Bundle Configuration Research Articles

Analysis of a Mn–Zn Ferrite Bundle EMI Suppressor Using Different Suppressing Principles and Configurations

A novel round cable electromagnetic interference (EMI) suppressor comprising a bundle of Mn-Zn ferrite tubes was realized using different principles of suppressing, such as direct suppressing, inverting/suppressing, transform/inverting suppressing, and transform/short circuited secondary suppressing. Different primary to secondary configurations were realized for each suppressing principle and characterized in the EMI frequency region. The results obtained for different bundle configurations were compared with known commercial round cable ferrite suppressors and the initial bundle configuration made of a half turn wire through the central ferrite tube of the bundle. The results obtained for different principles and configurations were correlated in order to optimize the electromagnetic coupling between primary and secondary circuits. The values such as maximums of impedance Zm, frequency of maximum impedance Fm and suppressing range Δf around Fm calculated on 0.707 Zm were defined as the main parameters for each configuration. Certain correlations were noticed between impedance Zm and frequency Fm changes. Finally, the realized configurations were considered as devices suitable for EMI suppressing applications.

Techno-economic analysis of tube bundle orientation for high capacity brine recycle MSF desalination plants

As of today, the Multi Stage Flash (MSF) evaporator capacity has reached to 20 MIGD of desalinated water using traditional brine recycle and cross tube bundle configuration. However, on the way of scaling-up evaporator unit production beyond 20 MIGD, there are some technical barriers and economical aspects that need to be considered. This work presents a techno-economic comparison between long tube (LT) and cross tube (CT) bundles of MSF evaporator for a unit production of equal and greater than 20 MIGD.Process calculations showed that the heat transfer surface area of MSF-LT is 25% lower than that of MSF-CT. This is mainly owing to an enhancement in heat transfer process. The pumping power in LT evaporator decreases by 8% due to the lower friction loss. For a large size project of 100 MIGD, the saving in the total capital investment of MSF-LT evaporator is 15% lower than that of MSF-CT. The operating cost is the same.A novel layout of MSF-LT configuration is proposed in which the stages are arranged in triple decks to reduce the footprint up to 51%. The novel configuration enables a significant reduction in the water box size and numbers.

Assessing the power transfer performance of a lattice tower overhead line system

This study examines the overall performance of overhead power lines (OHL) considering their electro-mechanical properties, with a focus on lattice tower structures. Performance analysis of commonly used aluminium alloy conductors on a 275 kv lattice tower system and subsequent comparison with the corresponding performance of the conductors on a 33 kV wood pole structure highlights the effect of the OHL structure strength on overall system performance. Further results from the analysis of the lattice tower structure help to evaluate the effect of span length, conductor weight and bundle configuration on OHL system performance. Finally, a holistic analysis illustrating the benefits of the use of novel conductors on lattice tower structures at ‘normal’ operating temperatures to avoid increased losses is reported and discussed.

Numerical Analysis of Flow and Heat transfer in Sub-channel of Supercritical Water Reactor

Investigation on the thermal-hydraulic behaviour in the High performance Light Water Reactor (HPLWR) fuel assembly has obtained a significant attention in GENERATION-IV. In this paper, CFD analysis is carried out to study the heat transfer behaviour of supercritical water in sub-channels of squared annular assembly. Effect of various parameters, e.g. thermal boundary conditions and pitch-to-diameter ratio on the thermal–hydraulic behaviour is investigated. Boundary conditions, i.e., constant heat flux at the outer surface of cladding are applied. The effect of pitch-to-diameter ratio (P/D) on the distributions of surface temperature and heat transfer coefficient (HTC) was analyzed .For typical (gap between two rod) channel analysis, it is found that HTC increases with p/d first and then decreases significantly when p/d is <1.2. If P/D is larger than 1.2 heat transfer deterioration (HTD) occurs as main stream enthalpy is quite small. One/eight channel of 40 pin fuel assembly show that the structure of the secondary flow mainly depends on the rod bundle configuration as well as the pitch-to-diameter ratio, whereas, the amplitude of the secondary flow is affected by the thermal boundary conditions, as well. Furthermore, the HTD under wire-wrapped spacer were evaluated.

Boiling on a Tube Bundle: Part II—Heat Transfer and Pressure Drop

An extensive experimental study was undertaken to measure nucleate pool boiling heat transfer coefficients, local bundle boiling heat transfer coefficients, and two-phase bundle pressure drops for R134a and R236fa on one plain tube bundle configuration. The experimental database allowed the refinement of frictional pressure drop models previously developed at the Laboratory of Heat and Mass Transfer. Together with the new onset of dryout prediction method presented in part I (preceding article in this issue), this constitutes a significant improvement in such prediction methods. The local bundle boiling heat transfer data highlighted the dependency of the heat transfer coefficient on the heat flux as expected for the present conditions. The new method was proposed and worked well versus the present database and was also validated against additional refrigerants from independent studies. It was proven to also work reasonably well for falling film evaporation data, proving the new prediction method is applicable for a wide range of operating conditions.

Carbon nanotube bundles under electric field perturbations

Here we address the important role played by electric fields applied in carbon nanotube bundles in providing convenient scenarios for their use in electronic devices. We show that a gap modulation may be derived depending on the bundle configuration and the details of the applied field configuration. The system is described by a tight binding Hamiltonian and the Green function formalism is used to calculate the local density of states. Small bundles were used to validate our model on the basis of ab initio calculations. Further analysis shows that the number of tubes, geometrical configuration details and field intensities may be controlled to tune the electronic structure close to the Fermi energy, envisaging atomic-scale devices.

Heat transfer in high volume fraction CNT nanocomposites: Effects of inter-nanotube thermal resistance

Monte Carlo simulations were employed to investigate the effective thermal conductivity of carbon nanotube–polystyrene (CNT–PS) nanocomposites at different wt.% of CNT loadings and temperatures. By validating with experimental data, values of phonon transmission probability as well as Kapitza resistance at the CNT–PS interface and at the CNT–CNT contact were calculated. In addition, the observed poor enhancement of thermal conductivity at high CNT concentrations was found to be the result of the CNT–CNT thermal resistance and of the bundle configuration.

Dark-field illuminated reflectance fiber bundle endoscopic microscope

We propose a reflectance fiber bundle microscope using a dark-field illumination configuration for applications in endoscopic medical imaging and diagnostics. Our experiment results show that dark-field illumination can effectively suppress strong specular reflection from the proximal end of the fiber bundle. We realized a lateral resolution of 4.4 μm using the dark-field illuminated fiber bundle configuration. To demonstrate the feasibility of using the system to study cell morphology, we obtained still and video images of two thyroid cancer cell lines. Our results clearly allow differentiation of different cancer cell types.

MIND: A Nonparametric Decision Fusion Method for Accurate Indoor Localization using Sensors with Monotonically Increasing Error Functions

A nonparametric fusion method for extracting accurate distance measurements from low-quality sensors is proposed. The method applies to sensors with error functions that are monotonically increasing with respect to (w.r.t.) the actual value to be measured (arguments are presented on why a monotonically increasing error function is something to be expected with range-estimating sensors). The proposed method has been developed in order to enhance the performance of localization systems that utilize commercially available sensors for range estimation to achieve localization through triangulation of range estimates. The proposed method is based on evaluating multiple sensor measurements and using the minimum measured distance as a more efficient estimate of the real distance compared with calculating and selecting the distance average. Thus, the proposed method is code-named MIND (from MINimum Distance). It is shown analytically that MIND outperforms, in terms of location estimation accuracy, the sensor with the minimum mean error when used in a multi-sensor configuration. An experimental testbed consisting of four Cricket sensors in a symmetric bundle configuration was used to evaluate the MIND fusion method experimentally. For each Cricket sensor, performance characteristics were established through extensive laboratory analysis and were found to yield highly inaccurate range estimates. However, when these low-quality Cricket sensors were fused in a four-sensor symmetric configuration, it was shown experimentally that the MIND fusion method exhibits near-optimal performance and largely overcomes most of the flaws of the underlying low-quality Cricket sensors, delivering a localization solution of extended accuracy, availability, and robustness.

Experimental and calculation results of the integral reflood test QUENCH-14 with M5® cladding tubes

The QUENCH-14 experiment investigated the effect of M5® cladding material on bundle oxidation and core reflood, in comparison with tests QUENCH-06 (ISP-45) that used standard Zircaloy-4 and QUENCH-12 that used VVER E110-claddings. The PWR bundle configuration of QUENCH-14 with a single unheated rod, 20 heated rods, and four corner rods was otherwise identical to QUENCH-06. The test was conducted in principle with the same protocol as QUENCH-06, so that the effects of the change of cladding material could be observed more easily. Pre-test calculations were performed by the Paul Scherrer Institut (Switzerland) using the SCDAPSIM, SCDAP/RELAP5 and MELCOR codes. Follow-on post-test analyses were performed using SCDAP/RELAP5 and MELCOR as part of an ongoing programme of model validation and code assessment. Alternative oxidation correlations were used to examine the possible influence of the M5® cladding material on hydrogen generation, in comparison with Zircaloy-4. The experiment started with a pre-oxidation phase in steam, lasting ∼3000 s at ∼1500 K peak bundle temperature. After a further temperature increase to maximum bundle temperature of 2073 K the bundle was flooded with 2 g/s/rod water from the bottom. The peak temperature of ∼2300 K was measured on the bundle shroud, shortly after quench initiation. The electrical power was reduced to average value of 2 W/cm during the reflood phase to simulate effective decay heat level. Complete bundle cooling was reached in 300 s after reflood initiation. The development of the oxide layer growth during the test was essentially defined by measurements performed on the three Zircaloy-4 corner rods withdrawn successively from the bundle. The withdrawal of Zircaloy-4 and E110 corner rods after the test allowed a comparison of the different alloys in one test. One heated rod with M5 cladding was withdrawn after the test for a detailed analysis of oxidation degree and measurement of absorbed hydrogen. Post-test examinations showed neither breakaway cladding oxidation nor noticeable melt relocation between rods. Different from the QUENCH-14 (M5®) findings, the QUENCH-12 test with the E110 claddings performed under similar conditions had resulted in intensive breakaway effect at cladding and shroud surfaces during the pre-oxidation phase and local melt relocation on reflood initiation. The hydrogen production in QUENCH-14 up to reflood was similar to QUENCH-06 and QUENCH-12 bundle tests. During reflood 6 g hydrogen were released which is similar to QUENCH-06 (4 g) but much less than during quench phase of QUENCH-12 (24 g). The reason for the different behaviour of the Zr1%Nb cladding alloys is the different oxide scale properties of the materials.

Influence of hair bundle configuration on biomimetic hair sensor sensitivity.

Hair cells are the sensory receptors of the auditory system. When the stereocilia (hair buddles) sitting on top of the hair cells are stimulated, a current flows through the hair cell transducing mechanical stimuli into electrical response. For the outer hair cell (OHC), the hair bundles are stimulated by displacement of the tectorial membrane relative to the reticular lamina. For the inner hair cell (IHC), the hair bundles are stimulated by force due to motion of the fluid around the hair bundle. In addition, OHC and IHC hair bundles are shaped differently. In this paper, biomimetic micromachined hair sensors are designed, fabricated, and tested to investigate how the configurations of the hair bundles affect the sensitivity of the hair sensor. These hair sensors use a capacitive scheme and have different hair configurations including the W and U shape representing OHC and IHC hair bundles. Computational results achieved to date indicate that sensitivity can be strongly affected by the placement of the engineered hair bundles. Microfabrication and experimental work are ongoing.

A multiple-bundle model to characterize the mechanical behavior of the cruciate ligaments

Measurements of elongations of the cruciate ligaments have been used to study the behaviors of these ligaments in-vitro and in-vivo, mostly based on simplified two-bundle models of the cruciates. The complex fiber anatomy of the cruciates may suggest a complex deformation behavior across the continuum of their substance that cannot be captured by only two measurement points. In this study, a new methodology was introduced to include more detailed fiber anatomy and to take into consideration the wrapping of the PCL around the intercondylar notch of the femur in deep flexion. The method was used in comparison to the conventional two-bundle models on three sample cadaver knees that underwent a passive flexion up to 150°. The elongation ratios of the bundles were measured as the ratio of change in the length of the bundles over their lengths at 0° flexion. The multiple-bundle models showed ranges of variations across the attachment sites of the cruciates which at all flexion angles were significantly larger than those observed from the conventional two-bundle models. When expressed in percentages, at 150° flexion the ranges of variations in the elongation ratio of the bundles were 32.7% ± 31.9% and 34% ± 8.6% for the ACL and PCL, respectively. Results of this study showed that important variations of elongation across the body of the cruciates can be obscured to the conventional two-bundle model of the cruciates, and therefore a more detailed bundle configuration is suggested for the purpose of studying elongation behaviors of these ligaments.

Porous Medium Modeling of Air-Cooled Condensers

This article presents a porous media transport approach to model the performance of an air-cooled condenser. The finned tube bundles in the condenser are represented by a porous matrix, which is defined by its porosity, permeability, and the form drag coefficient. The porosity is equal to the tube bundle volumetric void fraction and the permeability is calculated by using the Karman–Cozney correlation. The drag coefficient is found to be a function of the porosity, with little sensitivity to the way this porosity is achieved, i.e., with different fin size or spacing. The functional form was established by analyzing a relatively wide range of tube bundle size and topologies. For each individual tube bundle configuration, the drag coefficient was selected by trial and error so as to make the pressure drop from the porous medium approach match the pressure drop calculated by the heat exchanger design software ASPEN B-JAC. The latter is a well-established commercial heat exchanger design program that calculates the pressure drop by using empirical formulae based on the tube bundle properties. A close correlation is found between the form drag coefficient and the porosity with the drag coefficient decreasing with increasing porosity. A second order polynomial is found to be adequate to represent this relationship. Heat transfer and second law (of thermodynamics) performance of the system has also been investigated. The volume-averaged thermal energy equation is able to accurately predict the hot spots. It has also been observed that the average dimensionless wall temperature is a parabolic function of the form drag coefficient. The results are found to be in good agreement with those available in the open literature.

Does firm performance reveal its own causes? the role of Bayesian inference

AbstractA central problem in strategic management is how the inference ‘sustainable competitive advantage generates sustainable superior performance’ can be put into practice. In this article we develop a theoretical framework to understand the causal relationships among (1) sustainable competitive advantage, (2) configuration, (3) dynamic capability, and (4) sustainable superior performance. We propose that a firm's competitive advantage, resource bundle configuration, and dynamic learning capability cannot be comprehended by outsiders. Its operational performance, however, can be captured by financial indicators. We promote an inductive Bayesian interpretation of the sustainable competitive advantage proposition. From this viewpoint, the presence or absence of competitive advantage may be reflected in the causal relationship between resource configuration, dynamic capability, and observable financial performance. We apply this theoretical framework to an example drawn from the global semiconductor industry, an area in which resource configuration and dynamic capability are essential to performance. The paper concludes with a summary of the proposed model and suggestions for future theoretical development of strategic management. Copyright © 2009 John Wiley &amp; Sons, Ltd.

Observation of Suspended Carbon Nanotube Configurations Using an Atomic Force Microscopy Tip

Mechanical behaviors of suspended carbon nanotubes (CNTs) or their bundles over a trench fabricated on a Si substrate were investigated by monitoring the oscillation amplitude of an atomic force microscopy (AFM) tip that interacts with the CNTs. The amplitude was considered as a function of the vertical distance between the center of the oscillating tip and the equilibrium position of the CNTs. The amplitude–distance curve (AD curve) obtained in air is interpreted as a simple model that includes the mechanical response of the suspended CNTs to the oscillating tip, the attachment/detachment of the CNTs onto the tip surface, and the oscillation of the CNTs attached to the tip. Dependences of AD curves on CNT length, bundle configuration, and the type of environment during the oscillation were investigated, and it has been found that this technique can be applied to the in situ monitoring of CNT arrangements during the manipulation of CNT networks.

An analytical approach to bundling in the presence of customer transition effects

Service product bundling is a widespread practice in current e-commerce environment. While many studies have examined optimal bundling and pricing in a static time domain, there has been a lack of attention to the dynamic nature of customer transition among bundles and the consequent long-term strategy. This paper considers subscription-based service bundling problem. In this context, an existing customer can choose the same bundle or switch to another bundle, whereas a new customer can adopt any of the bundles that are being offered. An analytical model that explicitly captures the customer transition over multiple time periods is developed using a dynamic systems approach. Using this model, we analyze the effect of adoption, retention, and switching simultaneously on optimal bundle configuration and pricing. We discuss several managerial insights, along with numerical examples and validating simulations, which are relevant to bundling strategy. We provide analytical results which enable an effective and efficient decision support tool to predict future demand stream for different bundles. We present a monotonicity property for the optimality condition which significantly reduces the computational burden.

CFD analysis of thermal–hydraulic behavior in SCWR typical flow channels

Investigations on thermal–hydraulic behavior in SCWR fuel assembly have obtained a significant attention in the international SCWR community. However, there is still a lack of understanding and ability to predict the heat transfer behavior of supercritical water. In this paper, CFD analysis is carried out to study the flow and heat transfer behavior of supercritical water in sub-channels of both square and triangular rod bundles. Effect of various parameters, e.g. thermal boundary conditions and pitch-to-diameter ratio on the thermal–hydraulic behavior is investigated. Two boundary conditions, i.e., constant heat flux at the outer surface of cladding and constant heat density in the fuel pin are applied. The results show that the structure of the secondary flow mainly depends on the rod bundle configuration as well as the pitch-to-diameter ratio, whereas, the amplitude of the secondary flow is affected by the thermal boundary conditions, as well. The secondary flow is much stronger in a square lattice than that in a triangular lattice. The turbulence behavior is similar in both square and triangular lattices. The dependence of the amplitude of the turbulent velocity fluctuation across the gap on Reynolds number becomes prominent in both lattices as the pitch-to-diameter ratio increases. The effect of thermal boundary conditions on turbulent velocity fluctuation is negligibly small. For both lattices with small pitch-to-diameter ratios ( P/ D < 1.3), the mixing coefficient is about 0.022. Both secondary flow and turbulent mixing show unusual behavior in the vicinity of the pseudo-critical point. Further investigation is needed. A strong circumferential non-uniformity of wall temperature and heat transfer is observed in tight lattices at constant heat flux boundary conditions, especially in square lattices. In the case with constant heat density of fuel pin, the circumferential conductive heat transfer significantly reduces the non-uniformity of circumferential distribution of wall temperature and heat transfer, which is favorable for the design of SCWR fuel assemblies.

NUMERICAL SIMULATION OF AN IN-LINE TUBE BUNDLE USING THE URANS APPROACH

ABSTRACTIn the present work, a turbulent flow across a square in-line tube bundle is computedusing the Unsteady Reynolds Averaged Navier-Stokes (URANS) approach. The pitchratio used in the tube bundle configuration is P/D=T/D=1.44 and the Reynolds numberis 70000 based on tube diameter. Both 2D and 3D computational domains areconsidered. Turbulence models tested include the standard k–e model of Jones et al.[12], the k-ω Shear Stress Transport (SST) model of Menter [10] and the ReynoldsStress Model of Speziale et al. [11] (SSG). In addition, the recently developed, SST- as Cmodel by Revell [1] is also tested. The unstructured industrial code Code-Saturne hasbeen used for the present study. In general, the flow predictions using the 2D grid fail tocapture correctly the general flow physics; while on the other hand, the 3D calculationsgive predictions of pressure fields and velocity profiles that are in broad agreement withboth LES results [2] and the more recent experimental data [4]. With regards toturbulence models, a comparison of the pressure coefficient and velocity profilesrevealed that the SST- as C and RSM models, both seem to give reasonable predictionsof the flow, capturing the asymmetric behaviour of the flow as the reference data. Asexpected, the standard κ – e model fails to capture this behaviour and predicts a rathersymmetric flow field. The pressure spectra from the SST- as C calculation indicates asingle clear peak at around the frequency 45Hz (St=0.84), similar to that observed inLES predictions. This suggests that both large and small re-circulations coexist on thewake of centre tubes resulting in the shear stress to be higher in the bottom than on thetop of the tubes.

Tow Methods for Deepwater Riser-Tower Transportation in West-of-Africa Environment

This article, written by Technology Editor Dennis Denney, contains highlights of paper OTC 17892, "Novel Tow Methods for Deepwater Riser-Towers Transportation in West-of-Africa Environment," by R. Di Silvestro, F. Casola, G. Fatica, A. Mameli, and A. Prandi, Saibos SAS, prepared for the 2006 Offshore Technology Conference, Houston, 1–4 May. Riser towers are characterized by very low service-fatigue damage in deep-water fields with floating production facilities. However, transportation from the fabrication yard to site can be of concern. This phase can use a significant portion of the allowable fatigue damage. Longer tow distances use more of the allowable fatigue damage. Two tow configurations that minimize the fatigue damage and allow longer tow distances are presented. Introduction The use of riser towers in deepwater fields west of Africa has increased in recent years. In addition to low service-fatigue damage, high thermal performance and the ability to accommodate many risers and umbilicals are advantages over the more traditional riser concepts. The presence of a floating production, storage, and offloading (FPSO) vessel is not required before installation of the tower, improving the installation sequence and reducing the time to first oil production after the FPSO arrives. Transportation of the tower from the fabrication yard to the field is a critical operation that consumes much of the allowed fatigue. Management of towing is a key aspect in this phase of the oil industry driven by the growing distance between fabrication and installation sites as new fields are found in deeper waters. Two tow methods were developed for transporting the riser tower developed in line with the bundle-hybrid-offset-riser (BHOR) concept. Both surface and submerged configurations were considered to mitigate the dynamic-fatigue response of the tower to wave periods and facilitate tow operation lasting many days. BHOR Overview The BHOR is based on the steel-hybrid-riser concept and is a freestanding assembly with several risers in a bundle configuration. In Fig. 1, the assembly is top tensioned by a buoyancy tank and anchored to the seabed by means of a gravity-skirted foundation. The connection of the bundle main section (BMS) to the seabed foundation is made by means of a mechanical flexible joint similar to that used for a tension-leg-platform tendon that is able to accommodate the small angular excursions of the bundle with a limited stiffness. A similar connection is used to connect the buoyancy tank to the top part of the tower. The buoyancy tank is a standalone structure that is installed after the upending of the BMS and docking it to the foundation. The buoyancy-tank structure is derived from the typical pressure-vessel design. The schedules for fabrication and installation of the bundle and the buoyancy tank are independent.

Flow distribution analysis by helical scanning in polysulfone hemodialyzers: Effects of fiber structure and design on flow patterns and solute clearances

The efficiency of a hemodialyzer is largely dependent on its ability to facilitate diffusion, as this is the main mechanism by which small solutes are removed. The diffusion process can be impaired if there is a mismatch between blood and dialysate flow distribution in the dialyzer. The objective of the paper was to study the impact of different fiber bundle configurations on blood and dialysate flow distribution and urea clearances. The Optiflux 200 NR hemodialyzer was studied and the standard F 80 A hemodialyzer was used as a control for the study. Six dialyzers of each type were studied in vitro in the radiology department utilizing a new generation of helical computed tomography (CT) scan following contrast medium injection into the blood and dialysate compartment. Dynamic sequential imaging of longitudinal sections of the dialyzer was undertaken to detect flow distribution, average and peak velocities, and calculate wall shear rates. Six patients were dialyzed with 2 different dialyzers in random consecutive sequence. In these patients, 2 consecutive dialyses were carried out with identical operational parameters (Qb = 300 mL/min, Qd = 500 mL/min). In each session, blood and dialysate side urea clearances were measured at 30 and 150 min of treatment. Macroscopic and densitometrical analysis revealed that flow distribution was most homogeneous in the dialyzer with a new bundle configuration. Significantly increased urea clearances (p < 0.001) were seen with the Optiflux dialyzer compared with the standard dialyzer. In conclusion, more homogeneous dialysate blood and dialysate flow distribution and improved small solute clearances can be achieved by modifying the configuration of the filter bundle. These effects are achieved probably as a result of reduced blood to dialysate mismatch with reduction of flow channeling. The used radiological technique allows detailed flow distribution analysis and has the potential for testing future modifications to dialyzer design.