.The distribution characteristics of field synergy angles reveal that the distribution is quite uniform through whole shell side of the exchangers.The investigation on local heat transfer characteristics in different regions on the shell side shows that the heat transfer rate in the central region of the heat exchanger increases with the increase of Reynolds number.%采用商用软件GAMBIT和FLUENT对3种不同螺旋角的螺旋折流板换热器周期性模型进行了三维数值模拟计算分析.计算发现40°角模型的Nusselt数最高而平均协同角最小,结论符合场协同原理.揭示了螺旋折流板换热器内场协同角的分布特征,发现螺旋折流板换热器整场的场协同角分布相当均匀.同时,对螺旋折流板换热器内不同区域的局部换热特征进行了研究,发现中心区域的换热强度随Reynolds数逐渐增强.

  14. Wandering, Growing, Fighting and Baffling:A narrative analysis on the peasant-worker of the new generation%漂泊·成长·抗争·迷茫--新生代农民工的打工叙事分析

    Institute of Scientific and Technical Information of China (English)

    刘霞

    2013-01-01

      文章以田野调查资料为基础,运用叙事分析的质性研究方法剖析新生代农民工漂泊与迷茫的生存特点。新生代力图通过自己的努力融入城市或实现自我发展,但制度性障碍和歧视性政策依然将他们挡在了城市边缘,他们的漂泊已经从时空的频繁转换延伸为一种内心深处的漂泊感受,个人生命周期的发展阶段又加剧了他们的抗争和迷茫。新生代从农民工转变成工人,转变为城市居民,需要国家相应的制度安排和政策支持。%Based on field data and narrative analysis,this article elaborates on the surviving characteristics of the peasant-worker of the new generation,who attempts to assimilate themselves into the big cities and achieve their own self-development. Howev-er,their efforts are hindered by institutional barriers and discriminated policies. The wandering of the peasant-worker of the new generation has shifted from spaces to inner feeling,and their fighting and baffling are intensified by their development. The suc-cess of their change from peasant-workers into works or city dwellers should be supported by the government’s policy.

  15. Evaluation of shell side performance and analysis on continuous helical baffled heat exchangers with elliptical tubes%椭圆管连续螺旋折流板换热器壳侧性能评价及三场协同分析

    Institute of Scientific and Technical Information of China (English)

    杜文静; 王红福; 袁晓豆; 程林

    2013-01-01

    提出了一种新型的椭圆管连续螺旋折流板换热器.利用ANSYS CFX软件对壳侧流动与传热进行了数值模拟,并采用性能评价图及三场协同原理分析其壳侧性能.结果表明:在研究范围内,以椭圆管替代传统圆管管束后,在维持传热面积基本不变的前提下,壳侧压降降低72%~80%,综合换热性能提高32%~40%.应用性能评价图分析发现椭圆管在强化换热的同时也大大减小了压降.这是由于在相同的速度场与温度场协同前提下,椭圆管使速度场与压力场更好地协同,实现高效低阻强化传热的目的.%A novel continuous helical baffled heat exchanger with elliptical tubes was proposed. Numerical simulation was used to obtain shell side flow and transfer performance with ANSYS CFX. The shell-side performance was further analyzed based on the performance evaluation criterion diagram and the three-field synergy principle. Results show that in the heat exchanger, its shell-side pressure drop is reduced by 72%-80% and comprehensive heat transfer performance is improved 32%-40%, compared with traditional circular tube heat exchangers. Performance evaluation criterion diagram shows that elliptical tubes can enhance heat transfer and reduce flow resistance, since the structure of elliptical tubes brings a better synergy between velocity field and pressure filed with the synergy between velocity field and temperature field, which is favorable for heat transfer enhancement.

  16. Degradation performance and product of anaerobic baffled reactor treating simulated wastewater containing tartrazine%厌氧折流板反应器(ABR)处理柠檬黄模拟废水的效果及产物分析

    Institute of Scientific and Technical Information of China (English)

    谢琴; 伍健东; 周兴求

    2013-01-01

    In this research, an anaerobic baffled reactor (ABR) was used to treat simulated wastewater containing tartrazine, and the effect of hydraulic retention time (HRT) on the removal of tartrazine and COD was also studied. Results showed that the removal rate of tartrazine and COD reached 96. 4% and 97. 9% respectively after anaerobic treatment by ABR with HRT of 30 h. Meanwhile, infrared spectroscopy, UV-Vis spectra and ion chromatography was used to analyze the degradation products of tartrazine. From the results of infrafed spectroscopy and UV-Vis spectra, the azo bond of tartrazine was found broken after anaerobic treatment by ABR, and reduced to aromatic amines which can be further degraded to compounds containing benzene ring or naphthalene ring. In addition, the analysis of ion chromatography showed that the sulfonic acid group in tartrazine molecular could be transformed into SO2 -4 .%  采用厌氧折流板反应器(ABR)处理柠檬黄模拟废水,研究在不同水力停留时间(HRT)下,ABR 对柠檬黄及 COD 的去除效果,实验结果表明,HRT 为30 h 时,柠檬黄经 ABR 厌氧处理后的去除率达96.4%,COD去除率达97.9%.同时利用红外光谱、UV-Vis、离子色谱分析柠檬黄的降解产物.从红外光谱和 UV-Vis 分析得出,柠檬黄经 ABR 厌氧处理后偶氮键断裂,生成的芳香胺类化合物被进一步降解为含苯环、含萘环的化合物;离子色谱定性分析得出柠檬黄分子中的磺酸基转化成了硫酸根.

  17. I love my baffling, backward, counterintuitive, overly complicated magnitudes

    Science.gov (United States)

    Sirola, Christopher

    2017-02-01

    All professions have their jargon. But astronomy goes the extra parsec. Here's an example. Vega, one of the brighter stars in the night sky, has an apparent magnitude (i.e., an apparent brightness) of approximately zero. Polaris, the North Star, has an apparent magnitude of about +2. Despite this, Vega appears brighter than Polaris, and not by two, but by a factor of about six times.

  18. Physical-chemical and operational performance of an anaerobic baffled reactor (ABR treating swine wastewater = Desempenho físico-químico e operacional de um reator anaeróbio compartimentado (RAC como tratamento biológico preliminar de efluentes de suinocultura

    Directory of Open Access Journals (Sweden)

    Erlon Lopes Pereira

    2010-10-01

    Full Text Available Since hog raising concentrates a huge amount of swine manure in smallareas, it is considered by the environmental government organizations to be one of the most potentially pollutant activities. Therefore the main objective of this research was to evaluate by operational criteria and removal efficiency, the performance of a Anaerobic Baffled Reactor (ABR, working as a biological pre-treatment of swine culture effluents. The physical-chemical analyses carried out were: total COD, BOD5, total solids (TS, fix (TFS and volatiles (TVS, temperature, pH, total Kjeldahl nitrogen, phosphorus, total acidity and alkalinity. The ABR unit worked with an average efficiency of 65.2 and 76.2%, respectively, concerning total COD and BOD5, with a hydraulic retention time (HRT about 15 hours. The results for volumetric organic loading rate (VOLR, organic loading rate (OLR andhydraulic loading rate (HLR were: 4.46 kg BOD m-3 day-1; 1.81 kg BOD5 kg TVS-1 day-1 and 1.57 m3 m-3 day-1, respectively. The average efficiency of the whole treatment system for total COD and BOD5 removal were 66.5 and 77.8%, showing an adequate performancein removing the organic matter from swine wastewater.A suinocultura por ser uma atividade pecuária concentradora de dejetos em pequenas áreas é considerada, pelos órgãos de gerência ambiental, como uma das atividades mais degradadoras do meio ambiente. Nesta pesquisa objetivou-se, por conseguinte, avaliar a utilização de um reator anaeróbio compartimentado (RAC, como unidade de prétratamento de um reator tipo UASB, em escala piloto, na adequação ambiental dos efluentes de suinocultura, avaliando critérios operacionais e a eficiência. As análises físico-químicasrealizadas foram: DQOtotal, DBO5, sólidos totais (ST, fixos (SF e voláteis (SV, temperatura, pH, nitrogênio total Kjeldahl, fósforo, acidez total e alcalinidade. A unidade RAC trabalhou com eficiência de 65,2 e 76,2% para a remoção de DQOtotal e DBO5

  19. Desempenho de processo anaeróbio em dois estágios (reator compartimentado seguido de reator UASB para tratamento de águas residuárias de suinocultura Performance of two-stage anaerobic process (baffled reactor (ABR followed by an upflow sludge blanket reactor (UASB treating swine wastewater

    Directory of Open Access Journals (Sweden)

    Gracie F. R. Fernandes

    2006-04-01

    Full Text Available Avaliou-se o efeito das águas residuárias de suinocultura com concentrações de sólidos suspensos totais em torno de 6.000 mg L-1 (DQOtotal variando de 7.557 a 11.640 mg L-1 no desempenho de processo anaeróbio em dois estágios compostos por reator compartimentado (ABR e reator de fluxo ascendente com manta de lodo (UASB, instalados em série, em escala-piloto (volumes de 530 e 120 L, respectivamente, submetidos a tempos de detenção hidráulica (TDH de 56 a 18 h no primeiro reator e de 13 a 4 h no segundo reator. As eficiências médias de remoção de DQOtotal variaram de 71,1 a 87,5% no reator ABR e de 41,5 a 50,1% no reator UASB, resultando em valores médios de 86,8 a 94,9% para o sistema de tratamento anaeróbio em dois estágios com carga orgânica volumétrica (COV, na faixa de 5,05 a 10,12 kg DQOtotal (m³ d-1, no reator ABR, e de 2,83 a 9,63 kg DQOtotal (m³ d-1, no reator UASB. As eficiências de remoção de SST e SSV foram da ordem de 95,6%. O teor de metano no biogás manteve-se acima de 70% para os dois reatores. A produção volumétrica de metano máxima de 0,755 m³ CH4 (m³ d-1 ocorreu no reator 1, com COV de 10,12 kg DQOtotal (m³ d-1 e TDH de 18 h. Os valores médios de pH variaram na faixa de 7,2 a 8,0 para os efluentes dos reatores 1 e 2. Os ácidos voláteis totais mantiveram-se estáveis com concentrações abaixo de 200 mg L-1. Com variações abruptas e acentuadas de concentrações de SST e DQOtotal do afluente, os reatores mantiveram as eficiências de remoção de DQO e sólidos suspensos, em torno de 70%, e a qualidade do biogás, com 80% de CH4.In this work it was evaluated the effect of swine wastewater with total suspended solid (TSS concentration around 6000 mg L-1 (CODtotal from 7557 to 11640 mg L-1 on the performance of two stage anaerobic process constituted of anaerobic baffled reactors (ABR and an upflow sludge blanket reactor (UASB installed in series, in pilot scale testing (volumes of 530 L and

  20. 基于 VFAs 抑制系数的 ABR 基质降解与产甲烷预测模型%Modeling of substrate degradation and methane production in anaerobic baffled reactor based on inhibition parameter of volatile fatty acids

    Institute of Scientific and Technical Information of China (English)

    施恩; 李建政; 马天楠

    2016-01-01

    利用 Andrews 模型构建了4格室厌氧折流板反应器(ABR)的基质降解动力学模型,并将其与甲烷发酵的化学计量学耦合,构建出有机废水产甲烷预测模型。在 HRT 40 h、35℃和进水 COD 分阶段从2000提高到8000 mg·L−1条件下,校准的 Andrews 模型能准确模拟 COD 在系统中的变化规律,通过拟合得出的最大比基质去除速率(k)和饱和常数(Ks)在不同进水 COD 浓度下均为2 d−1和100 mg COD·L−1,而挥发性脂肪酸(VFAs)对甲烷发酵的抑制系数(Ki)随进水 COD 的提高而增大。VFAs 的当量 COD 在第1格室接近或高于 Ki,对甲烷发酵抑制明显;而在后3格室低于 Ki 且逐格降低,抑制甲烷发酵的作用越来越小。第1~第4格室的甲烷产量实测值分别为1.12~6.42,2.54~8.96,1.24~4.48和0.16~0.58 L·d−1,而构建的产甲烷预测模型能够准确预测这一变化趋势。校准的 Andrew模型和甲烷预测模型可为 ABR 的设计与调控运行提供指导。%A 4-compartment anaerobic baffled reactor (ABR) was operated for organic wastewater treatment at a constant hydraulic retention time (HRT) of 40 h and temperature of 35°C, with the influent COD increased from 2000 to 8000 mg·L−1 stage by stage. Based on the reactor performance, Andrews model was constructed firstly for substrate degradation in the ABR. And then a prediction model for methane production was constructed by combining the stoichiometry of methane fermentation with the developed substrate degradation model. The results showed that the simulated COD of the calibrated Andrews model was well agreed with the measured data in the ABR. The experimental data were used to calibrate the dynamics parameters. k as the estimated maximum specific substrate degradation rate and Ks as the semi-saturation constant were kept at 2 d−1 and 100 mg COD·L−1, respectively, though the influent COD increased by stages. On the contrary, Ki as the inhibition

  1. Remoção de matéria orgânica, de nutrientes e de coliformes no processo anaeróbio em dois estágios (reator compartimentado seguido de reator UASB para o tratamento de águas residuárias de suinocultura Organic matter, nutrients and coliforms removal in two-stage anaerobic process (anaerobic baffled reactor followed by UASB reactor for swine wastewater treatment

    Directory of Open Access Journals (Sweden)

    Mário S. de Abreu Neto

    2009-03-01

    Full Text Available Neste trabalho, avaliou-se o efeito das águas residuárias de suinocultura, com concentrações médias de sólidos suspensos totais variando de 4.591 a 13.001 mg L-1, no desempenho de processo anaeróbio, em dois estágios, compostos por reator compartimentado (ABR e reator de fluxo ascendente com manta de lodo (UASB, instalados em série, em escala- -piloto (volumes de 530 e 120 L, respectivamente, submetidos a tempos de detenção hidráulica (TDH de 60; 36 e 24 h no primeiro reator, e de 13,6; 8,2 e 5,4 h no segundo reator. As eficiências médias de remoção de DQOtotal variaram de 69 a 84% no reator ABR e de 39 a 58% no reator UASB, resultando em valores médios de 87 a 94% para o sistema de tratamento anaeróbio em dois estágios, com carga orgânica volumétrica (COV na faixa de 11,5 a 18,0 g DQOtotal (L d-1 no reator ABR, e de 4,2 a 13,4 g DQOtotal (L d-1 no reator UASB. A produção volumétrica máxima de metano de 0,227 m³ CH4 (m³ reator d-1 ocorreu no reator UASB, com COV de 10,6 g DQOtotal (L d-1 e TDH de 5,4 h. As maiores eficiências de remoção de coliformes totais e termotolerantes (99,7%, DQOdiss (94%, SST (96%, NTK (71%, P-total (61% e outros nutrientes, no sistema de tratamento anaeróbio em dois estágios, foram obtidas com o TDH de 73,6 h e temperatura climatológica média de 24,6 °C, aplicando-se a menor COV (de 11,5 g DQOtotal (L d-1 no reator ABR, e de 4,2 g DQOtotal (L d-1 no reator UASB com a maior concentração de SST do afluente (13.001 mg L-1.In this work it was evaluated the effect of swine wastewater with mean total suspended solid (TSS concentration ranging from 4.591 to 13.001 mg L-1 on the performance of the anaerobic process in two stages composed of anaerobic baffled reactors (ABR and an upflow sludge blanket reactor (UASB, installed in series, in pilot scale testing (volumes of 530 and 120 L, respectively and with hydraulic detention times (HDT of 60; 36 and 24 h in the ABR reactor and 13.6; 8.2 and

  2. Evaluation Of Communal Wastewater Treatment Plant Operating Anaerobic Baffled Reactor And Biofilter

    Directory of Open Access Journals (Sweden)

    Evy Hendriarianti

    2016-02-01

    Full Text Available Construction of communal Waste Water Treatment Plant, WWTP in city of Malang since 1998 but until recently had never done an evaluation the performance. Communal WWTP performance evaluation is needed to see how far the efficiency of processing result. Until now, Environmental Agency Malang City only measure effluent from WWTP Communal  to know the suitability  with domestic wastewater quality standards. Effluent quality data in 2014 showed value above the quality standard of domestic wastewater from East Java Governor Regulation No. 72 in 2013 for parameters BOD and COD. WWTP Communal USRI research objects are on a six (6 locations by involving the user community during the planning, construction, operation and maintenance. Technology choice of ABR followed by a biofilter reactor with the stone media proved capable of processing organic matter of BOD and COD with the removal levels respectively by 78% -99% and 71% -99%. As for the parameters of TSS, NO3 and PO4 have the ranges of removal respectively by 56% -100%, (43% - 72%, (2% - 13%. Ratio BOD and COD in influent are low and ranged from 0.22 to 0.41. From the evaluation shows that high organic matter concentrations in influent along with the HRT and operation time high will result in a higher removal level

  3. A Study of Resonant-Cavity and Fiberglass-Filled Parallel Baffles as Duct Silencers.

    Science.gov (United States)

    1982-04-01

    The one adopted was the Kurze Ingard and Ising (ref. 13) give the following expres- method described in references 9 and 12. Kurze sion for Rh... Ingard , U.; and Ising, H.: Acoustic Nonlinearity Testing Capability by Modifying the 40- by of an Orifice. JASA, vol. 42, no. 1, July 1967, 80-Foot Wind

  4. Active control of radiated sound power from a baffled, rectangular panel

    DEFF Research Database (Denmark)

    Mørkholt, Jakob

    1996-01-01

    with an array of eleven microphones in front of the panel, is very close to minimising the actual radiated sound power. Practical experiments where such an array estimate has been minimised using the filtered X LMS algorithm have shown that substantial reductions of radiated sound power can be obtained over...

  5. Effect of segmental baffles on the shell-and-tube heat exchanger effectiveness

    OpenAIRE

    Vukić Mića V.; Tomić Mladen A.; Živković Predrag M.; Ilić Gradimir S.

    2014-01-01

    In this paper, the results of the experimental investigations of fluid flow and heat transfer in laboratory experimental shell-and-tube heat exchanger are presented. Shell-and-tube heat exchanger is with one pass of warm water on the shell side and two passes of cool water in tube bundle. Shell-and-tube heat exchanger is with 24x2 tubes (U-tube) in triangle layout. During each experimental run, the pressure drops and the fluid temperatures on shell side, al...

  6. INADEQUACY IN DIAGNOSIS OF BLUNT TRAUMA ABDOMEN - CAN ANAESTHESIOLOGIST BE BAFFLED BY CATASTROPHIC INTRAOPERATIVE FINDINGS?

    Directory of Open Access Journals (Sweden)

    Joyanta Kumar

    2015-08-01

    Full Text Available The magnitude of injury inflicted by Blunt trauma abdomen has varied manifestations ranging from minor single - system injury to devastating, multi - system injury .Blunt trauma abdomen alone or in association with polytrauma is a frequent presentation in the emergency department. High index of suspicion and clinical acumen is required during evaluation of blunt abdominal injuries because physical signs and symptoms indicating presence of visceral lesions may poorly correlate with clinical presentation. Diagnostic peritoneal tapping is considered safe initial option with high accuracy but carries possibility of significant false positive and false negative result. Ultrasonography (FAST ha s its own limitations; although CT findings can be conclusive it involves time for analysis and the patient should be cooperative. Blunt trauma abdomen may present with life threatening internal haemorrhage due to visceral or vascular injuries prompting em ergency surgical intervention at odd hours with limited investigations and resources, Pre anaesthetic optimization by maintenance of adequate tissue oxygenation with optimal blood volume replacement and judicious use of inotropes, determine outcome of such emergency procedures. Careful selection of anaesthetic techniques and drugs particularly the inducing agents can be life - saving. Agility of the attending anesthesiologist to handle unforeseen intra operative critical events plays a pivotal role in overall outcome. We are discussing Anaesthetic management of a 23 year old victim of road traffic accident, who sustained blunt trauma abdomen about 24 hrs. Back, was conscious, oriented and ambulatory till the time of shifting to the operating theatre but on exp loration sudden gush of blood from a preoperatively undetected 7 cms long tear of the sub diaphragmatic part of IVC, and lacerated liver almost exsanguinated the patient.

  7. "It Beckons, and It Baffles--": Resurrecting Emily Dickinson (and Poetry) in the Student-Centered Classroom.

    Science.gov (United States)

    Thomas, P. L.

    1998-01-01

    Describes an efficient, open-ended set of instructional activities for high school students that has students analyze song lyrics of R.E.M. (an alternative rock band from Athens, Georgia) for literary techniques, topics, themes, and form as preparation to experiment with reading, deciphering, and mimicking Emily Dickinson. (SR)

  8. A Specular Chamber for Off-Axis Response Evaluations of High-Rejection Optical Baffling System

    Science.gov (United States)

    1976-06-01

    eliminate the need for external attenuators if a stable but variable power source is available. The source is set at a low power for the near-field...light Intensity as funcions of wavelength and angle for several aerool size distributions. Penndorf (1956) has compiled an extensive table of computed...associated power transfer coefficient. Each node thus represents a variable (the power avalable for reflection or diffraction from the surface or knife edge

  9. Effect of the LHC Beam Screen Baffle on the Electron Cloud Buildup

    CERN Document Server

    Romano, Annalisa; Li, Kevin; Rumolo, Giovanni

    2016-01-01

    Electron Cloud (EC) has been identified as one of the major intensity-limiting factors in the CERN Large Hadron Collider (LHC). Due to the EC, an additional heat load is deposited on the perforated LHC beam screen, for which only a small cooling capacity is available. In order to preserve the superconducting state of the magnets, pumping slots shields were added on the outer side of the beam screens. In the framework of the design of the beam screens of the new HL-LHC triplets, the impact of these shields on the multipacting process was studied with macroparticle simulations. For this purpose multiple new features had to be introduced in the PyECLOUD code. This contribution will describe the implemented simulation model and summarize the outcome of this study.

  10. Heat Transfer and Hydrodynamic Investigations of a Baffled Slurry Bubble Comumn

    Institute of Scientific and Technical Information of China (English)

    S.C.Saxena; Z.D.Chen

    1992-01-01

    Heat transfer and hydrodynamic investigations have been conducted in a 0.108 m internal diameter bubble column at ambient conditions,The colum is equipped with seven 19mm diameter tubes arranged in an equilateral triangular pitch of 36.5mm.A monsanto synthetic heat transfer fluid,Therminol-66 having a viscosity of 39.8 cP at 303 K,is used as a liquid medium,Magnetite powders.average diameters 27.7 and 36.6um,in five concentrations up to 50 weitht percent in the slurry,are used,As a ges phase,industrial grade nitrogen of purity 99.6 percent is employed.Gas holdup in different operating modes and regimes have been measured for the two-and three-phase systems over a superficial gas velocity range up to 0.20 m/s in the semi-batch moed.Heat transfer coefficients are measured at different tube locations in the bundle at different radial and vertical locations over a range of operating conditions,all these data are compared with the existing literature correlations and models.New correlations are proposed.

  11. The Design, Construction and Test of stray light suppression baffles for the CHAMP satellite

    DEFF Research Database (Denmark)

    Jørgensen, John Leif

    1997-01-01

    The Advanced Stellar Compass, to be delivered from IAU to the CHAMP project, requires some kind of stray-light suppressing shade to be mounted in front of the lens, in order to minimize the thermal impact and to maximize the performance envelope when subjected to non-stellar external light source....... Design, production and verification methods are given....

  12. Effects of operational factors on soluble microbial products in a carrier anaerobic baffled reactor treating dilute wastewater

    Institute of Scientific and Technical Information of China (English)

    FENG Huajun; HU Lifang; SHAN Dan; FANG Chengran; HE Yonghua; SHEN Dongsheng

    2008-01-01

    The effects of feed strength,hydraulic residence time(HRT),and operational temperatures on soluble microbial product(SMP) production were investigated,to gain insights into the production mechanism.A carrier anaerobic batfled reactor (CABR) treating dilute wastewater was operated under a wide range of operational conditions,namely,feed strengths of 300-600 mg/L,HRTs of 9-18 h,and temperatures of 10-28℃.Generally, SMP production increased with increasing feed strength and decreasing temperature.At high temperature (28℃),SMP production increased with decreasing HRT. As the temperature Was decreased to 18 and 10℃.the SMP production was at its peak for 12 h HRT Therefore,temperature could be an important determinant of SMP production along with HRT. A higher SMP to soluble chemical oxygen demand (SCOD) ratio Was found at high temperature and long HRT because of complete volatile fatty acid degradation.SMP accounted for 50%-75% of the SCOD in the last chamber of the CABR.As a secondary metabolite.some SMP could be consumed at lower feed strength.

  13. The influence of perforated baffles on the mixing and segregation of a binary group B mixture in a gas-solid fluidized bed

    NARCIS (Netherlands)

    Hartholt, G.P; laRiviere, R.; Hoffmann, A.C; Janssen, L.P.B.M.; Rivière, R. la

    1997-01-01

    This paper presents a method of influencing the axial mixing of particles and promoting segregation in fluidized beds without otherwise changing the character of the bed substantially (at least at low to moderate gas velocities). The method is based on the introduction in the bed of horizontal scree

  14. Boiler with Baffle, Heat Accumulation Smoke Dispersal and Dust Removal%吊胆折流积热消烟除尘锅炉

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    @@ 由三河市环发锅炉有限公司开发的吊胆折流积热消烟除尘锅炉,品种齐全,有60个品种,供暖面积可由100m2到1.8万m2,适用于农村、小城镇、山区、平原,学校、机关、部队、铁路及中小企业平房、楼房的供暖、开水、淋浴之用.

  15. 阻碍女性职业发展的因素分析%Glass Ceiling Factor Analysis of Baffling Occupational Women Development

    Institute of Scientific and Technical Information of China (English)

    赵慧军

    2006-01-01

    本文从性别平等的视角,对国内外关于职业女性发展问题的研究进行综述,从女性个人特质、组织雇佣和社会文化三个层面分析阻碍女性在组织中晋升和发展的障碍,指出正确对待女性发展问题、更好地创造开发女性人力资源潜力的社会与组织环境的理论与实际意义.

  16. 通风橱导流板的设计与模拟%Design and simulation of baffle of fume hood

    Institute of Scientific and Technical Information of China (English)

    李汛; 王晓华

    2004-01-01

    为解决通风橱对烟气适应能力差的问题,设计了一种导流板.采用K-ε湍流模型,应用两相流理论,对通风橱的流场进行了数值模拟.计算表明,在一定的烟气量范围内,导流板能够有效地将烟气与通风橱的入口隔开,保证烟气的顺利排出,使通风橱的安全性和适应能力得到明显提高.

  17. Acoustic modeling of a three-dimensional rectangular opened enclosure coupled with a semi-infinite exterior field at the baffled opening.

    Science.gov (United States)

    Jin, Guoyong; Shi, Shuangxia; Liu, Zhigang

    2016-11-01

    A modeling method is proposed for the acoustic analysis of a three-dimensional (3D) rectangular opened enclosure coupled with a semi-infinite exterior field by a rectangular opening of arbitrary size, and with general wall impedance. In contrast to existing modeling methods that solve the differential equations, the energy principle in combination with a 3D modified Fourier cosine series is employed in the present method for the modeling of this system. Under this theoretical framework, the effect of an opening in the wall of a rectangular enclosure is taken into account via the work done by the sound pressure acting on the opening between the finite enclosure and exterior domain. The sound pressure inside the opened enclosure is expressed as the combination of a 3D trigonometric cosine series and one supplementary 2D expansion introduced to ensure uniform convergence of the solution over the entire solution domain including opening boundary. The acoustic responses of the opened enclosure are obtained based on the energy expressions for the enclosure system. The effectiveness and reliability of the current method are checked against the results obtained by the boundary element method and experimental results, and excellent agreement is achieved. The effects of sizes and positions of the opening and wall impedance on the acoustic behaviors of opened enclosure system are investigated.

  18. An experimental investigation of heat-transfer and flow in channels with streamwise-periodic flow

    Energy Technology Data Exchange (ETDEWEB)

    Habib, M.A. (King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia)); Mobarak, A.M.; Attya, A.M.; Aly, A.Z. (Cairo Univ. (Egypt). Faculty of Engineering)

    1992-11-01

    We investigate the enhancement of heat transfer and the consequent conservation of energy in channels with segmented baffles. The influence of Reynolds number, baffle spacing, baffle material, and heat flux on local and average heat-transfer coefficients have been studied. Our results show that the flow must pass over three to six baffles before it becomes periodic and fully-developed. Augmentation of heat transfer was obtained with increases in Reynolds number, thermal conductivity of the baffles and decreases in baffle spacing and wall heat flux. (Author).

  19. Nonlinear Sloshing and the Coupled Dynamics of Liquid Propellants and Spacecraft

    Science.gov (United States)

    1992-02-29

    asdsytmshaerahr oplx isinreureenswhc dnd h ofli theu~ liquido slohtng for hreedimesionl liuid Loshn iutio. Flid ynmic and. fudlaig nldn oa oc n impc...VERTICAL EXCITATION AND ITS CONTROL BY BAFFLES ............................................ 29 CHAPTER 4 THE CONTROL OF LATERAL SLOSHING IN RECTANGULAR...TANK - THE EFFECTIVENESS OF FIXED BAFFLE AND MOVING BAFFLE WITH FEEDBACK CONTROL ............................................. 32 CHAPTER 5 THE IMPACT

  20. 连拱空箱式挡土墙结构形式的探讨%Discussion of the Structural Form of Continuous Arc Empty Box Type Soil Baffle

    Institute of Scientific and Technical Information of China (English)

    谢文东

    2003-01-01

    连拱空箱式挡土墙是一种适用于在软土地基上建造高挡墙的新型结构.它在墙身部位采用了拱型和T型结构,受力明确,各种筑墙材料能够充分发挥其力学特性,做到既合理又经济.本文通过实例对连拱空箱式挡土墙进行稳定验算,并与钢筋混凝土扶壁式挡墙进行对比,结果证明连拱空箱式挡土墙在软弱地基上的适应性远胜于钢筋混凝土扶壁式挡墙.此外,它造价低廉、筑墙材料多样化以及一旦发生事故可进行有效的补救都是其独到之处.

  1. 梅花形孔板支撑换热器壳程流场的数值分析%Numerical Analysis of Flow Field in Shell Side of Cinquefoil Orifice-Baffle Support Type Heat Exchanger

    Institute of Scientific and Technical Information of China (English)

    戴玉龙; 李志安; 王翠华; 陈玉博

    2007-01-01

    提出了梅花形孔板支撑换热器壳程的单元简化模型,应用CFD软件FLUENT对换热器进行数值分析,得到流场、温度场的细观信息,通过不同跨距折流板的数值模拟,拟合出相应公式,为梅花形孔板支撑换热器的结构优化设计提供了依据.

  2. 孔板支撑换热器壳程流场的数值预测%Numerical Prediction of Flow Field in Shell Side of the Orifice-Baffle Support Type Heat Exchanger

    Institute of Scientific and Technical Information of China (English)

    董其伍; 吴金星; 刘敏珊; 魏新利

    2003-01-01

    孔板支撑换热器用整圆形孔板代替传统的弓形折流板来支撑管束,消除了大部分传热死区,并由于小孔射流和扰流作用在较低雷诺数下提高了传热效率.本文提出了孔板支撑换热器的单元流道简化模型,用数值方法预测了大管孔孔板和小圆孔孔板支撑单元流道的流场.结果证明孔板支撑强化传热的主要机理是破坏管壁表面的液体边界层,大管孔孔板的综合性能优于小圆孔孔板.

  3. Numerical Simulation of Flow in Shell Side of Shell-and-Tube Heat Exchangers with Helical Baffles%螺旋折流板换热器壳侧流动的数值模拟

    Institute of Scientific and Technical Information of China (English)

    邓斌; 吴扬; 陶文铨

    2004-01-01

    采用多孔介质、分布阻力模型、阶梯逼近技术对螺旋折流板换热器壳侧的流动进行了三维数值模拟,湍流方程组的求解采用了改进的k-ε模型和壁面函数法.数值模拟结果表明,在相同的进口内径及相同的进口流量条件下,螺旋折流板换热器壳侧的压降明显低于弓形折流板换热器的,且随着螺旋角的增加,压降呈减小的趋势.在小流量条件下,计算所得的换热器进出口总压降与实验值之间的偏差大部分在14% 以下,最大为18%,能符合工程计算的需要.

  4. 折流板开孔改进管壳式换热器性能的CFD分析%Analysing the effect of drilling holes on the baffles of shell-and-tube heat exchanger based on the CFD

    Institute of Scientific and Technical Information of China (English)

    熊智强; 喻九阳; 曾春

    2006-01-01

    利用计算流体动力学(CFD)技术对管壳式换热器弓形折流板附近流场进行了数值模拟,发现在弓形折流板背面,有部分区域的流速较低,一定程度上存在着流动死区.采用在弓形折流板上开孔的方法后,CFD计算结果显示其传热效率提高了5.4%,壳侧压降减小了7.3%.

  5. Simulation & experimental research on shell passage performance of rod baffle heat exchanger with triangular tube layout%三角形布管折流杆换热器壳程性能模拟与实验研究

    Institute of Scientific and Technical Information of China (English)

    郭崇志; 胡崇举

    2013-01-01

    三角形布管折流杆换热器是一种有别于传统方形布管折流杆换热器的新形式,其性能评估与算法都没有现成的资料.文中应用CFD软件Fluent进行分段模型的流动与传热研究,将数值模拟的局部流动与传热数据综合整理得到了整体法关联式,经与文中的实验数据和C.C.Gentry提出的实验关联式进行对比,发现方形布管的模拟结果与C.C.Gentry关联式符合良好;三角形布管的模拟结果与本文改进的C.C.Gentry关联式比较,发现传热关联式精度很高,而压力降关联式的平均误差也可以接受.由此提出了三角形布管壳程的折流杆换热器流动与传热设计评估的计算方法.验证还发现,包含E间隙的换热器模型模拟更符合实测数据结果.

  6. 改进的萤火虫群优化算法及其非线性盲源分离%Nonlinear Blind Source Separation Algorithm Using Glowworm Swarm Optimization with Baffle Effect

    Institute of Scientific and Technical Information of China (English)

    黄浦博; 尉宇

    2015-01-01

    根据萤火虫算法的特点,针对萤火虫算法较早进入局部收敛的不足进行改进,引入了“挡板效应”的方法,扩大种群多样性,并提出了BGSO算法.在分析了非线性盲源分离模型的基础上,利用系统两次遍历萤火虫群,比较评价函数,获得最优解的方式.其有效性被仿真结果所证实.

  7. 麦金太尔解决休谟伦理难题的贡献与困惑%MacIntyre's Contributions to the Solving of Hume's Baffling Problem in Ethics and its Difficulty

    Institute of Scientific and Technical Information of China (English)

    杨泽波

    2002-01-01

    麦金太尔《德性之后》的一个重要意义,是试图解决休谟伦理难题,即"是"与"应该"的矛盾.本文对此作一个初步的分析,力图证明麦金太尔在这个方面的贡献以及存在的不足.

  8. The effects of nutrient limitation (nitrogen and phosphorus) on BOD removal from post-coagulated Pinus radiata sulfite pulp and paper mill wastewater in a baffled aerated stabilisation basin-laboratory pilot scale study.

    Science.gov (United States)

    Dewi, R; Van Leeuwen, J A; Everson, A; Nothrop, S C; Chow, C W K

    2011-01-01

    The use of coagulation and flocculation for tertiary treatment of pulp and paper mill effluent was investigated, where the evaluation was based on the removal of nitrogen (N), phosphorus (P) and BOD from post-coagulated wastewater. The study was undertaken on laboratory scale aerobic stabilisation basins (ASB). Two post coagulated (alum) wastewaters were studied, where the BOD:N:P ratios were 100:1.3:0.06 and 100:1.3:0.3. These wastewaters were treated in two identical concurrent simulations (A & B). The influent ratio for 'A' was selected representing the composition of actual coagulated Pinus radiata sulfite pulp effluent mixed with paper mill effluent. The input composition for 'B' represented a typical P concentration found in existing pulp and paper mill effluents. Unmodified sludge collected from a mill-pond was added at 4% v/v to each simulation replicating the treatment conditions at full-scale. Similar high percentage removals of BOD and COD occurred after 28 days (two HRTs) which were 94 and 67% respectively for 'A', and 98 and 70% respectively for 'B', where both remained at steady state during the third HRT. A statistical analysis of the data revealed that there was no significant difference in the sample variance of the BOD and COD results.

  9. Anaerobic baffled reactor-biological contact oxidationg process for cider-processing wastewater treatment%厌氧折流板反应器-接触氧化工艺处理果汁废水

    Institute of Scientific and Technical Information of China (English)

    杨学朝; 郑重

    2008-01-01

    某果业有限公司果汁废水水量为1 500 m3/d,COD为4 500 mg/L,BOD为2 500 mg/L,,ss为2 500 mg/L,pH为6~7.采用厌氧折流板反应器(ABR)一接触氧化工艺处理该废水,出水COD为70 mg/L,BOD为10 mg/L,SS为55 mg/L,pH为8,达到(GB 8978-1996)一级排放标准.

  10. 厌氧折流板反应器处理退浆废水的启动研究%Start-up of the anaerobic baffled reactor for treating desizing wastewater

    Institute of Scientific and Technical Information of China (English)

    周建冬; 奚旦立; 李小琴; 刘荣荣

    2009-01-01

    The start-up of anaerobic bamed reactor(ABR) for treating desizing wastewater has been studied. The results show that: after the start-up of the ABR has run for 90 d, and when the reactor is at 32-34 ℃, the up-removal rate is above 55%, the COD of outflow is about 4 500 mg/L, the alkalinity is between 700 mg/L to 850 mg/L. The running situation indicates that since the pH of each compartment at the early days of the start-up varies greatly, to control the pH efficiently is an important key of the start-up. At the latter days of the start-up, the pH of each compartment keeps stably from 6.8 to 7,3, and the concentration of volatile fatty acid (VFA) is from 300 mg/L to 500 mg/L. Along with the transverse process of compartments, the SS, VSS and SS/VSS of sludge grow greatly, it is predicted that anaerobic microorganism phases in the ABR has been separated distinctly.%对采用厌氧折流板反应器(ABR)处理难降解退浆废水的启动过程进行了研究.实验结果表明:经过90 d的运行,反应器在32~34℃、上流速度8 m/h、水力停留时间6 d、COD容积负荷1.80 kg/(m3·d)的条件下,COD去除率达到55%以上,启动成功.出水COD稳定在4 500 mg/L左右,碱度约为700~850 mg/L.运行情况表明,启动初期反应器各隔室的pH变化较大,有效控制pH是系统启动成功的关键.启动后期,各隔室pH稳定在6.8~7.3之间,挥发性脂肪酸(VFA)质量浓度为300~500mg/L.随着隔室的横向推移,污泥的SS、VSS和SS/VSS不断增大,推测反应器中厌氧微生物相分离现象显著.

  11. 基于Por/Mechanica与Ansys的推台锯横挡板结构的有限元分析%Finite element analysis of the table saw horizontal baffle structure based on Por / Mechanica and Ansys

    Institute of Scientific and Technical Information of China (English)

    董路平; 战丽

    2012-01-01

    利用Proe5.0软件建立推台锯横挡板的三维模型,针对其结构强度的有关校核,提出了利用Por/Mechanica模块对其进行应力有限元分析,并结合Ansys Workbench软件对其进行有关的后处理受力分析.

  12. Production of bioenergy in anaerobic baffled reactor (ABR) and sludge blanket (UASB) in the treatment os swine waste water; Producao de bioenergia em reatores anaerobios compartimentado (RAC) e de manta de lodo (UASB) no tratamento de efluentes de suinocultura

    Energy Technology Data Exchange (ETDEWEB)

    Moterani, Fabricio; Pereira, Erlon Lopes; Campos, Claudio M.M. [Universidade Federal de Lavras (DEG/UFLA), MG (Brazil). Dept. de Engenharia], email: fabricio_moterani@yahoo.com.br

    2011-07-01

    The biogas is obtained in the processes of degradation of organic matter by the action of bacterial consortium in the environment. The aim of this study was to evaluate the biogas production in anaerobic UASB and ABR in swine wastewater treatment. For this we used the theoretical estimated and actual production of biogas measured by anaerobic gasometers installed in the units. Methane was determined by gas chromatography (GC) and its theoretical output was 66 LCH4 kgSVT d{sup -1} and 11.9 LCH4 kgSVT d{sup -1} and 24.7 m{sup 3} d{sup -1} and 5.4 m{sup 3} d{sup -1} to ABR and UASB, respectively. Regarding the actual production of biogas in the reactor provided by the gas tank, found the values of 1,166.4 m{sup 3}; 0.1 m{sup 3}; 27.4 m{sup 3} and 12,598.5 m{sup 3} of biogas for compartments 1, 2 and 3 and ABR for the UASB reactor, respectively, totaling, production of 13,792.4 m{sup 3} in the units together, with an average of 113 m{sup 3} of biogas per day. But, it concludes with this research that the use of effluent from produce energy through biogas in swine farming is effective, which can be used in rural productive system itself. (author)

  13. 喷嘴式隔板与纵向肋式隔板阻尼效应分析%Analysis on damping effect of vibration baffles with protruded injectors and longitudinal ribs

    Institute of Scientific and Technical Information of China (English)

    郭灿琳; 卢钢; 陈建华; 吴海波

    2013-01-01

    利用声学模型和单喷嘴声学模拟试验研究了喷嘴式隔板的耗散机理;用数值方法分析了纵向肋式隔板周围的涡流;用声学理论研究了纵向肋式隔板的声场.研究结果表明:选取合适的管间隙将会使喷嘴式隔板具有更好的稳定性作用;肋片周围是涡流产生的主要区域;肋高对燃烧室声学特性的影响远大于肋长.

  14. 从中西认识论传统之比较重新解读"李约瑟难题"%Reinterpreting Joseph Lee's Baffling Problem by Comparing Cognitive Paradigms in China and the West

    Institute of Scientific and Technical Information of China (English)

    李刚

    2005-01-01

    首先对"李约瑟难题"本身所蕴涵的逻辑矛盾进行了揭示;然后从中西不同的认识论范式的比较分析的视角对"李约瑟难题"予以重新解读,从而得出结论:"形而下"与"形而上"的差别实际上标志出了中西传统认识论的根本分水岭,中西不同的认识论范式对应着两种不同的科学范式,古代中国只有自然哲学和实用科学而从来没有理论科学,我国自始至终缺乏理论科学得以生长的文化基因(数学理性、逻辑理性、实验理性和自由精神等).因此,我国当前必须重新审视"李约瑟难题",避免"李约瑟难题"带来的负面效应,大力培育适于科学生长的文化土壤才是当务之急.

  15. 我国社会资本现状及其对公民政策参与的阻滞%The Current Situation of Social Capital in China and Its Baffle to Citizen Policy Participation

    Institute of Scientific and Technical Information of China (English)

    蔡新燕

    2012-01-01

    With the new progress of China's democratic and political construction, the importance of citizen policy participation has increasingly been the focus. The effective policy participate is relied on the good trust and cooperative relations between government and citizens, and the establishment of such relation is based on the full development of social capital as a precondition. Now social capital in our country has many defects, such as lack of social credit system, the non-perfect of rules and system, the weakness of organizational foundation of citizen policy participation, and the path dependence on traditional policy process, which restricts our citizen policy participation.%随着中国民主政治建设的新进展,公民政策参与的重要性日益为人们所重视。有效的政策参与依赖于政府与公民之间的良好信任与合作关系,而信任与合作关系的建立以社会资本的充分发展为前提。目前我国的社会资本存在诸多缺陷,如社会诚信体系的缺失、各种规则和制度的不健全、公民政策参与组织基础的薄弱以及传统政策过程的路径依赖等,制约着我国公民政策参与。

  16. Staged electrostatic precipitator

    Science.gov (United States)

    Miller, Stanley J.; Almlie, Jay C.; Zhuang, Ye

    2016-03-01

    A device includes a chamber having an air inlet and an air outlet. The device includes a plurality of stages including at least a first stage adjacent a second stage. The plurality of stages are disposed in the chamber and each stage has a plurality of discharge electrodes disposed in an interior region and is bounded by an upstream baffle on an end proximate the air inlet and bounded by a downstream baffle on an end proximate the air outlet. Each stage has at least one sidewall between the upstream baffle and the downstream baffle. The sidewall is configured as a collection electrode and has a plurality of apertures disposed along a length between the upstream baffle and the downstream baffle. The upstream baffle of the first stage is positioned in staggered alignment relative to the upstream baffle of the second stage and the downstream baffle of the first stage are positioned in staggered alignment relative to the downstream baffle of the second stage.

  17. Investigating Morphological Stability of Faceted Interfaces with Axial Heat Processing (AHP) Technique

    Science.gov (United States)

    Abbaschian, Reza; Balikci, Ercan; Deal, Andrew; Gonik, Michael; Golyshev, Viladimir D.; Leonardi, Eddie; deVahlDavis, G.; Chen, P. Y. P.; Timchenko, V.

    2003-01-01

    Successful processing of homogeneous semiconductor single crystals from their melts depends strongly on precise control of thermal and fluid flow conditions near the solid/liquid interface. In this project, we utilize a novel crystal growth technique called Axial Heat Processing (AHP) that uses a baffle, positioned inside the melt near the interface, to supply and/or conduct heat axially to the interface. The baffle, which may or may not have a heater encased in it, can promote more stable and planar growth as well as reduce buoyancy driven convection. The latter is because the baffle reduces the aspect ratio of the melt as it separates the melt into three sections, above the baffle, in the feed gap between the baffle and the crucible wall, and below the baffle between the baffle base and the interface. AHP also enables a close monitoring and/or control of thermal boundaries near the solid/liquid interface during crystal growth by means of thermocouples placed in the baffle. The interface is kept planar when a heating element in the baffle is used. However, a proper choice of melt height is necessary to keep the interface planar when using the baffle without a heater. This study addresses the influence of melt height and growth velocity on the segregation profile of AHP-grown Sb doped Ge single crystals.

  18. Relay telescope for high power laser alignment system

    Science.gov (United States)

    Dane, C. Brent; Hackel, Lloyd; Harris, Fritz B.

    2006-09-19

    A laser system includes an optical path having an intracavity relay telescope with a telescope focal point for imaging an output of the gain medium between an image location at or near the gain medium and an image location at or near an output coupler for the laser system. A kinematic mount is provided within a vacuum chamber, and adapted to secure beam baffles near the telescope focal point. An access port on the vacuum chamber is adapted for allowing insertion and removal of the beam baffles. A first baffle formed using an alignment pinhole aperture is used during alignment of the laser system. A second tapered baffle replaces the alignment aperture during operation and acts as a far-field baffle in which off angle beams strike the baffle a grazing angle of incidence, reducing fluence levels at the impact areas.

  19. Increasing thermal efficiency of solar flat plate collectors

    Science.gov (United States)

    Pona, J.

    A study of methods to increase the efficiency of heat transfer in flat plate solar collectors is presented. In order to increase the heat transfer from the absorber plate to the working fluid inside the tubes, turbulent flow was induced by installing baffles within the tubes. The installation of the baffles resulted in a 7 to 12% increase in collector efficiency. Experiments were run on both 1 sq ft and 2 sq ft collectors each fitted with either slotted baffles or tubular baffles. A computer program was run comparing the baffled collector to the standard collector. The results obtained from the computer show that the baffled collectors have a 2.7% increase in life cycle cost (LCC) savings and a 3.6% increase in net cash flow for use in domestic hot water systems, and even greater increases when used in solar heating systems.

  20. AXAF-I ghost ray study: On orbit case

    Science.gov (United States)

    Gaetz, T. J.

    1993-01-01

    The problem of baffles for control of singly reflected (and nonreflected) ghost rays is considered. The theory of baffle design for Wolter Type I grazing incidence optics is reviewed, and a set of sample baffle parameters is obtained subject to the assumptions of nominal mirror figures and perfect manufacture and alignment of baffles. It is found that baffles forward of the optics (in the thermal precollimator) and between the mirror elements (at the CAP) are sufficient to allow the simultaneous ghost image and vignetting requirements to be satisfied for HRMA shells P1H1, P3H3, and P4H4. However, these baffles are not sufficient for the innermost shell P6H6; at best the requirements are slightly violated and there is no margin for tolerances. The addition of a baffle interior to the P6 space at an axial station about one third of the way forward from the aft end of the paraboloid will allow the ghost ray and vignetting requirements to be met. The minimum ghost ray angles and the vignetting angles are sensitive functions of the baffle positions and radii; tolerances of considerably better than 1 mm will be required. The sensitivities are coupled and correlated; further investigations should be undertaken in order to obtain baffle parameters which, combined with likely achievable tolerances, will minimize the risk of the vignetting/ghost ray requirements not being met. The lightweight carbon-epoxy composite used for thermal baffles has insufficient X-ray opacity to be a suitable material for construction of the controlling X-ray baffles; further study is needed to determine an appropriate material and to investigate its thermal and mechanical implications.

  1. Root cause analysis of the fatigue failures of the pulsation dampers of a large underground gas storage (UGS) system

    NARCIS (Netherlands)

    Eijk, A.; Lange, D. de; Maljaars, J.; Tenbrock-Ingenhorst, A.; Gottmer, A.

    2014-01-01

    Two large identical 6-cylinder Ariel JGB/6 reciprocating compressors each of 7.5 MW, are used for an underground gas storage system (UGS) plant of RWE Gasspeicher GmbH located in Epe, Germany. The system is in operation since 2005. In 2011 several internals parts (baffle plates and baffle choke tube

  2. MULTISTAGE FLUIDIZED BED REACTOR

    Science.gov (United States)

    Jonke, A.A.; Graae, J.E.A.; Levitz, N.M.

    1959-11-01

    A multistage fluidized bed reactor is described in which each of a number of stages is arranged with respect to an associated baffle so that a fluidizing gas flows upward and a granular solid downward through the stages and baffles, whereas the granular solid stopsflowing downward when the flow of fluidizing gas is shut off.

  3. Üniversite Sanayi İşbirliği ve Fen Bilimleri Enstitüleri

    Directory of Open Access Journals (Sweden)

    Mehmet Cengiz KAYACAN

    2014-07-01

    Full Text Available The scope of this work is to investigate the effects of baffle cut and baffle spacing on the heat transfer coefficient and pressure drop in a shell and tube heat exchanger. For this aim, analyses are made for a standard dimensioned heat exchanger with variable baffle cut and spacing. It is observed that both heat transfer coefficient and pressure drops values decrease with the increase of baffle cut and baffle spacing. This paper demonstrates successful application of Genetic Algorithm for the optimal design of shell-and-tube heat exchangers. Approximate design methods for shell-and-tube have been investigated and a generalized procedure has been developed to run the GA algorithm and to find the global minimum heat exchanger area

  4. Sızma Testleri İçin Bir Model Ağ Üzerinde Siber Saldırı Senaryolarının Değerlendirilmesi

    Directory of Open Access Journals (Sweden)

    Tuncay YİĞİT

    2014-06-01

    Full Text Available The scope of this work is to investigate the effects of baffle cut and baffle spacing on the heat transfer coefficient and pressure drop in a shell and tube heat exchanger. For this aim, analyses are made for a standard dimensioned heat exchanger with variable baffle cut and spacing. It is observed that both heat transfer coefficient and pressure drops values decrease with the increase of baffle cut and baffle spacing. This paper demonstrates successful application of Genetic Algorithm for the optimal design of shell-and-tube heat exchangers. Approximate design methods for shell-and-tube have been investigated and a generalized procedure has been developed to run the GA algorithm and to find the global minimum heat exchanger area

  5. APPARATUS FOR CONDENSATION AND SUBLIMATION

    Science.gov (United States)

    Schmidt, R.J.; Fuis, F. Jr.

    1958-10-01

    An apparatus is presented for the sublimation and condensation of uranium compounds in order to obtain an improved crystalline structure of this material. The apparatus comprises a vaporizing chamber and condensing structure connected thereto. There condenser is fitted with a removable liner having a demountable baffle attached to the liner by means of brackets and a removable pin. The baffle is of spiral cross-section and is provided with cooling coils disposed between the surfaces of the baffle for circulation of a temperature controlling liquid within the baffle. The cooling coll provides for controlllng the temperature of the baffle to insure formatlon of a satisfactory condensate, and the removable liner facilitates the removal of condensate formed during tbe sublimation process.

  6. High performance internal reforming unit for high temperature fuel cells

    Science.gov (United States)

    Ma, Zhiwen; Venkataraman, Ramakrishnan; Novacco, Lawrence J.

    2008-10-07

    A fuel reformer having an enclosure with first and second opposing surfaces, a sidewall connecting the first and second opposing surfaces and an inlet port and an outlet port in the sidewall. A plate assembly supporting a catalyst and baffles are also disposed in the enclosure. A main baffle extends into the enclosure from a point of the sidewall between the inlet and outlet ports. The main baffle cooperates with the enclosure and the plate assembly to establish a path for the flow of fuel gas through the reformer from the inlet port to the outlet port. At least a first directing baffle extends in the enclosure from one of the sidewall and the main baffle and cooperates with the plate assembly and the enclosure to alter the gas flow path. Desired graded catalyst loading pattern has been defined for optimized thermal management for the internal reforming high temperature fuel cells so as to achieve high cell performance.

  7. 厌氧折流板污泥对偶氮染料酸性大红GR的生物降解性能研究%Biodegradation of azo dye C.I.Acid Red 73 in anaerobic baffled reactor sludge

    Institute of Scientific and Technical Information of China (English)

    康晓鹍; 王世和; 晏再生; 马玉

    2009-01-01

    研究了厌氧折流板反应器(ABR)活性厌氧污泥对偶氮染料酸性大红GR的吸附与生物降解性能,并与失活污泥进行了对比.试验结果表明,35℃时厌氧活性污泥2h、12h、6d的脱色率分别为78.2%、86.0%、98.9%.无论在反应初始阶段还是稳定阶段,ABR活性厌氧污泥对染料的去除效果都明显优于失活污泥.而且,由于非有效吸附位置染料脱落等原因,反应期间,失活污泥混合液中染料浓度还会升高.在初始COD为1152mg/L的情况下,活性厌氧污泥混合液出水COD为86.0mg/L,去除率约为92.5%.这说明ABR厌氧污泥微生物在短时间内便可以得到驯化,一旦厌氧微生物适应生长环境,生物降解便开始对染料发挥作用.

  8. Three-dimensional Numerical Simulation of Fluid Flow and Heat Transfer in the Shell Side of Quincunx Orifice Baffle Longitudinal Flow Type Heat Exchanger%梅花孔板纵向流换热器壳程流动与传热的三维数值模拟

    Institute of Scientific and Technical Information of China (English)

    李雅侠; 娄岩; 战洪仁; 张静; 吴剑华

    2015-01-01

    基于梅花孔板纵向流换热器的三维物理模型,采用RNGK-ε流模型,对其壳程流动与传热特性进行了数值模拟,以空气为工作介质,考察了孔板开孔率ψ=0.148,0.18和0.214的换热器在雷诺数Re=4000~ 12 000范围内的传热和压降.结果表明,流体流过梅花孔后产生贴壁射流,射流的卷吸和二次流作用有利于流体的混合与传热.换热器壳程平均努塞尔数Nu和单位长度压降△P/L2均随开孔率ψ和折流板间距L减小而增大;与相同条件下弓形折流板换热器相比,在研究范围内,该流换热器的Nu提高了14.9%~52.88%,△P增减幅度为152.85%~-16.62%,综合性能系数PEC为1.03~1.44,适当增大开孔率ψ和孔板间距L可提高换热器的综合传热性能.

  9. Numerical simulation study on the effects of orifice structure on the shell-side heat transfer of cinquefoil orifice baffle heat exchanger%孔板结构对梅花形孔板换热器壳程传热影响的模拟研究

    Institute of Scientific and Technical Information of China (English)

    罗朝嘉; 韩东; 牟春燕; 姚瑶; 何纬峰

    2016-01-01

    采用ANSYS CFX对梅花形孔板换热器壳程的流动和传热进行了数值模拟研究,通过分析壳程流场揭示了孔板换热器壳程强化换热机理,得到了3种不同开孔率的孔板换热器壳程平均努塞尔数Nu以及压降Δp随雷诺数变化的规律.结果表明:由于孔板处流道面积较小,流体产生射流效应并伴有二次流现象,在破坏流动边界层的同时增强了流体扰动,强化了换热;3种换热器的Nu和Δp都随雷诺数的增加而增大,开孔率越低换热器的换热性能越好,但壳程压降也越大;开孔率0.215的换热器综合性能参数(Nu/Δp)比开孔率0.173和0.130的换热器平均高28.8%和50.14%.

  10. Analysis of Flow Accelerating Corrosion on Baffle Plate in Low-pressure Drum of a Combined Cycle Unit%联合循环机组低压汽包内折流挡板流动加速腐蚀分析

    Institute of Scientific and Technical Information of China (English)

    赵志祥; 薛巍

    2012-01-01

    针对某联合循环机组低压汽包折流挡板发生的流动加速腐蚀,从折流挡板材质、汽包运行温度、炉水处理工况、炉水流动状态等方面分析了导致腐蚀的原因,指出了汽包内部装置中其他部件发生流动加速腐蚀的可能性,提出了抑制低压汽包内部装置流动加速腐蚀的方法.

  11. 太阳电池生产用管式扩散炉的数值模拟——匀流板对流场的影响%CFD SIMULATION ON SOLAR CELLS DIFFUSION FURNACE——Influence of Baffle Plate to the Flow Field

    Institute of Scientific and Technical Information of China (English)

    侯立宏; 刘祖明; 申兰先; 张卫东; 朱勋梦; 王文仪

    2014-01-01

    以晶硅电池生产用管式扩散炉的内部流体状况为研究对象,用计算流体力学方法对管式扩散炉进行数学建模及流体力学数值模拟计算;对扩散炉内放置与未放置匀流板的流场状况进行对比研究;分析匀流板对扩散炉内部温度场、速度场、密度梯度场的影响及成因;认为装有匀流板的扩散炉内流体的速度场可给予硅片更为充足的磷源;发现匀流板附近存在着复杂的涡流区,认为该涡流区是决定扩散炉内温度场分布均匀程度的根本原因与关键因素.

  12. 导向型折流栅强化换热器壳程传热的数值模拟%Numerical Simulation on Heat Transfer Enhancement in Shell Side of Shell-and-Tube Heat Exchanger with Leading Type Shutter Baffles

    Institute of Scientific and Technical Information of China (English)

    古新; 董其伍; 刘敏珊; 周雅宁

    2010-01-01

    提出壳程流体"斜向流"的新概念,解决了管壳式换热器性能提升的同时伴随流体流动阻力大幅增加的矛盾.研制了具有导向型折流栅管束支撑结构的新型高效节能斜向流管壳式换热器.采用场协同理论分析该换热器的强化传热机理,证明在此类换热器壳程中流体速度场与温度梯度场具有良好的协同关系.数值模拟了几何结构对传热和压降的影响规律,模拟结果与实验数据吻合良好.

  13. Numerical Studies on Performance of Double Shell-pass Heat Exchangers With Sleeve Tubes and Continuous Helical Baffles%套管双壳程连续螺旋折流板换热器性能数值模拟研究

    Institute of Scientific and Technical Information of China (English)

    宋素芳

    2013-01-01

    研究了一种新型套管双壳程连续螺旋折流板换热器,套管将壳程分为内外两部分,内壳程无折流板,外壳程采用连续螺旋折流板.建立了换热器的三维模型,采用分离式求解器,SIMPLE算法,k-ε湍流模型,借用CFD软件FLUENT对套管双壳程连续螺旋折流板换热器和传统弓形折流板及传统单壳程连续螺旋折流板换热器壳程流动和换热特性进行模拟研究,结果表明:相同壳程进口流速下,套管双壳程连续螺旋折流板换热器的壳程压力降比弓形折流板和单壳程连续螺旋折流板换热器降低平均值分别为62.17%和22.76%,传热速率比这两种换热器均提高了25.98%和21.79%,单位传热量的压力降相比于这两种换热器降低平均值分别为68.93%和38.69%.

  14. 三角形布管帘式折流片换热器传热和流阻性能研究%Research on Heat Transfer and Flow Resistance Performance of Shutter Baffle Heat Exchanger With Triangle Tube Layout in Shell Side

    Institute of Scientific and Technical Information of China (English)

    古新; 王珂; 刘冰; 朱培纳; 郝建设

    2013-01-01

    采用CFD数值模拟方法和周期性全截面计算模型,对三角形布管方式下的帘式折流片换热器折流栅装配方式、折流栅间距、折流片倾角和折流片宽度等几何结构参数对传热和压降的影响规律进行了数值研究,并采用实验测试验证了数值模拟方法及其结果的正确性和准确度.研究结果表明,折流栅间距、折流片倾角对帘式折流片换热器壳程流体传热和阻降性能有显著影响,折流栅装配方式、折流片宽度对其影响较小,建议折流栅间距取为150 mm以内,折流片倾角取为45°以内较为合适.

  15. 管壳式换热器新型管支撑结构在传热强化方面的进展%The Developments on Heat Transfer Enhancement in The New Pattern Baffle of Shell-and-Tube Heat Exchangers

    Institute of Scientific and Technical Information of China (English)

    陈姝; 高学农; 徐娓; 王端阳

    2006-01-01

    本文讨论了管壳式换热器新型管支撑结构在强化传热方面所取得的一些进展、传热机理及应用范围,并简介了CFD技术同管壳式换热器结合研究的情况,提出将几种强化技术和计算机辅助设计手段结合起来是将来换热器的发展方向.

  16. Characteristics of surface sound pressure and absorption of a finite impedance strip for a grazing incident plane wave.

    Science.gov (United States)

    Sum, K S; Pan, J

    2007-07-01

    Distributions of sound pressure and intensity on the surface of a flat impedance strip flush-mounted on a rigid baffle are studied for a grazing incident plane wave. The distributions are obtained by superimposing the unperturbed wave (the specularly reflected wave as if the strip is rigid plus the incident wave) with the radiated wave from the surface vibration of the strip excited by the unperturbed pressure. The radiated pressure interferes with the unperturbed pressure and distorts the propagating plane wave. When the plane wave propagates in the baffle-strip-baffle direction, it encounters discontinuities in acoustical impedance at the baffle-strip and strip-baffle interfaces. The radiated pressure is highest around the baffle-strip interface, but decreases toward the strip-baffle interface where the plane wave distortion reduces accordingly. As the unperturbed and radiated waves have different magnitudes and superimpose out of phase, the surface pressure and intensity increase across the strip in the plane wave propagation direction. Therefore, the surface absorption of the strip is nonzero and nonuniform. This paper provides an understanding of the surface pressure and intensity behaviors of a finite impedance strip for a grazing incident plane wave, and of how the distributed intensity determines the sound absorption coefficient of the strip.

  17. Shell-side distribution and the influence of inlet conditions in a model of a disc-and-doughnut heat exchanger

    Science.gov (United States)

    Founti, M. A.; Vardis, C.; Whitelaw, J. H.

    1985-09-01

    Measurements of wall pressure and of three orthogonal velocity components with their corresponding fluctuations are reported for two systems of alternating and equi-spaced doughnut and disc baffles axisymmetrically located in a water turbulent pipe flow, simulating the isothermal shell-side flow in shell and tube heat exchangers. The influence of inlet Reynolds number and of asymmetric inlet flow conditions was studied for two geometries. The velocity field was dominated by the pressure gradient and the flow around each individual baffle was influenced by the relative position of its neighbouring baffles.

  18. An Investigation of the Ranger V-770-8 Engine Installation for the Edo XOSE-1 Airplane I : Cooling

    Science.gov (United States)

    Emmons, M. Arnold; Conway, Robert N.

    1945-01-01

    Engine temperature data and cooling correlating analyses of the engine and oil cooler are presented in connection with an investigation of the cowling and cooling of the ranger V-770-8 engine installation in the Edo XOSE-1 airplane. Three types of baffles were installed in the course of the tests: the conventional, the turbulent-flow, and the NACA diffuser baffles. Each of the types was of merit in cooling a different region on the cylinder. Incorporation of the best features of the three types into one baffle, a method which appears to be feasible, would provide improvements in cylinder cooling.

  19. Flow mechanism and heat transfer enhancement in longitudinal-flow tube bundle of shell-and-tube heat exchanger

    Institute of Scientific and Technical Information of China (English)

    LIU Wei; LIU ZhiChun; WANG YingShuang; HUANG SuYi

    2009-01-01

    ormer is superior to that of the latter.Compared with rod baffle heat exchanger,heat transfer coefficient of the heat exchanger under investigation is higher under same pressure drop,especially under the high Reynolds numbers.

  20. Numerical Model Analysis of Fluid-Elastic Instability of Thin Rectangular Plate Due to Overflow

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    A circular thermal baffle weir is located close to the main vessel of liquid sodium cooled pool type fast breeder reactors (fast reactor for short thereafter). During operation of the fast reactor, a little part of liquid sodium flows from

  1. The Big Idea

    CERN Multimedia

    Matthews, Robert

    2005-01-01

    Symmetry has shaped our Universe, and has inspired some of the world's greatest scientists to unlock the secrets of the Universe, but also baffled many more along the way. Symmetry is not as simple as it may at first appear...

  2. A New Method Solving Contact/Detach Problem in Fluid and Structure Interaction Simulation with Application in Modeling of a Safety Valve

    Directory of Open Access Journals (Sweden)

    Zheng Guo

    2010-01-01

    Full Text Available A new virtual baffle methodology is implemented to solve contact/detach problem which is often encountered in fluid and structure interaction simulations while using dynamic grids technique. The algorithm is based on tetrahedral unstructured grid, and a zero thickness baffle face is generated between actually contacted two objects. In computation process, this baffle face is divided into two parts representing convective and blocked area, respectively; the area of each part is calculated according to the actual displacement between the two objects. Convective part in a baffle face is treated as inner interface between cells, and on blocked part wall boundary condition is applied; so convective and blocking effect can be achieved on a single baffle face. This methodology can simulate real detaching process starting from contact, that is, zero displacement, while it has no restriction to minimum grid cell size. The methodology is then applied in modeling of a complicated safety valve opening process, involving multidisciplinary fluid and structure interaction and dynamic grids. The results agree well with experimental data, which proves that the virtual baffle method is successful.

  3. 三角形布管方式下2种换热器的场协同分析%Field synergy analysis on two kinds of heat exchangers with triangle tube layout in shell side

    Institute of Scientific and Technical Information of China (English)

    古新; 刘冰; 王永庆; 董其伍; 王华良

    2012-01-01

    Based on the shell fluid flow and heat transfer numerical calculation results of shutter baffle heat exchanger and baffle-plate heat exchanger with the periodic whole cross-section computation model, the field synergy principle was adopted to analyze the heat transfer performance of the two kinds of heat exchangers. The shell-side velocity and turbulence in different position of the shutter baffle heat exchanger as well as field synergy angle and surface convective heat transfer coefficient were analyzed, followed by making comparison with the baffle-plate heat exchanger. The results show that the shell fluid of baffle-plate heat exchanger is horizontal flow and that of shutter baffle heat exchanger is vertical flow, so the average velocity and turbulence of baffle-plate heat exchanger are slightly higher than those of shutter baffle heat exchanger, with its average velocity 1. 15 times that of shutter baffle heat exchanger and its turbulence intensity 1. 4 times that of shutter baffle heat exchanger; the average value of local field synergy angle on two validation lines in baffle-plate heat exchanger is less than that of shutter baffle heat exchanger, thus the convective heat transfer effect of baffle-plate heat exchanger is better than that of shutter baffle heat exchanger. The results provide references for the structure and performance improvement of tubular heat exchanger, and the structural feature of shutter baffle heat exchanger is also important for energy saving.%基于采用周期性全截面计算模型得到的帘式折流片换热器和折流板换热器壳程流体流动和传热数值计算结果,应用场协同原理对二者传热性能进行了分析.分析了帘式折流片换热器在壳程不同位置处的速度和湍流度,以及场协同角和对流传热系数,并与折流板换热器相同位置处的情况进行了对比.由于折流板壳程流体为横向流动,而帘式折流片壳程总体上是纵向流

  4. Performance Investigation of Heat Transfer and Flow Resistance in Two Kinds of Heat Exchangers of Tube Bundle Arrangement with Equilateral Triangles%三角形布管方式下两种换热器传热与流阻性能研究

    Institute of Scientific and Technical Information of China (English)

    古新; 刘冰; 董其伍; 刘敏珊; 王永庆

    2012-01-01

    采用CFD数值模拟方法和折流板换热器、帘式折流片换热器周期性全截面计算模型,对两种换热器在正三角形布管方式下的传热系数、阻力、综合性能随Re数的变化情况进行了数值研究.研究结果表明,两种换热器对应的换热系数和壳程压力损失均随Re数的增加而增大,折流版换热器的传热系数大于帘式折流片换热器,约是帘式折流片的1.32倍,但其阻力大幅高于帘式折流片换热器,是帘式折流片换热器的2.4倍左右,两种换热器的综合性能均随Re数的增大而下降,帘式折流片换热器的α/△P几乎是折流板换热器的2倍,体现了帘式折流片换热嚣在保持较高的传热效果的情况下,具有显著的流动减阻性能.%In this paper, CFD numerical simulation and periodic whole cross-ssection computation model of baffle-plate heat exchanger and shutter baffle heat exchanger which tube bundle arrangement with equilateral triangles are adopted to study the changes of the performance of heat transfer coefficient, flow resistance, comprehensive performance with Re. The simulation results indicate that two kinds of heat exchangers' heat transfer coefficient and shell-side pressure loss increases with the increase of Re, baffle-plate heat exchanger' heat transfer coefficient is greater than shutter baffle heat exchanger, it is about 1.32 times larger than shutter baffle heat exchanger, but the pressure drop is much greater than shutter baffle heat exchanger, it is about 2. 4 times larger than shutter baffle heat exchanger, their comprehensive performance decline with the increase of Re, a/ AP of shutter baffle is almost 2 times larger than baffle-plate heat exchanger, this reflects shutter baffle heat exchanger has significant flow drag reduction performance in the case of higher heat transfer.

  5. Protection of carbon steel against hot corrosion using thermal spray Si- and Cr-base coatings

    Science.gov (United States)

    Porcayo-Calderon, J.; Gonzalez-Rodriguez, J. G.; Martinez, L.

    1998-02-01

    A Fe75Si thermal spray coating was applied on the surface of a plain carbon steel baffle plate. Beneath this coating, a Ni20Cr coating was applied to give better adherence to the silicon coating. The baffle was installed in the high-temperature, fireside, corrosion zone of a steam generator. At the same time, an uncoated 304 stainless steel baffle was installed nearby for comparison. For 13 months the boiler burned heavy fuel oil with high contents of vanadium. The samples were studied employing scanning electron microscopy, x-ray microanalysis, and x-ray diffraction techniques. After that, it was possible to inspect the structural state of the components, and it was found that the stainless steel baffle plates were destroyed almost completely by corrosion, whereas the carbon steel coated baffle plate did not suffer a significant attack, showing that the performance of the thermal spray coating was outstanding and that the coating was not attacked by vanadium salts of the molten slag.

  6. 3D numerical study on flow structure and heat transfer in a circular tube with V-baffles☆

    Institute of Scientific and Technical Information of China (English)

    Withada Jedsadaratanachai; Nuthvipa Jayranaiwachira; Pongjet Promvonge

    2015-01-01

    A 3D numerical investigation has been carried out to examine periodic laminar flow and heat transfer character-istics in a circular tube with 45° V-baffles with isothermal wal . The computations are based on the finite volume method (FVM), and the SIMPLE algorithm has been implemented. The fluid flow and heat transfer characteristics are presented for Reynolds numbers ranging from 100 to 2000. To generate main longitudinal vortex flows through the tested section, V-baffles with an attack angle of 45° are mounted in tandem and in-line arrangement on the opposite positions of the circular tube. Effects of tube blockage ratio, flow direction on heat transfer and pressure drop in the tube are studied. It is apparent that a pair of longitudinal twisted vortices (P-vortex) created by a V-baffle can induce impingement on a wal of the inter-baffle cavity and lead a drastic increase in heat trans-fer rate at tube wall. In addition, the larger blockage ratio results in the higher Nusselt number and friction factor values. The computational results show that the optimum thermal enhancement factor is around 3.20 at baffle height of B=0.20 and B=0.25 times of the tube diameter for the V-upstream and V-downstream, respectively. © 2014 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. Al rights reserved.

  7. Seasonal variations of microbial community in a full scale oil field produced water treatment plant

    Directory of Open Access Journals (Sweden)

    Q. Xie

    2016-01-01

    Full Text Available This study investigated the microbial community in a full scale anaerobic baffled reactor and sequencing batch reactor system for oil-produced water treatment in summer and winter. The community structures of fungi and bacteria were analyzed through polymerase chain reaction–denaturing gradient gel electrophoresis and Illumina high-throughput sequencing, respectively. Chemical oxygen demand effluent concentration achieved lower than 50 mg/L level after the system in both summer and winter, however, chemical oxygen demand removal rates after anaerobic baffled reactor treatment system were significant higher in summer than that in winter, which conformed to the microbial community diversity. Saccharomycotina, Fusarium, and Aspergillus were detected in both anaerobic baffled reactor and sequencing batch reactor during summer and winter. The fungal communities in anaerobic baffled reactor and sequencing batch reactor were shaped by seasons and treatment units, while there was no correlation between abundance of fungi and chemical oxygen demand removal rates. Compared to summer, the total amount of the dominant hydrocarbon degrading bacteria decreased by 10.2% in anaerobic baffled reactor, resulting in only around 23% of chemical oxygen demand was removed in winter. Although microbial community significantly varied in the three parallel sulfide reducing bacteria, the performance of these bioreactors had no significant difference between summer and winter.

  8. An approximate method to acoustic radiation problems: element radiation superposition method

    Institute of Scientific and Technical Information of China (English)

    wANG Bin; TANG weilin; FAN Jun

    2008-01-01

    An approximate method is brought forward to predict the acoustic pressure based on the surface velocity.It is named Element Radiation Superposition Method(ERSM).The study finds that each element in Acoustic Transfer Vector(ATV)equals the acoustic pressure radiated by the corresponding surface element vibrating in unit velocity and other surface elements keep still.that is the acoustic pressure radiated by the corresponding baffled pistonvibrating in unit velocity.So,it utilizes the acoustic pressure radiated by a baffled piston to establish the transfer relationship between the surfaEe velocity and the acoustic pressure.The total acoustic pressure is obtained through summing up the products of the surface velocity and the transfer quantity.It adopts the regular baffle to fit the actual baffle in order to calculate the acoustic pressure radiated by the baffled piston.This approximate method has larger advantage in calculating speed and memory space than Boundary Element Method.Numerical simulations show that this approximate method is reasonable and feasible.

  9. Enhancement of azo dye Acid Orange 7 removal in newly developed horizontal subsurface-flow constructed wetland.

    Science.gov (United States)

    Tee, Heng-Chong; Lim, Poh-Eng; Seng, Chye-Eng; Mohd Nawi, Mohd Asri; Adnan, Rohana

    2015-01-01

    Horizontal subsurface-flow (HSF) constructed wetland incorporating baffles was developed to facilitate upflow and downflow conditions so that the treatment of pollutants could be achieved under multiple aerobic, anoxic and anaerobic conditions sequentially in the same wetland bed. The performances of the baffled and conventional HSF constructed wetlands, planted and unplanted, in the removal of azo dye Acid Orange 7 (AO7) were compared at the hydraulic retention times (HRT) of 5, 3 and 2 days when treating domestic wastewater spiked with AO7 concentration of 300 mg/L. The planted baffled unit was found to achieve 100%, 83% and 69% AO7 removal against 73%, 46% and 30% for the conventional unit at HRT of 5, 3 and 2 days, respectively. Longer flow path provided by baffled wetland units allowed more contact of the wastewater with the rhizomes, microbes and micro-aerobic zones resulting in relatively higher oxidation reduction potential (ORP) and enhanced performance as kinetic studies revealed faster AO7 biodegradation rate under aerobic condition. In addition, complete mineralization of AO7 was achieved in planted baffled wetland unit due to the availability of a combination of aerobic, anoxic and anaerobic conditions.

  10. Flow mechanism and heat transfer enhancement in longitudinal-flow tube bundle of shell-and-tube heat exchanger

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The flow disturbance and heat transfer mechanism in the tube bundle of rod baffle shell-and-tube heat exchanger were analyzed, on the basis of which and combined with the concept of heat transfer enhancement in the core flow, a new type of shell-and-tube heat exchanger with combination of rod and van type spoiler was designed. Corresponding mathematical and physical models on the shell side about the new type heat exchanger were established, and fluid flow and heat transfer characteristics were numerically analyzed. The simulation results showed that heat transfer coefficient of the new type of heat exchanger approximated to that of rod baffle heat exchanger, but flow pressure drop was much less than the latter, indicating that comprehensive performance of the former is superior to that of the latter. Compared with rod baffle heat exchanger, heat transfer coefficient of the heat exchanger under investigation is higher under same pressure drop, especially under the high Reynolds numbers.

  11. Effect of tube-support interaction on the dynamic responses of heat exchanger tubes. [LMFBR

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Y.S.; Jendrzejczyk, J.A.; Wambsganss, M.W.

    1977-01-01

    Operating heat exchangers have experienced tube damages due to excessive flow-induced vibration. The relatively small inherent tube-to-baffle hole clearances associated with manufacturing tolerances in heat exchangers affect the tube vibrational characteristics. In attempting a theoretical analysis, questions arise as to the effects of tube-baffle impacting on dynamic responses. Experiments were performed to determine the effects of tube-baffle impacting in vertical/horizontal tube orientation, and in air/water medium on the vibrational characteristics (resonant frequencies, mode shapes, and damping) and displacement response amplitudes of a seven-span tube model. The tube and support conditions were prototypic, and overall length approximately one-third that of a straight tube segment of the steam generator designed for the CRBR. The test results were compared with the analytical results based on the multispan beam with ''knife-edge'' supports.

  12. Critical velocity of floatables in combined sewer overflow (CSO) chambers.

    Science.gov (United States)

    Cigana, J; Lefebvre, G; Marche, C

    2001-01-01

    Although the efficiency of underflow baffles has never been clearly proven, these underflow baffles have gained in popularity over the last few years as a viable means to intercept floatables in Combined Sewer Overflows (CSOs). These pilot scale essays, performed in a 17.0 metres basin at various flowrates, show that a critical horizontal velocity (V(CR)) may develop in the overflow chamber. Whenever this critical velocity is exceeded, floatables that would normally rise to the surface are kept within the flow and never intercepted, thus rendering the underflow baffle ineffective. The equation relating the critical horizontal velocity to the vertical velocity is found to be: V(CR) = 16 w R(H) 1/6.

  13. Numerical Modeling of the Fluid Flow in Continuous Casting Tundish with Different Control Devices

    Directory of Open Access Journals (Sweden)

    Zhu He

    2013-01-01

    Full Text Available Numerical simulations were conducted to study the melt flow under the influence of control devices in a T-type two-strand bloom caster tundish via the open source Computational Fluid Dynamics software OpenFOAM. Three different cases were studied: a bare tundish, a tundish with two pairs of baffles, and a tundish equipped with a turbulence inhibitor and a pair of baffles. Turbulence inhibitor and baffles arrangement showed an improvement of the fluid flow characteristics, yielding lower values of dead volume and higher values of plug flow. With a turbulence inhibitor, the velocity of metal which flows directly toward the tundish floor is smaller and the turbulence kinetic energy of the melt top surface is lower than the other two arrangements.

  14. An analysis of process heat recovery in a gas-solid shallow fluidized bed

    Directory of Open Access Journals (Sweden)

    A. A. B. Pécora

    2006-12-01

    Full Text Available This work presents an experimental study of a continuous gas-solid fluidized bed with an immersed horizontal tube. Silica sand (254mm diameter was used as solid particles and air was used for fluidization in a 900mm long and 150mm wide heat exchanger. Measurements were made under steady state conditions for a solid particle mass flow rate from 14 to 95kg.h-1 and a number of baffles from 0 to 8. Results showed that the heat transfer coefficient increases with the solid particle mass flow rate and with the number of baffles, suggesting that these are important factors to be considered in the design of such equipment. An empirical correlation for the heat transfer coefficient is proposed as a function of solid particle and gas mass flow rate, number of baffles and gas velocity.

  15. Determination of heat and mass transfer coefficients in a rotary shaker used in fermentation processes

    Directory of Open Access Journals (Sweden)

    Mario Arias Zabala

    2011-12-01

    Full Text Available In this paper the volumetric oxygen transfer (kLa and overall heat transfer (Ua coefficients were determined in flasks which were subjected to rotary shaker action, also provided with a temperature control chamber. Likewise, it was determined the effect over such coefficients of some parameters like surrounding temperature, shaking speed, closure type, liquid volume, capacity and baffles presence or absence in each flask, to determine the optimal work conditions in the rotary shaker. The used liquid in these experiments was distilled water. The kLa and Ua coefficients were also determined in the alcoholic fermentation of glucose by Saccharomyces cerevisiae yeast, in order to establish comparison standards. The maximum and minimum values of referred coefficients to distilled water and the operation conditions were:   kLa of 6.2 x 10-3 s-1, working at 25 ºC, 100 rpm, 50 ml of liquid volume, erlenmeyer of 500 ml with baffles and plastic closure. kLa of 4.107 x 10-3 s-1, working at 45 ºC, 60 rpm, 150 ml of liquid volume, erlenmeyer of 250 ml without baffles and cotton closure. Ua of 31.9963 J/min °C, working at 45 ºC, 150 rpm, 150 ml of liquid volume, erlenmeyer of 500 ml with baffles and cotton closure. Ua of 6.0179 J/min °C, working at 35 ºC, 60 rpm, 50 ml of liquid volume, erlenmeyer of 250 ml without baffles and plastic closure. The kLa and Ua values in the alcoholic fermentation and the operation conditions were: kLa of 2.6 x 10-4 s-1 and Ua of 12.8907 J/min °C, working at 35 °C, 150 rpm, 150 ml of liquid volume, Erlenmeyer of 250 ml, with baffles and cotton closure.  

  16. Flow in Idealised Compliant Human Cystic Duct Models

    Science.gov (United States)

    Al-Atabi, M.; Chin, S. B.; Beck, S.; Luo, X. Y.

    The functions of the cystic duct and the role of its complicated geometry (in particular the valves of Heister), in the delivery of bile flow have always been a subject of speculation. This paper reports on an experimental investigation of the flow in idealised, compliant cystic duct models. The valves of Heister were idealised using eight semi-circular alternating baffles fitted inside the compliant tubes. These tubes were arranged in configurations representing the anatomical configurations of real cystic ducts. Models both with and without baffles were tested for comparison. The results show that the valves of Heister seem to play a role in facilitating both the filling and emptying of the gallbladder.

  17. Advanced manufacturing technologies for the BeCOAT telescope

    Science.gov (United States)

    Sweeney, Michael N.; Rajic, Slobodan; Seals, Roland D.

    1994-02-01

    The beryllium cryogenic off-axis telescope (BeCOAT) uses a two-mirror, non re-imaging, off- axis, Ritchey Chretian design with all-beryllium optics, structures and baffles. The purpose of this telescope is the system level demonstration of advanced manufacturing technologies for optics, optical benches, and baffle assemblies. The key issues that are addressed are single point diamond turning of beryllium optics, survivable fastening techniques, minimum beryllium utilization, and technologies leading to self-aligning, all-beryllium optical systems.

  18. Prediction of Heat Transfer Rates for Shell-and-Tube Heat Exchangers by Artificial Neural Networks Approach

    Institute of Scientific and Technical Information of China (English)

    Qiuwang WANG; Gongnan XIE; Ming ZENG; Laiqin LUO

    2006-01-01

    This work used artificial neural network (ANN) to predict the heat transfer rates of shell-and-tube heat exchangers with segmental baffles or continuous helical baffles, based on limited experimental data. The Back Propagation (BP) algorithm was used in training the networks. Different network configurations were also studied. The deviation between the predicted results and experimental data was less than 2%. Comparison with correlation for prediction shows ANN superiority. It is recommended that ANN can be easily used to predict the performances of thermal systems in engineering applications, especially to model heat exchangers for heat transfer analysis.

  19. Centrifugal pyrocontactor

    Science.gov (United States)

    Chow, Lorac S.; Leonard, Ralph A.

    1993-01-01

    A method for mixing and separating immiscible liquid salts and liquid metals in a centrifugal contractor. The method includes introducing the liquids into an annular mixing zone and intensely mixing the liquids using vertical vanes attached to a rotor cooperating with vertical baffles, a horizontal baffle, and bottom vanes attached to the contactor housing. The liquids enter the contactor in the range of 700-800 degrees Celsius. The liquids are separated in the rotor into a dense phase and a light phase which are discharged from the contactor.

  20. A note on the calibration of pressure-velocity sound intensity probes

    DEFF Research Database (Denmark)

    Jacobsen, Finn; Jaud, Virginie

    2006-01-01

    from a small hole in a plane baffle, a near field method where the sound is emitted from a hole in a spherical baffle, and a method that involves an impedance tube. The performance of the two near field methods is examined both in an anechoic room and in various ordinary rooms. It is shown that whereas......A pressure-velocity sound intensity probe is a device that combines a pressure microphone with a particle velocity transducer. Various methods of calibrating such sound intensity probes are examined: a far field method that requires an anechoic room, a near field method that involves sound emitted...

  1. System and process for biomass treatment

    Science.gov (United States)

    Dunson, Jr., James B; Tucker, III, Melvin P; Elander, Richard T; Lyons, Robert C

    2013-08-20

    A system including an apparatus is presented for treatment of biomass that allows successful biomass treatment at a high solids dry weight of biomass in the biomass mixture. The design of the system provides extensive distribution of a reactant by spreading the reactant over the biomass as the reactant is introduced through an injection lance, while the biomass is rotated using baffles. The apparatus system to provide extensive assimilation of the reactant into biomass using baffles to lift and drop the biomass, as well as attrition media which fall onto the biomass, to enhance the treatment process.

  2. Modified Senning Procedure for Correction of Atrioventricular Discordance With Total Anomalous Pulmonary Venous Return, Atrial Situs Inversus, Dextrocardia, and Bilateral Superior Venae Cavae.

    Science.gov (United States)

    Sebastian, Vinod A; Guleserian, Kristine J; Juraszek, Amy; Kane, Colin; Hamzeh, Rabih; Forbess, Joseph M

    2015-10-01

    The Senning and Mustard baffles remain important techniques for the treatment of congenitally corrected transposition (cc-TGA), isolated ventricular inversion, and D-transposition of the great arteries with delayed presentation. We describe the treatment of an 8-month old infant with atrioventricular discordance, ventriculoarterial concordance, and dextrocardia with atrial situs inversus. A modified Senning procedure was performed through the "left-sided" atrium. Modifications of the Senning and Mustard baffles remain important tools in the treatment of rare conditions like isolated ventricular inversion.

  3. Experimental comparison of alternative convection suppression arrangements for concentrating integral collector storage solar water heaters

    Energy Technology Data Exchange (ETDEWEB)

    Smyth, M.; McGarrigle, P.; Eames, P.C. [Ulster Univ., School of the Built Environment, Newtownabbey, Northern Ireland (United Kingdom); Norton, B. [Dublin Inst. of Technology, Dublin (Ireland)

    2005-02-01

    An experimental investigation of an inverted absorber integrated collector storage solar water heater mounted in the tertiary cavity of a compound parabolic concentrator with a secondary cylindrical reflector has been performed under simulated solar conditions. The solar water heaters performance was determined with the aperture parallel to the simulator for a range of transparent baffles positioned at different locations within the collector cavity. Results indicate that glass baffles located at the upper portion of the exit aperture of the CPC can reduce thermal losses through convection suppression without significantly increasing optical losses. (Author)

  4. Use of a Three Dimensional Printed Cardiac Model to Assess Suitability for Biventricular Repair.

    Science.gov (United States)

    Farooqi, Kanwal M; Gonzalez-Lengua, Carlos; Shenoy, Rajesh; Sanz, Javier; Nguyen, Khanh

    2016-05-01

    Three dimensional (3D) printing is rapidly gaining interest in the medical field for use in presurgical planning. We present the case of a seven-year-old boy with double outlet right ventricle who underwent a bidirectional Glenn anastomosis. We used a 3D cardiac model to assess his suitability for a biventricular repair. He underwent a left ventricle-to-aorta baffle with a right ventricle-to-pulmonary artery conduit placement. He did well postoperatively and was discharged home with no evidence of baffle obstruction and good biventricular function. A 3D printed model can provide invaluable intracardiac spatial information in these complex patients.

  5. Repair of Dam Intake Structures and Conduits: Case Histories

    Science.gov (United States)

    1988-01-01

    II/ 1’~’--·J . ’,,: iT( I I ·lr ! I L h ,. - - ,, h h L __ ..._il~-- .-----~•:s __ .. !:..._ .d......__ -- • !Voncl:;-;;-;., M""’f" ldh IS A...emergency gate and one about 2 ft downstream of the area to be coated. Tlle two baffles were con- nected by a piece of 2-in. polyvinyl chloride ( PVC ...pipe through which water could drain. The upstream baffle would catch the water flowing past the gate and transfer it via the PVC pipe to the

  6. Synergetic Effects of Runaway and Disruption Induced by VDE on the First Wall Damage in HL-2A

    Institute of Scientific and Technical Information of China (English)

    宋先瑛; 杨进蔚; 李旭; 袁国梁; 张轶泼

    2012-01-01

    The plasma facing component in HL-2A has been damaged seriously after disruption, and for this reason its operation is suspended for maintenance. The experimental phenomena and plasma configurations, calculated by the current filament code (CF-code) using the plasma parameters measured by diagnostics and the signals of the magnetic probes, confirm that the first wall is damaged by the synergetic effects of runaway electrons and disruption induced by a vertical displacement event (VDE). When the plasma column is displaced upward/downward, the strong runaway electrons normally hit the baffle plate of the MP3 or MP1 coil in the upper and lower divertor during the disruption, causing the baffle plates to be holed and wrinkled by the energetic runaway current, and water (for cooling or heating the baffle plates) to leak into the vacuum vessel. Another disastrous consequence is that bellows underlying the baffle plate and outside the coil of MP3 for connecting two segments of the jacket casing pipe are punctured by arcing. The arc may be part of the halo current that forms a complete circuit. The experimental phenomena are indirect but compelling evidence for the existence of a halo current during the disruption and VDE, though the halo current has not been measured by the diagnostics in the HL-2A tokamak.

  7. 49 CFR 178.348-2 - Material and thickness of material.

    Science.gov (United States)

    2010-10-01

    ... Bulkheads and Baffles When Used as Tank Reinforcement) Using Mild Steel (MS), High Strength Low Alloy Steel (HSLA), Austenitic Stainless Steel (SS), or Aluminum (AL)—Expressed in Decimals of an Inch After Forming... Steel (MS), High Strength Low Alloy Steel (HSLA), Austenitic Stainless Steel (SS), or Aluminum...

  8. Beryllium assessment and recommendation for application in ITER plasma facing components

    Energy Technology Data Exchange (ETDEWEB)

    Barabash, V.; Tanaka, S.; Matera, R. [ITER Joint Central Team, Muenchen (Germany)

    1998-01-01

    The design status of the ITER Plasma Facing Components (PFC) is presented. The operational conditions of the armour material for the different components are summarized. Beryllium is the reference armour material for the Primary Wall, Baffle and Limiter and the back-up material for the Divertor Dome. The activities on the selection of the Be grades and the joining technologies are reviewed. (author)

  9. Variation Theory: A Theory of Learning and a Useful Theoretical Framework for Chemical Education Research

    Science.gov (United States)

    Bussey, Thomas J.; Orgill, MaryKay; Crippen, Kent J.

    2013-01-01

    Instructors are constantly baffled by the fact that two students who are sitting in the same class, who have access to the same materials, can come to understand a particular chemistry concept differently. Variation theory offers a theoretical framework from which to explore possible variations in experience and the resulting differences in…

  10. A Systems Approach to Military Construction.

    Science.gov (United States)

    1982-11-01

    supplied con’.tioned air through the suspended finished ceiling into the inhabited space. a. Air supply must be dispersed throughout the habitable...floors -- 20 percent. 4) Lamp Lumen Depreciation (LLD): 0.87. 5) Luminaire Dust Depreciation ( LDD ): 0.82 (if baffled, 0.92). 6) Assume 2-1/2 percent

  11. A method of determining combustion gas flow

    Science.gov (United States)

    Bon Tempi, P. J.

    1968-01-01

    Zirconium oxide coating enables the determination of hot gas flow patterns on liquid rocket injector face and baffle surfaces to indicate modifications that will increase performance and improve combustion stability. The coating withstands combustion temperatures and due to the coarse surface and coloring of the coating, shows the hot gas patterns.

  12. Astronomical performance of the engineering model Ørsted Advanced Stellar Compass

    DEFF Research Database (Denmark)

    Eisenman, Allan R.; Liebe, Carl Christian; Jørgensen, John Leif

    1996-01-01

    large star data bases which enable the computer to recognize star patterns in the field-of-view, to quickly solve the lost-in-space acquisition problem and to derive the attitude of the ASC camera head. The flight model of the camera head has a mass and a power consumption of 127 grams (without baffle...

  13. 33 CFR 159.107 - Rolling test.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Rolling test. 159.107 Section 159.107 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION... the plane of the bottom of the device, and parallel to any tank baffles. The device must then...

  14. Consumer perception of risk

    DEFF Research Database (Denmark)

    Scholderer, Joachim

    2001-01-01

    Scientists and regulators are regularly baffled by public responses to risk, especially when the issue at stake seemed unproblematic or at least technocratically solvable as long as it was only discussed within the expert community. In terms of such polarizations, the 1970s were the age of dissen...... these perceptions related to consumers' attitudes and choice behavior....

  15. A computational fluid dynamics model for designing heat exchangers based on natural convection

    NARCIS (Netherlands)

    Dirkse, M.H.; Loon, van W.K.P.; Walle, van der T.; Speetjens, S.L.; Bot, G.P.A.

    2006-01-01

    A computational fluid dynamics model was created for the design of a natural convection shell-and-tube heat exchanger with baffles. The flow regime proved to be turbulent and this was modelled using the k¿¿ turbulence model. The features of the complex geometry were simplified considerably resulting

  16. Deep simplicity chaos, complexity and the emergence of life

    CERN Document Server

    Gribbin, John

    2005-01-01

    The world around us can be a complex, confusing place. Earthquakes happen without warning, stock markets fluctuate, weather forecasters seldom seem to get it right - even other people continue to baffle us. How do we make sense of it all? This title illuminates the harmony underlying our existence.

  17. Combating African Questions about the Legitimacy of AFRICOM

    Science.gov (United States)

    2008-03-19

    the colonial and neocolonial legacy and current African sensitivities about outsiders or they will always be baffled by African interpretations of... neocolonial legacies demystified some of the sensitivities surrounding the role of outsiders in Africa. The complex and dynamic nature of conflict and its

  18. The influence of the wind on the flight of the uncontrollable aircrafts

    Directory of Open Access Journals (Sweden)

    Vasiliy Makeyev

    2015-01-01

    Full Text Available This article represents research of influence of wind on flight of uncontrollable flying devices. It is offered the method of taking into account influence of permanent wind as well as baffling wind on flight of uncontrollable aircrafts stabilized with rotation and empennage

  19. Open Code - Open Content - Open Law. Building a Digital Commons

    Science.gov (United States)

    2007-11-02

    keep porn away from kids. And while I’m all for defeating COPA or the CDA, or whatever “C” word they come up with the next time around, I am...completely baffled about the priorities. Sure, civil liberties will be compromised if COPA stands; sure, cyberspace will be different if porn is not available

  20. Taking wind into account in the design of waste stabilisation ponds.

    Science.gov (United States)

    Badrot-Nico, F; Guinot, V; Brissaud, F

    2010-01-01

    Up to now, most investigations on the dependency of the fluid flow patterns and performance of waste stabilisation ponds (WSPs) on wind speed and direction and pond layout have been performed using 2D and 3D CFD steady state isothermal models. 3D non steady state models integrating thermal processes and boundary conditions taking into account the full influence of meteorological factors are likely to provide more realistic predictions of WSP performance. Such modelling was undertaken for 4 pond layouts, 2 without baffles and 2 with baffles. Wind speed and direction were kept constant throughout each simulation while other meteorological forcings were derived from field measurements. Twelve wind directions and 2, 4 and 6 m s(-1) wind speeds were considered for each WSP layout. Simulations allowed verifying that the pond performance is dependent on the wind direction and velocity, that baffles may improve WSP performance and that the addition of well-designed baffles has the advantage of reducing its sensitivity to the wind.

  1. FLOW REGIMES, GAS HOLD-UP AND AXIAL GAS MIXING IN THE GAS-LIQUID MULTISTAGE AGITATED CONTACTOR

    NARCIS (Netherlands)

    BREMAN, BB; BEENACKERS, AACM; BOUMA, MJ

    1995-01-01

    Experimental data are reported on Row regimes, gas hold-up and axial gas mixing of a gas-liquid Multi-stage Agitated Contactor (MAC), consisting of nine compartments [height, H, over diameter, D = 1; D = 0.09 m) separated by horizontal baffles with an opening of 0.04 m and with one centrally positio

  2. Whose Confession? Which Tradition? (A Preliminary Critique of Penny Thompson, 2004)

    Science.gov (United States)

    Doble, Peter

    2005-01-01

    What does Penny Thompson really want? Reading her article in "BJRE" 26 (1) proved a baffling experience: it clearly wanted to say something, and to say it passionately, yet signally failed to do so. It fails largely because it lacks an argument; there seems also to be conceptual muddle at its heart. A fuller critique will need to attend…

  3. Updating Older Fume Hoods.

    Science.gov (United States)

    Saunders, G. Thomas

    1985-01-01

    Provides information on updating older fume hoods. Areas addressed include: (1) adjustment of the hood's back baffle; (2) hood air leakage; (3) light level; (4) hood location in relation to room traffic and room air; and (5) establishing and maintaining hood performance. (JN)

  4. Alveolar targeting of aerosol pentamidine. Toward a rational delivery system

    Energy Technology Data Exchange (ETDEWEB)

    Simonds, A.K.; Newman, S.P.; Johnson, M.A.; Talaee, N.; Lee, C.A.; Clarke, S.W. (Royal Free Hospital, London (England))

    1990-04-01

    Nebulizer systems that deposit a high proportion of aerosolized pentamidine on large airways are likely to be associated with marked adverse side effects, which may lead to premature cessation of treatment. We have measured alveolar deposition and large airway-related side effects (e.g., cough, breathlessness, and effect on pulmonary function) after aerosolization of 150 mg pentamidine isethionate labeled with {sup 99m}Tc-Sn-colloid. Nine patients with AIDS were studied using three nebulizer systems producing different droplet size profiles: the Acorn System 22, Respirgard II, and Respirgard II with the inspiratory baffle removed. Alveolar deposition was greatest and side effects least with the nebulizer producing the smallest droplet size profile (Respirgard II), whereas large airway-related side effects were prominent and alveolar deposition lowest with the nebulizer producing the largest droplet size (Acorn System 22). Values for alveolar deposition and adverse airway effects were intermediate using the Respirgard with inspiratory baffle removed, thus indicating the importance of the baffle valve in determining droplet size. Addition of a similar baffle valve to the Acorn System 22 produced a marked improvement in droplet size profile. Selection of a nebulizer that produces an optimal droplet size range offers the advantage of enhancing alveolar targeting of aerosolized pentamidine while reducing large airway-related side effects.

  5. Characterisation of blast loading in complex, confined geometries using quarter symmetry experimental methods

    Science.gov (United States)

    Anthistle, T.; Fletcher, D. I.; Tyas, A.

    2016-11-01

    Explosions in confined spaces lead to complicated patterns of shock wave reflection and interactions which are best investigated by use of experimental tests or numerical simulations. This paper describes the design and outcome of a series of experiments using a test cell to measure the pressures experienced when structures were placed inside to alter the propagation of shock waves, utilising quarter symmetry to reduce the size of the required test cell and charge. An 80 g charge of PE4 (a conventional RDX-based plastic explosive) was placed at half height in one corner of the test cell, which represents the centre of a rectangular enclosure when symmetry is taken into consideration. Steel cylinders and rectangular baffles were placed within the test cell at various locations. Good reproducibility was found between repeated tests in three different arrangements, in terms of both the recorded pressure data and the calculated cumulative impulse. The presence of baffles within the test cell made a small difference to the pressures and cumulative impulse experienced compared to tests with no baffles present; however, the number and spacing of baffles was seen to make minimal difference to the experienced pressures and no noticeable difference to the cumulative impulse history. The paper presents useful experimental data that may be used for three-dimensional code validation.

  6. Mapping the geothermal potential of fault zones in the Belgium-Netherlands border region

    NARCIS (Netherlands)

    Loveless, S.; Pluymaekers, M.P.D.; Lagrou, D.; Boever, E. de; Doornenbal, H.; Laenen, B.

    2014-01-01

    Faults can determine the success or failure of low enthalpy geothermal projects. This is due to their capacity to behave as pathways or baffles to geothermal water (or both simultaneously) and their prevalence throughout the subsurface. Here we present an initial assessment of the possibility for fa

  7. Nitrate Salt Surrogate Blending Scoping Test Plan

    Energy Technology Data Exchange (ETDEWEB)

    Anast, Kurt Roy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-13

    Test blending equipment identified in the “Engineering Options Assessment Report: Nitrate Salt Waste Stream Processing”. Determine if the equipment will provide adequate mixing of zeolite and surrogate salt/Swheat stream; optimize equipment type and operational sequencing; impact of baffles and inserts on mixing performance; and means of validating mixing performance

  8. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: STORMWATER MANAGEMENT STORMFILTER® TREATMENT SYSTEM USING PERLITE MEDIA

    Science.gov (United States)

    Verification testing of the Stormwater Management, Inc. StormFilter® Using Perlite Filter Media was conducted on a 0.7 acre drainage basin near downtown Griffin, Georgia. The system consists of an inlet bay, flow spreader, cartridge bay, overflow baffle, and outlet bay, housed in...

  9. Integrated boiler, superheater, and decomposer for sulfuric acid decomposition

    Science.gov (United States)

    Moore, Robert; Pickard, Paul S.; Parma, Jr., Edward J.; Vernon, Milton E.; Gelbard, Fred; Lenard, Roger X.

    2010-01-12

    A method and apparatus, constructed of ceramics and other corrosion resistant materials, for decomposing sulfuric acid into sulfur dioxide, oxygen and water using an integrated boiler, superheater, and decomposer unit comprising a bayonet-type, dual-tube, counter-flow heat exchanger with a catalytic insert and a central baffle to increase recuperation efficiency.

  10. Separation of Flue-Gas Scrubber Sludge into Marketable Products

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-02-28

    The reduction of sulfur oxides from high sulfur coal burning utility companies has resulted in the production of huge quantities of wet flue-gas desulfurization scrubber sludge. A typical 400 MW power station burning a coal containing 3.5% sulfur by weight and using a limestone absorbent would produce approximately 177,000 tons (dry weight) of scrubber sludge per year. This brownish colored, finely divided material contains calcium sulfite (CaSO{sub 3} {center_dot} 1/2 H{sub 2}O), calcium sulfate (CaSO{sub 4} {center_dot} 2H{sub 2}O), unreacted limestone (CaCO{sub 3}), and various other impurities such as fly-ash and iron oxide particles. The physical separation of the components of scrubber sludge would result in the re-use of this material. The primary use would be conversion to a highly pure synthetic gypsum. This technical report concentrates on the effect of baffle configuration on the separation of calcium sulfite/sulfate from limestone. The position of the baffles as they related to the feed inlet, and the quantity of the baffles were examined. A clean calcium sulfite/sulfate (less than 2.0% limestone by weight) was achieved with the combination of water-only cyclone and horizontally baffled column.

  11. Numerical investigation of flow and heat transfer in a novel configuration multi-tubular fixed bed reactor for propylene to acrolein process

    Science.gov (United States)

    Jiang, Bin; Hao, Li; Zhang, Luhong; Sun, Yongli; Xiao, Xiaoming

    2015-01-01

    In the present contribution, a numerical study of fluid flow and heat transfer performance in a pilot-scale multi-tubular fixed bed reactor for propylene to acrolein oxidation reaction is presented using computational fluid dynamics (CFD) method. Firstly, a two-dimensional CFD model is developed to simulate flow behaviors, catalytic oxidation reaction, heat and mass transfer adopting porous medium model on tube side to achieve the temperature distribution and investigate the effect of operation parameters on hot spot temperature. Secondly, based on the conclusions of tube-side, a novel configuration multi-tubular fixed-bed reactor comprising 790 tubes design with disk-and-doughnut baffles is proposed by comparing with segmental baffles reactor and their performance of fluid flow and heat transfer is analyzed to ensure the uniformity condition using molten salt as heat carrier medium on shell-side by three-dimensional CFD method. The results reveal that comprehensive performance of the reactor with disk-and-doughnut baffles is better than that of with segmental baffles. Finally, the effects of operating conditions to control the hot spots are investigated. The results show that the flow velocity range about 0.65 m/s is applicable and the co-current cooling system flow direction is better than counter-current flow to control the hottest temperature.

  12. Physics and Psychophysics of High-Fidelity Sound. Part III: The Components of a Sound-Reproducing System: Amplifiers and Loudspeakers.

    Science.gov (United States)

    Rossing, Thomas D.

    1980-01-01

    Described are the components for a high-fidelity sound-reproducing system which focuses on various program sources, the amplifier, and loudspeakers. Discussed in detail are amplifier power and distortion, air suspension, loudspeaker baffles and enclosures, bass-reflex enclosure, drone cones, rear horn and acoustic labyrinth enclosures, horn…

  13. Mutual Radiation Impedance of Uncollapsed CMUT Cells with Different Radii

    CERN Document Server

    Ozgurluk, Alper; Atalar, Abdullah; Koymen, Hayrettin

    2015-01-01

    A polynomial approximation is proposed for the mutual acoustic impedance between uncollapsed capacitive micromachined ultrasonic transducer (CMUT) cells with different radii in an infinite rigid baffle. The resulting approximation is employed in simulating CMUTs with a circuit model. A very good agreement is obtained with the corresponding finite element simulation (FEM) result.

  14. A revision of the genus Matuta Weber, 1795 (Crustacea: Brachyura: Calappidae)

    NARCIS (Netherlands)

    Galil, B.S.; Clark, P.F.

    1994-01-01

    Introduction Amid the gaudily-coloured parade of tropical crabs few are more splendidly patterned than the matutine genera. But the patterns decorating these species brought about taxonomic disarray and from the very beginning they baffled their researchers. Already in 1817 Leach remarked: "the char

  15. Retention and distribution of Cu, Pb, Cr, and Zn in a full-scale hybrid constructed wetland receiving municipal sewage

    NARCIS (Netherlands)

    Xiao, H.W.; Zhang, S.L.; Zhai, J.; He, Q.; Mels, A.R.; Ning, K.J.; Liu, J.

    2013-01-01

    This study was conducted to investigate the retention and distribution of Cu, Pb, Cr, and Zn in a hybrid constructed wetland (CW) that consists of both vertical baffled flow wetlands (VBFWs) and horizontal subsurface flow wetlands (HSSFs) with unique flow regimes and oxygen distribution. The heavy m

  16. A Geometric Proof of Riemann Hypothesis

    OpenAIRE

    2003-01-01

    Beginning from the formal resolution of Riemann Zeta function, by using the formula of inner product between two infinite-dimensional vectors in the complex space, the author proved the world's baffling problem -- Riemann hypothesis raised by German mathematician B. Riemann in 1859.

  17. From Pupa to Butterfly

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    IN front of me is the Floating Stone, an autobiography-like novel written by a farmer writer. With a not very eye-catching cover and a somewhat baffling name, the book is not quite interesting to me. Care-freely, I took up the book and scanned it. Unexpectedly, I was attracted and finished reading the

  18. Gas entrainment in scaled model of pool type LMFBR

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, I.; Chandra, L.; Laxman, D.; Kumar, A.; Gopal, C.A.; Shivakumar, N.S.; Padmakumar, G.; Anand Babu, C.; Vaidyanathan, G. [Fast Reactor Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu (India)

    2007-07-01

    The reactor Thermal hydraulics plays an important role for successful operation of Prototype Fast Breeder Reactor (PFBR), which is under construction at Kalpakkam, India. One of the issues to be resolved in PFBR is argon cover gas entrainment problem from free liquid sodium surface. The entrained cover gas may hinder the normal reactor operation. High free surface velocity along with the presence of various immersed components in the hot pool is the cause of gas entrainment from free surface. To reduce the free surface velocity and hence gas entrainment, ring type baffle plates were considered. Initially the optimum geometry of the baffle plate was arrived through numerical analysis using PHOENICS, a commercial computational fluid dynamics tool. Finally the experiments were conducted in a 1/4 scale water model of PFBR primary circuit with selected baffle plate geometry. It was found that a baffle plate with radial width of 125 mm in the model and located above intermediate heat exchanger is very effective to reduce the gas entrainment problem in PFBR. (authors)

  19. A Study of the Discount Retail Industry and Wal-Mart Corporation

    Science.gov (United States)

    2007-11-02

    lilith /no- wal/index.html.; Internet, accessed 14 August 1997. 115 Deirdre McMurdy, "Baffling Bentonville: Executives from the Arkansas-based Retail...December 1997. "Up Against the Wal! Facts You Should Know About Wal-Mart," http://tdg.uoguelph.ca? lilith /no-wal/index.html; Internet; accessed 14

  20. Fluid dynamics simulation of the reheating furnace of the continuous mill line of VBM

    Energy Technology Data Exchange (ETDEWEB)

    Soares, Lis Nunes; Silva, Ricardo Junqueira [V e M do Brasil S.A., Belo Horizonte. MG (Brazil)

    2009-11-01

    V and M do Brazil is an integrated steel mill with the production of seamless steel pipe. The manufacture process comprises heating and reheating fuel fired furnaces within two rolling mills lines. The Continuous Mill line reheating furnace has no baffle between heating and soaking zone that might cause a thermofluidodynamics influence between control zones and consequently an overall unbalance within the furnace. The combustion control mesh is based at the real measured temperature per zone. If the thermocouples of the heating zone are influenced by the heat flux coming from the soaking zone, the mesh might receive a wrong temperature signal and send to the heating zone burners a lower thermal demand than the real needed one. The flux unbalance may cause homogeneity problems and/or early equipment worn out. Using the software FLUENT, it was made a 2D fluid dynamic simulation of the reheating furnace with and without a baffle in order to have a qualitative view of its influence in the hot gas flux inside the furnace. Through the simulation it was possible to check the furnace homogeneity gain potential with the installation of the baffle and its better position. The results of this study supported the company decision to actually invest in a baffle installation in this furnace. Further studies will be done to quantify the results of the process. (author)

  1. Development of a CFD Model for Secondary Final Settling Tanks in Water Pollution Control Plants

    Science.gov (United States)

    Gong, Minwei; Xanthos, Savvas; Ramalingam, Krish; Fillos, John

    2007-11-01

    To assess performance and evaluate alternatives to improve efficiency of the New York City the Wards Island Water Pollution Control Plant (WPCP) FSTs at peak loads, a 3D CFD model has been developed. Fluent was utilized as the base platform, where sub-models of the Suspended Solids (SS), settling characteristics, density currents and SS flocculation were incorporated. This was supplemented by field and bench scale experiments to quantify the coefficients integral to the sub-models. Model calibration and validation have been carried out by using the extensive set of data collected. The model can be used to evaluate different modes of operation, alternate hydraulic and solids loading rates, as well as addition of auxiliary components such as baffles to improve process performance. The model is being used to compare potential benefits for different alternatives of design and operation of the existing FSTs. After comparing series of inlet baffles, a baffle with 4 horizontal and 7 vertical slots has been recommended for installation in the FSTs. Additional baffle type, configurations and locations within the tank are also being evaluated to improve the performance of the FSTs especially during periods of poor settling and peak flow conditions.

  2. 7 CFR 58.128 - Equipment and utensils.

    Science.gov (United States)

    2010-01-01

    ... and shall be elevated above the floor and protected sufficiently with the necessary covers or baffles... for cleaning of floors and adjacent wall areas, the receiving tank shall be equipped with wheels or... treating, pasteurizing or thermal processing unit to record the heating process. (ii) Additional use...

  3. Sensitivity to plant modelling uncertainties in optimal feedback control of sound radiation from a panel

    DEFF Research Database (Denmark)

    Mørkholt, Jakob

    1997-01-01

    Optimal feedback control of broadband sound radiation from a rectangular baffled panel has been investigated through computer simulations. Special emphasis has been put on the sensitivity of the optimal feedback control to uncertainties in the modelling of the system under control.A model of a re...

  4. Time-domain Simulations of the Acoustic Streaming Produced by a Propagating Wave Radiated by a Circular Piston

    DEFF Research Database (Denmark)

    Santillan, Arturo Orozco

    2013-01-01

    Results of numerical simulations of the sound field produced by a circular piston in a rigid baffled are presented. The aim was to calculate the acoustic streaming and the flow of mass generated by the sound field. For this purpose, the classical finite-difference time-domain method was implemented...

  5. Decrease in light/dark cycle of microalgal cells with computational fluid dynamics simulation to improve microalgal growth in a raceway pond.

    Science.gov (United States)

    Yang, Zongbo; Cheng, Jun; Ye, Qing; Liu, Jianzhong; Zhou, Junhu; Cen, Kefa

    2016-11-01

    In this study, computational fluid dynamics (CFD) was used to systemically analyze the movement of algae in a vortex flow field produced by up-down chute baffles. The average cell light/dark (L/D) cycle period, vertical fluid velocity, fraction of time the algae was resides in light zone and the L/D cycle period were investigated under different paddlewheel speeds and microalgal concentrations. Results showed that the L/D cycle period decreased but the vertical fluid velocity increased when the up-down chute baffles were used. The L/D cycle period decreased by 24% (from 5.1s to 3.9s), and vertical fluid velocity increased by 75% when up-down chute baffles were used with paddlewheel speed of 30r/min. The probability of L/D cycle period of 3s increased by 52% from 0.29 to 0.44 with the up-down chute baffles. This led to approximately 22% increase in biomass yield without changing the paddlewheel speed.

  6. 77 FR 112 - Effluent Limitations Guidelines and Standards for the Construction and Development Point Source...

    Science.gov (United States)

    2012-01-03

    ... included non-numeric requirements to: Implement erosion and sediment controls; Stabilize soils; Manage..., water from culvert sites and caissons at bridge construction sites that was impounded in a baffled... (grab sample, flow or time-weighted composite, continuous turbidity measurement, etc.);...

  7. A Stylistic Study on the Linguistic Deviations in E. E. Cummings' Poetry

    Science.gov (United States)

    Li, Xin; Shi, Mengchen

    2015-01-01

    Regarded as the pioneer of experimental poetry, E. E. Cummings' unconventional treatment of poetic language has reached an unprecedented acme, which has intrigued and baffled numerous scholars, researchers and readers alike. Nevertheless, the very existence of poetry, like other types of literary texts, demonstrates the significance and value of…

  8. UVES abundances of stars in nearby dwarf spheroidal galaxies

    NARCIS (Netherlands)

    Tolstoy, E; Venn, K; Shetrone, M; Primas, F; Hill, [No Value; Kaufer, A; Szeifert, T

    2002-01-01

    It is a truth universally acknowledged, that a galaxy in possession of a good quantity of gas must want to form stars. It is the details of how and why that baffle us all. The simplest theories either would have this process a carefully self-regulated affair, or one that goes completely out of contr

  9. Innovative Fabric Show Every Month in Shanghai

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    It normally costs a long term for fabric manufacturers to develop a new product. The delay of marketing the innovative fabric not only affect the benefit of the textile mills, but also baffle the development of the industry. Shanghai Fabric Hall responses to this with a regular exhibition of

  10. 低温油封冷却器的结构优化及数值模拟%Structure Optimization and Numerical Simulation of Low-Temperature Oil Seal Cooler

    Institute of Scientific and Technical Information of China (English)

    高海; 喻九阳; 徐建民; 郑小涛; 林纬

    2016-01-01

    Aiming at the shell-and-tube heat transfer existing stagnant zones at the back of baffle,we optimized the structure of the baffle in shell-side of the heat exchanger,and studied the effects of the baffle with round and taper hole on the performance of heat transfer and pressure-drop of the low-temperature oil seal cooler by numeri⁃cal simulation respectively. Result shows that the baffle with round hole is more conductive to reduce stagnant zones at the back of baffle and improve the performance of heat transfer of the cooler when the velocity of shell-side entrance is less than 1.3 m/s;and the baffle with taper hole is more advantageous to enhance the heat transfer of the cooler when the velocity of shell-side entrance is more than 2 m/s. Moreover,the baffles with round and taper hole are beneficial to reduce the pressure-drop of shell-side with almost the same effects.%针对管壳式换热器折流板背部存在流动死区的问题,对换热器壳程折流板的结构进行优化,并且通过数值模拟分别研究了折流板开圆孔和锥形孔对低温油封冷却器换热性能和压降的影响.数值模拟结果表明,当壳程入口速度低于1.3 m/s,折流板开圆孔更有利于减小折流板背部流动死区,改善冷却器壳程的强化传热性能;当壳程入口流速大于2m/s时,折流板开锥形孔更有利于冷却器壳程的强化传热.折流板开圆孔和锥形孔均有利于减小冷却器壳程压降,两者对压降的影响无明显差别.

  11. Histochemical study of the oviducal gland and analysis of the sperm storage tubules of Mustelus schmitti Springer, 1939 (Chondrichthyes, Triakidae

    Directory of Open Access Journals (Sweden)

    Fernanda Gabriela Elías

    2015-08-01

    Full Text Available Abstract: The paired oviducal glands of immature and mature females of Mustelus schmitti were examined macro and microscopically. Findings indicate that these glands possessed the same zonation as in most chondrichthyans from anterior to posterior: club, papillary, baffle and terminal zones. The whole gland is composed by simple tubular glands that connect with transverse grooves all along the organ. The club zone presents a typical indian club shape with a simple columnar and ciliated epithelium including secretory cells PAS (+ and AB (+. The papillary zone is characterized by lamella forming small and long cones in numbers of three. The epithelium of this zone contains ciliated cells with apical nuclei and secretory cells with basal nuclei that stain AB (+The baffle zone consists of apically flattened lamellae alternating with spinnerets which are small projections disposed by both sides of the plateau. This whole structure is present in number of 8 or 9 units. A simple columnar ciliated epithelium covers the plateau and spinnerets and no AB or PAS staining is observed. The epithelium of the terminal zone is PAS (- and AB (+, and elongated tubules, that run adjacent to the baffle zone are the site where groups of spermatozoa are clearly observed in the lumen. The epithelium of the sperm storage tubules do not stain with any of the dyes tested. Sperm was also observed in the baffle zone, presumably in its way to the fecundation in the oviduct because it displays no aggregation pattern and was between the folds of the epithelium. By scanning electron microscopy sperm was observed in the club and baffle zones in a gland which belonged to a pregnant female.

  12. 斜向流换热器壳程流场均匀化研究%Research on Flow Field Homogenization in Shell Side of Sidelling Flow Heat Exchanger

    Institute of Scientific and Technical Information of China (English)

    古新; 王珂; 董其伍; 王永庆

    2012-01-01

    传统弓形折流板换热器壳程流体横向流动时存在流动阻力和传热死区大等缺点。为克服上述不足,研究开发了一种新型高效节能的斜向流管壳式换热器,采用导向型折流栅替代传统弓形折流板,倾斜流道内流体斜向冲刷换热管束。考察和对比了斜向流换热器和弓形折流板换热器壳程主流区的流体流速分布和变化规律,证实了导向型折流栅具有显著的控涡均化壳程流场和提高壳程流体整体流速的作用,有助于减小壳程压降,增大有效换热面积,为管壳式换热器结构改良提供了参考依据。%There are some disadvantages in the traditional segmental baffle heat exchanger for the transversal fluid flow in its shell side,such as the high flow resistance,large heat transfer dead region, and so on.For overcoming those above disadvantages,a kind of new efficient and energy saving shell-and-tube heat exchanger with sidelling flow in shell side is developed,the traditional segmental baffles are substituted by leading type shutter baffles,therefore,the fluid in some local regions flows over tubes inclinedly.The velocity distribution and velocity variation at the same position of main flow region in sidelling flow heat exchanger and segmental baffle heat exchanger is studied and compared.It is confirmed that,with the leading type shutter baffles in shell side,the vortex in shell side is weaken,flow field is greatly homogenized,and the velocity in shell side is increased.Shutter baffles are helpful to reduce the pressure drop in shell side and increase effective heat transfer area, which provides references for structure improving of shell-and-tube heat exchanger.

  13. 管壳式换热器壳程特性的数值模拟研究%Numerical Simulation Research on Features in Shell Side of Shell-and-Tube Heat Exchanger

    Institute of Scientific and Technical Information of China (English)

    廖国进; 张军强

    2012-01-01

      Three dimensional numerical simulations of one tube-and-shell heat exchanger were carried out by using the FLUENT software. The influences caused by the segmental baffle number, inlet flow rate and baffle nick’s height on the pressure drop and outlet temperature of the tube-and-shell heat exchanger’s shell side, were analyzed. The results expatiate as the segmental baffle number increases, the pressure drop and outlet temperature increase, and that as the inlet flow rate increases, the pressure drop increases with dropping tendency quickening, but the outlet temperature is dropping, and that as the segmental baffle nick’s height increases, the pressure drop and the outlet temperature decrease, and the pressure drop rate tends to slow down. And under the same pressure drop condition, it’s better to change the baffle number to increase the outlet temperature than to change the inlet flow rate and baffle nick’s height.%  利用 FLUENT 软件对一管壳式换热器壳程流场进行了三维数值模拟,分析研究了折流板数目、进口流速和折流板缺口高度对换热器壳程压降、出口温度的影响,结果显示,随着折流板数目增加,壳程压降和出口温度逐渐增大;随着进口流速增大,壳程压降逐渐增大且趋势加快,而出口平均温度下降,但是温度下降不大;随着折流板缺口高度增大,壳程压降和出口平均温度逐渐减小,但是压降减小逐渐趋于缓和;相同的压降条件下,通过改变折流板数目提高出口温度比改变进口流速和折流板缺口高度更有效

  14. Various methods to improve heat transfer in exchangers

    Directory of Open Access Journals (Sweden)

    Pavel Zitek

    2015-01-01

    Full Text Available The University of West Bohemia in Pilsen (Department of Power System Engineering is working on the selection of effective heat exchangers. Conventional shell and tube heat exchangers use simple segmental baffles. It can be replaced by helical baffles, which increase the heat transfer efficiency and reduce pressure losses. Their usage is demonstrated in the primary circuit of IV. generation MSR (Molten Salt Reactors. For high-temperature reactors we consider the use of compact desk heat exchangers, which are small, which allows the integral configuration of reactor. We design them from graphite composites, which allow up to 1000°C and are usable as exchangers: salt-salt or salt-acid (e.g. for the hydrogen production. In the paper there are shown thermo-physical properties of salts, material properties and principles of calculations.

  15. Technology demonstration for reducing mercury emissions from small-scale gold refining facilities.

    Energy Technology Data Exchange (ETDEWEB)

    Habegger, L. J.; Fernandez, L. E.; Engle, M.; Bailey, J. L.; Peterson, D. P.; MacDonell, M. M.; U.S. Environmental Protection Agency

    2008-06-30

    Gold that is brought from artisanal and small-scale gold mining areas to gold shops for processing and sale typically contains 5-40% mercury. The uncontrolled removal of the residual mercury in gold shops by using high-temperature evaporation can be a significant source of mercury emissions in urban areas where the shops are located. Emissions from gold shop hoods during a burn can exceed 1,000 mg/m{sup 3}. Because the saturation concentration of mercury vapor at operating temperatures at the hood exhaust is less than 100 mg/m{sup 3}, the dominant component of the exhaust is in the form of aerosol or liquid particles. The U.S. Environmental Protection Agency (EPA), with technical support from Argonne National Laboratory (Argonne), has completed a project to design and test a technology to remove the dominant aerosol component in the emissions from gold shops. The objective was to demonstrate a technology that could be manufactured at low cost and by using locally available materials and manufacturing capabilities. Six prototypes designed by Argonne were locally manufactured, installed, and tested in gold shops in Itaituba and Creporizao, Brazil. The initial prototype design incorporated a pebble bed as the media for collecting the mercury aerosols, and a mercury collection efficiency of over 90% was demonstrated. Though achieving high efficiencies, the initial prototype was determined to have practical disadvantages such as excessive weight, a somewhat complex construction, and high costs (>US$1,000). To further simplify the construction, operation, and associated costs, a second prototype design was developed in which the pebble bed was replaced with slotted steel baffle plates. The system was designed to have flexibility for installation in various hood configurations. The second prototype with the baffle plate design was installed and tested in several different hood/exhaust systems to determine the optimal installation configuration. The significance of

  16. PIV Investigations of Flow Patterns in the Entrance Configuration of Plate-fin Heat Exchanger%基于PIV技术对板翅式换热器入口结构内部流场的研究与改进

    Institute of Scientific and Technical Information of China (English)

    文键; 厉彦忠; 周爱民; 马岩松

    2006-01-01

    Flow characteristics in the entrance of plate-fin heat exchanger have been investigated by means of particle image velocimetry (PIV). The flow field was measured using the two-frame cross-correlation technique. Streamline and velocity contour graphs at different cross-sections were obtained in the experiment. The experimental results indicate that flow maldistribution in the conventional header is very serious, while the improved header configuration with punched baffle can effectively improve the uniformity. The flow maldistribution parameter in plate-fin heat exchanger has been reduced from 1.21 to 0.21, and the ratio of the maximum velocity to the minimum is reduced from 23.2 to 1.8 by installing the punched baffle. The results suggest room for the optimum design of plate-fm heat exchanger.

  17. Investigation of Horizontal Velocity Fields in Stirred Vessels with Helical Coils by PIV

    Directory of Open Access Journals (Sweden)

    Volker Bliem

    2014-01-01

    Full Text Available Horizontal velocity flow fields were measured by particle image velocimetry for a stirred vessel with baffles and two helical coils for enlargement of heat transfer area. The investigation was carried out in a cylindrical vessel with flat base and two different stirrers (radial-flow Rushton turbine and axial-flow propeller stirrer. Combined velocity plots for flow fields at different locations are presented. It was found that helical coils change the flow pattern significantly. Measurements for the axial-flow Rushton turbine showed a strong deflection by the coils, leading to a mainly tangential flow pattern. Behind baffles large areas of unused heat transfer area were found. First results for the axial-flow propeller reveal an extensive absence of fluid movement in the horizontal plane. Improved design considerations for enhanced heat transfer by more compatible equipment compilation are proposed.

  18. Status of the eROSITA Telescope testing and calibrating the x-ray mirror assemblies

    Science.gov (United States)

    Burwitz, Vadim; Predehl, Peter; Bräuninger, Heinrich; Burkert, Wolfgang; Dennerl, Konrad; Eder, Josef; Friedrich, Peter; Fürmetz, Maria; Grisoni, Gabriele; Hartner, Gisela; Marioni, Fabio; Menz, Benedikt; Pfeffermann, Elmar; Valsecchi, Giuseppe

    2013-09-01

    The eROSITA X-ray observatory that will be launched on board the Russian Spectrum-RG mission comprises seven X-ray telescopes, each with its own mirror assembly (mirror module + X-ray baffle), electron deflector, filter wheel, and CCD camera with its control electronics. The completed flight mirror modules are undergoing many thorough X-ray tests at the PANTHER X-ray test facility after delivery, after being mated with the X-ray baffle, and again after both the vibration and thermal-vacuum tests. A description of the work done with mirror modules/assemblies and the test results obtained will be reported here. We report also on the environmental tests that have been performed on the eROSITA telescope qualification model.

  19. Various methods to improve heat transfer in exchangers

    Science.gov (United States)

    Pavel, Zitek; Vaclav, Valenta

    2015-05-01

    The University of West Bohemia in Pilsen (Department of Power System Engineering) is working on the selection of effective heat exchangers. Conventional shell and tube heat exchangers use simple segmental baffles. It can be replaced by helical baffles, which increase the heat transfer efficiency and reduce pressure losses. Their usage is demonstrated in the primary circuit of IV. generation MSR (Molten Salt Reactors). For high-temperature reactors we consider the use of compact desk heat exchangers, which are small, which allows the integral configuration of reactor. We design them from graphite composites, which allow up to 1000°C and are usable as exchangers: salt-salt or salt-acid (e.g. for the hydrogen production). In the paper there are shown thermo-physical properties of salts, material properties and principles of calculations.

  20. Improving microalgal growth with reduced diameters of aeration bubbles and enhanced mass transfer of solution in an oscillating flow field.

    Science.gov (United States)

    Yang, Zongbo; Cheng, Jun; Lin, Richen; Zhou, Junhu; Cen, Kefa

    2016-07-01

    A novel oscillating gas aerator combined with an oscillating baffle was proposed to generate smaller aeration bubbles and enhance solution mass transfer, which can improve microalgal growth in a raceway pond. A high-speed photography system (HSP) was used to measure bubble diameter and generation time, and online precise dissolved oxygen probes and pH probes were used to measure mass-transfer coefficient and mixing time. Bubble diameter and generation time decreased with decreased aeration gas rate, decreased orifice diameter, and increased water velocity in the oscillating gas aerator. The optimized oscillating gas aerator decreased bubble diameter and generation time by 25% and 58%, respectively, compared with a horizontal tubular gas aerator. Using an oscillating gas aerator and an oscillating baffle in a raceway pond increased the solution mass-transfer coefficient by 15% and decreased mixing time by 32%; consequently, microalgal biomass yield increased by 19%.

  1. DAMPING COMPUTATION OF LIQUID SLOSHING IN CONTAINERS ABOARD SPACECRAFT

    Institute of Scientific and Technical Information of China (English)

    宝音贺西; 李俊峰; 高云峰; 王照林

    2003-01-01

    Under the non-rotating assumption, a method for the calculation of damping of fuel sloshing with small amplitude in containers aboard spacecraft is proposed in the present paper. And we have presented an eigen-value equation for sloshing damping and frequency computation. This equation may be solved by Ritz or Galerkin methods for a container of simple geometry or by finite element method for a container of arbitrary geometric shape even with rigid baffles. The simulated results show that the equivalent damping coefficients is directly proportional to fuel's viscosity, whereas it almost exhibits no influence on sloshing frequencies. The drawback of the proposed method lies in expensive computation cost. Thus far, it hasn't yet be applied to a container with elastic baffles.

  2. Study of mixing behavior of cstr using CFD

    Directory of Open Access Journals (Sweden)

    D. Rajavathsavai

    2014-03-01

    Full Text Available The continuous stirred tank reactor (CSTR is a widely used equipment in chemical related industries. The flow behaviour of fluid inside the reactor may either change from dispersion to ideal or ideal to dispersion mixing state. It is studied using the computational fluid dynamics (CFD simulation software ANSYS Fluent. The mixing behaviour is predicted in terms of age distribution function, I (θ. For the CSTR without impeller and baffles, I (θ is found by the tracer injection method. It is measured and predicted by the impeller swept volume method for the CSTR in the presence of impeller and baffles. The predicted results are found to be in good agreement with the literature experimental data. Effect of rpm of the impeller, Reynolds number and viscosity of the process fluid on the mixing characteristics has been investigated.

  3. The Implication of the Narrator's Puzzlement in Invisible Man

    Institute of Scientific and Technical Information of China (English)

    张吟松

    2008-01-01

    Ellison's Invisible Man tells the experiences of a young black in search of his cultural identity in American society in the first half of the 20th century. Because of the racial discrimination, tangible or intangible, his efforts were hindered every now and then and he was often baffled, not knowing "who he was". His confusion reflects the serious situation in which the American blacks were involved. His endeavors also suggest the American blacks' dream of establishing themselves in the society.

  4. Optical Coating Performance for Heat Reflectors of the JWST-ISIM Electronic Component

    Science.gov (United States)

    Rashford, Robert A.; Perrygo, Charles M.; Garrison, Matthew B.; White, Bryant K.; Threat, Felix T.; Quijada, Manuel A.; Jeans, James W.; Huber, Frank K.; Bousquet, Robert R.; Shaw, Dave

    2011-01-01

    A document discusses a thermal radiator design consisting of lightweight composite materials and low-emittance metal coatings for use on the James Webb Space Telescope (JWST) structure. The structure will have a Thermal Subsystem unit to provide passive cooling to the Integrated Science Instrument Module (ISIM) control electronics. The ISIM, in the JWST observatory, is the platform that provides the mounting surfaces for the instrument control electronics. Dissipating the control electronic generated-heat away from JWST is of paramount importance so that the spacecraft s own heat does not interfere with the infrared-light gathering of distant cosmic sources. The need to have lateral control in the emission direction of the IEC (ISIM Electronics Compartment) radiators led to the development of a directional baffle design that uses multiple curved mirrorlike surfaces. This concept started out from the so-called Winston non-imaging optical concentrators that use opposing parabolic reflector surfaces, where each parabola has its focus at the opposite edge of the exit aperture. For this reason they are often known as compound parabolic concentrators or CPCs. This radiator system with the circular section was chosen for the IEC reflectors because it offers two advantages over other designs. The first is that the area of the reflector strips for a given radiator area is less, which results in a lower mass baffle assembly. Secondly, the fraction of energy emitted by the radiator strips and subsequently reflected by the baffle is less. These fewer reflections reduced the amount of energy that is absorbed and eventually re-emitted, typically in a direction outside the design emission range angle. A baffle frame holds the mirrors in position above a radiator panel on the IEC. Together, these will direct the majority of the heat from the IEC above the sunshield away towards empty space.

  5. Characterization of Decommissioned PWR Vessel Internals Material Samples: Tensile and SSRT Testing (Nonproprietary Version)

    Energy Technology Data Exchange (ETDEWEB)

    M.Krug, R.Shogan

    2004-09-01

    Pressurized water reactor (PWR) cores operate under extreme environmental conditions due to coolant chemistry, operating temperature, and neutron exposure. Extending the life of PWRs requires detailed knowledge of the changes in mechanical and corrosion properties of the structural austenitic stainless steel components adjacent to the fuel (internals) subjected to such conditions. This project studied the effects of reactor service on the mechanical and corrosion properties of samples of baffle plate, former plate, and core barrel from a decommissioned PWR.

  6. 新型管壳式换热器三维流场分析%Analysis of Fluid Flow Field in Shell Sides of Shell-and-Tube Heat Exchangers

    Institute of Scientific and Technical Information of China (English)

    王珂; 王永庆; 董晓琳; 古新

    2011-01-01

    Analysis of fluid flow characteristics is carried out in shell sides of shell-and-tube heat exchangers with segmental baffle, rod baffle and H-shape baffle, by using periodic numerical models. The main distinction of the three typical flow types corresponding to these heat exchangers lies in different fluid transversal velocity component. The ratio magnitude of fluid transversal velocity component to longitudinal velocity component remains a constant for each flow type in different fluxes. The difference of pressure drop and heat transfer coefficient between shell-and-tube heat exchangers with varied baffles is caused mainly by different ratio magnitude of fluid transversal velocity component to longitudinal velocity component.%本文应用周期性简化模型,对弓型、杆式以及H型壳程支撑结构的管壳式换热器壳程内的流动特性进行了分析。对于其对应的三种典型流态,反映在壳程内流体流动方面的主要差别是壳程内横向流速度分量的不同,且三种流态各自在不同流量下的横向流速度分量与纵向流速度分量之比几乎均为一定值。具有不同管束支撑结构的管壳式换热器壳程内流体阻力降与传热系数不同,主要原因在于其壳程内流体的横向流速度分量的大小存在差别。

  7. Tis the Season for Learning

    Institute of Scientific and Technical Information of China (English)

    USHA; SANKAR

    2008-01-01

    Gray skies which a weak sun strug- gles to break through.Short,short afternoons,as dark evenings appear suddenly with the clock face reading just 4 p.m.The Beijing winter is well and truly here.And,of course,with the year drawing to a close,the silly season too. In the three years that I have lived in this baffling city,2007 must rank at the top for its yuletide overdose.Everywhere I

  8. Development and Evaluation of a Prototype Wheeled Ultra-High Pressure Extinguisher System with Novec 1230

    Science.gov (United States)

    2016-01-01

    annulus ) and three baffles positioned along the inside of the inner cylinder. The fixture is equipped with three spray nozzles that allow fuel to flow...effective after a small number of practice fire suppression tests were conducted to familiarize the firefighter with the equipment. However, initial tests...2000 psi revealed that the discharge time was too long, indicating that the nozzle orifice size was too small . Increasing the initial pressure

  9. Correlation of Power Consumption for Several Kinds of Mixing Impellers

    Directory of Open Access Journals (Sweden)

    Haruki Furukawa

    2012-01-01

    Full Text Available The authors reviewed the correlations of power consumption in unbaffled and baffled agitated vessels with several kinds of impellers, which were developed in a wide range of Reynolds numbers from laminar to turbulent flow regions. The power correlations were based on Kamei and Hiraoka's expressions for paddle and pitched paddle impellers. The calculated correlation values agreed well with experimental ones, and the correlations will be developed the other types of impellers.

  10. Examples of modifications and reparations made on vessel internal components of PWR; Exemples de modifications et reparations realisees sur les equipements internes de cuves REP

    Energy Technology Data Exchange (ETDEWEB)

    Lemaire, E. [Electricite de France (EDF/CAPE), Centre d' Appui au Parc en Exploitation, 93 - Saint-Denis (France); Ligneau, N. [Electricite de France (EDF/SEPTEN), Div. Reacteur, 92 - Courbevoie (France). Service Etudes et Projets Thermiques et Nucleaires; Piniguel, C. [Electricite de France (EDF/RD/MFTT), 78 - Chatou (France)

    2005-07-01

    Modifications and repair work have been made on internal components since their original design. The aim was to face and handle aging-related issues such as stress corrosion, thermal creep or accidental shocks (that might happen while handling equipment during unit outage). This paper deals with the modifications involving the baffle assembly, the hold-down spring, support pins and the upper support plate of the core. Positive feedback has comforted the choice the unit operators made. (A.C.)

  11. An Investigation of the Ranger V-770-8 Engine Installation for the Edo XOSE-1 Airplane II : Aerodynamics

    Science.gov (United States)

    Dennard, John S.

    1945-01-01

    Investigations were made to determine the cowling and cooling characteristics of the Ranger V-770-8 engine installation in an observation seaplane. Final cowl configurations possessed ample engine and oil-cooler pressure drops for cooling in the critical normal-power climb condition with any of the three baffle configurations tested. The indicated critical Mach number of the cowling was found to be 0.70 as determined by the pressure on the lower lip of the inlet.

  12. The writing strategies of three freshman students at Middle East Technical University

    OpenAIRE

    Alpaslan, Özge

    2002-01-01

    Cataloged from PDF version of article. One of the baffling areas for the designers and instructors of EAP programs is that of academic writing. What academic writing exactly includes, what parts of it and how it should be taught, are issues that have been much debated on. Another issue in the teaching and learning of languages, learning strategies, also much debated, has gained popularity in recent years and has found its way into the classroom. The combination of these two ...

  13. Molten metal reactor and method of forming hydrogen, carbon monoxide and carbon dioxide using the molten alkaline metal reactor

    Science.gov (United States)

    Bingham, Dennis N.; Klingler, Kerry M.; Turner, Terry D.; Wilding, Bruce M.

    2012-11-13

    A molten metal reactor for converting a carbon material and steam into a gas comprising hydrogen, carbon monoxide, and carbon dioxide is disclosed. The reactor includes an interior crucible having a portion contained within an exterior crucible. The interior crucible includes an inlet and an outlet; the outlet leads to the exterior crucible and may comprise a diffuser. The exterior crucible may contain a molten alkaline metal compound. Contained between the exterior crucible and the interior crucible is at least one baffle.

  14. Gone With the Wind?

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    While the answer to China's clean energy efforts might just be blowing in the wind, a wide range of obstacles lie ahead Poyanghu Lake in Jiangxi Province is a lake that holds deep mystery for locals. Since the 1960s, more than 100 ships have inexplicably sunk in its murky waters. The only conclusion, baffled experts can think of, is that the strong winds, caused by air currents being squeezed through mountains

  15. Focusing on EFL reading theory and practice

    CERN Document Server

    Al-Mahrooqi, Rahma

    2014-01-01

    Reading, a complex and multi-faceted skill, is essential for life and academic success. While its mysteries still baffle first-language research, the nature of reading in a foreign language presents an even greater puzzle. However, given reading's importance for EFL students who study their specializations in English, and whose future employment may depend on their competence in it, researchers must continue to investigate foreign language reading and devise ways of improving students' capaci...

  16. Miniaturized cathodic arc plasma source

    Science.gov (United States)

    Anders, Andre; MacGill, Robert A.

    2003-04-15

    A cathodic arc plasma source has an anode formed of a plurality of spaced baffles which extend beyond the active cathode surface of the cathode. With the open baffle structure of the anode, most macroparticles pass through the gaps between the baffles and reflect off the baffles out of the plasma stream that enters a filter. Thus the anode not only has an electrical function but serves as a prefilter. The cathode has a small diameter, e.g. a rod of about 1/4 inch (6.25 mm) diameter. Thus the plasma source output is well localized, even with cathode spot movement which is limited in area, so that it effectively couples into a miniaturized filter. With a small area cathode, the material eroded from the cathode needs to be replaced to maintain plasma production. Therefore, the source includes a cathode advancement or feed mechanism coupled to cathode rod. The cathode also requires a cooling mechanism. The movable cathode rod is housed in a cooled metal shield or tube which serves as both a current conductor, thus reducing ohmic heat produced in the cathode, and as the heat sink for heat generated at or near the cathode. Cooling of the cathode housing tube is done by contact with coolant at a place remote from the active cathode surface. The source is operated in pulsed mode at relatively high currents, about 1 kA. The high arc current can also be used to operate the magnetic filter. A cathodic arc plasma deposition system using this source can be used for the deposition of ultrathin amorphous hard carbon (a-C) films for the magnetic storage industry.

  17. 两种新型油冷却器传热性能对比实验研究%Two Kinds of New Type of High-efficiency Oil Cooler Heat Transfer Performance Contrast Experimental Research

    Institute of Scientific and Technical Information of China (English)

    梁建活; 江楠; 曾纪成

    2014-01-01

    The experimental validation is used to study the heat transfer performance of two kinds of high-efficiency oil cooler.A fin tube type oil cooler with aluminum fin tubes supported by segmental baffles and an oil cooler with spiral tubes supported by helical baffles are explored in the research respectively.The test results show that the fin tube type oil cooler get a better com-prehensive performance.The heat flow rate of fin tube type oil cooler is larger and the pressure drop through the shell pass is smaller than the values of the helical baffle oil cooler under the same condition of low to moderate oil flow rate.The heat transfer capacity of unit pressure drop in the fin tube type oil cooler is 1 .5 times as that of the helical baffle oil cooler.Furthermore,the compact structure of the fin tube type oil cooler is good enough to meet the development trend of miniaturization equipment and high efficiency.%对采用铝翅片扩展表面与弓形折流板支撑结构相结合的新型叠片式油冷却器和采用螺纹强化管的螺旋折流板油冷却器分别进行实验测试研究。结果表明,叠片式油冷却器具有更优良的综合性能;在中、小油流量时,其热交换量大、壳程压降较小,单位压降下的换热量要比螺旋折流板油冷却器约高50%,结构的紧凑性能够较好地满足设备小型及高效的发展趋势。

  18. Development of a flocculation sub-model for a 3-D CFD model based on rectangular settling tanks.

    Science.gov (United States)

    Gong, M; Xanthos, S; Ramalingam, K; Fillos, J; Beckmann, K; Deur, A; McCorquodale, J A

    2011-01-01

    To assess performance and evaluate alternatives to improve the efficiency of rectangular Gould II type final settling tanks (FSTs), New York City Department of Environmental Protection and City College of NY developed a 3D computer model depicting the actual structural configuration of the tanks and the current and proposed hydraulic and solids loading rates. Fluent 6.3.26™ was the base platform for the computational fluid dynamics (CFD) model, for which sub-models of the SS settling characteristics, turbulence, flocculation and rheology were incorporated. This was supplemented by field and bench scale experiments to quantify the coefficients integral to the sub-models. The 3D model developed can be used to consider different baffle arrangements, sludge withdrawal mechanisms and loading alternatives to the FSTs. Flocculation in the front half of the rectangular tank especially in the region before and after the inlet baffle is one of the vital parameters that influences the capture efficiency of SS. Flocculation could be further improved by capturing medium and small size particles by creating an additional zone with an in-tank baffle. This was one of the methods that was adopted in optimizing the performance of the tank where the CCNY 3D CFD model was used to locate the in-tank baffle position. This paper describes the development of the flocculation sub-model and the relationship of the flocculation coefficients in the known Parker equation to the initial mixed liquor suspended solids (MLSS) concentration X0. A new modified equation is proposed removing the dependency of the breakup coefficient to the initial value of X0 based on preliminary data using normal and low concentration mixed liquor suspended solids values in flocculation experiments performed.

  19. Numerical Analysis of Flow Distribution in a Sodium Chamber of a Finned-tube Sodium-to-Air Heat Exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Youngchul; Son, Seokkwon; Kim, Hyungmo; Eoh, Jaehyuk; Jeong, Jiyoung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    DHR systems consist of two diverse heat removal loops such as passive and active DHR systems, and the heat load imposed on the primary sodium pool is safely rejected into the environment through different kinds of sodium-to-air heat exchangers, e.g. M-shape and helical-coil type air-coolers. The former is called as an FHX(Forced-draft sodium-to-air Heat Exchanger) and the latter is simply called as an AHX(natural-draft sodium-to-Air Heat Exchanger). In a general sodium-to-air heat exchanger design, convection resistance in a shell-side air flow path becomes dominant factor affecting the mechanism of conjugate heat transfer from the sodium flow inside the tube to the air path across the sodium tube wall. Hence verification of the flow and heat transfer characteristics is one of the most important tasks to demonstrate decay heat removal performance. To confirm a kind of ultimate heat sink heat exchanger, a medium-scale Sodium thermal-hydraulic Experiment Loop for Finned-tube sodium-to-Air Heat exchanger (here after called the SELFA) has been designed and is recently being constructed at KAERI site. The introduction of the flow baffle inside the upper sodium chamber of the model FHX unit in the SELFA facility is briefly proposed and discussed as well. The present study aims at introducing a flow baffle design inside the upper sodium chamber to make more equalized flowrates flowing into each heat transfer tube of the model FHX unit. In the cases without the flow baffle geometry, it was observed lager discrepancies in flowrates at the heat transfer tubes. However it was also found that those kinds of discrepancies could be definitely decreased at around 1/10 by employing a flow baffle.

  20. RLE (Research Laboratory of Electronics) Progress Report Number 125.

    Science.gov (United States)

    1983-01-01

    Millikan oil - drop experiment); (3) molecular-beam deflection experiments. In 1973 King and Dylla’ pioneered a new technique based on the fact that an...temperature. The system is pumped by a baffled oil diffusion pump. Photoionization occurs by absorption of four identical photons at a wavelength...gives no observable signal, the lifetime drops to 2.8 ns indication energy transfer from Rh640 to Ox725 has taken place. The experiments will continue

  1. Research Laboratory of Electronics Annual Report Number 125.

    Science.gov (United States)

    1983-01-01

    a container; (2) tests for a charge on an isolated body (analogous to the Millikan oil - drop experiment); (3) molecular-beam deflection experiments...to liquid helium temperature. The system is pumped by a baffled oil diffusion pump. Photoionization occurs by absorption of four identical photons at a...lifetime drops to 2.8 ns indication energy transfer from Rh640 to 0x725 has taken place. The experiments will continue, subject to the constraints of Dr

  2. Environmental Assessment of the Construction of the Joint Use Small Arms Range for the 934th Airlift Wing at Minneapolis-St. paul International Airport Air Reserve Station, Minnesota

    Science.gov (United States)

    2006-10-01

    design must preclude escape of both direct-fired projectiles and ricochets. “Blue sky ” should not be visible from any firing position or as one...travels downrange towards the target. Overhead baffles prevent “blue sky ” visibility. The bullet trap at the existing small arms range has exposed... starling (Sturnus vulgaris). Other species might include the common garter snake (Thamnophis sirtalis) and the American toad (Bufo americanus) (934 AW

  3. Oscillatory flow chemical reactors

    Directory of Open Access Journals (Sweden)

    Slavnić Danijela S.

    2014-01-01

    Full Text Available Global market competition, increase in energy and other production costs, demands for high quality products and reduction of waste are forcing pharmaceutical, fine chemicals and biochemical industries, to search for radical solutions. One of the most effective ways to improve the overall production (cost reduction and better control of reactions is a transition from batch to continuous processes. However, the reactions of interests for the mentioned industry sectors are often slow, thus continuous tubular reactors would be impractically long for flow regimes which provide sufficient heat and mass transfer and narrow residence time distribution. The oscillatory flow reactors (OFR are newer type of tube reactors which can offer solution by providing continuous operation with approximately plug flow pattern, low shear stress rates and enhanced mass and heat transfer. These benefits are the result of very good mixing in OFR achieved by vortex generation. OFR consists of cylindrical tube containing equally spaced orifice baffles. Fluid oscillations are superimposed on a net (laminar flow. Eddies are generated when oscillating fluid collides with baffles and passes through orifices. Generation and propagation of vortices create uniform mixing in each reactor cavity (between baffles, providing an overall flow pattern which is close to plug flow. Oscillations can be created by direct action of a piston or a diaphragm on fluid (or alternatively on baffles. This article provides an overview of oscillatory flow reactor technology, its operating principles and basic design and scale - up characteristics. Further, the article reviews the key research findings in heat and mass transfer, shear stress, residence time distribution in OFR, presenting their advantages over the conventional reactors. Finally, relevant process intensification examples from pharmaceutical, polymer and biofuels industries are presented.

  4. Pengaruh Laju Alir Volumetrik Umpan Static In-Line Mixer Terhadap Performance Bioreaktor Pada Pembuatan Biogas Dari Limbah Cair Kelapa Sawit Skala Pilot Plant

    OpenAIRE

    Sitepu, Juliananta

    2015-01-01

    Indonesia as the second country for production CPO in the world is very potesially in biogas industry. Something make it very potensial is POME (Palm Oil Effulent).POME is the most important in biogas because it can be change to biogas. Production biogas is in thermofilik anaerob with recyle sludge 34% through in four tank. They are pretreatment tank, mixing tank, bioreactor, and gravity thickner.The mixing tank is a tank with motor (machine), impeller and any baffle. For...

  5. New approach for distinguishing the similarity of links

    Institute of Scientific and Technical Information of China (English)

    Jianyun XIANG; Maozhong GE; Zhiping WANG

    2008-01-01

    Based on the problem of distinguishing the similarity of links in the regenerative innovation design of a kinematic chain, a new approach using the standard power matrix of the adjacent matrix is presented in this paper. The implementation of the approach is illustrated with an example. This method solves the technically baffling problem in mechanism type synthesis and reduced redundant design scheme, and raises the reliability and the efficiency of the regenerative innova-tion design of the kinematic chain.

  6. Indicators for technological, environmental and economic sustainability of ozone contactors.

    Science.gov (United States)

    Zhang, Jie; Tejada-Martinez, Andres E; Lei, Hongxia; Zhang, Qiong

    2016-09-15

    Various studies have attempted to improve disinfection efficiency as a way to improve the sustainability of ozone disinfection which is a critical unit process for water treatment. Baffling factor, CT10, and log-inactivation are commonly used indicators for quantifying disinfection credits. However the applicability of these indicators and the relationship between these indicators have not been investigated in depth. This study simulated flow, tracer transport, and chemical species transport in a full-scale ozone contactor operated by the City of Tampa Water Department and six other modified designs using computational fluid dynamics (CFD). Through analysis of the simulation results, we found that baffling factor and CT10 are not optimal indicators of disinfection performance. We also found that the relationship between effluent CT obtained from CT transport simulation and baffling factor depends on the location of ozone release. In addition, we analyzed the environmental and economic impacts of ozone contactor designs and upgrades and developed a composite indicator to quantify the sustainability in technological, environmental and economic dimensions.

  7. Optimization of a Finned Shell and Tube Heat Exchanger Using a Multi-Objective Optimization Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Heidar Sadeghzadeh

    2015-08-01

    Full Text Available Heat transfer rate and cost significantly affect designs of shell and tube heat exchangers. From the viewpoint of engineering, an optimum design is obtained via maximum heat transfer rate and minimum cost. Here, an analysis of a radial, finned, shell and tube heat exchanger is carried out, considering nine design parameters: tube arrangement, tube diameter, tube pitch, tube length, number of tubes, fin height, fin thickness, baffle spacing ratio and number of fins per unit length of tube. The “Delaware modified” technique is used to determine heat transfer coefficients and the shell-side pressure drop. In this technique, the baffle cut is 20 percent and the baffle ratio limits range from 0.2 to 0.4. The optimization of the objective functions (maximum heat transfer rate and minimum total cost is performed using a non-dominated sorting genetic algorithm (NSGA-II, and compared against a one-objective algorithm, to find the best solutions. The results are depicted as a set of solutions on a Pareto front, and show that the heat transfer rate ranges from 3517 to 7075 kW. Also, the minimum and maximum objective functions are specified, allowing the designer to select the best points among these solutions based on requirements. Additionally, variations of shell-side pressure drop with total cost are depicted, and indicate that the pressure drop ranges from 3.8 to 46.7 kPa.

  8. Measures for Improving Velocity Distribution in Oxidation Ditch%改善氧化沟流速分布的措施

    Institute of Scientific and Technical Information of China (English)

    曹瑞钰; 付见中

    2001-01-01

    Velocity distribution in oxidation ditch can be improved by installing front baffle and back baffle based on researches and simulation tests,so that sludge deposit in the bottom of oxidation ditch can be eliminated.The velocity distribution diagrams of different cross-section before and after installing the baffles are presented in this paper.Moreover related suggestion on the problems appeared in design and construction of oxidation ditch is also given.%通过多年的研究和模拟试验,提出了加装前后导流板的措施以改善氧化沟的流速分布,消除目前氧化沟所存在的通病——池底积泥现象,而且很直观地给出了安装导流板前后的氧化沟各断面流速分布图。另外,还就目前氧化沟的设计和建造中出现的问题提出了相关的建议。

  9. The experimental of methane-air flame propagation in the tube with quadrate cross section

    Institute of Scientific and Technical Information of China (English)

    GUO Zi-ru; SHEN Zhao-wu; LU Shou-xiang; ZHOU Ning

    2005-01-01

    The flame propagation of methane-air mixture with various methane concentrations was experimentally investigated at venting flame acceleration tube with quadrate cross section under different obstacles presented. The flame shape and propagation speed was observed by high-speed color video camera. The explosion pressure was determined by piezoelectricity pressure transducers. The results are: The flame propagates in the shape of a hemisphere before the flame reaches the first baffle and flame propagation speed is not more than 15 m/s. When the flame propagates across the baffle, the flame begins to accelerate due to turbulence induced by obstacle.Blockage ratio has relatively greater effect on the flame propagation speed than repeated baffle number does. The flame propagation speed and the pressure at different location along the tube are maximum when methane-air mixture is near the chemical stoichoimetric ratio. The pressure increases with the distance from ignition end at first and the maximum pressure was obtained at the middle of tube, but the pressure decreases and again increases at venting end.

  10. Removal of Fecal Indicators, Pathogenic Bacteria, Adenovirus, Cryptosporidium and Giardia (oo)cysts in Waste Stabilization Ponds in Northern and Eastern Australia.

    Science.gov (United States)

    Sheludchenko, Maxim; Padovan, Anna; Katouli, Mohammad; Stratton, Helen

    2016-01-02

    Maturation ponds are used in rural and regional areas in Australia to remove the microbial loads of sewage wastewater, however, they have not been studied intensively until present. Using a combination of culture-based methods and quantitative real-time PCR, we assessed microbial removal rates in maturation ponds at four waste stabilization ponds (WSP) with (n = 1) and without (n = 3) baffles in rural and remote communities in Australia. Concentrations of total coliforms, E. coli, enterococci, Campylobacter spp., Salmonella spp., F+ RNA coliphage, adenovirus, Cryptosporidium spp. and Giardia (oo) cysts in maturation ponds were measured at the inlet and outlet. Only the baffled pond demonstrated a significant removal of most of the pathogens tested and therefore was subjected to further study by analyzing E. coli and enterococci concentrations at six points along the baffles over five sampling rounds. Using culture-based methods, we found a decrease in the number of E. coli and enterococci from the initial values of 100,000 CFU per 100 mL in the inlet samples to approximately 1000 CFU per 100 mL in the outlet samples for both bacterial groups. Giardia cysts removal was relatively higher than fecal indicators reduction possibly due to sedimentation.

  11. Strategies for Observing Self-excitation in the Madison Dynamo Experiment

    Science.gov (United States)

    Taylor, N. Z.; Kaplan, E. J.; Kendrick, R. D.; Nornberg, M. D.; Rahbarnia, K.; Rasmus, A. M.; Forest, C. B.; Spence, E. J.

    2010-11-01

    In the Madison Dynamo Experiment(MDE) two counter-rotating impellers drive a turbulent flow of liquid sodium in a one meter-diameter sphere. One of the goals of the experiment is to observe the spontaneous generation of magnetic field. Initial runs of the MDE saw intermittent bursts of a transverse dipole field similar to the induced field predicted by laminar kinematics, but no sustained self-excited field was observed. This poster will present recent results from the MDE after an equatorial baffle was installed to stabilize the position of the shear layer between the two counterrotating hemispheres and to help in the reduction of of large-scale turbulence and the motors were run up to maximum power. Required motor power indicates that the baffle has decreased the amount of turbulence in the flow. When run up to full power still no self-excited dynamo was observed, but there was significant amplification of the transverse dipole field with extended decay rates indicating we may be approaching the dynamo threshold. Future modifications to the experiment will also be presented exploring a subcritical dynamo transition by supplying a sufficiently strong magnetic field and the addition of poloidal baffles to optimize the helicity of the mean flow. This work is supported by the NSF/DOE partnership in plasma physics.

  12. Design and optimization of anode flow field of a large proton exchange membrane fuel cell for high hydrogen utilization

    Science.gov (United States)

    Yesilyurt, Serhat; Rizwandi, Omid

    2016-11-01

    We developed a CFD model of the anode flow field of a large proton exchange membrane fuel cell that operates under the ultra-low stoichiometric (ULS) flow conditions which intend to improve the disadvantages of the dead-ended operation such as severe voltage transient and carbon corrosion. Very small exit velocity must be high enough to remove accumulated nitrogen, and must be low enough to retain hydrogen in the active area. Stokes equations are used to model the flow distribution in the flow field, Maxwell-Stefan equations are used to model the transport of the species, and a voltage model is developed to model the reactions kinetics. Uniformity of the distribution of hydrogen concentration is quantified as the normalized area of the region in which the hydrogen mole fraction remains above a certain level, such as 0.9. Geometry of the anode flow field is modified to obtain optimal configuration; the number of baffles at the inlet, width of the gaps between baffles, width of the side gaps, and length of the central baffle are used as design variables. In the final design, the hydrogen-depleted region is less than 0.2% and the hydrogen utilization is above 99%. This work was supported by The Scientific and Technolo-gical Research Council of Turkey, TUBITAK-213M023.

  13. Example study for granular bioreactor stratification: Three-dimensional evaluation of a sulfate-reducing granular bioreactor

    Science.gov (United States)

    Hao, Tian-wei; Luo, Jing-hai; Su, Kui-zu; Wei, Li; Mackey, Hamish R.; Chi, Kun; Chen, Guang-Hao

    2016-01-01

    Recently, sulfate-reducing granular sludge has been developed for application in sulfate-laden water and wastewater treatment. However, little is known about biomass stratification and its effects on the bioprocesses inside the granular bioreactor. A comprehensive investigation followed by a verification trial was therefore conducted in the present work. The investigation focused on the performance of each sludge layer, the internal hydrodynamics and microbial community structures along the height of the reactor. The reactor substratum (the section below baffle 1) was identified as the main acidification zone based on microbial analysis and reactor performance. Two baffle installations increased mixing intensity but at the same time introduced dead zones. Computational fluid dynamics simulation was employed to visualize the internal hydrodynamics. The 16S rRNA gene of the organisms further revealed that more diverse communities of sulfate-reducing bacteria (SRB) and acidogens were detected in the reactor substratum than in the superstratum (the section above baffle 1). The findings of this study shed light on biomass stratification in an SRB granular bioreactor to aid in the design and optimization of such reactors. PMID:27539264

  14. Research and constructive solutions on the reduction of slosh noise

    Science.gov (United States)

    Manta (Balas, M.; Balas, R.; Doicin, C. V.

    2016-11-01

    The paper presents a product design making of, over a “delicate issue” in automotive industry as slosh noise phenomena. Even though the current market tendency shows great achievements over this occurrence, in this study, the main idea is to design concepts of slosh noise baffles adapted for serial life existing fuel tanks in the automotive industry. Moreover, starting with internal and external research, going further through reversed engineering and applying own baffle technical solutions from conceptual sketches to 3D design, the paper shows the technical solutions identified as an alternative to a new development of fuel tank. Based on personal and academic experience there were identified several problematics and the possible answers based on functional analysis, in order to avoid blocking points. The idea of developing baffles adapted to already existent fuel tanks leaded to equivalent solutions analyzed from functional point of view. Once this stage is finished, a methodology will be used so as to choose the optimum solution so as to get the functional design.

  15. Evaluation of Boundary Dam spillway using an Autonomous Sensor Fish Device

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Z. D.; Duncan, J. P.; Arnold, J. L.; Fu, T.; Martinez, J.; Lu, J.; Titzler, P. S.; Zhou, D.; Mueller, R. P.

    2017-03-01

    Fish passage conditions over spillways are important for the operations of hydroelectric dams because spillways are usually considered as a common alternative passage route to divert fish from the turbines. The objectives of this study were to determine the relative potential of fish injury during spillway passage both before and after the installation of baffle blocks at Boundary Dam, and to provide validation data for a model being used to predict total dissolved gas levels. Sensor Fish were deployed through a release system mounted on the face of the dam in the forebay. Three treatments, based on the lateral position on the spillway, were evaluated for both the baseline and post-modification evaluations: Left Middle, Right Middle, and Right. No significant acceleration events were detected in the forebay, gate, or transition regions for any release location; events were only observed on the chute and in the tailrace. Baseline acceleration events observed in the chute region were all classified as strikes, whereas post-modification events included strike and shear on the chute. While the addition of baffle blocks increased the number of significant events observed on the spillway chute, overall fewer events were observed in the tailrace post-modification. Analysis of lateral positioning of passage indicated that the Right Middle treatment was potentially less injurious to fish based on relative frequency of significant events at each location. The construction of baffle blocks on the spillway visibly changed the flow regime. Prior to installation the flow jet was relatively thin, impacting the tailrace as a coherent stream that plunged deeply, possibly contributing to total dissolved gas production. Following baffle block construction, the discharge jet was more fragmented, potentially disrupting the plunge depth and decreasing the time that bubbles would be at depth in the plunge pool. The results in this study support the expected performance of the modified

  16. Technology demonstration for reducing mercury emissions from small-scale gold refining facilities.

    Energy Technology Data Exchange (ETDEWEB)

    Habegger, L. J.; Fernandez, L. E.; Engle, M.; Bailey, J. L.; Peterson, D. P.; MacDonell, M. M.; U.S. Environmental Protection Agency

    2008-06-30

    Gold that is brought from artisanal and small-scale gold mining areas to gold shops for processing and sale typically contains 5-40% mercury. The uncontrolled removal of the residual mercury in gold shops by using high-temperature evaporation can be a significant source of mercury emissions in urban areas where the shops are located. Emissions from gold shop hoods during a burn can exceed 1,000 mg/m{sup 3}. Because the saturation concentration of mercury vapor at operating temperatures at the hood exhaust is less than 100 mg/m{sup 3}, the dominant component of the exhaust is in the form of aerosol or liquid particles. The U.S. Environmental Protection Agency (EPA), with technical support from Argonne National Laboratory (Argonne), has completed a project to design and test a technology to remove the dominant aerosol component in the emissions from gold shops. The objective was to demonstrate a technology that could be manufactured at low cost and by using locally available materials and manufacturing capabilities. Six prototypes designed by Argonne were locally manufactured, installed, and tested in gold shops in Itaituba and Creporizao, Brazil. The initial prototype design incorporated a pebble bed as the media for collecting the mercury aerosols, and a mercury collection efficiency of over 90% was demonstrated. Though achieving high efficiencies, the initial prototype was determined to have practical disadvantages such as excessive weight, a somewhat complex construction, and high costs (>US$1,000). To further simplify the construction, operation, and associated costs, a second prototype design was developed in which the pebble bed was replaced with slotted steel baffle plates. The system was designed to have flexibility for installation in various hood configurations. The second prototype with the baffle plate design was installed and tested in several different hood/exhaust systems to determine the optimal installation configuration. The significance of

  17. Final Report: DOE/ID/14215

    Energy Technology Data Exchange (ETDEWEB)

    Kenneth Bryden; J. Richard Hess; Thomas Ulrich; Robert Zemetra

    2008-08-18

    efficiently engineer high-fidelity and high throughput separation systems for biomass components. INL and Iowa State University developed a computational modeling strategy for simulating multi-phase flow with an integrated solver using various computational fluid dynamics (CFD) codes. ISU set up a classic multi-phase test problem to be solved by the various CFD codes. The benchmark case was based on experimental data for bubble gas holdup and bed expansion for a gas/solid fluidized bed. Preliminary fluidization experiments identified some unexpected fluidization behavior, where rather than the bed uniformly fluidizing, a “blow out” would occur where a hole would open up in the bed through which the air would preferentially flow, resulting in erratic fluidization. To improve understanding of this phenomena and aid in building a design tool, improved computational tools were developed. The virtual engineering techniques developed were tested and utilized to design a separation baffle in a CNH combine. A computational engineering approach involving modeling, analysis, and simulation was used in the form of virtual engineering to design a baffle separator capable of accomplishing the high-fidelity residue separation established by the performance targets. Through the use of the virtual engineering model, baffle designs were simulated to (1) determine the effect of the baffle on the airflow of the combine cleaning system, and (2) predict the effectiveness of the baffle in separating the residue streams. A baffle design was selected based on the virtual engineering modeling, built into the INL selective harvest test combine. The result of the baffle changes improved the crop separation capability of the combine, enabling downstream improvement in composition and theoretical ethanol yield. In addition, the positive results from the application of the virtual engineering tools to the CNH combine design resulted in further application of these tools to other INL areas of research

  18. The Numerical Simulation Analysis on Heat Transfer Efficiency Influence Factors of Shell and Tube Heat Exchanger%管壳式换热器传热效率影响因素及数值模拟分析∗

    Institute of Scientific and Technical Information of China (English)

    王庆锋; 庞鑫; 赵双

    2015-01-01

    多数管壳式换热器基于传统的经验设计方法,换热器质量大且能耗高。鉴于此,采用Fluent仿真模拟的方法,研究了换热管类型、折流板间距、折流板切率变化与换热器对流传热系数的关系,并用HTFS工程软件进行了模型验证。研究结果表明,采用特型管(如波节管和波纹管等)代替光管,可以增强管内流体扰动,提高湍流程度,增大管程对流传热系数,但同时也增大了压降;折流板间距越大,壳程对流传热系数越小,压降也越小,当折流板间距为330 mm时,换热器最高效,此时换热器在较小的压降下可以获得较大的对流传热系数;折流板切率越大,压降越小,当管束错流流速与折流窗口流速相等时,壳程对流传热系数最大,折流板切率35%为最优值,换热器效率最高。最后提出了管壳式换热器优化设计方法,将优化设计的换热器用于某化肥厂氮氢气压缩机级间冷却,同等热负荷条件下换热面积减小了21�37%。研究结果为换热器的结构参数优化提供了依据。%Most of shell and tube heat exchanger design based on traditional experiences have the issues of high weight and high energy consumption�The effects of heat transfer tube types, baffle spacing, and baffle plate cut rate on the heat exchanger convective heat transfer coefficient have been studied by suing fluent simulation method�The model is validated by HTFS engineering software�The results showed that the alternative special⁃shaped tube for the smooth tube, like the corrugated tube and bellows, could enhance fluid disturbances and the turbu⁃lence level, increase the tube convective heat transfer coefficient, but also increases the pressure drop�Increase the baffle plate spacing will decrease the shell side convective heat transfer coefficient and the pressure drop�The heat exchanger is the most efficient when the baffle plate

  19. 三种管壳式换热器传热与流阻性能对比实验研究%Contrast Experimental Research on Heat Transfer and Flow Resistance Performance for Three Kinds of Shell--and--tube Heat Exchangers

    Institute of Scientific and Technical Information of China (English)

    古新; 董其伍; 王珂; 刘敏珊

    2012-01-01

    There are some disadvantages in segmental baffle heat exchanger for the transversal flow over tubes in its shell side,such as the high flow resistance,large heat transfer dead region,and so on. The fluid flows longitudinally in the shell side of rod baffle heat exchanger, but the heat transfer performance is not perfect when the Reynolds number in shell side is low. For overcoming above men- tioned disadvantages, a kind of new efficient and energy saving shell--and--tube heat exchanger with sideling flow in shell side was developed, the fluid flowed longitudinally in general, and the fluid in some local regions flowed over tubes inclinedly. Contrast experiments on heat transfer and flow resist- ance performances among this new kind of heat exchanger and segmental baffle heat exchanger, rod baffle heat exchanger were carried out, it is indicated that with the same fluid flow in shell side, the heat transfer coefficient,pressure drop, and over--all performance of sideling flow heat exchanger lie in between of those of segmental baffle heat exchanger and rod baffle heat exchanger. With this new kind of heat exchanger, the new technique and products are provided for the upgrade and update of shell--and--tube heat exchanger,and the important basis are also provided by research results for the structure selection and optimization design of heat exchangers in thermal system.%弓形折流板换热器壳程流体横向冲刷换热管时存在流动阻力大和传热死区大等缺点,折流杆换热器壳程流体纵向流动,但当壳程流体雷诺数Re较小时传热性能不佳。为克服上述缺点,研究开发了一种新型高效节能的斜向流管壳式换热器,该换热器壳程流体总体呈纵向流动,局部区域流体倾斜冲刷换热管束。对斜向流换热器与折流板换热器和折流杆换热器传热与流阻性能的对比实验研究表明,在同等壳程流体流量下,斜向流管壳式换热器的传热系数、压降和综合性能均

  20. Effects of propeller layout position on flow characteristics in oxidation ditch%推流器布置对氧化沟流场特性的影响

    Institute of Scientific and Technical Information of China (English)

    陈斌; 王炳祺; 张华; 王强; 王震

    2016-01-01

    针对环形跑道式氧化沟污泥沉积现象,在池形结构不变的前提下,改变推流器的布置位置,以 STARCCM+软件为仿真平台,采用多面体网格划分方式,调用标准 k -ε湍流模型,对4台推流器同时开启状态下进行全流场模拟.分析流道各断面的速度分布、整体流场的流速分布以及流场死区率(速度低于某一值所占区域的比例),寻找适合于该池型结构的推流器最优布置方式.结果表明:推流器的安装位置对流速的分布至关重要,其与中间导流墙的间距偏大或偏小都会导致流场速度分布不均匀,死区率较高,而当其间距为环形导流墙半径与偏置距离之和的0.85倍时,整体的流速分布最为均匀,主要断面的平均流速较高,且均在0.35 m /s 以上,死区率最低;在环形导流墙背后以及中间导流墙的两端不可避免地会出现脱流区域,但可以通过改变推流器位置进行改善;在氧化沟的弯道处受推流以及壁面阻碍作用有明显的涡旋现象.%To avoid sludge deposition in a running track type oxidation ditch,the layout position of four propellers was altered when the pool structure remained unchanged.The steady fluid flow field in the whole ditch is simulated by means of STARCCM + software plus the standard k -εturbulence model when these propellers were in operation.The velocity distribution in each section in the ditch and the velocity distribution in the whole flow field as well as the dead water zone were analysed to specify the optimal propeller layout position for the pool.The results show that the propellers′position has a great influence on velocity distribution,and a too large or too small distance between a propeller and the middle baffle wall can lead to an uneven velocity distribution and an enlarged dead water zone. Especially,when the distance is about 0.85 times the sum of the circular baffle wall radius and the

  1. 新型叠片式油冷却器传热及综合性能的研究%Study on Heat Transfer and Comprehensive Performance of a New Laminated Oil Cooler

    Institute of Scientific and Technical Information of China (English)

    魏小兵; 江楠; 梁帅

    2012-01-01

    探讨一种铝叠片和弓形折流板相结合的新型叠片式油冷却器,对其传热及综合性能进行了研究,并与螺纹管弓形折流板油冷却器进行了对比.试验结果表明,新型叠片式油冷却器热交换量较螺纹管弓形折流板油冷却器平均提高52.5%,单位压降热交换量较螺纹管弓形折流板油冷却器平均提高24.1%.在整体结构方面,其单位体积换热面积为螺纹管弓形折流板油冷却器的2.84倍,而材料总重量仅为螺纹管弓形折流板油冷却器的60.7%,说明新型叠片式油冷却器具有体积小、换热面积大、重量轻的优点;从经济效益角度看,新型叠片式油冷却器相比螺纹管弓形折流板油冷却器更加节省耗材成本,体现了新型换热器的高效性、紧凑性和节能性.%The heat transfer and comprehensive performance of a new laminated oil cooler which is combined aluminum plates with segmental baffle in shell side was studied and compared with spiral tube and segmental baffle oil cooler. Experimental results indicated that the heat quantity of new laminated oil cooler improves about 52. 5% than the spiral tube and segmental baffle oil cooler,and the heat quantity unit pressure drop increases about 24.1%. At the aspect of integral structure, its heat transfer area unit volume is 2.84 times as much as the spiral tube and segmental baffle oil cooler,and the total material weight is only 60.1% of the spiral tube and segmental baffle oil cooler, which shows the advantages of small volume, large heat transfer area and light weight;From an economic point view,the new laminated oil cooler saves more material cost than the spiral tube and segmental baffle oil cooler which embodies the high - efficiency , compactness and energy conservation of new type of heat exchanger.

  2. Prediction of Liquid Slosh Damping Using a High Resolution CFD Tool

    Science.gov (United States)

    Yang, H. Q.; Purandare, Ravi; Peugeot, John; West, Jeff

    2012-01-01

    Propellant slosh is a potential source of disturbance critical to the stability of space vehicles. The slosh dynamics are typically represented by a mechanical model of a spring mass damper. This mechanical model is then included in the equation of motion of the entire vehicle for Guidance, Navigation and Control analysis. Our previous effort has demonstrated the soundness of a CFD approach in modeling the detailed fluid dynamics of tank slosh and the excellent accuracy in extracting mechanical properties (slosh natural frequency, slosh mass, and slosh mass center coordinates). For a practical partially-filled smooth wall propellant tank with a diameter of 1 meter, the damping ratio is as low as 0.0005 (or 0.05%). To accurately predict this very low damping value is a challenge for any CFD tool, as one must resolve a thin boundary layer near the wall and must minimize numerical damping. This work extends our previous effort to extract this challenging parameter from first principles: slosh damping for smooth wall and for ring baffle. First the experimental data correlated into the industry standard for smooth wall were used as the baseline validation. It is demonstrated that with proper grid resolution, CFD can indeed accurately predict low damping values from smooth walls for different tank sizes. The damping due to ring baffles at different depths from the free surface and for different sizes of tank was then simulated, and fairly good agreement with experimental correlation was observed. The study demonstrates that CFD technology can be applied to the design of future propellant tanks with complex configurations and with smooth walls or multiple baffles, where previous experimental data is not available.

  3. Hybrid Surgery Options for Complex Clinical Scenarios in Adult Patients with Congenital Heart Disease: Three Case Reports

    Science.gov (United States)

    Rapetto, Filippo; Kenny, Damien; Turner, Mark; Parry, Andrew; Stoica, Serban; Uzun, Orhan; Caputo, Massimo

    2017-01-01

    The strategy for the management of adult patients with congenital heart disease (CHD) often represents a challenge for cardiac surgeons and cardiologists due to complex anatomy, wide range of clinical presentations, and a high-risk profile. However, hybrid approach may represent an attractive solution. We report three cases of adult patients previously operated for CHD and recently treated with a hybrid approach in our institution. Case 1: a 76-year-old woman with permanent atrial fibrillation, lung disease, chronic kidney disease, microcytic anemia, and type II diabetes mellitus, previously operated for atrial septal defect closure and pulmonary valvotomy, presented with severe pulmonary regurgitation and advanced right ventricular failure. In order to minimize the surgical risk, a hybrid approach was used: an extensive right ventricular outflow tract (RVOT) plication was followed by implantation of an Edwards Sapien XT prosthesis in the RVOT through the right ventricular apex, without cardiopulmonary bypass. Case 2: a 64-year-old man with previous atrial septum excision and pericardial baffle for partial anomalous pulmonary venous drainage with intact interatrial septum, presented with worsening dyspnea, right ventricular failure, and pulmonary hypertension caused by baffle stenosis. His comorbidities included coronary artery disease, atrial flutter, and previous left pneumonectomy. After performing a redo longitudinal median sternotomy, a 20-mm stent was implanted in the baffle with access through the superior vena cava. Case 3: a 50-year-old man, with previous atrioventricular septal defect repair, followed by mitral valve replacement with a mechanical prosthesis, subsequently developed a paravalvular leak (PVL) with severe mitral regurgitation and severe left ventricular dysfunction. He underwent a transapical PVL device closure with two Amplatzer Vascular Plugs. In our opinion, hybrid surgery is a promising therapeutic modality that increases the available

  4. 汽车动力总成磁流变悬置的磁路模拟分析与试验验证%Magnetic Circuit Simulation and Experimental Verification of A Magneto-rheological (MR) Mount for Automobile Powertrain

    Institute of Scientific and Technical Information of China (English)

    袁杰; 李俊; 苏思超; 付元磊

    2012-01-01

    根据磁流变液的流变特性设计了一种新型半主动磁流变悬置结构,并简述了该悬置结构和工作原理.利用ANSYS电磁场分析模块对悬置结构内部磁场进行了有限元分析,研究了相同磁流变液悬置结构下,不同隔板材料对磁流变液悬置磁场分布的影响,并分别测试了采用不同隔板材料时磁流变液悬置的动特性.结果表明,所选择的低磁导率铝合金隔板材料可改善悬置性能:在磁流变悬置的设计过程中引入ANSYS的电磁场分析方法可行并具有一定的通用性.%According to the special properties of Magnetorheological Fluids (MRF), a new semi-active structure of magneto-rheological (MR) mount is designed, structure and operating principle of this mount is outlined in the paper. FEA is made to the internal magnetic field of the mount using ANSYS electromagnetic field analysis module, which studies the effect of different baffle plate material on distribution of magnetic field of MR mount under the same MR mount structure, dynamic characteristic of the MR mount is tested with different baffle plate material. The results show that the low permeability aluminum alloy baffle plate material can improve performance of the mount; introduction of ANSYS electromagnetic field analysis method in designing MR mount has commonality.

  5. Evaluación del mezclado mediante transporte de trazadores en reactores de flujo oscilatorio utilizando CFD

    OpenAIRE

    Cano Asís, José Antonio

    2014-01-01

    El objetivo general del Proyecto Final de Carrera es desarrollar una simulación numérica que permita estudiar el proceso de mezclado en un reactor de flujo oscilatorio (Oscillatory Baffled Reactor, OBR), sin necesidad de desarrollar un prototipo y probarlo en banco de ensayos. El estudio se centra en el problema fluido-mecánico del flujo oscilatorio, sin abordar el problema térmico. La metodología de simulación consistirá en: • Desarrollo y mallado de las geometrías a simular con Gambit. S...

  6. Low Melt Height Solidification of Superalloys

    Science.gov (United States)

    Montakhab, Mehdi; Bacak, Mert; Balikci, Ercan

    2016-06-01

    Effect of a reduced melt height in the directional solidification of a superalloy has been investigated by two methods: vertical Bridgman (VB) and vertical Bridgman with a submerged baffle (VBSB). The latter is a relatively new technique and provides a reduced melt height ahead of the solidifying interface. A low melt height leads to a larger primary dendrite arm spacing but a lower mushy length, melt-back transition length, and porosity. The VBSB technique yields up to 38 pct reduction in the porosity. This may improve a component's mechanical strength especially in a creep-fatigue type dynamic loading.

  7. Repetitively pulsed electric laser acoustic studies. Volume 1. Final technical report, Jun 80-Jun 83

    Energy Technology Data Exchange (ETDEWEB)

    Ingard, K.U.; McMillan, C.F.

    1983-09-01

    This report summarizes a study of the acoustical characteristics of a closed loop duct system for pulsed lasers with emphasis on acoustic suppression technology. Several topics are considered involving wave propagation reflection and attenuation in a shock tube, in which pulse waves are generated, simulating those in a pulsed laser system. A detailed analysis of the design of parallel-baffle attenuators for suppression of acoustic waves is given, allowing for the contributions of the reflection transmitted and reverberant contributions to the sound pressure field in the optical cavity.

  8. Quantum Einstein, Bohr and the great debate about the nature of reality

    CERN Document Server

    Kumar, Manjit

    2008-01-01

    For most people, quantum theory is a byword for mysterious, impenetrable science. And yet for many years it was equally baffling for scientists themselves. Manjit Kumar gives a dramatic and superbly-written history of this fundamental scientific revolution, and the divisive debate at its heart.  For 60 years most physicists believed that quantum theory denied the very existence of reality itself. Yet Kumar shows how the golden age of physics ignited the greatest intellectual debate of the twentieth century.  Quantum sets the science in the context of the great upheavals of the modern age. In 1

  9. Nonluminous Spray Combustion in a Jet-Mixing-Type Combustor

    OpenAIRE

    1990-01-01

    A new combustion system called a jet-mixing-type combustor was designed to obtain a nonluminous blue flame of a kerosene spray. A spray was injected by a conventional-type swirl atomizer into the combustor, and combustion air was introduced through a baffle plate with 16 inlet holes. The principle of this combustion method was revealed as a prompt mixing of the air and spray, which was achieved by high-speed air jets. The combustion characteristics such as combustion stability, temperature di...

  10. The influence of turbulence on aggregation of small particles in agitated vessels

    Science.gov (United States)

    Kusters, Karel Antonius

    The influence of the hydrodynamics in baffled turbine agitated vessels on the turbulent coagulation of small solid particles is studied, with focus on the dependence of the aggregate size on stirrer speed, concentration of solids, destabilizer concentration, and vessel size. The following studies are presented: aggregation theory; hydrodynamics in stirred tanks; numerical particle tracking in a turbine agitated vessel; aggregation kinetics in stirred tanks; and maximum aggregate size in stirred tanks. The application of the model to describe the aggregation process in strirred tanks to experimental conditions other than those tested and to particulate systems with different physical properties is discussed.

  11. Rushton桨搅拌槽中气液两相流动的全流场数值模拟%Numerical Simulation of Gas-Liquid Flow in a Stirred Tank with a Rushton Impeller

    Institute of Scientific and Technical Information of China (English)

    王卫京; 毛在砂

    2002-01-01

    The gas-liquid flow field in a stirred tank with a Rushton disk turbine, including the impeller region,was numerically simulated using the improved inner-outer iterative procedure. The characteristic features of the stirred tank, such as gas cavity and accumulation of gas at the two sides of wall baffles, can be captured by the simulation. The simulated results agree well with available experimental data. Since the improved inner-outer iterative algorithm demands no empirical formula and experimental data for the impeller region, and the approach seems generally applicable for simulating gas-liquid stirred tanks.

  12. Numerical Simulation of Gas—Liquid Flow in a Stirred Tank with a Rushton Impeller

    Institute of Scientific and Technical Information of China (English)

    WANGWeijing; MAOZaisha

    2002-01-01

    The gas-liquid flow field in a stirred tank with a Rushton disk turbine,including the impeller region,was numerically simulated using the improved inner-outer iterative procedure.The characteristic features of the strirred tank,such as gas cavity and accumulation of gas at the two sides of wall baffles,can be captured by the simulation.The simulated results agree well with available experimental data.Since the improved inner-outer iterative algorithm demands no empirical formula and experimental data for the impeller region,and the approach seems generally applicable for simulating gas-liquid stirred tanks.

  13. Samsung Galaxy S6 for dummies

    CERN Document Server

    Hughes, Bill

    2015-01-01

    Explore the capabilities of your Samsung Galaxy S 6 with this definitive guide! Learning to use a new phone can be both difficult and frustrating. With confusing documentation and baffling support, the references provided by phone manufacturers can be intimidating. Enter Samsung Galaxy S 6 For Dummies! This extensive yet practical guide walks you through the most useful features of your new Samsung Galaxy S 6-and it shows you all the best tricks to getting the most out of your device. With an accessible and fun, yet informative writing style, this is a text that you'll refer to again and agai

  14. R-C光学系统设计及杂散光分析%Optical Design and Stray Light Analysis of R-C System

    Institute of Scientific and Technical Information of China (English)

    闫佩佩; 樊学武

    2011-01-01

    将光学系统设计与杂散光分析相结合,介绍了一种焦距2000 mm、F/#=10、2ω=1.66°的空间用R-C光学系统,系统像质优良,结构紧凑.同时,针对R-C系统的特点,考虑轴外渐晕的影响,计算了主、次镜内遮光罩的尺寸,给出外遮光罩的设计方法,对该R-C望远镜系统进行了遮光罩设计,并用光学软件进行杂散光分析,计算得到方位角为0°时的PST曲线.结果表明,当离轴角度大于太阳临界入射角时,PST值小于10-8量级,满足要求.%Combining optical design and stray light analysis, a kind of R-C optical system used in space was introduced. The system had an effective focal length of 2000 mm, an F-Number of F/10, and a field of view of 2ω= 1.66°. The system had high image quality and compact system structure. Meanwhile, the size of primary baffle and secondary baffle was calculated when basing the characteristic and taking account of vignette of R-C system. The design method of outer baffle was given. The method was used to design a baffle for this R-C telescope system, and the true stray light condition was simulated with optical ray trace software. According to the simulated datum, the PST curve at azimuth 0° are drawn, and the curve shows that PST values are less than 10-8 when off-axis angles are larger than the solar critical angle which satisfies requirement.

  15. Integrated airlift bioreactor system for on-site small wastewater treatment.

    Science.gov (United States)

    Chen, S L; Li, F; Qiao, Y; Yang, H G; Ding, F X

    2005-01-01

    An integrated airlift bioreactor system was developed, which mainly consists of a multi-stage loop reactor and a gas-liquid-solid separation baffle and possesses dual functions as bioreactor and settler. This integrated system was used for on-site treatment of industrial glycol wastewater in lab-scale. The strategy of gradually increasing practical wastewater concentration while maintaining the co-substrate glucose wastewater concentration helped to accelerate the microbial acclimation process. Investigation of microbial acclimation, operation parameters evaluation and microbial observation has demonstrated the economical and technical feasibility of this integrated airlift bioreactor system for on-site small industrial wastewater treatment.

  16. Loudspeaker impedance emulator for multi resonant systems

    DEFF Research Database (Denmark)

    Iversen, Niels Elkjær; Knott, Arnold

    2015-01-01

    Specifying the performance of audio amplifiers is typically done by playing sine waves into a pure ohmic load. However real loudspeaker impedances are not purely ohmic but characterised by its electrical, mechanical and acoustical properties. Therefore a loudspeaker emulator capable of adjusting...... to emulate the loudspeaker impedance infinite baffle-, closed box- and the multi resonant vented box-loudspeaker by tuning the component values in the proposed circuit. Future work is outlined and encourage that the proposed impedance emulator is used as part of a control circuit in a switch-mode based...

  17. Soil separator and sampler and method of sampling

    Science.gov (United States)

    O'Brien, Barry H [Idaho Falls, ID; Ritter, Paul D [Idaho Falls, ID

    2010-02-16

    A soil sampler includes a fluidized bed for receiving a soil sample. The fluidized bed may be in communication with a vacuum for drawing air through the fluidized bed and suspending particulate matter of the soil sample in the air. In a method of sampling, the air may be drawn across a filter, separating the particulate matter. Optionally, a baffle or a cyclone may be included within the fluidized bed for disentrainment, or dedusting, so only the finest particulate matter, including asbestos, will be trapped on the filter. The filter may be removable, and may be tested to determine the content of asbestos and other hazardous particulate matter in the soil sample.

  18. Numerical Study on Comprehensive Performance of New Laminated Oil Cooler%新型叠片式油冷却器综合性能的数值研究

    Institute of Scientific and Technical Information of China (English)

    涂盛辉; 冯毅; 刘敏

    2015-01-01

    A three-dimensional model of new laminated oil cooler was established.And using FLUENT to analyze its heat transfer and pressure drop characteristics under different baffle spacing and gap height conditions.An experiment was carried out to demonstrate the accuracy of the simulation results.Using comprehensive factor(α/Δp) to evaluate heat transfer performance.The results showed that the shell side heat transfer coefficient and pressure drop became higher with the decreasing of baffle spacing and baffles gap height had little effect on the shell side pressure drop.Shell heat transfer coefficient increased slightly with gap height decreased.When the baffle plate spacing is 90 mm and gap height is 0.2D,laminated oil cooler had better comprehensive heat transfer performance.The results of simulation and experiment agree well,so conclusions have certain reference value.%对新型叠片式油冷却器进行整体三维建模,并使用FLUENT对其在不同折流板间距和缺口高度条件下进行换热与阻力性能数值分析,对模拟结果准确性进行试验论证,采用综合因子α/Δp对传热性能进行综合评价. 结果表明:折流板间距越小,壳程传热系数和压降越大,折流板缺口高度对壳程压降影响不大,壳程传热系数随缺口高度减小增幅较小;折流板间距为90 mm,缺口高度为0.2D时,有较好的综合传热性能. 模拟结果和试验吻合度良好,因此研究结论具有一定参考意义.

  19. 管壳式换热器流动与传热的三维数值模拟%A Three-Dimension Numerical Study on the Heat Transfer and Fluid Flow of a Shell-and-tube Heat Exchanger

    Institute of Scientific and Technical Information of China (English)

    俞接成; 诸葛一然

    2012-01-01

    应用计算流体力学软件FLUENT对一小型管壳式换热器的流动与传热问题进行了三维数值模拟.换热器壳体直径为130 mm,12根φ20 mm×1 500 mm的换热管正方形排列,折流板为30%缺口的弓形折流板,模拟了3种不同折流板间距的情况.模拟过程采用雷诺应力湍流模型,压力速度耦合选用SIMPLEC格式,压力方程的离散选用Standard格式,其他方程的离散均选用QUICK格式.数值模拟结果表明:减小折流板间距对总体传热系数的增加不太明显,但却显著增加了壳程的流动阻力.最后应用Bell法对3种不同折流板间距的数值模拟结果进行了校核,他们之间的最大误差为6.57%,表明数值模拟结果准确可靠.%A three-dimension numerical study on the heat transfer and fluid flow of a small shell-and-tube heat exchanger is performed by using the commercial CFD software package FLUENT. The shell diameter of the heat exchanger is 130 mm, which has twelve ψp20 × 1500 mm tubes arranged by square mode, and a segmental baffle with 30% cut, simulating three different baffle spacing. The Reynolds stress model for turbulent flow, SIMPLEC scheme for pressure-velocity coupling, standard scheme for pressure equation discretization and QUICK scheme for other equation discretization are selected in this numerical study. The numerical results show that the overall heat transfer coefficient increases relatively small by decreasing the baffle spacing, but the shell drag increases significantly. Finally, the numerical result of the three different baffle spacing is checked by Bell method, and their maximal deviation is 6. 57%, which confirmed the numerical result. The numerical method can be utilized further to optimize the internal structure and enhance the overall performance of the heat exchanger.

  20. 读书(英文)

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    1 The Insider's Guide to Beijig《北京指南》Editor:Adam Pillsbury Publisher:True Run Media Beijing is an overwhelming place.The language barrier,urban sprawl,gridlock and culture shock combine to make expats'first weeks in the Chinese capital a baffling experience.How is a newcomer,who can't even direct a taxi driver to his apartment,supposed to find a block of cheese,a pair of shoes or a Western hairstylist in this metropolis? The answer is in the"Insider's Guide to Beijing."

  1. Experiment on fluidelastic instability of loosely supported tube arrays in crossflow

    Energy Technology Data Exchange (ETDEWEB)

    Chen, S.S.; Zhu, S.; Cai, Y.

    1994-06-01

    A tube array supported by baffle plates in crossflow may be subjected to fluidelastic instability in the tube-support-plate-inactive mode. An experimental study is presented to characterize the tube motion. Three series of tests were performed to measure tube displacements as a function of flow velocity for different clearances. The motion was examined by root-mean-square values of tube displacements, power spectral densities, phase planes, Poincare maps, and Lyapunov exponents. The experimental data agree reasonably well with the analytical model, based on the unsteady flow theory.

  2. Experiment on fluidelastic instability of loosely supported tube arrays in crossflow

    Energy Technology Data Exchange (ETDEWEB)

    Chen, S.S.; Zhu, S.; Cai, Y.

    1993-06-01

    A tube array supported by baffle plates in crossflow may be subjected to fluidelastic instability in the tube-support-plate-inactive mode. An experimental study is presented to characterize the tube motion. Three series of tests were performed to measure tube displacements as a function of flow velocity for different clearances. The motion was examined by root-mean-square values of tube displacements, power spectral densities, phase planes, Poincare maps, and Lyapunov exponents. The experimental data agree reasonably well with the analytical model, based on the unsteady flow theory.

  3. An extension to artifact-free projection overlaps

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jianyu, E-mail: jianyulin@hotmail.com [Department of Electrical and Computer Engineering, Curtin University, GPO Box U1987, Perth, Western Australia 6845 (Australia)

    2015-05-15

    Purpose: In multipinhole single photon emission computed tomography, the overlapping of projections has been used to increase sensitivity. Avoiding artifacts in the reconstructed image associated with projection overlaps (multiplexing) is a critical issue. In our previous report, two types of artifact-free projection overlaps, i.e., projection overlaps that do not lead to artifacts in the reconstructed image, were formally defined and proved, and were validated via simulations. In this work, a new proposition is introduced to extend the previously defined type-II artifact-free projection overlaps so that a broader range of artifact-free overlaps is accommodated. One practical purpose of the new extension is to design a baffle window multipinhole system with artifact-free projection overlaps. Methods: First, the extended type-II artifact-free overlap was theoretically defined and proved. The new proposition accommodates the situation where the extended type-II artifact-free projection overlaps can be produced with incorrectly reconstructed portions in the reconstructed image. Next, to validate the theory, the extended-type-II artifact-free overlaps were employed in designing the multiplexing multipinhole spiral orbit imaging systems with a baffle window. Numerical validations were performed via simulations, where the corresponding 1-pinhole nonmultiplexing reconstruction results were used as the benchmark for artifact-free reconstructions. The mean square error (MSE) was the metric used for comparisons of noise-free reconstructed images. Noisy reconstructions were also performed as part of the validations. Results: Simulation results show that for noise-free reconstructions, the MSEs of the reconstructed images of the artifact-free multiplexing systems are very similar to those of the corresponding 1-pinhole systems. No artifacts were observed in the reconstructed images. Therefore, the testing results for artifact-free multiplexing systems designed using the

  4. 搅拌槽内液-固两相体系的数值研究(Ⅱ)临界搅拌转速的预测%Numerical Study of Solid-Liquid Two-Phase Flow in Stirred Tanks with Rushton Impeller(Ⅱ) Prediction of Critical Impeller Speed

    Institute of Scientific and Technical Information of China (English)

    王峰; 毛在砂; 沈湘黔

    2004-01-01

    The critical impeller speed, NJs, for complete suspension of solid particles in the agitated solid-liquid two-phase system in baffled stirred tanks with a standard Rushton impeller is predicted using the computational procedure proposed in Part I. Three different numerical criteria are tested for determining the critical solid suspension. The predicted NJS is compared with those obtained from several empirical correlations. It is suggested the most reasonable criterion for determining the complete suspension of solid particles is the positive sign of simulated axial velocity of solid phase at the location where the solid particles are most difficult to be suspended.

  5. Influence of different factors on momentum transfer in mechanically agitated multiphase systems

    Directory of Open Access Journals (Sweden)

    Cudak Magdalena

    2016-03-01

    Full Text Available A comparative analysis concerning the influence of different factors on momentum transfer in mechanically agitated systems was carried out on the basis of experimental results for solid-liquid, gas-liquid and gas-solid-liquid systems. The effects of the impeller - baffles system geometry, scale of the agitated vessel, type and number of impellers and their off-bottom clearance, as well as physical properties of the multiphase systems on the critical impeller speeds needed to produce suspension or dispersion, power consumption and gas hold-up were analysed and evaluated.

  6. A new practical guide to the Luria-Delbrück protocol.

    Science.gov (United States)

    Zheng, Qi

    2015-11-01

    Since 2000 several review papers have been published about the analysis of experimental data obtained using the Luria-Delbrück protocol. These timely papers cleared much of the confusion surrounding various methods for estimating or comparing mutation rates. As a result, today the fluctuation test is more widely applied with much improved accuracy. The present paper provides guidelines on a few remaining problems that continue to baffle mutation researchers. Among the issues addressed are incomplete plating, relative fitness, and comparison of experiments where average final cell population sizes differ. It also offers a fresh view on the estimation methods that are based on the sample median.

  7. Time a traveler's guide

    CERN Document Server

    Pickover, Clifford A

    1998-01-01

    ""Bucky Fuller thought big,"" Wired magazine recently noted, ""Arthur C. Clarke thinks big, but Cliff Pickover outdoes them both."" In his newest book, Cliff Pickover outdoes even himself, probing a mystery that has baffled mystics, philosophers, and scientists throughout history--What is the nature of time? In Time: A Traveler's Guide, Pickover takes readers to the forefront of science as he illuminates the most mysterious phenomenon in the universe--time itself. Is time travel possible? Is time real? Does it flow in one direction only? Does it have a beginning and an end? What is eternity? P

  8. 折流板式微生物燃料电池处理含铜废水及其产电性能%BaffIed-microbiaI fueI ceII for treating copper containing wastewater and eIectricity producing capacity

    Institute of Scientific and Technical Information of China (English)

    陈月美; 刘维平

    2016-01-01

    实验构建折流板式微生物燃料电池,以模拟有机废水为阳极底物,以活性污泥中的混合菌为阳极接种微生物,以模拟含铜废水为阴极液,探讨折流板式MFC对产电性能及废水处理的影响规律。结果表明:当阴极液CuSO4为5000 mg/L时,折流板式MFC的产电性能最优,开路电压最高为666 mV,功率密度最大为88.0 mW/m2,电流密度最大为491.7 mA/m2。折流板式MFC能有效处理有机废水和含铜废水,对有机废水COD的去除率最高可达74.9%;对Cu2+的去除率最高可达到95.8%。折流板式MFC可回收铜,阴极板上的沉积物经XRD检测,为Cu2O和单质铜的混合物。%In the experiments,the baffled-microbial fuel cell has been constructed by using simulated organic waste-water as anodic substrate,the mixed bacteria in activated sludge as anodic inoculation microbial,and simulated co-pper-containing wastewater as catholyte. The results show that when catholyte CuSO4 is 5 000 mg/L,the electricity producing capacity of baffled-microbial fuel cell (MFC)is the best,the highest open circuit voltage is 666 mV,the maximum power density 88.0 mW/m2,and the maximum electric current density 491.7 mA/m2. The baffled-MFC can effectively treat organic wastewater and copper-containing wastewater. The maximum removing rate of organic wastewater COD can reach 74.9%,and the maximum removing rate of Cu2+can reach 95.8%. The baffle-MFC can recover copper. The XRD detected sediment on negative plate is a mixture of Cu2O and elemental copper.

  9. Hacker's guide to Microsoft Excel (how to use Excel, shortcuts, modeling, macros, and more)

    CERN Document Server

    Hudson, Kimberly

    2012-01-01

    ABOUT THE BOOK Microsoft Excel is a user-friendly spreadsheet program that lets you organize data, create charts, program time-saving shortcuts, and make reports. It is part of the Microsoft Office Suite. There are multiple versions of Microsoft Excel out there, the latest being part of the Microsoft Office 2010 Suite. Although you may be baffled by Excel now, don't give up! Once you read what Excel can do, you will quickly use simple functions to answer questions, create charts, and increase productivity. MEET THE AUTHOR Kimberly Hudson is a professional writer who lives and works in Ma

  10. Selected papers on optomechanical design

    Science.gov (United States)

    O'Shea, Donald C.

    The papers included in this volume deal with a variety of topics in optical and optoelectronic science, engineering, and technology under the following headings: design, materials, tolerancing and specification, mounting, mechanical analysis, thermal analysis, stabilization, baffling, assembly and alignment, and scanning. Particular topics discussed include selection of materials and processes for metal optics, trends and limits in the production of optical elements and optical systems, aerospace mounts for down-to-earth optics, and thermal effects in optical systems. Papers are also presented on integrating Nd:YAG lasers into optical systems, line-of-sight steering and stabilization, and motors and control systems for rotating mirror deflectors.

  11. The Bitter-Sweetness of Reading

    Institute of Scientific and Technical Information of China (English)

    史志康

    2006-01-01

    @@ Reading and studying regularly calls for a painstaking effort, whether it is meant for passing an exam, writing a thesis or pursuing an academic degree.② T'ao Yuanming, a famous scholar in Jin Dynasty, who doted on reading ③, might probably feel baffled if he were living today and had to take exams for getting into universities or graduate programs or to score well in such tests as the TOEFL. I'm afraid he might fail the exam in Political Economics, as the result of his motto "staying content with superficial reading".④

  12. Column flotation in coal: does it make `cents?`

    Energy Technology Data Exchange (ETDEWEB)

    Laurila, M.J.

    1997-01-01

    Column flotation technology was introduced into the coal industry in 1986. The column can produce higher grade concentrates than conventional cells. This has created a niche market for columns in recovering ultrafine (-100 mesh) coal from waste streams. However, column flotation is much more expensive than froth flotation and columns can only process a maximum of 20 tons per hour per unit and consume more reagents than conventional cells. Researchers at Michigan Technological University have found that baffles along the axis of a column vastly improved performance. Today only two companies in the US participate in the column flotation market, ICF Kaiser and Deister.

  13. Exposure conditions of reactor internals of Rovno VVER-440 NPP units 1 and 2

    Energy Technology Data Exchange (ETDEWEB)

    Grytsenko, O.V.; Pugach, S.M.; Diemokhin, V.L.; Bukanov, V.N. [Inst. for Nuclear Research, Kyiv, 03680 (Ukraine); Marek, M.; Vandlik, S. [Nuclear Research Inst. Rez Plc., Rez, 25068 (Czech Republic)

    2011-07-01

    Results of determination of irradiation conditions for vessel internals of VVER-440 reactor No. 1 and 2 at Rovno Nuclear Power Plant, obtained by specialists at Inst. for Nuclear Research Kyiv (Ukraine)), and Nuclear Research Inst. Rez (Czech Republic)), are presented. To calculate neutron transport, detailed calculation models of these reactors were prepared. Distribution of neutron flux functionals on the surface of reactor VVER-440 baffle and core barrel for different core loads was studied. Agreement between results obtained by specialists at Inst. for Nuclear Research and at Nuclear Research Inst. is shown. (authors)

  14. DAWN OF A NEW COUNTRYSIDE The government is emphasizing modernization, innovation and mechanization to revitalize the farm sector in the current Five-Year Plan

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The "farm question" has long baffled China's planners. Since 1979, when China began the reform and opening up process, the economy has developed rapidly, especially the secondary and tertiary sectors. By 2005, China's GDP was 18.2321 trillion yuan, nearly 30 times that in 1979. However, the primary sector has largely been left out of this growth with its proportion in GDP dropping from 25.6 percent in 1979 to 12.4 percent in 2005. Rural areas remain poor and living standards low. Past efforts to change t...

  15. The Application of Compulational Fluid Dynamics to Design of Vehicle Cooling Wind Tunnel

    Institute of Scientific and Technical Information of China (English)

    BI Xiao-ping; HUANG Xiao-hui

    2009-01-01

    A computational fluid dynamics (CFD) calculation model for the airflow and heat transfer in an armored vehicle cooling wind tunnel is established. A practical method to determine computation region outside power train compartment, produce grid and ensure grid quality is put forward. A commercial software FLUENT can be used to obtain solutions numerically in 3-D space. Precision of CFD calculation results is verified. The CFD model is used in designing a vehicle cooling wind tunnel, and air flow resistance of fan blast baffle is calculated. The calculated results show feasibility of the CFD model and the method.

  16. Fundamental Particle Combustion Kinetics Measurement in the Shock Tube in Support of Enhanced Blast Weapons Development

    Science.gov (United States)

    2012-07-01

    project focused. Frequent interactions with Dr. Bill Wilson, Dr. Fan Zhang, Dr. Kibong Kim and Dr. Ed Dreizin were essential developing the experiments...test, the baffles and the liner were removed, as applicable. The liner was misted with distilled water and wiped clean with a squeegee. This process...l i g h t . 1 2 2 .. • • • .. • • • • .. • • • • 1.2 3.2 5.2 7.2 9.2 11.2 13.2 Distancefrom Detonator fan ) ABC DE F G Beam Column

  17. NUMERICAL SIMULATION BY COMPUTATIONAL FLUID DYNAMICS AND EXPERIMENTAL STUDY ON STIRRED BIOREACTOR WITH PUNCHED IMPELLER

    Institute of Scientific and Technical Information of China (English)

    WANG Yu; HE Pingting; YE Hong; XIN Zhihong

    2007-01-01

    Instantaneous flow field and temperature field of the two-phase fluid are measured by particle image velocimetry (PIV) and steady state method during the state of onflow. A turbulent two-phase fluid model of stirred bioreactor with punched impeller is established by the computational fluid dynamics (CFD), using a rotating coordinate system and sliding mesh to describe the relative motion between impeller and baffles. The simulation and experiment results of flow and temperature field prove their warps are less than 10% and the mathematic model can well simulate the fields, which will also provide the study on optimized-design and scale-up of bioreactors with reference value.

  18. Ion source based on the cathodic arc

    Science.gov (United States)

    Sanders, David M.; Falabella, Steven

    1994-01-01

    A cylindrically symmetric arc source to produce a ring of ions which leave the surface of the arc target radially and are reflected by electrostatic fields present in the source to a point of use, such as a part to be coated. An array of electrically isolated rings positioned in the source serves the dual purpose of minimizing bouncing of macroparticles and providing electrical insulation to maximize the electric field gradients within the source. The source also includes a series of baffles which function as a filtering or trapping mechanism for any macroparticles.

  19. A brief review of JPL's electric propulsion technology activities

    Science.gov (United States)

    Barnett, John W.; Chopra, Ann; Deininger, William D.; Garner, Charles E.; Pivirotto, Thomas J.; Sercel, Joel C.

    1989-01-01

    Near-term objectives and recent technological progress of JPL's electric propulsion program are discussed. Particular attention is given to accomplishments for ion, magnetoplasmadynamic (MPD), electron-cyclotron resonance (ECR), and arcjet thrusters. Xenon ion thruster erosion tests indicate a 15-fold reduction in tantalum baffle erosion when nitrogen is added to the xenon propellant and steady-state cylindrical MPD thruster tests at powers up to 72 kW show distinct self-constricted and diffuse discharge modes. An ECR thruster was operated at up to 7 kW with plasma acceleration at energies up to 7 kW; there was plasma acceleration at energies approaching 100 electron volts.

  20. An imaginary tale the story of [the square root of] -1

    CERN Document Server

    Nahin, Paul J

    2006-01-01

    Today complex numbers have such widespread practical use--from electrical engineering to aeronautics--that few people would expect the story behind their derivation to be filled with adventure and enigma. In An Imaginary Tale, Paul Nahin tells the 2000-year-old history of one of mathematics' most elusive numbers, the square root of minus one, also known as i. He recreates the baffling mathematical problems that conjured it up, and the colorful characters who tried to solve them.In 1878, when two brothers stole a mathematical papyrus from the ancient Egyptian burial site in the Valley of Kings

  1. 金属光造形複合加工金型を用いた射出成形サイクルタイムの短縮

    OpenAIRE

    米山, 猛; 香川, 博之; 末廣, 栄覚; 阿部, 諭; 宮丸, 充

    2007-01-01

    By composing a cooling channel just near the mold surface using the milling-combined laser metal sintering method, cooling during injection is promoted and the cooling time is reduced. In order to evaluate this effect, a cone with ribs inside the upper part is picked up. A spiral-cooling channel is fabricated along the side surface of the mold core and also between the ribs in the upper part. To compare with this, a steel mold with machined baffle channels was made. The diameter of the upper ...

  2. Design of a cyclic multiverse

    Energy Technology Data Exchange (ETDEWEB)

    Piao Yunsong, E-mail: yspiao@gucas.ac.c [College of Physical Sciences, Graduate School of Chinese Academy of Sciences, Beijing 100049 (China)

    2010-08-09

    Recently, it has been noticed that the amplification of the amplitude of curvature perturbation cycle by cycle can lead to a cyclic multiverse scenario, in which the number of universes increases cycle by cycle. However, this amplification will also inevitably induce either the ultimate end of corresponding cycle, or the resulting spectrum of perturbations inside corresponding universe is not scale invariant, which baffles the existence of observable universes. In this Letter, we propose a design of a cyclic multiverse, in which the observable universe can emerges naturally. The significance of a long period of dark energy before the turnaround of each cycle for this implementing is shown.

  3. PIV Experimental Investigation on the Flow in a Model of Closed Pump Sump

    Institute of Scientific and Technical Information of China (English)

    MANSA Kante; ZHANG Botao(张波涛); LI Xiaoming(李小明); LI Yong(李永); WU Yulin(吴玉林)

    2003-01-01

    Vortices in the flow of a pump sump present an important problem in pump station operation. In the present study, the flow patterns in two model pump sumps with specially designed structures are analyzed using the particle image velocimetry (PIV) technique. The data is analyzed to reveal a number of parameters including the internal flow field with velocity distribution, the streamline distribution, and the turbulent kinetic energy. The analysis certifies that a modified pump with added T-type baffle below the sump exhibits good performance for realistic working conditions.

  4. Application of divertor cryopumping to H-mode density control in DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Mahdavi, M.A.; Ferron, J.R.; Hyatt, A.W. [and others

    1993-11-01

    In this paper we describe the method and the results of experiments where a unique in-vessel cryopump-baffle system was used to control density of H-mode plasmas. We were able to independently regulate current and density of ELMing H-mode plasmas, each over a range of factor two, and measure the H-mode confinement scaling with plasma density and current. With a modest pumping speed of {approx}40 kl/s, particle exhaust rates as high as 2 {times} 10{sup 22} atom/s{sup {minus}1} have been observed.

  5. LARGE EDDY SIMULATIONS OF THE TURBULENT FLOW IN A STIRRED TANK

    DEFF Research Database (Denmark)

    Fan, Jianhua; Wang, Yundong; Fei, Weiyang

    2005-01-01

    Computational fluid dynamics (CFD) simulations of the fluid flow in a baffled, stirred tank with a single Rushton turbine are performed. The simulations are carried out on the “Shengcao-21C” supercomputer via commercial CFD software CFX5, using k-ε and large eddy simulation (LES) turbulence model...... respectively. Results show that CFD simulations using k-ε and LES model agree well with DPIV measurements. From the LES simulation, the velocity fluctuation is shown to occur with the development of vortices and eddies. This shows that LES simulation is better than k-ε simulation, although it demands a lot...

  6. LARGE EDDY SIMULATIONS OF THE TURBULENT FLOW IN A STIRRED TANK

    DEFF Research Database (Denmark)

    Fan, Jianhua; Wang, Yundong; Fei, Weiyang

    Computational fluid dynamics (CFD) simulations of the fluid flow in a baffled, stirred tank with a single Rushton turbine are performed. The simulations are carried out on the “Shengcao-21C” supercomputer via commercial CFD software CFX5, using k-ε and large eddy simulation (LES) turbulence model...... respectively. Results show that CFD simulations using k-ε and LES model agree well with DPIV measurements. From the LES simulation, the velocity fluctuation is shown to occur with the development of vortices and eddies. This shows that LES simulation is better than k-ε simulation, although it demands a lot...

  7. Chemical vapor deposition reactor. [providing uniform film thickness

    Science.gov (United States)

    Chern, S. S.; Maserjian, J. (Inventor)

    1977-01-01

    An improved chemical vapor deposition reactor is characterized by a vapor deposition chamber configured to substantially eliminate non-uniformities in films deposited on substrates by control of gas flow and removing gas phase reaction materials from the chamber. Uniformity in the thickness of films is produced by having reactive gases injected through multiple jets which are placed at uniformally distributed locations. Gas phase reaction materials are removed through an exhaust chimney which is positioned above the centrally located, heated pad or platform on which substrates are placed. A baffle is situated above the heated platform below the mouth of the chimney to prevent downdraft dispersion and scattering of gas phase reactant materials.

  8. The placebo effect in psychiatry: problem or solution?

    Science.gov (United States)

    Huculak, Susan

    2014-06-01

    This opinion piece aims to situate the placebo effect within the field of psychiatric treatment. To accomplish this, the placebo is explored at the centre of an often heated debate between three discrete perspectives: the clinical trial researcher, the placebo researcher and the clinician. Each occupational perspective has its own vested interests and practical concerns that drive how the placebo concepts are negotiated and applied. It is argued that because the trial and placebo researchers typically represent opposing viewpoints, clinicians are generally uncomfortable or even baffled by placebo concepts, and this three-way tension has crucial implications for the field's progress.

  9. A numerical study of a vertical solar air collector with obstacle

    Science.gov (United States)

    Moumeni, A.; Bouchekima, B.; Lati, M.

    2016-07-01

    Because of the lack of heat exchange obtained by a solar air between the fluid and the absorber, the introduction of obstacles arranged in rows overlapping in the ducts of these systems improves heat transfer. In this work, a numerical study using the finite volume methods is made to model the dynamic and thermal behavior of air flow in a vertical solar collector with baffles destined for integration in building. We search essentially to compare between three air collectors models with different inclined obstacles angle. The first kind with 90° shows a good performance energetic and turbulent.

  10. The brave new world revealed: wrestling with reality, rationing, and rationality.

    Science.gov (United States)

    Manthous, Constantine A; White, Douglas B; Carson, Shannon S

    2012-08-01

    When Dr. Joseph Lynch, editor of Seminars in Respiratory and Critical Care Medicine, invited us to organize and edit this topic we-and our contributors-were initially baffled about how we could marry outcomes, ethics, and economics. His perspective as an elder-statesman, who has observed the evolution of critical care medicine over 4 decades, provided perspective as to how these three areas are intimately related and that their synthesis is essential if the US medical system is to best serve our populace as resources become increasingly limited.

  11. CPI,Cost of Living and Politics

    Institute of Scientific and Technical Information of China (English)

    赵忠德

    2000-01-01

    All economic decisions are made basedupon statistics,which are supposed to comefrom facts in real life.However,people aresometimes baffled by the conclusions drawnfrom different statistics,which present differ-ent pictures of our lives and society.Consumer Price Index(CPI),one of theprice indexes that government normally usesto judge the cost of living,measures the pricesof a fixed market basket of some 300 con-sumer goods and services purchased by a“typ-ical”urban consumer(McConnell & Brue,p.

  12. Hydraulic characteristics of converse curvature section and aerator in high-head and large discharge spillway tunnel

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The hydraulic characteristics and cavitation erosion near the converse curvature section in the high-head and large discharge spillway tunnel have been important issues of concern to the hydropower project.In this paper,the evolutions of hydraulic elements such as pressure,flow velocity,wall shear stress,etc.in the converse curvature section are analyzed and the impacts of bottom aerator on hydraulic characteristics are discussed,with the commercial software FLUENT6.3 as a platform and combining the k-model and VOF method.The flow pattern in the converse curvature section of spillway tunnel is given by the three-dimensional numerical simulation.It indicates that the pressure changes rapidly with great pressure gradient from the beginning to the end of the curve.It also shows that the shear stress on side wall just downstream the end of the converse curvature curve is still increasing;the aeration cavity formed downstream the bottom aerator may cause the side wall pressure decreased to worsen the cavitation characteristics near the side wall.By means of the physical model experiment,the three-dimensional aerator composed of side wall baffling aerator and bottom aerator is studied,the baffling aerator suitable for the water flow conditions with water depth of 6.0 to 8.0 m and flow velocity of 35 to 50 m/s is proposed.

  13. Statistics of fluctuation induced transport in the scrape-off layer of Alcator C-Mod

    Science.gov (United States)

    Kube, Ralph; Garcia, Odd Erik; Theodorsen, Audun; Labombard, Brian; Terry, James

    2016-10-01

    The fluctuation induced transport in the scrape-off layer of Alcator C-Mod is investigated in an ohmically heated lower single-null discharge using Mirror Langmuir Probes. The probes are connected to a horizontal scanning probe which dwells at the outboard mid plane limiter radius and to electrodes in the outer divertor baffle. At the limiter radius the electron density, electron temperature and plasma potential are correlated with linear correlation coefficients r of approximately r=0.8. The bursts show a steep rise and a decay on a time scales of approximately 5 and 10 microseconds respectively. Amplitudes of bursts in the density, temperature, and plasma potential time series are correlated with r approximately 0.7-0.8. Conditionally averaged bursts in the radial particle and heat flux time series are less coherent and less reproducible, their amplitudes are correlated to the amplitude of bursts in the density time series with r=0.4. Statistics of the fluctuating plasma parameters at the outer divertor baffle are qualitatively similar to those at outboard midplane. Histograms, as well as statistics for level crossings and excess times spent above a given threshold for the time series compare favorably to a stochastic model for time series of scrape-off layer plasmas.

  14. Use of MCNP for characterization of reactor vessel internals waste from decommissioned nuclear reactors

    Energy Technology Data Exchange (ETDEWEB)

    Love, E.F.; Pauley, K.A.; Reid, B.D.

    1995-09-01

    This study describes the use of the Monte Carlo Neutron-Photon (MCNP) code for determining activation levels of irradiated reactor vessel internals hardware. The purpose of the analysis is to produce data for the Department of Energy`s Greater-Than-Class C Low-Level Radioactive Waste Program. An MCNP model was developed to analyze the Yankee Rowe reactor facility. The model incorporates reactor geometry, material compositions, and operating history data acquired from Yankee Atomic Electric Company. In addition to the base activation analysis, parametric studies were performed to determine the sensitivity of activation to specific parameters. A component sampling plan was also developed to validate the model results, although the plan was not implemented. The calculations for the Yankee Rowe reactor predict that only the core baffle and the core support plates will be activated to levels above the Class C limits. The parametric calculations show, however, that the large uncertainties in the material compositions could cause errors in the estimates that could also increase the estimated activation level of the core barrel to above the Class C limits. Extrapolation of the results to other reactor facilities indicates that in addition to the baffle and support plates, core barrels may also be activated to above Class C limits; however the classification will depend on the specific operating conditions of the reactor and the specific material compositions of the metal, as well as the use of allowable concentration averaging practices in packaging and classifying the waste.

  15. The method to control the submarine horseshoe vortex by breaking the vortex core

    Institute of Scientific and Technical Information of China (English)

    LIU Zhi-hua; XIONG Ying; TU Cheng-xu

    2014-01-01

    The quality of the inflow across the propeller is closely related with the hydrodynamic performance and the noise characteristics of the propeller. For a submarine, with a horseshoe vortex generated at the junction of the main body and the appendages, the submarine wake is dominated by a kind of highly non-uniform flow field, which has an adverse effect on the performance of the submarine propeller. In order to control the horseshoe vortex and improve the quality of the submarine wake, the flow field around a submarine model is simulated by the detached eddies simulation (DES) method, and the vortex configuration is displayed using the second invariant of the velocity derivative tensor. The state and the transition process of the horseshoe vortex are analyzed, then a modified method to break the vortex core by a vortex baffle is proposed. The flow numerical simulation is carried out to study the effect of this method. Numerical simulations show that, with the breakdown of the vortex core, many unstable vortices are shed and the energy of the horseshoe vortex is dissipated quickly, and the uniformity of the submarine wake is improved. The submarine wake test in a wind tunnel has verified the effect of the method to control the horseshoe vortex. The vortex baffle can improve the wake uniformity in cases of high Reynolds numbers as well, and it does not have adverse effects on the maneuverability and the speed ability of the submarine.

  16. Design of a dynamic sensor inspired by bat ears

    Science.gov (United States)

    Müller, Rolf; Pannala, Mittu; Reddy, O. Praveen K.; Meymand, Sajjad Z.

    2012-09-01

    In bats, the outer ear shapes act as beamforming baffles that create a spatial sensitivity pattern for the reception of the biosonar signals. Whereas technical receivers for wave-based signals usually have rigid geometries, the outer ears of some bat species, such as horseshoe bats, can undergo non-rigid deformations as a result of muscular actuation. It is hypothesized that these deformations provide the animals with a mechanism to adapt their spatial hearing sensitivity on short, sub-second time scales. This biological approach could be of interest to engineering as an inspiration for the design of beamforming devices that combine flexibility with parsimonious implementation. To explore this possibility, a biomimetic dynamic baffle was designed based on a simple shape overall geometry based on an average bat ear. This shape was augmented with three different biomimetic local shape features, a ridge on its exposed surface as well as a flap and an incision along its rim. Dynamic non-rigid deformations of the shape were accomplished through a simple actuation mechanism based on linear actuation inserted at a single point. Despite its simplicity, the prototype device was able to reproduce the dynamic functional characteristics that have been predicted for its biological paragon in a qualitative fashion.

  17. Development of Design Software for Shell and Tube Heat Exchanger%管壳式换热器设计软件的开发

    Institute of Scientific and Technical Information of China (English)

    孙琪; 李贝贝

    2012-01-01

    In order to improve efficiency of the shell and tube heat exchanger design, using VB programming language as a platform, based on heat transfer performance index of the shell-side of heat exchanger, the calculation software of the shell and tube heat exchanger is designed. Users can use the software not only to design a series of national standard of segmental baffle heat exchanger structure which meet the requirements of heat exch-anger and provided certain safety factor of pressure drop conditions; but also can design anew type of helical baffles heat exchanger. Software have high accuracy, can be used for engineering design and similar software development reference.%为提高管壳式换热器设计效率,以VB程序语言为平台,基于换热器壳侧传热性能指标,设计开发了管壳式换热器计算软件.用户通过使用软件既可设计出满足给定换热量要求、规定压降条件的一系列国家标准弓行板式换热器结构;又可设计新型螺旋折流板换热器.软件计算准确性较高,可供工程设计及类似软件开发借鉴.

  18. Simulated annealing technique to design minimum cost exchanger

    Directory of Open Access Journals (Sweden)

    Khalfe Nadeem M.

    2011-01-01

    Full Text Available Owing to the wide utilization of heat exchangers in industrial processes, their cost minimization is an important target for both designers and users. Traditional design approaches are based on iterative procedures which gradually change the design and geometric parameters to satisfy a given heat duty and constraints. Although well proven, this kind of approach is time consuming and may not lead to cost effective design as no cost criteria are explicitly accounted for. The present study explores the use of nontraditional optimization technique: called simulated annealing (SA, for design optimization of shell and tube heat exchangers from economic point of view. The optimization procedure involves the selection of the major geometric parameters such as tube diameters, tube length, baffle spacing, number of tube passes, tube layout, type of head, baffle cut etc and minimization of total annual cost is considered as design target. The presented simulated annealing technique is simple in concept, few in parameters and easy for implementations. Furthermore, the SA algorithm explores the good quality solutions quickly, giving the designer more degrees of freedom in the final choice with respect to traditional methods. The methodology takes into account the geometric and operational constraints typically recommended by design codes. Three different case studies are presented to demonstrate the effectiveness and accuracy of proposed algorithm. The SA approach is able to reduce the total cost of heat exchanger as compare to cost obtained by previously reported GA approach.

  19. [Impacts of the hydraulic characteristics of pilot clearwell on chlorine disinfection efficiency].

    Science.gov (United States)

    Liu, Qing; Liu, Wen-Jun; Gao, Jing-Wei; Zhang, Su-Xia

    2009-09-15

    A pilot clearwell was used to simulate the chlorine disinfection process with the Bacillus subtilis spores as the target microbe. The effluent of the activated carbon filter tank was radiated by low pressure UV lamp and then used as the influent the pilot clearwell. The impacts of hydraulic characteristics of pilot clearwell on disinfection efficiency of Bacillus subtilis spores was studied under different hydraulic characteristics which was changed by the number of the baffles. Under the conditions of this experiment, the inactivation coefficients of Bacillus subtilis spores with NaC10 as disinfectant which were calculated by Ct10 value were almost same under different hydraulic characteristics, but the inactivation coefficients which were calculated by CT value were very different under different hydraulic characteristics. This verified that it was more reasonable to evaluate the disinfection efficiency by Ct10 value than CT value. When Ct10 value was in the range of 100 - 300 mg x min/L, the inactivation coefficient of Bacillus subtilis spores with NaClO as disinfectant was 0.001 6 L(mg x min), which highly coincided with others' results. When CT value was in the range of 100 - 700 mg x min/L, under the same CT value, the disinfection efficiency of target microbe would be notably enhanced by increasing the number of baffles which would improve the hydraulic characteristics. So the results verified that the disinfection efficiency could be enhanced by improving the hydraulic characteristics of the clearwell.

  20. A three-channel miniaturized optical system for multi-resolution imaging

    Science.gov (United States)

    Belay, Gebirie Y.; Ottevaere, Heidi; Meuret, Youri; Thienpont, Hugo

    2013-09-01

    Inspired by the natural compound eyes of insects, multichannel imaging systems embrace many channels that scramble their entire Field-Of-View (FOV). Our aim in this work was to attain multi-resolution capability into a multi-channel imaging system by manipulating the available channels to possess different imaging properties (focal length, angular resolution). We have designed a three-channel imaging system where the first and third channels have highest and lowest angular resolution of 0.0096° and 0.078° and narrowest and widest FOVs of 7° and 80°, respectively. The design of the channels has been done for a single wavelength of 587.6 nm using CODE V. The three channels each consist of 4 aspherical lens surfaces and an absorbing baffle that avoids crosstalk among the neighbouring channels. The aspherical lens surfaces have been fabricated in PMMA by ultra-precision diamond tooling and the baffles by metal additive manufacturing. The profiles of the fabricated lens surfaces have been measured with an accurate multi-sensor coordinate measuring machine and compared with the corresponding profiles of the designed lens surfaces. The fabricated lens profiles are then incorporated into CODE V to realistically model the three channels and also compare their performances with those of the nominal design. We can conclude that the performances of the two latter models are in a good agreement.

  1. Cross-fault pressure depletion, Zechstein carbonate reservoir, Weser-Ems area, Northern German Gas Basin

    Energy Technology Data Exchange (ETDEWEB)

    Corona, F.V.; Brauckmann, F.; Beckmann, H.; Gobi, A.; Grassmann, S.; Neble, J.; Roettgen, K. [ExxonMobil Production Deutschland GmbH (EMPG), Hannover (Germany)

    2013-08-01

    A cross-fault pressure depletion study in Upper Permian Zechstein Ca2 carbonate reservoir was undertaken in the Weser-Ems area of the Northern German Gas Basin. The primary objectives are to develop a practical workflow to define cross-fault pressures scenarios for Zechstein Ca2 reservoir drillwells, to determine the key factors of cross-fault pressure behavior in this platform carbonate reservoir, and to translate the observed cross-fault pressure depletion to fault transmissibility for reservoir simulation models. Analysis of Zechstein Ca2 cross-fault pressures indicates that most Zechstein-cutting faults appear to act as fluid-flow baffles with some local occurrences of fault seal. Moreover, there appears to be distinct cross-fault baffling or pressure depletion trends that may be related to the extent of the separating fault or fault system, degree of reservoir flow-path tortuosity, and quality of reservoir juxtaposition. Based on the above observations, a three-part workflow was developed consisting of (1) careful interpretation and mapping of faults and fault networks, (2) analysis of reservoir juxtaposition and reservoir juxtaposition quality, and (3) application of the observed cross-fault pressure depletion trends. This approach is field-analog based, is practical, and is being used currently to provide reliable and supportable pressure prediction scenarios for subsequent Zechstein fault-bounded drill-well opportunities.

  2. Hydrodynamic behavior of shaking flasks used for producing a recombinant protein by filamentous bacteria

    Science.gov (United States)

    Cordova Aguilar, Maria Soledad; Garcia, Monica; Trujillo-Roldan, Mauricio Alberto; Ascanio, Gabriel; Zenit, Roberto; Soto, Enrique

    2012-11-01

    Shake flasks are widely used for culture research. The agitation rate is one of the factors that determines the mass transfer. However, it has not been studied in detail. In this work, a comparison of the hydrodynamic performance for conventional, baffled and coiled spring Erlenmeyer flasks is presented. The velocity fields for a horizontal plane were measured by means of a Particle Image Velocimetry (PIV) technique and high speed videos were recorded to observe the behavior of the interface as a function of the agitation rate. It was observed not only that there is a strong dependence between the geometry and the hydrodynamics, but also there is a good agreement with the results obtained previously by Gamboa et al., in 2011, with the evaluation of the influence of culture conditions of S. lividans on protein O-glycosylation. The turbulence intensity increases with shaken rate. However, for the baffled geometry, it was observed a decrease for a critical speed, which is related with the in-phase and out-phase regions. These results can be an explanation for the variations in protein productivity as a function of the flask geometry and the differences in aggregation morphology and the pattern of O-glycosylation of the recombinant protein.

  3. Investigation of carbon dust accumulation in the JT-60U tokamak vacuum vessel

    Energy Technology Data Exchange (ETDEWEB)

    Asakura, N., E-mail: asakura.nobuyuki@jaea.go.jp [Japan Atomic Energy Agency, Rokkasho, Aomori 039-3212 (Japan); Hayashi, T. [Japan Atomic Energy Agency, Naka, Ibaraki 311-0193 (Japan); Ashikawa, N. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Fukumoto, M. [Japan Atomic Energy Agency, Naka, Ibaraki 311-0193 (Japan)

    2013-07-15

    Dust generated by plasma–wall interaction is a potential source of tritium retention in a fusion reactor. Evaluation of the dust accumulation in the entire vacuum vessel is required to estimate the total amount of tritium retention, but it was particularly difficult to measure for plasma-unexposed areas behind the PFC structures, i.e. “shadow areas”. Dust samples were collected at 3, 5 and 2–4 different toroidal locations on the first wall, divertor surface and the exhaust route under the divertor in JT-60U, respectively. On the tile surface, large mass area density was found at the inner divertor and baffle, in particular, upper tiles compared to the lower target tile where the thick deposition layers were produced. Mass area density was significantly increased at the shadow areas, i.e. under the divertor structure such as the divertor and baffle tiles and the divertor dome. It was found that the poloidal distribution is relatively symmetrical in the toroidal direction within a factor of three. In comparison with the previous collection just before major change of the plasma operations, dust accumulation was increased both at the exposed and shadow areas due to change in the operating conditions.

  4. Investigation of carbon dust accumulation in the JT-60U tokamak vacuum vessel

    Science.gov (United States)

    Asakura, N.; Hayashi, T.; Ashikawa, N.; Fukumoto, M.

    2013-07-01

    Dust generated by plasma-wall interaction is a potential source of tritium retention in a fusion reactor. Evaluation of the dust accumulation in the entire vacuum vessel is required to estimate the total amount of tritium retention, but it was particularly difficult to measure for plasma-unexposed areas behind the PFC structures, i.e. "shadow areas". Dust samples were collected at 3, 5 and 2-4 different toroidal locations on the first wall, divertor surface and the exhaust route under the divertor in JT-60U, respectively. On the tile surface, large mass area density was found at the inner divertor and baffle, in particular, upper tiles compared to the lower target tile where the thick deposition layers were produced. Mass area density was significantly increased at the shadow areas, i.e. under the divertor structure such as the divertor and baffle tiles and the divertor dome. It was found that the poloidal distribution is relatively symmetrical in the toroidal direction within a factor of three. In comparison with the previous collection just before major change of the plasma operations, dust accumulation was increased both at the exposed and shadow areas due to change in the operating conditions.

  5. Design of optics for compact star sensors

    Science.gov (United States)

    Xu, Minyi; Shi, Rongbao; Shen, Weimin

    2016-10-01

    In order to adapt to small size and low cost space platform such as mini-satellites, this paper studies the design of optics for compact star sensor. At first, the relationship between limiting magnitude and optical system specifications which includes field of view and entrance pupil diameter is analyzed, based on its Pyramid identification algorithm and signal-to-noise ratio requirement. The specifications corresponding to different limiting magnitude can be obtained after the detector is selected, and both of the complexity of optical lens and the size of baffle can be estimated. Then the range of the limiting magnitude can be determined for the miniaturization of the optical system. Taking STAR1000 CMOS detector as an example, the compact design of the optical system can be realized when the limiting magnitude is in the interval of 4.9Mv 5.5Mv. At last, the lens and baffle of a CMOS compact star sensor is optimally designed, of which length and weight is respectively 124 millimeters and 300 grams.

  6. Computational Analyses of Pressurization in Cryogenic Tanks

    Science.gov (United States)

    Ahuja, Vineet; Hosangadi, Ashvin; Mattick, Stephen; Lee, Chun P.; Field, Robert E.; Ryan, Harry

    2008-01-01

    A) Advanced Gas/Liquid Framework with Real Fluids Property Routines: I. A multi-fluid formulation in the preconditioned CRUNCH CFD(Registered TradeMark) code developed where a mixture of liquid and gases can be specified: a) Various options for Equation of state specification available (from simplified ideal fluid mixtures, to real fluid EOS such as SRK or BWR models). b) Vaporization of liquids driven by pressure value relative to vapor pressure and combustion of vapors allowed. c) Extensive validation has been undertaken. II. Currently working on developing primary break-up models and surface tension effects for more rigorous phase-change modeling and interfacial dynamics B) Framework Applied to Run-time Tanks at Ground Test Facilities C) Framework Used For J-2 Upper Stage Tank Modeling: 1) NASA MSFC tank pressurization: a) Hydrogen and oxygen tank pre-press, repress and draining being modeled at NASA MSFC. 2) NASA AMES tank safety effort a) liquid hydrogen and oxygen are separated by a baffle in the J-2 tank. We are modeling pressure rise and possible combustion if a hole develops in the baffle and liquid hydrogen leaks into the oxygen tank. Tank pressure rise rates simulated and risk of combustion evaluated.

  7. 搅拌釜中层流流场的模拟%Numerical simulation of laminar flow field in a stirred tank

    Institute of Scientific and Technical Information of China (English)

    范茏; 王卫京; 杨超; 毛在砂

    2004-01-01

    Stirred tanks are used extensively in process industry and one of the most commonly used impellers in stirred tanks is the Rushton disk turbine.Surprisingly few data are available regarding flow and mixing in stirred-tank reactors with Rushton turbine in the laminar regime,in particular the laminar flow in baffled tanks.In this paper,the laminar flow field in a baffled tank stirred by a standard Rushton turbine is simulated with the improved inner-outer iterative method.The non-inertial coordinate system is used for the impeller region,which is in turn used as the boundary conditions for iteration.It is found that the simulation results are in good agreement with previous experiments.In addition,the flow number and impeller power number calculated from the simulated flow field are in satisfactory agreement with experimental data.This numerical method allows prediction of flow structure requiring no experimental data as the boundary conditions and has the potential of being used to scale-up and design of related process equipment.

  8. Plasma fluctuations in a Kaufman thruster. [root mean square magnitude, spectra and cross correlation

    Science.gov (United States)

    Serafini, J. S.; Terdan, F. F.

    1973-01-01

    Measurements of the RMS magnitude, spectra and cross-correlations for the fluctuations in the beam, discharge and neutralizer keeper currents are presented for a 30-cm diameter dished grid ion thrustor for a range of magnetic baffle currents and up to 2.0 amperes beam current. The ratio of RMS to mean ion beam current varied from 0.04 to 0.23. The spectra of the amplitudes of the beam and discharge current fluctuations were taken up to 9 MHz and show that the predominant amplitudes occur at frequencies of 10 kHz or below. The fall-off with increasing frequency is rapid. Frequencies above 100 kHz the spectral levels are 45 kb or more below the maximum peak amplitudes. The cross-correlations revealed the ion beam fluctuations to have large radial and axial scales which implied that the beam fluctuates as a whole or 'in-phase.' The cross-correlations of the beam and neutralizer keeper current fluctuations indicated the neutralizer contributions to the beam fluctuations to be small, but not negligible. The mode of operation of the thrustor (values of beam and magnetic baffle currents) was significant in determining the RMS magnitude and spectral shape of the beam fluctuations. The major oscillations were not found to be directly dependent on the power conditioner inverter frequencies.

  9. Validation Hydrodynamic Models of Three Topological Models of Secondary Facultative Ponds

    Directory of Open Access Journals (Sweden)

    Aponte-Reyes Alxander

    2014-10-01

    Full Text Available A methodology was developed to analyze boundary conditions, the size of the mesh and the turbulence of a mathematical model of CFD, which could explain hydrodynamic behavior on facultative stabilization ponds, FSP, built to pilot scale: conventional pond, CP, baffled pond, BP, and baffled-mesh pond, BMP. Models dispersion studies were performed in field for validation, taking samples into and out of the FSP, the information was used to carry out CFD model simulations of the three topologies. Evaluated mesh sizes ranged from 500,000 to 2,000,000 elements. The boundary condition in Pared surface-free slip showed good qualitative behavior and the turbulence model κ–ε Low Reynolds yielded good results. The biomass contained in LFS generates interference on dispersion studies and should be taken into account in assessing the CFD modeling, the tracer injection times, its concentration at the entrance, the effect of wind on CFD, and the flow models adopted as a basis for modeling are parameters to be taken into account for the CFD model validation and calibration.

  10. Developing Ecological Models on Carbon and Nitrogen in Secondary Facultative Ponds

    Directory of Open Access Journals (Sweden)

    Aponte-Reyes Alexander

    2014-07-01

    Full Text Available Ecological models formulated for TOC, CO2, NH4+, NO3- and NTK, based in literature reviewed and field work were obtained monitoring three facultative secondary stabilization ponds, FSSP, pilots: conventional pond, CP, baffled pond, BP, and baffled-meshed pond, BMP. Models were sensitive to flow inlet, solar radiation, pH and oxygen content; the sensitive parameters in Carbon Model were KCOT Ba, umax Ba, umax Al, K1OX, VAl, R1DCH4, YBh. The sensitive parameters in the Nitrogen model were KCOT Ba, umax Ba, umax Al, VAl, KOPH, KOPA, r4An. The test t–paired showed a good simulating of Carbon model refers to TOC in FSSP; on the other side, the Nitrogen model showed a good simulating of NH4+. Different topological models modify ecosystem ecology forcing different transformation pathways of Nitrogen; equal transformations of the Carbon BMP topology could be achieved using lower volumes, however, a calibration for a new model would be required. Carbon and Nitrogen models developed could be coupled to hydrodynamics models for better modeling of FSSP.

  11. Characterization of stirrers for screening studies of enzymatic biomass hydrolyses on a milliliter scale.

    Science.gov (United States)

    Riedlberger, Peter; Brüning, Stefanie; Weuster-Botz, Dirk

    2013-07-01

    The evaluation of mixing quality is an important factor for improving the geometry of stirred-tank reactors and impellers used in bioprocess engineering applications, such as the enzymatic hydrolysis of plant materials. Homogeneity depends on different factors, including the stirrer type and the reactor type (e.g., ratio of diameter/height, ratio of impeller tip diameter/reactor diameter) with or without baffles. This study compares two impellers for enzymatic hydrolysis of suspensions of biomass particles on a milliliter scale. Both impellers were derived from industrially relevant geometries, such as blade and grid stirrers, although the geometry of the second stirrer was slightly modified to an asymmetric shape. The stirrers were investigated with different stirrer-reactor configurations. This was done experimentally and with the aid of computational fluid dynamics. The flow field, mixing numbers, power characteristics and initial conversion rates of sugars were considered to compare the two stirrers. The simulated mixing numbers and power characteristics in baffled and unbaffled milliliter-scale reactors were found to be in good agreement with the measured mixing times and power consumption. The mixing numbers required to reach homogeneity were much higher for the symmetric impeller and remained at least twice as high as the mixing numbers required when using the asymmetric impeller. The highest initial sugar releases from milled corn stover suspensions were achieved with the asymmetric impeller shape. Regardless of the differences in the flow fields or mixing times, diverging enzymatic sugar releases could be confirmed for Newtonian media only.

  12. Structural and electronic studies of metal carbide clusterfullerene Sc2C2@Cs-C72

    Science.gov (United States)

    Feng, Yongqiang; Wang, Taishan; Wu, Jingyi; Feng, Lai; Xiang, Junfeng; Ma, Yihan; Zhang, Zhuxia; Jiang, Li; Shu, Chunying; Wang, Chunru

    2013-07-01

    We present a metal carbide clusterfullerene Sc2C2@Cs(10528)-C72, whose structure has been baffling for many years. A motional endohedral Sc2C2 cluster, special molecule geometry and electronic structure were found in Sc2C2@Cs(10528)-C72. The paramagnetic Sc2C2@Cs-C72 anion radical was successfully prepared by a chemical reduction method and hyperfine couplings in the ESR spectrum were observed.We present a metal carbide clusterfullerene Sc2C2@Cs(10528)-C72, whose structure has been baffling for many years. A motional endohedral Sc2C2 cluster, special molecule geometry and electronic structure were found in Sc2C2@Cs(10528)-C72. The paramagnetic Sc2C2@Cs-C72 anion radical was successfully prepared by a chemical reduction method and hyperfine couplings in the ESR spectrum were observed. Electronic supplementary information (ESI) available: Experimental details, HPLC chromatogram, and DFT calculations. CCDC 917712. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c3nr01739g

  13. FINITE DIFFERENCE ANALYSIS OF ACOUSTIC REFLECTION AND RADIATION FROM FLUID-LOADED PLATES

    Institute of Scientific and Technical Information of China (English)

    赵汉中

    2003-01-01

    A finite difference/boundary integral procedure to determine the acoustic reflected pressure from a fluid-loaded bi-laminate plate is described. The bi-laminate is composed of a piezoelectric layer and an elastic layer in contact with the fluid. The plate is either of finite length and held at its two ends in an acoustically hard baffle or of infinite length with periodically etched electrodes.In the numerical model, the fluid pressure at fluid/solid interface is replaced by a continuum of point sources weighted by the normal acceleration of the elastic plate, and the governing equation system is solved in the solid domain. It is demonstrated that an appropriate applied voltage potential across the baffled piezoelectric layer has the effect of cancelling the reflected pressure at any chosen field points,and a piecewise constant voltage potential with properly chosen amplitude and phase in the periodic structure has the effect of cancelling the fundamental propagating mode of the reflected waves.

  14. Effects of inflow conditions on discrete frequency noise generated by small, axial flow fans

    Science.gov (United States)

    Washburn, K. B.; Lauchle, G. C.

    1985-09-01

    Discrete frequency acoustic radiation is generated by subsonic axial flow fans through both steady and unsteady blade loading. Steady loading is a function of pumping requirement, and unsteady loading is generated by spatially periodic inflow distortions. The latter effect is the dominant generation mechanism when small fans are used to cool electronic equipment. Fans mounted to exhaust out of a device ingest distortions created by all objects within the unit. This work represents an empirical survey of noise generated by small axial flow cooling fans in the presence of upstream obstructions and various inlet configurations. The obstructions include a cylinder, a thin rectangle, a thick rectangle, and an electronic card gate model. Each of these represents obstructions found in a typical installation. Simple and modified inlet baffles, finger guards, and honeycomb flow straighteners are investigated. Design recommendations are offered to minimize discrete tone generation. These include aerodynamic shaping of unaviodable obstructions, a minimum axial distance of 0.3 fan radii for obstructions in the inlet, the avoidance of blockage in lateral inflow and the use of an inlet baffle to smooth inlet distortions. Account is taken of the spatial restictions of typical installations.

  15. Liquid Self-Balancing Device Effects on Flexible Rotor Stability

    Directory of Open Access Journals (Sweden)

    Leonardo Urbiola-Soto

    2013-01-01

    Full Text Available Nearly a century ago, the liquid self-balancing device was first introduced by M. LeBlanc for passive balancing of turbine rotors. Although of common use in many types or rotating machines nowadays, little information is available on the unbalance response and stability characteristics of this device. Experimental fluid flow visualization evidences that radial and traverse circulatory waves arise due to the interaction of the fluid backward rotation and the baffle boards within the self-balancer annular cavity. The otherwise destabilizing force induced by trapped fluids in hollow rotors, becomes a stabilizing mechanism when the cavity is equipped with adequate baffle boards. Further experiments using Particle Image Velocimetry (PIV enable to assess the active fluid mass fraction to be one-third of the total fluid mass. An analytical model is introduced to study the effects of the active fluid mass fraction on a flexible rotor supported by flexible supports excited by bwo different destabilizing mechanisms; rotor internal friction damping and aerodynamic cross-coupling. It is found that the fluid radial and traverse forces contribute to the balancing action and to improve the rotor stability, respectively.

  16. Impact of sludge layer geometry on the hydraulic performance of a waste stabilization pond.

    Science.gov (United States)

    Ouedraogo, Faissal R; Zhang, Jie; Cornejo, Pablo K; Zhang, Qiong; Mihelcic, James R; Tejada-Martinez, Andres E

    2016-08-01

    Improving the hydraulic performance of waste stabilization ponds (WSPs) is an important management strategy to not only ensure protection of public health and the environment, but also to maximize the potential reuse of valuable resources found in the treated effluent. To reuse effluent from WSPs, a better understanding of the factors that impact the hydraulic performance of the system is needed. One major factor determining the hydraulic performance of a WSP is sludge accumulation, which alters the volume of the pond. In this study, computational fluid dynamics (CFD) analysis was applied to investigate the impact of sludge layer geometry on hydraulic performance of a facultative pond, typically used in many small communities throughout the developing world. Four waste stabilization pond cases with different sludge volumes and distributions were investigated. Results indicate that sludge distribution and volume have a significant impact on wastewater treatment efficiency and capacity. Although treatment capacity is reduced with accumulation of sludge, the latter may induce a baffling effect which causes the flow to behave closer to that of plug flow reactor and thus increase treatment efficiency. In addition to sludge accumulation and distribution, the impact of water surface level is also investigated through two additional cases. Findings show that an increase in water level while keeping a constant flow rate can result in a significant decrease in the hydraulic performance by reducing the sludge baffling effect, suggesting a careful monitoring of sludge accumulation and water surface level in WSP systems.

  17. Assess and improve the sustainability of water treatment facility using Computational Fluid Dynamics

    Science.gov (United States)

    Zhang, Jie; Tejada-Martinez, Andres; Lei, Hongxia; Zhang, Qiong

    2016-11-01

    Fluids problems in water treatment industry are often simplified or omitted since the focus is usually on chemical process only. However hydraulics also plays an important role in determining effluent water quality. Recent studies have demonstrated that computational fluid dynamics (CFD) has the ability to simulate the physical and chemical processes in reactive flows in water treatment facilities, such as in chlorine and ozone disinfection tanks. This study presents the results from CFD simulations of reactive flow in an existing full-scale ozone disinfection tank and in potential designs. Through analysis of the simulation results, we found that baffling factor and CT10 are not optimal indicators of disinfection performance. We also found that the relationship between effluent CT (the product of disinfectant concentration and contact time) obtained from CT transport simulation and baffling factor depends on the location of ozone release. In addition, we analyzed the environmental and economic impacts of ozone disinfection tank designs and developed a composite indicator to quantify the sustainability of ozone disinfection tank in technological, environmental and economic dimensions.

  18. Numerical study of flow fluctuation attenuation performance of a surge tank

    Institute of Scientific and Technical Information of China (English)

    郭兰兰; 刘正刚; 耿介; 李东; 杜广生

    2013-01-01

    The surge tank plays an important role in ensuring the stability of a water flow standard device. To study the influence of the structure and the working conditions on the regulator performance of a surge tank, a three-dimensional model, including a surge tank, the pipeline and the water tank is built, and the VOF model in the Fluent software is used to simulate the two-phase pulsatile flow in the surge tank. The inlet flow pulsation is defined by the User Defined Functions (UDF), and the outlet flow is set to be a free jet. By calculating the flow fluctuation coefficient of the variation under different flow conditions, the influences of the pulse frequency, the initial water level height and the baffle plate structure on the flow stability are analyzed. It is shown that the surge tank has a good attenuation effect on high-frequency pulsations, there is an optimal initial water level to suppress the fluctuations, the round holes of the baffle should ensure a certain circulation area with the bore diameter small enough to have the necessary damping effect.

  19. Particle size analysis of dispersed oil and oil-mineral aggregates with an automated ultraviolet epi-fluorescence microscopy system.

    Science.gov (United States)

    Ma, X; Cogswell, A; Li, Z; Lee, K

    2008-07-01

    This paper describes recent advances in microscopic analysis for quantitative measurement of oil droplets. Integration of a microscope with bright-field and ultraviolet epi-fluorescence illumination (excitation wavelengths 340-380 nm; emission wavelengths 400-430 nm) fitted with a computer-controlled motorized stage, a high resolution digital camera, and new image-analysis software, enables automatic acquisition of multiple images and facilitates efficient counting and sizing of oil droplets. Laboratory experiments were conducted with this system to investigate the size distribution of chemically dispersed oil droplets and oil-mineral aggregates in baffled flasks that have been developed for testing chemical dispersant effectiveness. Image acquisition and data processing methods were developed to illustrate the size distribution of chemically dispersed oil droplets, as a function of energy dissipation rate in the baffled flasks, and the time-dependent change of the morphology and size distribution of oil-mineral aggregates. As a quantitative analytical tool, epifluorescence microscopy shows promise for application in research on oil spill response technologies, such as evaluating the effectiveness of chemical dispersant and characterizing the natural interaction between oil and mineral fines and other suspended particulate matters.

  20. Oxygen transfer in circular surface aeration tanks.

    Science.gov (United States)

    Rao, Achanta Ramakrishna; Patel, Ajey Kumar; Kumar, Bimlesh

    2009-06-01

    Surface aeration systems employed in activated sludge plants are the most energy-intensive units of the plants and typically account for a higher percentage of the treatment facility's total energy use. The geometry of the aeration tank imparts a major effect on the system efficiency. It is said that at optimal geometric conditions, systems exhibits the maximum efficiency. Thus the quantification of the optimal geometric conditions in surface aeration tanks is needed. Optimal geometric conditions are also needed to scale up the laboratory result to the field installation. In the present work, experimental studies have been carried out on baffled and unbaffled circular surface aeration tanks to ascertain the optimal geometric conditions. It is found that no optimal geometric conditions exist for the liquid/water depth in circular surface aeration tanks; however, for design purposes, a standard value has been assumed. Based on the optimal geometric conditions, a scale-up equation has been developed for the baffled circular surface aeration tanks.

  1. Ultra Low Surface Brightness Imaging with the Dragonfly Telephoto Array

    CERN Document Server

    Abraham, Roberto G

    2014-01-01

    We describe the Dragonfly Telephoto Array, a robotic imaging system optimized for the detection of extended ultra low surface brightness structures. The array consists of eight Canon 400mm f/2.8 telephoto lenses coupled to eight science-grade commercial CCD cameras. The lenses are mounted on a common framework and are co-aligned to image simultaneously the same position on the sky. The system provides an imaging capability equivalent to a 0.4m aperture f/1.0 refractor with a 2.6 deg X 1.9 deg field of view. The system has no obstructions in the light path, optimized baffling, and internal optical surfaces coated with a new generation of anti-reflection coatings based on sub-wavelength nanostructures. As a result, the array's point spread function has a factor of ~10 less scattered light at large radii than well-baffled reflecting telescopes. The Dragonfly Telephoto Array is capable of imaging extended structures to surface brightness levels below 30 mag/arcsec^2 in 10h integrations (without binning or foregro...

  2. Evaluation of carbon dioxide mass transfer in raceway reactors for microalgae culture using flue gases.

    Science.gov (United States)

    de Godos, I; Mendoza, J L; Acién, F G; Molina, E; Banks, C J; Heaven, S; Rogalla, F

    2014-02-01

    Mass transfer of CO2 from flue gas was quantified in a 100m(2) raceway. The carbonation sump was operated with and without a baffle at different liquid/gas ratios, with the latter having the greatest influence on CO2 recovery from the flue gas. A rate of mass transfer sufficient to meet the demands of an actively growing algal culture was best achieved by maintaining pH at ∼8. Full optimisation of the process required both pH control and selection of the best liquid/gas flow ratio. A carbon transfer rate of 10gCmin(-1) supporting an algal productivity of 17gm(-2)day(-1) was achieved with only 4% direct loss of CO2 in the sump. 66% of the carbon was incorporated into biomass, while 6% was lost by outgassing and the remainder as dissolved carbon in the liquid phase. Use of a sump baffle required additional power without significantly improving carbon mass transfer.

  3. Impact of carbon and nitrogen feeding strategy on high production of biomass and docosahexaenoic acid (DHA) by Schizochytrium sp. LU310.

    Science.gov (United States)

    Ling, Xueping; Guo, Jing; Liu, Xiaoting; Zhang, Xia; Wang, Nan; Lu, Yinghua; Ng, I-Son

    2015-05-01

    A new isolated Schizochytrium sp. LU310 from the mangrove forest of Wenzhou, China, was found as a high producing microalga of docosahexaenoic acid (DHA). In this study, the significant improvements for DHA fermentation by the batch mode in the baffled flasks (i.e. higher oxygen supply) were achieved. By applied the nitrogen-feeding strategy in 1000 mL baffled flasks, the biomass, DHA concentration and DHA productivity were increased by 110.4%, 117.9% and 110.4%, respectively. Moreover, DHA concentration of 21.06 g/L was obtained by feeding 15 g/L of glucose intermittently, which was an increase of 41.25% over that of the batch mode. Finally, an innovative strategy was carried out by intermittent feeding carbon and simultaneously feeding nitrogen. The maximum DHA concentration and DHA productivity in the fed-batch cultivation reached to 24.74 g/L and 241.5 mg/L/h, respectively.

  4. Numerical Simulation of Laminar Flow Field in a Stirred Tank

    Institute of Scientific and Technical Information of China (English)

    范茏; 王卫京; 杨超; 毛在砂

    2004-01-01

    Stirred tanks are used extensively in process industry and one of the most commonly used impellers in stirred tanks is the R.ushton disk turbine. Surprisingly few data are available regarding flow and mixing in stirred-tank reactors with Rushton turbine in the laminar regime, in particular the laminar flow in baffled tanks.In this paper, the laminar flow field in a baffled tank stirred by a standard R.ushton turbine is simulated with the improved inner-outer iterative method. The non-inertial coordinate system is used for the impeller region, which is in turn used as the boundary conditions for iteration. It is found that the simulation results are in good agreement with previous experiments. In addition, the flow number and impeller power number calculated from the simulated flow field are in satisfactory agreement with experimental data. This numerical method allows prediction of flow structure requiring no experimental data as the boundary conditions and has the potential of being used to scale-up and design of related process equipment.

  5. Non-Linear Dynamics and Stability of Circular Cylindrical Shells Containing Flowing Fluid. Part i: Stability

    Science.gov (United States)

    AMABILI, M.; PELLICANO, F.; PAÏDOUSSIS, M. P.

    1999-08-01

    The study presented is an investigation of the non-linear dynamics and stability of simply supported, circular cylindrical shells containing inviscid incompressible fluid flow. Non-linearities due to large-amplitude shell motion are considered by using the non-linear Donnell's shallow shell theory, with account taken of the effect of viscous structural damping. Linear potential flow theory is applied to describe the fluid-structure interaction. The system is discretiszd by Galerkin's method, and is investigated by using a model involving seven degrees of freedom, allowing for travelling wave response of the shell and shell axisymmetric contraction. Two different boundary conditions are applied to the fluid flow beyond the shell, corresponding to: (i) infinite baffles (rigid extensions of the shell), and (ii) connection with a flexible wall of infinite extent in the longitudinal direction, permitting solution by separation of variables; they give two different kinds of dynamical behaviour of the system, as a consequence of the fact that axisymmetric contraction, responsible for the softening non-linear dynamical behaviour of shells, is not allowed if the fluid flow beyond the shell is constrained by rigid baffles. Results show that the system loses stability by divergence.

  6. Final Report: DOE/ID/14215

    Energy Technology Data Exchange (ETDEWEB)

    Kenneth Bryden; J. Richard Hess; Thomas Ulrich; Robert Zemetra

    2008-08-18

    efficiently engineer high-fidelity and high throughput separation systems for biomass components. INL and Iowa State University developed a computational modeling strategy for simulating multi-phase flow with an integrated solver using various computational fluid dynamics (CFD) codes. ISU set up a classic multi-phase test problem to be solved by the various CFD codes. The benchmark case was based on experimental data for bubble gas holdup and bed expansion for a gas/solid fluidized bed. Preliminary fluidization experiments identified some unexpected fluidization behavior, where rather than the bed uniformly fluidizing, a “blow out” would occur where a hole would open up in the bed through which the air would preferentially flow, resulting in erratic fluidization. To improve understanding of this phenomena and aid in building a design tool, improved computational tools were developed. The virtual engineering techniques developed were tested and utilized to design a separation baffle in a CNH combine. A computational engineering approach involving modeling, analysis, and simulation was used in the form of virtual engineering to design a baffle separator capable of accomplishing the high-fidelity residue separation established by the performance targets. Through the use of the virtual engineering model, baffle designs were simulated to (1) determine the effect of the baffle on the airflow of the combine cleaning system, and (2) predict the effectiveness of the baffle in separating the residue streams. A baffle design was selected based on the virtual engineering modeling, built into the INL selective harvest test combine. The result of the baffle changes improved the crop separation capability of the combine, enabling downstream improvement in composition and theoretical ethanol yield. In addition, the positive results from the application of the virtual engineering tools to the CNH combine design resulted in further application of these tools to other INL areas of research

  7. 船用换热器三维流场数值模拟%Numerical Simulation of the 3D Flow Field for Marine Heat Exchangers

    Institute of Scientific and Technical Information of China (English)

    王冶; 徐筱欣

    2013-01-01

    This paper develops a three-dimensional model of the closed engineroom heat exchanger by us-ing the Pro/E software. Based on the obtained numerical model,the shell-side turbulent flow and heat transfer characteristics of the examined heat exchanger is analyzed with the aid of the Computational Fluid Dynamics(CFD)software Fluent. Particularly,by taking the shell-side pressure drop,the total heat trans-fer rate,and the flow rate as three comprehensive indicators,the field of velocity,temperature,and pres-sure of the heat exchanger under different baffle nick heights and numbers are investigated. The results show that as the segmental baffle number increases,the pressure drop at the shell-side rises and the outlet temperature drops;meanwhile,when the baffle nick height increases,the pressure drop decreases and the outlet temperature increases.%采用Pro/E软件对闭式机舱淡水海水换热器的三维建模,利用FLUENT软件对该换热器壳程流体的流动与传热进行了数值模拟计算,分别以壳程总压降、总传热率、速度这三个方面作为综合衡量标准,分析具有不同折流板弦高、折流板数目的几种淡水海水换热器模型的速度场、温度场和压力场。结果表明:随着折流板数目的增加,壳程流体的压降逐渐升高,出口温度逐渐减小;随着缺口高度的增加,壳程流体的压降明显下降,出口温度也明显增加。

  8. 扭曲椭圆管换热的壳程强化传热特性%Shell side heat transfer enhancement in twisted elliptical tube heat exchanger

    Institute of Scientific and Technical Information of China (English)

    谭祥辉; 孙赫; 张立振; 朱冬生

    2012-01-01

    通过搭建扭曲椭圆管换热器壳程传热与压降性能测试平台,对扭曲椭圆管换热器壳程传热与压降性能进行了实验测试,以实验数据为基础对前人得到的壳程传热与压降性能计算准则关系式的应用范围进行了分析,同时拟合得到了测试用扭曲椭圆管换热器壳程传热与压降性能计算准则关系式,设计了与测试扭曲椭圆管换热器结构类似的折流板换热器以及折流杆换热器,采用相关计算方法对换热器的传热与压降性能进行了计算和比较,并分析了3台换热器的综合性能,结果显示扭曲椭圆管换热器传热效果好、压降低,具有很好的工业应用前景.%Heat transfer and pressure drop of twisted elliptical tube heat exchanger with FrM = 79 are tested in the present work. Based on the experimental result, the application range of previous correlations for twisted elliptical tube heat exchanger with FrM>232 and FrM = 64 is analyzed, and correlations of the tested heat exchanger with FrM = 79 are derived. The testing result indicates that there exists a change of fluid flowing state when Re, increases to 8000. Two heat exchangers with similar geometric parameters to the tested one but supported by segmental baffles and rod baffles are designed. Their shell side heat transfer coefficients and pressure drops are calculated with Bell-Delaware method and Gentry's method, respectively. Heat transfer coefficients and pressure drops of the two designed heat exchangers are compared with the tested twisted elliptical tube heat exchanger. Comprehensive performance of the three heat exchangers is studied. The twisted elliptical tube heat exchanger gives the highest heat transfer coefficient and lowest pressure drop. This type of heat exchanger has the advantages of segmental heat exchanger and rod baffle heat exchanger and will be widely used in the industry.

  9. 连续热镀锌过程带钢边部气流特性的研究%Research on airflow characteristic of the strip edge in hot-dip galvanizing process

    Institute of Scientific and Technical Information of China (English)

    李培兴; 张红梅; 赵红阳; 富聿晶; 孙成钱; 张岩

    2014-01-01

    To explore the strip edge pressure decreases as gas⁃jet wiping in hot⁃dip galvanizing process, a gas impact plate experiment was carried out, and the process of gas jet wiping was also simulated using the measured results. The added edge baffle near the edge of strip which is used to prevent the wall pressure decreases in strip edge was optimized with the help of the analytic model of film thickness. The results show that the airflow of strip edge occurs lateral deflection and the wall pressure in the strip edge is lower than those in center, in addition, the edge air pressure attenuation increases with the rising distance between the air knife and the strip. The edge pressure decreases and the edge over coating problem can be reduced effectively by adding edge baffle, and the best result happens when the thickness of baffle is 2 mm.%为探究连续热镀锌气刀射流拭锌过程中发生的带钢边部压力衰减问题,设计了气流冲击平板实验,对带钢表面气流流向及压力进行测定。基于测量的参数,对该气刀射流喷吹过程进行数值模拟,并结合所推导的镀层厚度计算模型,对为减少带钢边部压力衰减所增设的边部挡板进行了厚度优化。研究结果表明:气刀喷吹时带钢边部气流发生横向偏转,使得带钢边部压力较中心处低,气压衰减率随气刀与带钢的间隔距离增加而增加,增设边部挡板能有效阻碍带钢边部压力衰减和降低边部过镀锌缺陷发生,且挡板厚度为2 mm时的作用效果最佳。

  10. ELAWD GROUT HOPPER MOCK-UP TESTING

    Energy Technology Data Exchange (ETDEWEB)

    Pickenheim, B.; Hansen, E.; Leishear, R.; Marzolf, A.; Reigel, M.

    2011-10-27

    . (3) The necessity of baffles in the hopper. The preference of the facility is not to have baffles in the hopper; however, if the initial testing indicates inadequate agitation or difficulties with the radar measurement, baffles will be tested.

  11. Measurement of Sky Brightness and Suppression of Scattering in Sky Brightness Monitor%日晕测量与日晕光度计外缘杂散光抑制试验

    Institute of Scientific and Technical Information of China (English)

    刘念平; 刘煜; 申远灯; 张雪飞; 曹文达; Arnaud Jean

    2011-01-01

    A modern Sky Brightness Monitor (SBM) was developed for the site survey in West China for the future large solar equipment installation. The performance of this new SBM was tested in the recent preliminary experiments. A lot of sky brightness data had been obtained at a few sites in Yunnan. The blue channel result shows that the sky brightness near the noon time on Jiaozi Snow Mountain is as low as a few millionths of the solar center intensity, indicating the low scattering level inside our SBM instrument. The scattering is mainly from two parts: the diffraction rings from the occulter edges, distributed in the inner field of view but outside the occulter region containing the ND4 filter; the diffraction from the baffle rings, distributed in the extreme edges of the field of view. To suppress the scattering of the latter part, experiments with different aperture sizes of baffle rings are made.The result shows that, by mounting new baffle rings with proper aperture size into the SBM telescope tube, diffraction in the extreme edges of the field of view can be effectively reduced.%为配合大型太阳设备西部选址工作,研制了一架现代日晕光度计(Sky Brightness Monitor,SBM).前期实验对日晕光度计性能进行了测试,同时积累了云南部分址点的日晕数据.资料分析结果显示,轿子雪山正午前后的日晕水平最低可至日面中心强度百万分之几的量级(蓝波段).这表明该日晕光度计内部杂散光水平已达到了国际同类产品的标准.日晕光度计的内部杂散光源主要来自两部分:镜筒前端中性滤光片(ND4)固定套圈的边缘衍射(视场靠内区域)和镜筒内置光阑的边缘衍射(视场靠外区域).针对后者进行的变换光阑孔径大小试验结果证实,适当缩小光阑孔径可有效减小数据中视场靠外区域的衍射光干扰.

  12. 进料蒸汽加热器的设计优化%Design and Optimization of Feed Steam Heater

    Institute of Scientific and Technical Information of China (English)

    彭强; 王汝军; 宋风莲; 李超

    2016-01-01

    HTRI software is used to design and optimize a steam feed heater. The effect of baffle spacing and cutting rate on the heater, and the difference between saturated steam and superheated steam in thermal resistance distribution and heat transfer coefficient are studied from process and equipment aspect. Univariate analysis shows that this heater has the best performance when the cutting rate is 40% and the baffle spacing is 350 mm. The calculation indicates that: when baffle spacing increases, the shell-side heat transfer coefficient and total heat transfer coefficient decreases; when cutting rate increases, shell-side heat transfer coeffi-cient and total heat transfer coefficient increases firstly and then decreases.Compared with the superheated steam,saturated steam brings larger total heat transfer coefficient and design mar-gin,and makes production operation easier to control.%利用HTRI软件对某进料蒸汽加热器进行了设计优化。采用单变量分析的方法,从工艺和结构两个方面,考察了折流板间距和切割率对加热器的影响,以及饱和蒸汽和过热蒸汽在热阻分布和传热系数等方面的差异,最终发现切割率为40%、折流板间距350 mm时进料蒸汽加热器性能最优。计算结果表明:随着折流板间距的提高,壳侧传热系数和总传热系数逐渐减小;随着折流板切割率的增大,壳侧传热系数及总传热系数均先增大后减小;与过热蒸汽相比,饱和蒸汽可以增大总传热系数,提高加热器设计裕量,并使生产操作更易于控制。

  13. Explore the Indoor Radon Concentration of Influential Factors%室内氡的质量浓度影响因素研究

    Institute of Scientific and Technical Information of China (English)

    张建强; 王雪英; 时宇桥; 刘超卓

    2013-01-01

    为测量室内空气中氡的质量浓度,本文选取面积为6 rn×4 m的房间作为研究对象,在保证没有人员出入的情况下,采用Model-1027型专业化氡连续检测仪进行不同条件下的实验测量,实验结果表明,在检测时间内,室内氡的质量浓度与温度的相关系数为-0.44,与相对湿度的相关系数为0.44;氡的质量浓度与墙壁之间的距离近似呈指数衰减的规律,随着与墙壁距离的增加,氡的质量浓度逐渐降低,最终达到平衡;在墙壁有隔板和无隔板时,测得氡的平均质量浓度分别为15.54 Bq/m3和22.57 Bq/m3,说明隔板对氡的空间分布产生一定的影响,即降低了室内氡的质量浓度.该研究对室内氡辐射的防护具有一定的积极作用.%For measuring the mass concentration of radon in the air indoor, a 6m×4m room is selected as the subject investigated. When this condition attained that the room is no access, the mass concentration of radon can be measured with Model -1027 continuous radon monitor under different conditions. The results show that, in monitoring time, the correlation coefficient of the radon's mass concentration indoor and temperature is —0. 44, but the relative humidity is 0. 44; the mass concentration of radon and the distance between the walls and appliance appear an exponential decay law approximately. The radon concentration decreases gradually with the increase of distance and finally achieves a balance. The radon's average mass concentrations measured are 15. 54 Bq/m3 with baffles and 22. 57 Bq/m3 without baffles, this prove that the baffles has a influence on spatial distribution of radon, or say that it can reduce the radon's mass concentration indoor. The study on radon radiation's indoor protection has certain positive role.

  14. 罐车制动时液体晃动的仿真分析%Simulation of liquid slosh in braking process of tank truck

    Institute of Scientific and Technical Information of China (English)

    刘奎; 康宁

    2009-01-01

    The liquid sloshing in braking process of tank truck was simulated by volume of fluid (VOF) model. The forces and their locations of a single room and weight distribution of a truck were calculated. The reliability of the calculation method was validated by comparing with experimental results. The results show that the maximum of F_x( force in direction x) , F_y( force in direction y) and C (The ratio of weight acting on the front axle and rear axle) increase as the deceleration increases without a baffle. When the liquid filling ratio increases, the maximum of F_z increases firstly and decreases afterwards, the maximum of F_y increase, and C increases in the starting and ending period of braking process and decreases during the period around 1 s. When there is a baffle, as the area of the baffle becomes bigger, the maximum of F_x, F_y and C decreases.%采用Volume of Fluid(VOF)模型对罐车制动时液体的晃动进行了数值模拟,对单室受力、受力位置及整车轴荷分配进行了计算,并通过与实验结果的对比验证了计算方法的可靠性.计算结果表明,无防波板时,随减速度增加,单室x,y方向受力峰值增大,整车轴荷比增大;随充液比增加,单室x方向受力峰值先增大后减小,y方向受力峰值增大,制动初始与结束时充液比越大轴荷比越大,1s左右充液比越大轴荷比越小;单室带防波板时,随防波板面积增加,x,y方向受力峰值减小,当防波板面积大于横截面的40%时,增加防波板面积能显著改善罐体受力,且防波板面积越大轴荷比峰值越小.

  15. Assessing the applicability of the 1D flux theory to full-scale secondary settling tank design with a 2D hydrodynamic model.

    Science.gov (United States)

    Ekama, G A; Marais, P

    2004-02-01

    The applicability of the one-dimensional idealized flux theory (1DFT) for the design of secondary settling tanks (SSTs) is evaluated by comparing its predicted maximum surface overflow (SOR) and solids loading (SLR) rates with that calculated with the two-dimensional computational fluid dynamics model SettlerCAD using as a basis 35 full-scale SST stress tests conducted on different SSTs with diameters from 30 to 45m and 2.25-4.1m side water depth (SWD), with and without Stamford baffles. From the simulations, a relatively consistent pattern appeared, i.e. that the 1DFT can be used for design but its predicted maximum SLR needs to be reduced by an appropriate flux rating, the magnitude of which depends mainly on SST depth and hydraulic loading rate (HLR). Simulations of the Watts et al. (Water Res. 30(9)(1996)2112) SST, with doubled SWDs and the Darvill new (4.1m) and old (2.5m) SSTs with interchanged depths, were run to confirm the sensitivity of the flux rating to depth and HLR. Simulations with and without a Stamford baffle were also performed. While the design of the internal features of the SST, such as baffling, has a marked influence on the effluent SS concentration while the SST is underloaded, these features appeared to have only a small influence on the flux rating, i.e. capacity, of the SST. Until more information is obtained, it would appear from the simulations that the flux rating of 0.80 of the 1DFT maximum SLR recommended by Ekama and Marais (Water Pollut. Control 85(1)(1986)101) remains a reasonable value to apply in the design of full-scale SSTs-for deep SSTs (4m SWD) the flux rating could be increased to 0.85 and for shallow SSTs (2.5m SWD) decreased to 0.75. It is recommended that (i) while the apparent interrelationship between SST flux rating and depth suggests some optimization of the volume of the SST, this be avoided and (ii) the depth of the SST be designed independently of the surface area as is usually the practice and once selected, the

  16. Comparison of the 1D flux theory with a 2D hydrodynamic secondary settling tank model.

    Science.gov (United States)

    Ekama, G A; Marais, P

    2004-01-01

    The applicability of the 1D idealized flux theory (1DFT) for design of secondary settling tanks (SSTs) is evaluated by comparing its predicted maximum surface overflow (SOR) and solids loading (SLR) rates with that calculated from the 2D hydrodynamic model SettlerCAD using as a basis 35 full scale SST stress tests conducted on different SSTs with diameters from 30 to 45m and 2.25 to 4.1 m side water depth, with and without Stamford baffles. From the simulations, a relatively consistent pattern appeared, i.e. that the 1DFT can be used for design but its predicted maximum SLR needs to be reduced by an appropriate flux rating, the magnitude of which depends mainly on SST depth and hydraulic loading rate (HLR). Simulations of the sloping bottom shallow (1.5-2.5 m SWD) Dutch SSTs tested by STOWa and the Watts et al. SST, all with doubled SWDs, and the Darvill new (4.1 m) and old (2.5 m) SSTs with interchanged depths, were run to confirm the sensitivity of the flux rating to depth and HLR. Simulations with and without a Stamford baffle were also done. While the design of the internal features of the SST, such as baffling, have a marked influence on the effluent SS concentration for underloaded SSTs, these features appeared to have only a small influence on the flux rating, i.e. capacity, of the SST, In the meantime until more information is obtained, it would appear that from the simulations so far that the flux rating of 0.80 of the 1DFT maximum SLR recommended by Ekama and Marais remains a reasonable value to apply in the design of full scale SSTs--for deep SSTs (4 m SWD) the flux rating could be increased to 0.85 and for shallow SSTs (2.5 m SWD) decreased to 0.75. It is recommended that (i) while the apparent interrelationship between SST flux rating and depth suggests some optimization of the volume of the SST, that this be avoided and that (ii) the depth of the SST be designed independently of the surface area as is usually the practice and once selected, the

  17. Recurrent Pneumonia and a Normal Heart: Late Complication after Repair of Hemianomalous Pulmonary Venous Drainage—A Cautionary Tale

    Directory of Open Access Journals (Sweden)

    Maryanne Caruana

    2010-01-01

    Full Text Available Hemianomalous pulmonary venous drainage with intact atrial septum is a rare congenital anomaly and reports of its surgical repair and the long-term complications related to the correction are only infrequently encountered in the literature. We report the case of a patient with hemianomalous pulmonary venous drainage and intact atrial septum who underwent surgical repair using a pericardial baffle and creation of an “atrial septal defect” aged 15 years. Dyspnoea and recurrent chest infections started 7 months after surgery when he was seen by a respiratory physician without cardiac followup. He presented again aged 28 years with a recurrent pneumonia investigated over 6 weeks and heart pronounced normal from examination and echocardiography. Correct diagnosis was made in Grown Up Congenital Heart (GUCH clinic stimulating review of data and catheterisation with pulmonary artery angiography which confirmed it. We feel that this case highlights the importance of specialist care and followup for GUCH patients.

  18. The Search for Another Earth

    Indian Academy of Sciences (India)

    2016-07-01

    Is there life anywhere else in the vast cosmos?Are there planets similar to the Earth? For centuries,these questions baffled curious minds. Eithera positive or negative answer, if found oneday, would carry a deep philosophical significancefor our very existence in the universe. Althoughthe search for extra-terrestrial intelligence wasinitiated decades ago, a systematic scientific andglobal quest towards achieving a convincing answerbegan in 1995 with the discovery of the firstconfirmed planet orbiting around the solar-typestar 51 Pegasi. Since then, astronomers have discoveredmany exoplanets using two main techniques,radial velocity and transit measurements.In the first part of this article, we shall describethe different astronomical methods through whichthe extrasolar planets of various kinds are discovered.In the second part of the article we shalldiscuss the various kinds of exoplanets, in particularabout the habitable planets discovered tilldate and the present status of our search for ahabitable planet similar to the Earth.

  19. Los Alamos passive test cell results for the 1981-82 winter

    Energy Technology Data Exchange (ETDEWEB)

    McFarland, R.D.; Hedstrom, J.C.; Balcomb, J.D.; Moore, S.W.

    1982-10-01

    This report covers Los Alamos test cell operation during the winter of 1981-82 including comparisons with the 1980-81 winter. Extensive data have been taken and computer-analyzed to determine performance parameters such as efficiency, solar savings fraction, and discomfort index. The data from different test cells are directly comparable because each has similar heating-load coefficient and collector area. Configurations include direct gain, unvented Trombe walls, water wall, phase-change wall, and sunspaces. Strategies for reducing heat loss include selective surfaces, two types of improved glazing systems, a heat pipe system, and convection suppression baffles. Significant differences in both auxiliary heat and comfort were observed among the various system types. The results are useful, not only for direct system comparisons, but also to provide data for validation of computer simulation programs. Availability of hourly data is described.

  20. Characterization of the Reflectivity of Various Black Materials

    CERN Document Server

    Marshall, Jennifer L; Rheault, Jean-Philippe; Prochaska, Travis; Allen, Richard D; DePoy, D L

    2014-01-01

    We present total and specular reflectance measurements of various materials that are commonly (and uncommonly) used to provide baffling and/or to minimize the effect of stray light in optical systems. More specifically, we investigate the advantage of using certain black surfaces and their role in suppressing stray light on detectors in optical systems. We measure the total reflectance of the samples over a broad wavelength range (250 < lambda < 2500 nm) that is of interest to astronomical instruments in the ultraviolet, visible, and near-infrared regimes. Additionally, we use a helium-neon laser to measure the specular reflectance of the samples at various angles. Finally, we compare these two measurements and derive the specular fraction for each sample.

  1. Quantum

    CERN Document Server

    Al-Khalili, Jim

    2003-01-01

    In this lively look at quantum science, a physicist takes you on an entertaining and enlightening journey through the basics of subatomic physics. Along the way, he examines the paradox of quantum mechanics--beautifully mathematical in theory but confoundingly unpredictable in the real world. Marvel at the Dual Slit experiment as a tiny atom passes through two separate openings at the same time. Ponder the peculiar communication of quantum particles, which can remain in touch no matter how far apart. Join the genius jewel thief as he carries out a quantum measurement on a diamond without ever touching the object in question. Baffle yourself with the bizzareness of quantum tunneling, the equivalent of traveling partway up a hill, only to disappear then reappear traveling down the opposite side. With its clean, colorful layout and conversational tone, this text will hook you into the conundrum that is quantum mechanics.

  2. Effect of solenoidal magnetic field on drifting laser plasma

    Science.gov (United States)

    Takahashi, Kazumasa; Okamura, Masahiro; Sekine, Megumi; Cushing, Eric; Jandovitz, Peter

    2013-04-01

    An ion source for accelerators requires to provide a stable waveform with a certain pulse length appropriate to the application. The pulse length of laser ion source is easy to control because it is expected to be proportional to plasma drifting distance. However, current density decay is proportional to the cube of the drifting distance, so large current loss will occur under unconfined drift. We investigated the stability and current decay of a Nd:YAG laser generated copper plasma confined by a solenoidal field using a Faraday cup to measure the current waveform. It was found that the plasma was unstable at certain magnetic field strengths, so a baffle was introduced to limit the plasma diameter at injection and improve the stability. Magnetic field, solenoid length, and plasma diameter were varied in order to find the conditions that minimize current decay and maximize stability.

  3. Performance of V-4Cr-4Ti material exposed to the DIII-D tokamak environment

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, H. E-mail: htsai@anl.gov; Johnson, W.R.; Yan, Y.; Trester, P.W.; Bozek, A.; King, J.F.; Smith, D.L

    2002-12-01

    As a first step to demonstrate the viability of using vanadium-base alloys for structural applications in fusion devices, six welded upper radiative divertor baffle support brackets made from a V-4Cr-4Ti alloy were installed in the DIII-D tokamak. To determine the effects of exposure to the tokamak environment, lead tests are being conducted on parent metal and weldment specimens. One of the issues to be addressed is whether excessive hydrogen uptake may occur to cause material embrittlement. Some of the lead tests have been completed. Data from samples exposed to up to four DIII-D operating cycles ({approx}4 years) indicate that the performance of the V-4Cr-4Ti alloy would not be significantly affected by the exposure. Brittle cleavage fractures are noted near the surface of some of the impact specimens, but only at very low (<-150 deg. C) test temperatures. Above -150 deg. C, all fractures are ductile.

  4. Prolegomena to any future metaphysics that will be able to come forward as science the Paul Carus translation

    CERN Document Server

    Kant, Immanuel

    1977-01-01

    Kant’s Prolegomena -- its full title, in the eighteenth-century manner, is Prolegomena to Any Future Metaphysics Which Will Be Able to Come Forth as Science -- is a classic in metaphysics and the theory of knowledge. It deals with the perennially baffling questions: How do we know? How much can we know? Its answers to these questions are interesting especially now. We live in one of the recurring periods of intellectual and cultural history that are skeptical and impatient of systems of speculative metaphysics, and a distrust of speculation is the leading motif of the Prolegomena. Though Kant's arguments against speculative metaphysics differ from those of our contemporaries, in some of his results he anticipates their negative conclusions. The Prolegomena, however, is not interesting merely as an historical anticipation of recent views; indeed, as such it has been as it were condemned in advance by Kant (Prolegomena, Introduction). Rather, its chief interest to the student of philosophy is probably the way...

  5. Fluctuation statistics in the scrape-off layer of Alcator C-Mod

    CERN Document Server

    Kube, Ralph; LaBombard, Brian; Terry, James L

    2014-01-01

    We study long time series of the ion saturation current and floating potential, obtained by Langmuir probes dwelled in the far-scrape off layer and installed in the divertor baffle of Alcator C-Mod, for a series of discharges with increasing line averaged plasma particle density. Using the ion saturation current as a proxy for the plasma particle density, we compare particle density amplitude histograms to best fits of a Gamma distribution, the Log-normal distribution and the sheath distribution [1]. Best fits of all three models agree with the observed histograms over multiple decades in normalized probability. Analysis of ion saturation current time series sampled at outboard midplane and at the divertor show that their dynamics are governed by intermittent large amplitude burst events and present a comparable conditionally averaged waveform. In both cases are histograms of the waiting times between successive large amplitude burst events and of the burst amplitudes well described by an exponential distribu...

  6. Single-Stage Repair of an Unusual Association: Congenital Gerbode Defect, Hypoplastic Aortic Arch, and Partially Anomalous Pulmonary Venous Return in an Infant.

    Science.gov (United States)

    Flores, Saul; Kimball, Thomas R; Nelson, David P; Morales, David L S

    2016-07-01

    We present the case of a two-month-old male with congenital Gerbode defect, hypoplastic aortic arch, and left-sided partially anomalous pulmonary venous return. The patient underwent single-stage surgical repair, which consisted of aortic arch advancement with resection of the coarctation segment, pulmonary vein repair, and primary closure of the Gerbode defect. The anomalous pulmonary vein posed a particular challenge due to its size and distance from the left atrium, which we approached with a posterior atrial wall trapdoor baffle technique, without mobilizing the affected vein. Postoperatively and at one year follow-up, there was no evidence of residual lesions and there was unobstructed flow pattern across the aortic arch and the affected pulmonary vein.

  7. Time is Money

    Science.gov (United States)

    Ausloos, Marcel; Vandewalle, Nicolas; Ivanova, Kristinka

    Specialized topics on financial data analysis from a numerical and physical point of view are discussed when pertaining to the analysis of coherent and random sequences in financial fluctuations within (i) the extended detrended fluctuation analysis method, (ii) multi-affine analysis technique, (iii) mobile average intersection rules and distributions, (iv) sandpile avalanches models for crash prediction, (v) the (m,k)-Zipf method and (vi) the i-variability diagram technique for sorting out short range correlations. The most baffling result that needs further thought from mathematicians and physicists is recalled: the crossing of two mobile averages is an original method for measuring the "signal" roughness exponent, but why it is so is not understood up to now.

  8. Integrated knowledge-based modeling and its application for classification problems

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Knowledge discovery from data directly can hardly avoid the fact that it is biased towards the collected experimental data, whereas, expert systems are always baffled with the manual knowledge acquisition bottleneck. So it is believable that integrating the knowledge embedded in data and those possessed by experts can lead to a superior modeling approach. Aiming at the classification problems, a novel integrated knowledge-based modeling methodology, oriented by experts and driven by data, is proposed. It starts from experts identifying modeling parameters, and then the input space is partitioned followed by fuzzification. Afterwards, single rules are generated and then aggregated to form a rule base. on which a fuzzy inference mechanism is proposed. The experts are allowed to make necessary changes on the rule base to improve the model accuracy. A real-world application, welding fault diagnosis, is presented to demonstrate the effectiveness of the methodology.

  9. Reflective practice: providing safe quality patient-centered pain management.

    Science.gov (United States)

    Sherwood, Gwen; McNeill, Jeanette

    2017-02-02

    Effective pain management continues to baffle clinicians in spite of numerous evidence-based guidelines and standards, focused clinical interventions and standardized assessments. Reflective practice is a mindful approach to practice that grounds clinicians in the moment with the individual patient to ask questions and then to listen to the patient's message about their pain experience. Reflective practice helps meld theoretical knowledge with lessons from experience to rethink mechanistic responses to patient pain. The subjective nature of pain means no two patients have the same experience, and, evidence based best practices are to be applied within the patient's preferences and context. The paper uses a case study to illustrate how to apply reflective practice to integrate the interprofessional quality and safety competencies to provide patient-centered pain management. Applying reflective questions throughout the care experience by all members of the healthcare team provides a mindful approach that focuses care on the individual patient.

  10. Observing the stars. Love in the age of systems

    Directory of Open Access Journals (Sweden)

    Kjetil Ansgar Jakobsen

    2010-11-01

    Full Text Available A number of scholars have demonstrated how the cultural industry involves people in a participatory culture in which users actively construct personal identities. However, the link between a public of mass-mediated entertainment and the private sphere of intimacy and personal identity is a paradox. A consistent theory to clarify that paradox is lacking in the cultural studies literature. I suggest that social systems theory in the Luhmannian tradition may explain in economical terms why the continuous performance and intensification of the paradox of mass-mediated intimacy is a major trait of contemporary culture. Nevertheless, the article does not address normative issues. It is neither an apology for the culture industry, nor a condemnation. The aim is simply to bring one of the most powerful tools of analysis in social theory today to bear on an aspect of modern society which is as important as it is baffling.

  11. Numerical simulation of flow induced by a pitched blade turbine. Comparison of the sliding mesh technique and an averaged source term method

    Energy Technology Data Exchange (ETDEWEB)

    Majander, E.O.J.; Manninen, M.T. [VTT Energy, Espoo (Finland)

    1996-12-31

    The flow induced by a pitched blade turbine was simulated using the sliding mesh technique. The detailed geometry of the turbine was modelled in a computational mesh rotating with the turbine and the geometry of the reactor including baffles was modelled in a stationary co-ordinate system. Effects of grid density were investigated. Turbulence was modelled by using the standard k-{epsilon} model. Results were compared to experimental observations. Velocity components were found to be in good agreement with the measured values throughout the tank. Averaged source terms were calculated from the sliding mesh simulations in order to investigate the reliability of the source term approach. The flow field in the tank was then simulated in a simple grid using these source terms. Agreement with the results of the sliding mesh simulations was good. Commercial CFD-code FLUENT was used in all simulations. (author)

  12. Turbulent precipitation of uranium oxalate in a vortex reactor - experimental study and modelling; Precipitation turbulente d'oxalate d'uranium en reacteur vortex - etude experimentale et modelisation

    Energy Technology Data Exchange (ETDEWEB)

    Sommer de Gelicourt, Y

    2004-03-15

    Industrial oxalic precipitation processed in an un-baffled magnetically stirred tank, the Vortex Reactor, has been studied with uranium simulating plutonium. Modelling precipitation requires a mixing model for the continuous liquid phase and the solution of population balance for the dispersed solid phase. Being chemical reaction influenced by the degree of mixing at molecular scale, that commercial CFD code does not resolve, a sub-grid scale model has been introduced: the finite mode probability density functions, and coupled with a model for the liquid energy spectrum. Evolution of the dispersed phase has been resolved by the quadrature method of moments, first used here with experimental nucleation and growth kinetics, and an aggregation kernel based on local shear rate. The promising abilities of this local approach, without any fitting constant, are strengthened by the similarity between experimental results and simulations. (author)

  13. Design and economic investigation of shell and tube heat exchangers using Improved Intelligent Tuned Harmony Search algorithm

    Directory of Open Access Journals (Sweden)

    Oguz Emrah Turgut

    2014-12-01

    Full Text Available This study explores the thermal design of shell and tube heat exchangers by using Improved Intelligent Tuned Harmony Search (I-ITHS algorithm. Intelligent Tuned Harmony Search (ITHS is an upgraded version of harmony search algorithm which has an advantage of deciding intensification and diversification processes by applying proper pitch adjusting strategy. In this study, we aim to improve the search capacity of ITHS algorithm by utilizing chaotic sequences instead of uniformly distributed random numbers and applying alternative search strategies inspired by Artificial Bee Colony algorithm and Opposition Based Learning on promising areas (best solutions. Design variables including baffle spacing, shell diameter, tube outer diameter and number of tube passes are used to minimize total cost of heat exchanger that incorporates capital investment and the sum of discounted annual energy expenditures related to pumping and heat exchanger area. Results show that I-ITHS can be utilized in optimizing shell and tube heat exchangers.

  14. Multidimensional numerical modeling of heat exchangers

    Science.gov (United States)

    Sha, W. T.; Yang, C. I.; Kao, T. T.; Cho, S. M.

    A comprehensive, multidimensional, thermal-hydraulic model is developed for the analysis of shell-and-tube heat exchangers for liquid-metal services. For the shellside fluid, the conservation equations of mass, momentum, and energy for continuum fluids are modified using the concept of porosity, surface permeability and distributed resistance to account for the blockage effects due to the presence of heat-transfer tubes, flow baffles/shrouds, the support plates, etc. On the tubeside, the heat-transfer tubes are connected in parallel between the inlet and outlet plenums, and tubeside flow distribution is calculated based on the plenum-to-plenum pressure difference being equal for all tubes. It is assumed that the fluid remains single-phase on the shell side and may undergo phase-change on the tube side, thereby simulating the conditions of Liquid Metal Fast Breeder Reactor (LMFBR) intermediate heat exchangers (IHX) and steam generators (SG).

  15. Some recent developments in the theory of acoustic transmission in tube bundles

    Science.gov (United States)

    Heckl, Maria A.; Mulholland, L. S.

    1995-01-01

    A comprehensive theoretical model for acoustic transmission in a tube bundle is presented. The tube bundle is considered as a series of diffraction gratings. Each grating consists of periodically spaced cylindrical tubes which obey the equations of motion of a cylindrical shell. Fluid loading is included. The model can be used for numerical simulations to calculate the sound field at any point in a tube bundle. Various phenomena can be predicted which are of interest for the development of acoustic diagnostics in heat exchangers. These include diffraction of a plane incident wave into several directions, the occurrence of passing and stopping bands in the transmission spectrum, features specific to oblique waves and the effect of dissipative losses. Tube bundles with baffle plates are also examined. The validity of the theoretical model is confirmed by comparison with experimental results.

  16. Structure and optical absorption properties of NiTiO3 nanocrystallites

    Science.gov (United States)

    Li, Ming-Wei; Yuan, Jin-Pei; Gao, Xiao-Mei; Liang, Er-Qian; Wang, Cheng-Yang

    2016-08-01

    Nickel titanate (NiTiO3) nanocrystallites are synthesized via a solid-state reaction from a precursor prepared by a homogeneous precipitation method. Ilmenite-structural NiTiO3 consists of alternating layers of NiO6 and TiO6 octahedra. It not only strongly absorbs ultraviolet light (wavelength photocatalytic activity in the degradation of methylene blue in water. It is proposed that the visible light absorbance peaks of NiTiO3 mainly originate from the Ni: d → d charge-transfer transitions within its valence band. NiTiO3 has wide energy gaps from the hybridized Ni 3 d and O 2 p orbitals to the Ti 3 d orbitals, which block both Ni2+ → Ti4+ and O2- → Ti4+ charge-transfer transitions between valence band and conduction band, and thus baffle its photocatalytic performance.

  17. Influence of Air-Knife Wiping on Coating Thickness in Hot-Dip Galvanizing

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yan; CUI Qi-peng; SHAO Fu-qun; WANG Jun-sheng; ZHAO Hong-yang

    2012-01-01

    In hot-dip galvanizing process, air jet wiping control is so crucial to decide the coating thickness and uni- formity of the zinc layer on the steel strip. The mathematical models developed predict the zinc coating thickness as a function of pressure and shear stress. The required pressure and shear stress profile on the strip surface were calcu- lated using regression analysis, and carried out using numerical simulation as FLUENT, a finite element analysis software. The influences of the outlet pressure, the nozzle to strip distance, the slot opening, the edge baffle plate, as well as the tilting angle of air knife were discussed. Combining with these results and regression analysis on the practical data, four first-order polynomial multi-parameter models were established for different targeted coating thicknesses with better regression coefficients. The validated model was used to carry out sensitivity analysis to de- termine the favorable controlling regime for the air jet wiping process.

  18. The forced sound transmission of finite ribbed plates, investigating the influence of point connections and periodicity

    DEFF Research Database (Denmark)

    Brunskog, Jonas

    2015-01-01

    Many engineering structures consist of plates being stiffened by ribs. The ribs can be connected to the plate in a line connection (welded or glued) or in point connections (screwed). It is well known that the rib stiffeners can significantly change the vibration field and the radiation behavior...... been derived, using a variational technique based on integral-differential equations of the fluid loaded plate. In this way an optimal solution is derived, using a very simple initial guess of the vibration field. The finite plate is assumed being mounted in a rigid baffle. The approach is based...... the model. The influence of point versus line connections, as well as periodicity effects, is investigated....

  19. Vocabulary Acquisition for Future Nursing Staff: authenticity in the classroom

    Directory of Open Access Journals (Sweden)

    Kirsten Hempkin

    2015-11-01

    Full Text Available Research suggests that many ESL teachers either modify or supplement the set textbooks they use in class, or develop their own materials for classroom use. Indeed, in recent years, the internet in particular has opened up a rich and at times perhaps baffling array of resources for those ESL practitioners who wish to incorporate authentic materials into their teaching. While the benefits of authentic materials are well-documented, their use is, however, not entirely unproblematic, and as research into the field of material (authentic or otherwise development grows, this raises a number of issues as to the form these materials should take and how they can best be employed. This article presents a set of vocabulary building activities for future nursing staff; these activities are in use at the Faculty of Health Sciences in Maribor. The article explains the rationale behind them in light of the theoretical framework of language acquisition that underpins them.

  20. A Trust Model Based on Service Classification in Mobile Services

    CERN Document Server

    Liu, Yang; Xia, Feng; Lv, Xiaoning; Bu, Fanyu

    2010-01-01

    Internet of Things (IoT) and B3G/4G communication are promoting the pervasive mobile services with its advanced features. However, security problems are also baffled the development. This paper proposes a trust model to protect the user's security. The billing or trust operator works as an agent to provide a trust authentication for all the service providers. The services are classified by sensitive value calculation. With the value, the user's trustiness for corresponding service can be obtained. For decision, three trust regions are divided, which is referred to three ranks: high, medium and low. The trust region tells the customer, with his calculated trust value, which rank he has got and which authentication methods should be used for access. Authentication history and penalty are also involved with reasons.