Energy Technology Data Exchange (ETDEWEB)

Corrosion is a materials degradation process that engineering personnel in the pulp and paper industry have had to accept as unavoidable to some degree, due to aggressive processing conditions prevalent in paper mills. The increasing incidence of corrosion-related failures in plant and equipment has resulted in the introduction of new techniques to monitor corrosion rates, since many of the more traditional methods do not provide data that is either recent or accurate enough. Thin layer activation (TLA) is a new corrosion monitoring technique which has recently been employed to measure corrosion trends inside a continuous pulp digester. With TLA a surface is irradiated by a particle beam from a nuclear accelerator, causing it to be labelled with an accurate depth profile and low level radioactivity. By monitoring this activity, it is possible to calculate how much of the surface has been removed by corrosion. 14 refs., 7 figs., 4 tabs.

Energy Technology Data Exchange (ETDEWEB)

Within the framework of the IEA project Annex 20 - Airflow patters within buildings , an airflow data base was built up as a prototype. It enables airflow profiles, comfort and interior air quality to be studied without having to carry out a 1:1 experiment or having to run an expensive simulation code. The data base contains a number of pre-calculated room airflow profiles with their associated depictions of air quality and risks of drafts for given premises and for different ventilation systems. figs., tabs., refs.

Science.gov (United States)

The adequacy of the nasopharyngeal airway has been found to be related to craniofacial development. Obstruction of the airway by adenoid tissue, nasal septal deviation or abnormal morphology of the area is associated with characteristic changes in craniofacial morphology such as long anterior face height, facial retrognathism, and a steep inclination of mandibular plane often with a high vaulted palate and crossbite. Some studies have shown the changes to be reversible after adenoidectomy which improves nasal airway patency and a control mechanism for facial growth has been proposed to account for the relationships between airway adequacy, craniofacial morphology and craniocervical postural relationships. It is therefore important to be able to measure nasal respiratory resistance so that the effect of operative procedures in the area such as rapid maxillary expansion (RME) can be determined. Nasal respiratory resistance (NRR) is a measure of airway adequacy. It can be recorded by ...

International Nuclear Information System (INIS)

The cross section and activity profile of different radioisotopes produced by #alpha#-induced nuclear reaction on natural zirconium, have been obtained by stacked foil activation using 40 MeV #alpha#-particles from Variable Energy Cyclotron (VEC) machine at Calcutta. The activity profile would be used to study the surface loss of zircaloy materials of engineering components by thin layer activation (TLA) technique. Generally, isotopes with suitable #gamma#-rays and long half-lives are the most useful in TLA technique, e.g., "9"2Nb, "9"5"gNb and "9"5Zr. (author). 2 refs., 1 tab.

KoreaScience (Korea)

Full Text Available

UK PubMed Central (United Kingdom)

BackgroundLymphangioleiomyomatosis (LAM) is a rare lung disease characterised by progressive airflow obstruction. No effective medical treatment is available but therapy with sirolimus...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Experimental and numerical investigations were performed for the laminar burning velocity and the flame structure of laminar premixed CH{sub 4}/O{sub 2}/CO{sub 2} flames. Measurements of the laminar burning velocity were conducted by using a flame cone angle method for a circular nozzle burner. Numerical simulation was performed using one-dimensional plane flame code including radiation heat loss with an optically thin model. It was shown that the laminar burning velocity decrease with CO{sub 2} addition even though the adiabatic flame temperature is the same as that for CH{sub 4}/Air flames. The radiation heat loss is significant for the CH{sub 4}/O{sub 2}/CO{sub 2}, flames, and the flame temperature and laminar burning velocity decreases when the radiation heat loss is considered. Effects of thermal properties, radiation, and chemical reaction on the determination of the ...

Energy Technology Data Exchange (ETDEWEB)

Apparatus for minimizing thermal loss in a windowless, open cavity solar receiver due to airflow at the receiver aperture includes means for deflecting wind away from the cavity opening such that flow stream reattachment occurs away from the receiver aperture to provide a dead air zone at the cavity opening. This prevents turbulent-mixing airflow exchange between ambient air and heated air within the solar receiver. The wind deflector apparatus includes either a passive annular deflection foil at the receiver aperture, or an active device for producing an outwardly projected air jet at the receiver aperture.

International Nuclear Information System (INIS)

This paper presents direct measurements of the aerodynamic forces on the wing of a free-flying, insect-like ornithopter that was modeled on a hawk moth (Manduca sexta). A micro differential pressure sensor was fabricated with micro electro mechanical systems (MEMS) technology and attached to the wing of the ornithopter. The sensor chip was less than 0.1% of the wing area. The mass of the sensor chip was 2.0 mg, which was less than 1% of the wing mass. Thus, the sensor was both small and light in comparison with the wing, resulting in a measurement system that had a minimal impact on the aerodynamics of the wing. With this sensor, the 'pressure coefficient' of the ornithopter wing was measured during both steady airflow and actual free flight. The maximum pressure coefficient observed for steady airflow conditions was 1.4 at an angle of attack of 30"0. In flapping flight, the coefficient was around 2.0 for angles of attack that ranged from 25"0 ...

Energy Technology Data Exchange (ETDEWEB)

During thirty years the techniques used for sensing the environment have changed dramatically. This paper describes the latest generation of sensors available. This new generation of sensors includes those two most critical gas sensors for methane and carbon monoxide and new sensors for airflow and air temperature. When these sensors are combined with the new sensors for machine condition monitoring it forms the heart of the Sentex system. 2 figs.

Science.gov (United States)

Numerical solutions for fully developed laminar flow in internally finned tubes with trapezoidal and triangular fin profiles were given with Finite Element Method (FEM): The heat transfer characteristics were obtained and compared under the boundary conditions of uniform heat flux, uniform wall temperature, and the third boundary condition with finite wall thermal conductivity considered. The numerical results show that boundary conditions have pronounced effects on the temperature field. Furthermore, a new mechanism on the heat transfer augmentation of internally finned tubes is proposed.

International Nuclear Information System (INIS)

Activation has been used for many kinds of useful applications, such as use of the radioisotopes for diagnosis and treatment of cancer, and wear (or corrosion) investigation for using thin layer activation (TLA) technique, etc. But activation also has severe problems for the post-processing of the samples; such as time-loss, inconvenience of sample handling, personal radiation safety, etc. For in-vitro experiments, we observed death of tumor cells by proton irradiation. The use of large activated container material can cause erroneous results in this case. To solve these problems, we studied why the samples were activated and how the level of the activation could be reduced. In proton beam irradiation experiments, the target materials could be defined as the container and sample itself. We could easily reduce activation of container material comparing to activation of sample itself. Therefore, we tried to find less activated container material by irradiating proton ...

Energy Technology Data Exchange (ETDEWEB)

An experimental campaign, aiming to investigate the perturbation effects induced by fixed obstacles on turbulence measurements in airflows at the air-sea interface, was carried out at the marine platform of the Italian Navy, located in the harbour of La Spezia (North Ligurian Sea, Italy) on 28., 29., and 30. June 1994. This study was prompted by the ever-growing interest in more reliable estimates of energy, mass, and momentum exchanges between water surfaces and atmosphere, whose measurements are severely limited by the geometrical constraints of floating or fixed platforms where they are installed. Two types of meteorological instruments have been used: fast response (20 and 21 Hz) ultrasonic anemometers and fluxmeters to measure turbulent momentum, sensible, and latent heat fluxes and slow-response sensors (less than 4 Hz and sampled at a rate of 10{sup 2} Hz) to measure average wind and temperature vertical profiles in the perturbed boundary layer. Both fast- ...

Energy Technology Data Exchange (ETDEWEB)

Four classrooms of two secondary schools located around Lyon in France have been monitored. The objectives are to analyse the quality of the indoor air and the thermal comfort and also the behaviour of the occupants towards opening of the windows. This paper briefly describes the context and the nature of the monitoring campaign, and presents the results of the measurements with direct interpretation of the ventilation needs. Results from this study show that allowable CO{sub 2} levels are overpassed several times in a school day. The presence of a mechanical ventilation system leads to lower peaks but the fresh airflow is too small to prevent an indoor confining, that is also revealed by the aerobiological analysis. (author)

CERN Document Server

We present an analytical model for jets in Fanaroff & Riley Class I (FRI) radio galaxies, in which an initially laminar, relativistic flow is surrounded by a shear layer. We apply the appropriate conservation laws to constrain the jet parameters, starting the model where the radio emission is observed to brighten abruptly. We assume that the laminar flow fills the jet there and that pressure balance with the surroundings is maintained from that point outwards. Entrainment continuously injects new material into the jet and forms a shear layer, which contains material from both the environment and the laminar core. The shear layer expands rapidly with distance until finally the core disappears, and all of the material is mixed into the shear layer. Beyond this point, the shear layer expands in a cone and decelerates smoothly. We apply our model to the well-observed FRI source 3C31 and show that there is a self-consistent ...

Science.gov (United States)

The flow and heat transfers associated with a plane laminar flow past a forward-facing step were analyzed using a power-law numerical scheme combined with a false vorticity-stream function approach. To improve the traditional wall-vorticity boundary condition, a novel method, based on an accurate description of the nonslip wall condition, was developed and utilized. The convergence for a 56 x 49 grid system was obtained in about 350 iterations. The computed reattachment distances in the upper separated region agree with the available experimental data for a blunt plate. The heat transfer augmentation is significant across the step; however, it is counterbalanced by the deterioration of heat transfer immediately upstream of the step.

Science.gov (United States)

Numerical results on aeroelastic standard configurations are presented. The methods used for two dimensional configurations include the small perturbations approach for inviscid flow, coupling methods for unseparated flow, coupling methods for unseparated or separated, laminar or turbulent boundary layers, and a numerical solution of the Euler equations for inviscid flow. The three dimensional configurations are studied by the transonic small disturbance approach. The detailed results are given.

Energy Technology Data Exchange (ETDEWEB)

A correlation was developed for laminar film condensation on vertical fluted surfaces. The theoretical analysis of Panchal and Bell was used for defining important physical property groups. The experimental data of Combs et al. were used to validate the proposed correlation. The experimental database used in the present study included four flute geometries that could be approximated to cosine-type flutes and seven fluids. The resulting correlation can predict the average condensate heat transfer coefficient within {+-}20%.

International Nuclear Information System (INIS)

This book presents the papers given at a conference on two-phase flow. Topics considered at the conference included the thermal hydraulics of a feedwater pipe breakage, pressure losses, measurement of void fraction in a rod bundle, laminar filmwise condensation, natural circulation, flow models, bubble dynamics, cavitation, water hammer, and heat transfer augmentation.

Science.gov (United States)

Natural laminar-flow (NLF) airfoils are those which can achieve significant extents of laminar flow (greater than or equal to 30% chord) solely through favorable pressure gradients. Studies have shown that vertical-axis wind turbines (VAWTs) using NLF sections as blade elements have the potential of producing energy at a significantly lower cost (approx. =20%) than turbines of current design. Sandia National Laboratories (SNL) is now in the process of procuring a blade set for its 17-m-diameter research turbine which will use NLF sections as blade elements. This paper describes the design of this blade set. The blade set design began with the definition of a family of three approximately 50% chord NLF sections (15, 18, and 21% t/c). These definitions involved numerically establishing airfoil contours giving section characteristics anticipated to be favorable in the VAWT context and then screening these using a VAWT performance model. Field ...

International Nuclear Information System (INIS)

The surface permeability of concrete walls and floors in houses was measured with a specially designed permeameter, based on measuring the air-flow induced by a pressure difference across a temporary test seal applied to a surface. The permeability of bulk concrete is 10"-"1"6 m"2. Areas free of surface defects had permeability ranging from 10"-"1"4 to 10-"1"6 m"2. However, surface defects are common on concrete wall surfaces, which increase the permeability to >10"-"1"2 m"2. This is too high for standard seal designs to be adequate as the only method of soil gas and radon exclusion. Satisfactory seals require either extended contact width or mechanical removal of the surface layer. (orig.). (2 figs., 1 tab.).

Energy Technology Data Exchange (ETDEWEB)

The data center in this study had a total floor area of 8,580 square feet (ft{sup 2}) with one-foot raised-floors. It was a rack lab with 440 racks, and was located in a 208,240 ft{sup 2} multi-story office building in San Jose, California. Since the data center was used only for testing equipment, it was not configured as a critical facility in terms of electrical and cooling supply. It did not have a dedicated chiller system but served by the main building chiller plant and make-up air system. Additionally, it was served by a single electrical supply with no provision for backup power. The data center operated on a 24 hour per day, year-round cycle, and users had all hour full access to the data center facility. The study found that data center computer load accounted for 23% of the overall building electrical load, while the total power consumption attributable to the data center including allocated cooling load and lighting was 30% of the total facility load. The density of ...

DEFF Research Database (Denmark)

It is well established from experiments in premixed, laminar flames, jet-stirred reactors, flow reactors, and batch reactors that SO2 acts to catalyze hydrogen atom removal at stoichiometric and reducing conditions. However, the commonly accepted mechanism for radical removal, SO2 + H(+M) reversible arrow HOSO(+M), HOSO + H/OH reversible arrow SO2 + H-2/H2O, has been challenged by recent theoretical and experimental results. Based on ab initio calculations for key reactions, we update the kinetic model for this chemistry and re-examine the mechanism of fuel/SO2 interactions. We find that the interaction of SO, with the radical pool is more complex than previously assumed, involving HOSO and SO, as well as, at high temperatures also HSO, SH, and S. The revised mechanism with a high rate constant for H + SO2 recombination and with SO + H2O, rather than SO2 + H-2, as major products of the HOSO + H reaction is in agreement with a range of experimental results from ...

Energy Technology Data Exchange (ETDEWEB)

A numerical study of laminar flow and heat transfer in an array of stacked rectangular plates is presented. The array is placed in a uniform stream, and the plates are subjected to a constant surface heat flux. This flow configuration is relevant to a number of practical heat transfer devices with finned surfaces. The computations were performed using a finite volume solution of the steady, two-dimensional Navier-Stokes equations and energy equation. A numerical scheme that reduces numerical diffusion is used to discretize the equations. The dominant feature of the flow is the separation, and subsequent reattachment of, the boundary layer, which takes place at Reynolds numbers greater than about 75. The separation first occurs downstream of the leading edge of the plate; then as Re increases, the separation point moves upstream and remains fixed at the leading edge, and the reattachment length increases linearly with Re. The appearance and growth of the separation ...

Energy Technology Data Exchange (ETDEWEB)

In order to investigate the effect of humidity on laminar burning velocity(S), the effect of humidity on the combustion reaction and radiation intensity was studied, taking account of dilution gases such as CO/sub 2/ and Ar which has the approximately identical characteristics to exhaust gas circulation(EGR) gas used to prevent NOx discharge from engines. According to the heat reaction theory, mean specific heat(C) of mixture, mean molecular weight(M) and adiabatic flame temperature(T) etc. were said to affect S but from experimental results, the effect of M and C could be ignored, compared with the effect of T. The relationship between S and H/sub 2/O, Ar of CO/sub 2/% in mixture of diluted gases was clarified. The effect of H/sub 2/O on S was mainly caused by changes of T. The effect of radical C/sub 2/, CH and OH on radiation intensity was similar to that of H/sub 2/O and Ar and the effect of H/sub 2/O on combustion was found only to be the physical effect. (10 ...

International Nuclear Information System (INIS)

Presented are the results of the investigation of the kinetics and micromechanism of the failure in impact bending of oriented-crystallized specimens having the eutectic composition Ni_3Al-Ni_3Nb and of the bimetal composed of 45 steel + M3 copper. The failure kinetics was studied by high-speed filming, whereas the fractures were studied by electron fractography. The particularities of the failure of the laminar-type composite materials were found. Analyzed was the effect of the kinetic factors and the mechanism of failure upon its energy consumption.

International Nuclear Information System (INIS)

To encourage the application of robotics technology for routine radiobench applications, a laboratory dedicated to the research and development of contained robotic systems is being constructed. The facility will have several robots located in laminar flow hoods, and the hoods are being designed to allow the possibility for multiple robots to work together. This paper presents both the design features of the hoods and the general layout of the laboratory, and also discusses an application of a robotic system for the routine nuclear counting of gamma tube samples. The gamma tube system is presently operating in one of the routine analysis laboratories. 5 figs.

Science.gov (United States)

Experimental investigation of the length of single burning jets of methane and hydrogen previously diluted with an inert gas (nitrogen or helium) was carried out. Efflux of fuel gases into the atmosphere occurred through cylindrical extension pieces 4 and 8 mm in diameter. The Reynolds numbers at the cut of a piece varied in the range from 400 to 12,000. A clearly defined dependence of the jet length on the quality of the added inert gas is obtained. The correlation of experimental data made it possible to recommend formulas for engineering calculations of free laminar and turbulent jets.

Science.gov (United States)

The present contribution deals with the thermophoresis particle deposition and thermal radiation effects on the flow, heat and mass transfer characteristics in a viscous fluid over a semi-infinite vertical porous plate. The governing boundary layer equations are written into a dimensionless form by similarity transformations. The transformed coupled nonlinear ordinary differential equations are solved numerically by means of the fourth-order Runge-Kutta method with a shooting technique. The effects of different parameters on the dimensionless velocity, temperature, and concentration profiles are shown graphically. In addition, results for the local skin-friction coefficient, the local Nusselt number, and the local Sherwood number are tabulated and discussed.

Energy Technology Data Exchange (ETDEWEB)

The concentric circular annular duct is a common geometry in many fluid flow and heat transfer devices. For the purpose of heat transfer augmentation, fins are often employed in the annular region, and such finned ducts find wide application in compact heat exchangers (5, 6). The analysis of flow and heat transfer in this geometry is, therefore, quite important from an engineering standpoint. For fully developed conditions, the problem has already been analyzed (7-10). However, no results are available for the developing flow in the entrance region. It is with this latter problem that the present paper is concerned.

Energy Technology Data Exchange (ETDEWEB)

This paper deals with the externally coal-fired combined cycle (EFCC). A process simulation for different configurations of the EFCC-process is carried out as well as an investigation of the effect of the key parameters such as the gas turbine inlet temperature and the compressor intake airflow. The results show a promising potential of the efficiency. One component of this combined gas and steam turbine cycle is a high temperature heat exchanger that has to withstand the extrem chemical and thermal operating conditions. Fibre reinforced ceramics and combinations of them with monolithic ceramics seem to be the most promising materials for this application. A cost estimating of the EFCC-process shows that a competitive operation should be possible. (orig.) [Deutsch] Die Ergebnisse der Prozesssimulationen weisen ein vielversprechendes Wirkungsgradpotential des extern kohlebefeuerten Gasturbinenprozesses auf. Der fuer dieses neue Kraftwerkskonzept notwendige ...

Energy Technology Data Exchange (ETDEWEB)

Sheep red blood cells (SRBCs) were labelled with a concanavalin A-luminol-bovine serum albumin conjugate specific for the transmembrane anion transport protein (Band 3) and exposed to 2450-MHz continuous-wave microwave radiation at an average specific absorption rate of 91W/kg for 10 min. The temperature was held constant at 25, 37, 40, 42, or 45C with an airflow heat-exchange system. Following exposure to microwave or air heating, the decrease in residual base-activated chemiluminescence (CL) of the SRBCs was measured as an indication of infield oxidase activity. Air heating resulted in a significant decrease in residual CL at temperatures above 37C (74% decrease at 45C). Microwave radiation inhibited the decline in residual CL above 37C. At 45C the inhibition was 40%. The results suggest microwave radiation either reversibly altered the thermodynamics of oxygen binding to haemoglobin or failed to energize a significant portion of the haemoglobin molecules in each ...

Energy Technology Data Exchange (ETDEWEB)

DF (decontamination factor) of two types of air filter was investigated against /sup 198/Au aerosol particles with AMAD (activity median aerodynamic diameter) = 1.2 ..mu..m and sigmag (geometric standard deviation) = 2.0. One of the filters, SO filter, is HEPA (high efficiency particulate air) filter media with 46 mmphi, and the other is HE-40T (cellulose-glass fiber filter for dust sampling) filter media with 40 mmphi. DF of the SO filter was found to be over 5 x 10/sup 4/ at air flow rate of 1 lmin. And DF of HE-40 T filter was determined to be 94+-4 at the same airflow rate. In the multistage HE-40 T filter system, DF decreased at each succeeding stage. It was confirmed by numerical simulation that the decrease of DF was not inconsistent with the decrease of collection performance in each successive filter. It was also confirmed that DF could be predicted by the numerical simulaiton, if particle penetration function of filter and size distribution function of ...

International Nuclear Information System (INIS)

Sealants for radon-resistant foundation construction must seal the gap between concrete sections. Modern sealants have such low permeability that seal performance depends only on the permeability of the material that contacts the sealant. The surface permeability of concrete walls and floors was measured by a specially designed permeameter, which measures the airflow induced by a pressure difference across a temporary test seal applied to the surface. The permeability of bulk concrete is about 10"-"1"5 m"2. Areas free of surface defects had surface permeability ranging from 10"-"1"4 to 10"-"1"6 m"2. However, surface defects are common on concrete wall surfaces, which increase the permeability to >10"-"1"2 m"2, too high for standard seal designs to be adequate as the only method of soil gas and radon exclusion. Radon-resistant seals require either extended contact widths or mechanical removal of the surface layer and defects. (au) (4 refs.).

Energy Technology Data Exchange (ETDEWEB)

In this paper, a mathematical model for a counterflow wet cooling tower is derived, which is based on one-dimensional heat and mass balance equations using the measured heat transfer coefficient. The balance equations are solved numerically to predict the temperature change of air and water, as well as the humidity as a function of the cooling tower high. Experimental measurements on two pilot-scale cooling towers were carried out in order to analyze the performance of different cooling tower filling materials. Also, the performance of other cooling tower elements, such as droplet separators and water spray nozzles, was investigated in the pilot experiments. The flow distribution, i.e. the velocity field, upstream to the filling material was predicted using the three-dimensional version of the computational fluid dynamics (CFD) code Fluent/UNS, version 4.2. The calculated flow fields are presented for different distances between the inlet of the air and the filling material. In ...

International Nuclear Information System (INIS)

MR images of steady and pulsatile disturbed flow, obtained with use of flow-compensated spin-echo (SE) and cine pulse sequences, revealed excellent flow visualization in three dimensions. Phantoms, built from molds of actual blood vessels, reproduced laminar, disturbed, or turbulent flow. Video recording (VR), performed under conditions equivalent to those of the MR experiments, showed separation zones identical to those seen on SE images. Pulsatile flow studies showed complex patterns of vortical flow on cine images and VR. Varying pulse sequence details changed contrast but not flow patterns. The validation of MR observations by VR has implications for clinical cine imaging and low abnormal signals observed on MR angiograms.

Energy Technology Data Exchange (ETDEWEB)

A catalytic converter of a ceramic monolith honeycomb substrate, coated with a washcoat of catalyst and attached to a natural gas/diesel dual fuel engine was simulated and studied experimentally. The paper describes the application of one-dimensional finite element model for the transient and steady state operation. Laminar flow was approximated using a dispersed plug flow model, and chemical kinetics were simulated using LHHW (Langmuir/ Hinshelwood/ Hougan/ Watson) type expressions. Simulation results were compared with experimental results for heating and cooling cycles which resulted from speed and load changes on the engine. The comparison showed a maximum difference between the two sets of emission levels of about 10 per cent, showing that the one-dimensional model is acceptable model for this dual fuel engine converter combination. 50 refs., 3 tabs., 13 figs.

Energy Technology Data Exchange (ETDEWEB)

As in all vehicles of this type, low weight and aerodynamic drag must be achieved without compromising safety, and in an extremely rugged structure. This has been done by using a chrome-molybdenum steel space-frame, surrounded by a Kevlar/foam sandwich body shell. The solar panel wing, which uses a laminar flow section to obtain low drag, does not tilt except when the vehicle is stationary. A high degree of redundancy is built into the vehicle; for example there are two motors and transmissions, the solar array is divided into seven parallel sub-arrays, and the power electronics is multiply redundant. Built entirely in the garage of a suburban house, the Australian Geographic Team Marsupial car cost less than US$50,000 to construct.

British Library Electronic Table of Contents (United Kingdom)

A three-dimensional numerical study is performed to explore the effect of pulsed spanwise-periodic surface thermal perturbation (also denoted as thermal bump) in a Mach 1.5 flat plate laminar boundary layer. A high-resolution upwind-biased Roe method is used with the compressive Van Leer harmonic limiter on a suitably refined mesh. The dependence of flow stability characteristics on the variation of thermal bump geometry (shape and dimension) and pulsing properties (disturbance amplitude and frequency) is assessed. It is shown that the finite-span thermal bumps generate streamwise vortices. When the thermal bump is pulsed, vortex shedding is observed, and the streamwise vorticity grows with the downstream distance. Analysis of the integrated disturbance energy indicates that the streamwise...

Energy Technology Data Exchange (ETDEWEB)

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

British Library Electronic Table of Contents (United Kingdom)

Beaked whales (Ziphiidae) often show highly specialized features, involving bone morphology or structure, in the rostral region of their skulls. Previous studies revealed an extremely derived and peculiar histological structure in the rostrum of the extant Mesoplodon densirostris. In order to assess if this structure is a general feature of ziphiids, the swollen premaxillae of Aporotus recurvirostris, a Miocene species from the North Sea, were studied histologically. These bones are pachyostotic and strongly osteosclerotic. However, their structural organization is entirely different from that of M. densirostris rostrum: they are basically made of a non-remodeled, laminar tissue that was cyclically deposited by the periosteum. As compared to the generalized structure of the premaxillae of ...

Energy Technology Data Exchange (ETDEWEB)

The authors study, in forced convection, the evaporation of an Ostwaldian film flowing over an isothermal inclined plane surface to determine the influence of the behaviour index of the liquid on the dynamic and thermal characteristics of liquid-air system. The liquid flow is considered partially two-dimensional whereas for the air it is two-dimensional. The coupled equations with the interfacial conditions are solved using a fully implicit finite differences method. From the study, it appears that the behaviour index influences considerably the transfers which are more important for pseudo-plastic liquids than for dilatant ones. (authors)

British Library Electronic Table of Contents (United Kingdom)

The heat transfer a characteristics and friction factor in the horizontal double pipes of flat tubes with full length helical screw element of different twist ratio and helical screw inserts with different spacer length are investigated. Cold and hot water are used as working fluid in tube side and shell side respectively. The experiments covered a range of Reynolds numbers 5.7x102Re1.31x103. The effect of spacer length on the heat transfer augmentation and friction factor and the effect of twist ratio on heat transfer augmentation and friction factor have been presented separately. The study shows that, the Nusslet number (Nu) and friction factor (f) decrease with the increase of S or Y for flat tube. The comparison between the data of present plain circular with that of previous plain ci...

Energy Technology Data Exchange (ETDEWEB)

The absorption of carbonyl sulfide in aqueous methyldiethanolamine (MDEA) was studied over a range of temperatures and MDEA concentrations. MDEA is commonly used for selective absorption of hydrogen sulfide in the presence of carbon dioxide. However, sulfur in the form of COS may also be present and it is necessary that estimates of absorption rates of this compound be made. The objective of this study is to determine the physiochemical properties needed to predict COS absorption rates in aqueous MDEA. Free gas solubility and the diffusivity of COS in MDEA solutions were measured over the temperature range 15 to 40{sup 0}C for MDEA concentrations up to 30 weight per cent using the nitrous oxide analogy method. Solubilities were measured volumetrically in an equilibrium cell and diffusivities were measured using a laminar liquid jet absorber. The kinetics of the reaction between COS and MDEA were studied by measuring absorption rates in a single wetted-sphere ...

Energy Technology Data Exchange (ETDEWEB)

This report documents the results of a project funded by DoD's Strategic Environmental Research and Development Program (SERDP) on the science behind development of predictive models for soot emission from gas turbine engines. Measurements of soot formation were performed in laminar flat premixed flames and turbulent non-premixed jet flames at 1 atm pressure and in turbulent liquid spray flames under representative conditions for takeoff in a gas turbine engine. The laminar flames and open jet flames used both ethylene and a prevaporized JP-8 surrogate fuel composed of n-dodecane and m-xylene. The pressurized turbulent jet flame measurements used the JP-8 surrogate fuel and compared its combustion and sooting characteristics to a world-average JP-8 fuel sample. The pressurized jet flame measurements demonstrated that the surrogate was representative of JP-8, with a somewhat higher tendency to soot formation. The premixed flame ...

Energy Technology Data Exchange (ETDEWEB)

Film boiling is the mode if boiling during which the hot surface is separated from the vaporizing liquid by a nearly continuous film vapor. Film boiling is usually considered a very undesirable boiling regime since it is a relatively quiet and inefficient mode of heat transfer, particularly as compared to nucleate boiling. It is customary to analyze the two-phase flow regime of laminar flow film boiling by assuming the two-phase flow regime of laminar flow film boiling by assuming an idealized vapor film flow characterized by a smooth liquid-vapor interface. However, during stable flow film boiling, the wavy nature of the liquid-vapor interface and its role in local heat and mass transport have been largely ignored. The vapor interface is rarely stationary. Interfacial waves may substantially augment the heat transfer rates throughout the layer. The present analysis treats stagnation point flow film boiling on a sphere immersed in a subcooled ...

Science.gov (United States)

Thermal models are constructed and analyses are performed of aluminum-based spent nuclear fuel (Al-SNF) in interim dry storage and geologic disposal configurations. Two models are developed, referred to as the interim storage model and the codisposal waste package (WP) model. Time-dependent source terms of Al-SNF forms and the defense high-level waste (DHLW) canisters are also developed for thermal performance analysis of the geologic codisposal WP.The interim storage model is a three-dimensional conduction-convection conjugate model to investigate the natural convection cooling of a sealed dry storage canister with vertical orientation in a dry storage vault. The analysis is made for various decay heat sources (equivalent to 25 to 35 kW/m{sup 3}) using various boundary conditions around the canister wall and with backfilled nitrogen or helium gas. Based on the data obtained from the Savannah River Site experimental work and available from the literature, an improved dimensionless ...

International Nuclear Information System (INIS)

Heat transfer augmentation in narrow rectangular channels in a target system is a very important method to remove high heat flux up to 12 MW/m"2 generated at target plates of a high-intensity proton accelerator of 1.5 GeV and 1 mA with a proton beam power of 1.5 MW. In this report, heat transfer coefficients and friction factors in narrow rectangular channels with one-sided rib-roughened surface were evaluated for fully developed flows in the range of the Reynolds number from 6,000 to 1,00,000; the rib pitch-to-height ratios (p/k) were 10,20 and 30; the rib height-to-equivalent diameter ratios (k/De) were 0.025, 0.03 and 0.1 by means of previous existing experimental correlations. The rib-roughened surface augmented heat transfer coefficients approximately 4 times higher than the smooth surface at Re=10,000, p/k=10 and k/De=0.1; friction factors increase around 22 times higher. In this case, higher heat flux up to 12 MW/m"2 could be removed from the rib-roughened surface without flow ...

Energy Technology Data Exchange (ETDEWEB)

This report investigates methods to utilize existing bulk tobacco kilns for curing (drying) of shelled corn, peanuts, and baled hay. In recent years Ontario tobacco producers have had to reduce production levels due to a declining demand for flue-cured tobacco. Many tobacco producers are currently diversifying into other crops. Some of these crops require curing and/or storage. Because of high capital costs to purchase conventional curing and/or storage facilities, tobacco producers wish to reduce their initial diversification costs by modifying their existing tobacco kilns (tobacco drying structures) and/or tobacco storage barns for this purpose. The investigation included high profile and low profile downdraft stick kilns, bulk kilns, and tobacco storage (pack) barns. Corn, peanuts, and hay were considered in relation to bulk kiln specifications and modifications, handling, drying and storage methods, energy requirements, cost, and quality of end product. The conclusions drawn from ...

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Numerical solutions given by a vorticity-velocity method are presented for combined free and forced laminar convection in the thermal entrance region of a horizontal rectangular channel without the assumptions of large Prandtl number and small Grashof number. The channel wall is heated with a uniform wall heat flux. Typical developments of temperature profile, secondary flow, and axial velocity at various axial positions in the entrance region are presented. Local friction factor and Nusselt number variations are shown for Rayleigh numbers Ra = 10{sup 4}, 3 {times} 10{sup 4}, 6 {times} 10{sup 4}, and 10{sup 5} with the Prandtl number as a parameter. The solution for the limiting case of large Prandtl number and small Grashof number obtained from the present study confirms the data of existing literature. It is observed that the large Prandtl number assumption is valid for Pr = 10 when Ra {le} 3 {times} 10{sup 4} but for a larger Prandtl number when the Rayleigh ...

CERN Document Server

Protoplanetary disks start their lives with a dust free inner region where the temperatures are higher than the sublimation temperature of solids. As the star illuminates the innermost particles, which are immersed in gas at the sublimation edge, these particles are subject to a photophoretic force. We examine the motion of dust particles at the inner edge of protoplanetary disks due to photophoretic drag. We find that, in a laminar disk, photophoretic drag increases the size of the inner hole after accretion onto the central body has become subdued. This region within the hole becomes an optically transparent zone containing gas and large dusty particles (>>10 cm), but devoid of, or strongly depleted in, smaller dust aggregates. Photophoresis can clear the inner disk of dust out to 10 AU in less than 1 Myr. At late times, the edge reaches a stable equilibrium between inward drift and photophoretic outward drift, at a distance of some tens of AU. Eventually, ...

International Nuclear Information System (INIS)

There are three main types of radiation-processed composite material derived from plastics and fibrous natural polymers. The first are the monomer-impregnated, radiation-treated wood-plastic composites (WPC). They became a commercial success in the early 1970s. More recently, work has focused on improving the WPCs by creating in them interpenetrating network (IPN) systems by the use of appropriate multifunctional oligomers and monomers. The main kinetic features of radiation-initiated chain polymerization remain applicable even in impregnated wood. The second type are the plastics filled or reinforced with dispersed wood fiber or other cellulosics (WFRP). In their case, radiation processing offers a new opportunity to apply radiation-reactive adhesion promoters between wood or cellulosic fibers and the thermoplastic matrices. The third type are the laminar composites made by electron beam coating of wood-based agglomerate sheets and boards. This chapter reviews the ...

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The suitability of the turbulent combustion flamelets model in order to predict the index of NO{sub x} production in turbulent flames of hydrogen diffusion is analyzed. In the flamelet approach, the turbulent flame is equivalent to a group of laminar flames submitted to a mechanical stretching which generates a chemical disequilibrium. This effect can be described by the stretching or by the scalar dissipation ratio. A numerical modeling is performed in order to evaluate the advantages of both approaches and to compare the behaviour of the NO{sub x} emission index with the experiments of Chen and Driscoll. This study shows that predictions of NO{sub x} emission indexes have a correct behaviour with respect to the Damkoehler number only when the scalar dissipation ratio is used as a parameter to describe the chemical state outside equilibrium. Predictions of the flamelet models are improving when the Damkoehler number increases. On the other hand, the absolute ...

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We intend to solve equations governing turbulent plane-vertical isotherm and non isotherm jets by taking into account inflow conditions at the exit of the nozzle. The analysis is focused on the influence of these conditions on this type of flow. Two cases are considered (uniform and parabolic velocity and temperature profiles). A finite difference scheme is developed to solve the governing equations. This numeric model allows us to show that the region of fully developed regime begins much nearer the nozzle for the turbulent case than for the laminar flow case. Indeed, the turbulence increases the mixing between the incoming gas from the nozzle and the ambient fluid, and consequently the size of the potential core zone decreases. The results are compared to other works introducing mathematical variables based on the energy conservation for the case of the mixed convection and the momentum conservation for the forced convection, which allows the validation of our ...

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In this study, the effects of hydrogen peroxide on laminar, premixed, methane-air flames at atmospheric pressure and temperature were investigated using CHEMKIN III and GRI 3.5 mechanism. The range of fuel/air equivalence ratio {phi} was varied from 0.6 to 1.2, and the amount of hydrogen peroxide was altered from 0% to 20% volumetric fraction of the methane-hydrogen peroxide (air excluded) mixture. The burning velocity was found to increase with increasing hydrogen peroxide addition, with a relatively larger increase for the fuel-richer mixtures ({delta}S{sub u} up to 15 cm/s for {phi} {approx}=1.2). The adiabatic flame temperature rose with hydrogen peroxide addition, and the temperature rise per unit hydrogen peroxide addition was more significant ({delta}T up to 100 K) for the leaner mixtures. For the same mixture stoichiometry, adding hydrogen peroxide also increased CO concentration and NO{sub x} emissions somewhat. Accordingly, the benefits of adding hydrogen ...

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Heat and momentum transport in self-sustained oscillatory viscous flows is investigated by direct numerical simulation using the spectral element method. Above a critical Reynolds number, these flows bifurcate to a time-periodic, self-sustained oscillatory state. Traveling waves are observed, even at moderately low Reynolds numbers, inducing self-sustained oscillations that result in very well-mixed flows, which, in turn, lead to convective heat transfer augmentation. These oscillatory states are investigated and correlations between the time- and space-averaged Nusselt and Reynolds numbers are obtained. The transport phenomena of heat and momentum due to the oscillatory components of the flow are analyzed by looking at the phase portraits of velocity and temperature, investigating the behavior of the terms involving their fluctuations, as well as considering the correlation coefficients between the fluctuating components. Results are presented for laminar and ...

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A multi-faceted research program has been performed to investigate in detail several aspects of free and forced convective cooling of underground electric cable systems. There were two main areas of investigation. The first one reported in this volume dealt with the fluid dynamic and thermal aspects of various components of the cable system. In particular, friction factors for laminar flow in the cable pipes with various configurations were determined using a finite element technique; the temperature distributions and heat transfer in splices were examined using a combined analytical numerical technique; the pressure drop and heat transfer characteristics of cable pipes in the transitional and turbulent flow regime were determined experimentally in a model study; and full-scale model experimental work was carried out to determine the fluid dynamic and thermal characteristics of entrance and exit chambers for the cooling oil. The second major area of activity, ...

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Flame lengths inside circular tubes, using an (in-shot) atmospheric burner design commonly found in gas-fired residential furnaces were visually observed for natural gas and air under various operating conditions. The flame length data were reduced into dimensionless flame lengths, which were shown to be linearly proportional to the Peclet number of the fuel and air mixture. The dimensionless flame length dependence reported does not scale according to the classical flame models: pre-mixed (laminar) flame or diffusion flame. Instead, the flame length dependence was found to scale with the fuel burn speed, gas/mixture properties (evaluated at the adiabatic flame temperature), and flow parameters. Currently, this is the only flame length study available for the standard atmospheric burner designs commonly used in residential heating products. The results and data reduction provide an easy method to compute flame length penetrations inside circular tubes for the ...

International Nuclear Information System (INIS)

Plasma surface interactions in tokamaks are known to create significant quantities of dust, which settles onto surfaces and accumulates in the vacuum vessel. In ITER, a loss of vacuum accident may result in the release of dust which will be radioactive and/or toxic, and provides increased surface area for chemical reactions or dust explosion. A new method of analysis has been developed for modeling dust resuspension and transport in loss of vacuum accidents. The aerosol dynamic equation is solved via the user defined scalar (UDS) capability in the commercial CFD code Fluent. Fluent solves up to 50 generic transport equations for user defined scalars, and allows customization of terms in these equations through user defined functions (UDF). This allows calculation of diffusion coefficients based on local flow properties, inclusion of body forces such as gravity and thermophoresis in the convection term, and user defined source terms. The code accurately reproduces analytical solutions ...

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The heat transfer a characteristics and friction factor in the horizontal double pipes of flat tubes with full length helical screw element of different twist ratio and helical screw inserts with different spacer length are investigated. Cold and hot water are used as working fluid in tube side and shell side respectively. The experiments covered a range of Reynolds numbers 5.7 x 10{sup 2} {<=} Re {<=} 1.31 x 10{sup 3}. The effect of spacer length on the heat transfer augmentation and friction factor and the effect of twist ratio on heat transfer augmentation and friction factor have been presented separately. The study shows that, the Nusslet number (Nu) and friction factor (f) decrease with the increase of S or Y for flat tube. The comparison between the data of present plain circular with that of previous plain circular tube showed a good agreement between them but the data of present plain flat tube showed a higher in heat transfer and pressure drop than that of plain ...

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Verification, calibration, and validation (VCV) of Computational Fluid Dynamics (CFD) codes is an essential element of the code development process. The exact manner in which code VCV activities are planned and conducted, however, is critically important. It is suggested that the way in which code validation, in particular, is often conducted--by comparison to published experimental data obtained for other purposes--is in general difficult and unsatisfactory, and that a different approach is required. This paper describes a proposed methodology for CFD code VCV that meets the technical requirements and is philosophically consistent with code development needs. The proposed methodology stresses teamwork and cooperation between code developers and experimentalists throughout the VCV process, and takes advantage of certain synergisms between CFD and experiment. A novel approach to uncertainty analysis is described which can both distinguish between and quantify various types of ...

International Nuclear Information System (INIS)

CT is the most accurate method to detect pulmonary emphysema in vivo. They compared prospectively two different methods for emphysema quantitation in 5 normal volunteers and 20 consecutive patients with chronic obstructive pulmonary disease (COPD). All subjects were submitted to function tests and HRCT; three scans were acquired at preselected levels during inspiration. The type and extent of pulmonary emphysema were defined by two independent observers under blind conditions. Disagreements were subsequently settled by consent. All subjects were also examined with expiratory spiral CT using a density mask program, at two different cut-off levels (-850,-900 HU). Visual score and expiratory spiral density mask values (-850 HU) were significantly correlated (r = 0.86), but the visual extent of emphysema was always higher than shown by expiratory spiral CT. The emphysema extent assessed with both CT methods correlated with the function result of expiratory airflow ...

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In cooling systems, an improved control of scale deposit and corrosion processes is a major challenge and an realistic evaluation tool for water treatments is of the utmost economic importance. In this study, a channel flow cell was used to allow in-situ electrochemical measurements in well defined electrolyte tube flowing conditions. An expression of the mass transfer towards the electrode was established where the diffusion-limited current is a function of Re{sup 1/3} in the laminar regime and was verified experimentally using the redox couples Fe[CN]{sub 6}{sup 4-}/ Fe[CN]{sub 6}{sup 3-} and O{sub 2}/OH{sup -}. This hydrodynamically controlled experimental device was developed to investigate scale deposit processes and to evaluate scale inhibitor efficiency using a electrochemical quartz crystal microbalance. Experiments were performed on three different waters, at various flow rates and temperatures. The efficiency of a well known phosphonate (HEDP) was tested ...

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A numerical simulation of two-dimensional laminar natural convection in a fully open tilted square cavity with an isothermally heated back wall is conducted. The remaining two walls of the cavity are adiabatic. Steady-state solutions are presented for Grashof numbers between 10{sup 2} and 10{sup 5} and for tilt angles ranging from {minus}60{degree} to 90{degree} (where 90{degree} represents a cavity with the opening facing down). The fluid properties are assumed to be constant except for the density variation with temperature that gives rise to the buoyancy forces, which is treated by the Boussinesq approximation. The fluid concerned is air with Prandtl number fixed at 0.71. The governing equations are expressed in a normalized primitive variables formulation. Numerical predictions of the velocity and temperature fields are obtained using the finite-volume-based power law (SIMPLER: Semi-Implicit Method for Pressure-Linked Equations Revised) algorithm. For a ...

Energy Technology Data Exchange (ETDEWEB)

A high power (200KV), intense current density, low emittance (71mmmrad), high brightness (8x10{sup 10}A/m rad) electron beam was generated in the 10cm long, high-voltage-resistive multi-gap hollow cathode pseudospark chamber filled with 15pa nitrogen and driven by an improved pulse line accelerator. The beam was ejected with the 1mm diameter, the 2.2KA beam current, and the 400ns pulse length, and could propagated 20cm in the drift tube. At a distance of 5cm from the anode it penetrated consecutively an acid-sensitive discoloring film and a 0.05mm-thick copper foil both stuck closely, left 0.6mm and 0.3mm holes on them, respectively. That 10 shots on an acid-sensitive film produced a hole of 1.6mm at 7cm downstream of anode showed its good repeatability. After 60 shots the pseudospark discharge chamber was disassembled and observed that almost no destructive damage traces left on the surfaces of its various electrodes and insulators. But on almost all the surfaces of changeable central ...

Energy Technology Data Exchange (ETDEWEB)

Experimental investigations were performed to assess the effects of different shaped obstructions on flame propagation in a rectangular confinement, 235 mm in height, with a 1000 x 950mm cross section and a large top-venting area of 1000 x 320mm. Four different single obstacles were used: rectangular, cylindrical, triangular, and square cross-sections with blockage ratios of 5 and 10%. Temporally resolved flame front images were recorded by a high-speed video camera to investigate the interaction between a propagating flame and the obstacle. The local flame displacement speeds and their probability density functions (pdfs) were obtained for the different obstacles. Before the freely propagating flame impinges on the obstacle, the flame propagation speed remains close to the laminar burning velocity, regardless of the obstacles used. As the propagating flame impinges on the obstacle, the local propagation speed increases due to the expansion of the burnt gas and the ...

Energy Technology Data Exchange (ETDEWEB)

Fully coupled, Newton-Krylov algorithms are investigated for solving strongly coupled, nonlinear systems of partial differential equations arising in the field of computational fluid dynamics. Primitive variable forms of the steady incompressible and compressible Navier-Stokes and energy equations that describe the flow of a laminar Newtonian fluid in two-dimensions are specifically considered. Numerical solutions are obtained by first integrating over discrete finite volumes that compose the computational mesh. The resulting system of nonlinear algebraic equations are linearized using Newton`s method. Preconditioned Krylov subspace based iterative algorithms then solve these linear systems on each Newton iteration. Selected Krylov algorithms include the Arnoldi-based Generalized Minimal RESidual (GMRES) algorithm, and the Lanczos-based Conjugate Gradients Squared (CGS), Bi-CGSTAB, and Transpose-Free Quasi-Minimal Residual (TFQMR) algorithms. Both Incomplete ...