Collector Section Research Articles

The assessment of the possibilities of improvement of the extraction evenness in multicyclone dedusters fitted in special vehicles

A modification of the structure of the dust collector has been made through partitioning of its chamber into separate dedusting channels to which a number of cyclones was assigned. Using the model of the dust collector a preliminary selection of the heights h1, h2, .... hi, at the intake was made of the individual channels of the dust collector sections to ensure identical flow resistance of the airstream through these channels. The model investigations of the sections of the dust collector were verified in flow investigations. The values of the stream was measured extracted from individual cyclones for several variants of the dust collector. An assessment of the improvement of the dedusting efficiency from individual cyclones has been performed.

Deflective Behavior of Charged Particles in a Two-Stage Electrostatic Precipitator

Even if smoke, fumes, mist or dust particles are removed by electrostatic precipitators (ESPs), the occurrence of ozone, which is harmful to human body, has to be severely restricted in the indoor environments of hospitals, offices, and workshops. Therefore, the two-stage ESP generating positive corona at the ionizer is typically used because it creates less ozone than the two-stage ESP generating negative corona at the ionizer.<BR> In order to predict the collection performance and the optimal design of the two-stage ESP applied to positive high-voltage, particle concentration is experimentally investigated in this paper. In addition, particle motion within the collector section is also numerically analyzed.<BR> The positive corona discharge current of the ionizer is found to be affected by the applied voltage in the collector section but less so by the particle concentration. Particle concentration shows a minimum near the high voltage electrode of the collector section. The minimum value of the collection efficiency is almost proportional to gas velocity. When the collector length decreases, the minimum value of the collection efficiency increases. Charged particles entering the collector region are linearly deflected towards the grounded plate by an electric field.<BR> From the above experimental and numerical results, two empirical equations on the concentration ratio and the collection efficiency are derived, and are in good agreement with the experimental data.

An Air-Based Cavity-Receiver for Solar Trough Concentrators

Abstract A cylindrical cavity-receiver containing a tubular absorber that uses air as the heat transfer fluid is proposed for a novel solar trough concentrator design. A numerical heat transfer model is developed to determine the receiver’s absorption efficiency and pumping power requirement. The 2D steady-state energy conservation equation coupling radiation, convection, and conduction heat transfer is formulated and solved numerically by finite volume techniques. The Monte Carlo ray-tracing and radiosity methods are applied to establish the solar radiation distribution and radiative exchange within the receiver. Simulations were conducted for a 50 m-long and 9.5 m-wide collector section with 120°C air inlet temperature, and air mass flows in the range 0.1–1.2 kg/s. Outlet air temperatures ranged from 260°C to 601°C, and corresponding absorption efficiencies varied between 60% and 18%. Main heat losses integrated over the receiver length were due to reflection and spillage at the receiver’s windowed aperture, amounting to 13% and 9% of the solar power input, respectively. The pressure drop along the 50 m module was in the range 0.23–11.84 mbars, resulting in isentropic pumping power requirements of 6.45×10−4−0.395% of the solar power input.

Simulation of Magnetic Fluid Applied to Plastic Sorting

The efficient large-scale recycling of plastic waste is of increasing interest from an ecological and economic point of view but it represents a goal that has yet to be achieved by the recycling industry. European project W2Plastics (FP7) aims at a fundamental change of the present status of plastics recycling by applying the Magnetic Density Separation (MDS) technology as well as the Ultrasound Imaging Technology to develop a separation device for the recycling of polyolefin's from complex wastes, i.e., wastes such as Waste from Electric and Electronic Equipment (WEEE), household waste and Automotive Shredder Residue (ASR). The sorting of plastics in W2Plastics is based on the use of a magfluid, magnetized water, to stratify the different plastics according to their densities and to collect them at different depths in an efficient way. One component of this project consists in simulating the particle paths into the water flow inside the separation device in order to understand the separation mechanisms and to optimize its configuration. The separation device is divided into three sections. The plastic particles enter the device with a strong turbulent mixing, necessary for an initial good separation between particles. The first section is the laminator section that tries to make the flow laminar in the shortest distance as possible. The second section is the separator section in which the particles are separated according to their densities, under the magnetic field. These particles are flowing to the last section, the collector section where each kind of plastics should flow at a different heights. From the numerical point of view, there are three main challenges. First, the Navier-Stokes solver should be robust and fast enough. This is accomplished using parallelized schemes together with efficient algebraic solvers, running on thousands of processors. The second challenge is the plastic particles tracking and their interactions with the flow. This will be carried out using a fixed grid method in order to avoid remeshing at each time step. Finally, the turbulent flow will be captured using a Variational Multiscale Method method, and the inlet turbulence will be treated using a synthetic turbulence generation.

Study of a new concept of photovoltaic–thermal hybrid collector

This work represents the second step of the development of a new concept of photovoltaic/thermal (PV/T) collector. This type of collector combines preheating of the air and the production of hot water in addition to the classical electrical function of the solar cells. The alternate positioning of the thermal solar collector section and the PV section permits the production of water at higher mean temperatures than most of existing hybrid collectors. These higher temperatures will allow the coupling of components such as solar cooling devices during the summer and obviously a direct domestic hot water (DHW) system without the need for additional auxiliary heating systems. In this paper, a simplified steady-state two-dimensional mathematical model of a PV/T bi-fluid (air and water) collector with a metal absorber is developed. Then, a parametric study (numerically and experimentally) is undertaken to determine the effect of various factors such as the water mass flow rate on the solar collector thermal performances. Finally, the results from an experimental test bench and the first simulation results obtained on full scale experiments are compared.

Simulation studies of the electron cooler for MUSES at RIKEN

Electron cooler (EC) of the accumulator cooler ring (ACR) at RIKEN consists of a gun section, two toroids and a collector section. The toroidal section with an angle of 90° cannot produce ideal solenoid field with axial symmetry. Therefore, a more realistic model should be employed for the analysis of the magnetic fields and the electron beam trajectories. Optimization of the EC has been carried out using a model of the magnetic field and the electron beam trajectory calculation. It was found that the fringe field of the toroidal magnet is an important parameter to lower transverse temperature of electron beams.

Flow velocities and shear stresses during flushing operations in sewer collectors

Many relevant problems of drainage systems such as first flush pollution, flow capacity reduction and consequent risks of surcharges are worsened by sediment accumulation in sewer collectors. For the solution of these problems several sediment cleansing methods and techniques, e.g. mechanical methods, traps and flushing devices, have been developed and applied in the last decades. In particular, simulation studies and experimental campaigns have shown the effectiveness of flushing methods as preventive cleansing strategy in sewer collectors. In this paper the results of a numerical investigation for determining flushing waves characteristics both in terms of duration and flow rate are presented. The collector section lengths where flow velocities and average shear stresses determined by flushing waves exceed minimum threshold values are evaluated using a dimensionless approach. The results, related to the operative ranges of the practical applications, are exposed by means of graphs and regressive equations.

Safety Evaluation of Freeway Traffic Management System in Toronto, Canada

A reduction in accidents, particularly secondary ones, is often cited as one of the primary benefits of a freeway traffic management system (FTMS) such as that implemented on a segment of Highway 401 in Toronto, Canada. The safety effect of this FTMS was estimated from the parameters of regression models calibrated for the preimplementation period (1989-1990) and the postimplementation period (1991-1992). Separate models were calibrated for express, collector, and conventional divided roadway sections and for rear-end, non-rear-end, and all injury accidents. For rear-end injury accidents, model parameters were estimated for day and night conditions. The aggregate results show a substantial decrease in the expected number of rear-end injury accidents on all three types of roadway following the implementation of the FTMS.

Safety Evaluation of Freeway Traffic Management System in Toronto, Canada

A reduction in accidents, particularly secondary ones, is often cited as one of the primary benefits of a freeway traffic management system (FTMS) such as that implemented on a segment of Highway 401 in Toronto, Canada. The safety effect of this FTMS was estimated from the parameters of regression models calibrated for the preimplementation period (1989–1990) and the postimplementation period (1991–1992). Separate models were calibrated for express, collector, and conventional divided roadway sections and for rear-end, non-rear-end, and all injury accidents. For rear-end injury accidents, model parameters were estimated for day and night conditions. The aggregate results show a substantial decrease in the expected number of rear-end injury accidents on all three types of roadway following the implementation of the FTMS.

Thermal performance of solar air heaters: mathematical model and solution procedure

A mathematical model and solution procedure for predicting the thermal performance of single-pass solar air collectors is presented. By omitting or providing a top glass cover over a plane absorber plate, or by providing a bottom plate under the absorber plate and circulating air over one or both of the air channels so formed, four common types of flat-plate solar air collector designs were considered. The surface temperatures of the walls surrounding the air streams were assumed uniform whereas the air temperatures were assumed to vary linearly along the collector. In the mathematical model, the solar collector was assumed sufficiently short for which the assumptions were valid. By considering a steady state heat transfer using the thermal network analysis procedure, a set of simultaneous equations for the mean temperature of the walls and the air streams were obtained. Instead of solving the simultaneous equations for mean temperatures explicitly, a matrix inversion method was employed using a standard sub-routine programme. Because heat transfer coefficients were temperature dependent, a set of mean temperatures was approximated which allowed the heat transfer coefficients to be evaluated as a first guess. An iterative process was then created that enabled the mean temperatures for the collector to be calculated. The newly-calculated mean temperatures were then compared with the initially-guessed temperatures. The iterative procedure was repeated until consecutive mean temperature values differed by less than 0.01°C. After this, another section of collector with a length equal to the previous one was added to the end of the first collector. The temperature conditions at the inlet of the second section were assumed equal to the outlet temperature conditions of the previous section. The iterative procedure to determine the mean temperatures was repeated for the next section. Additional sections were added until the required overall length of collector was considered. By this procedure, predictions of mean wall and air streams temperatures for a collector of any length could be obtained. Although only four, common single-pass types of flat-plate solar collectors are considered here, the solution procedure could be extended to encompass most other collector designs.

Thermal performance of solar air heaters: Mathematical model and solution procedure

A mathematical model and solution procedure for predicting the thermal performance of single-pass solar air collectors is presented. By omitting or providing a top glass cover over a plane absorber plate, or by providing a bottom plate under the absorber plate and circulating air over one or both of the air channels so formed, four common types of flat-plate solar air collector designs were considered. The surface temperatures of the walls surrounding the air streams were assumed uniform whereas the air temperatures were assumed to vary linearly along the collector. In the mathematical model, the solar collector was assumed sufficiently short for which the assumptions were valid. By considering a steady state heat transfer using the thermal network analysis procedure, a set of simultaneous equations for the mean temperature of the walls and the air streams were obtained. Instead of solving the simultaneous equations for mean temperatures explicitly, a matrix inversion method was employed using a standard sub-routine programme. Because heat transfer coefficients were temperature dependent, a set of mean temperatures was approximated which allowed the heat transfer coefficients to be evaluated as a first guess. An iterative process was then created that enabled the mean temperatures for the collector to be calculated. The newly-calculated mean temperatures were then compared with the initially-guessed temperatures. The iterative procedure was repeated until consecutive mean temperature values differed by less than 0.01°C. After this, another section of collector with a length equal to the previous one was added to the end of the first collector. The temperature conditions at the inlet of the second section were assumed equal to the outlet temperature conditions of the previous section. The iterative procedure to determine the mean temperatures was repeated for the next section. Additional sections were added until the required overall length of collector was considered. By this procedure, predictions of mean wall and air streams temperatures for a collector of any length could be obtained. Although only four, common single-pass types of flat-plate solar collectors are considered here, the solution procedure could be extended to encompass most other collector designs.

Wide-angle lenses and image collapsing subreflectors for nontracking solar collectors

This paper presents new optical methods for the design of nontracking solar energy concentrators with acceptance angles of 60 degrees in the elevation (altitude) plane and +/-50 degrees in azimuth sectors. We have designed and constructed a two-point corrected cylindrical stepped prism lens (SPL) with 30.48-cm aperture height and F/D congruent with 1, which focuses well over the acceptance interval. Image collapsing subreflector (ICS) surfaces are synthesized that reflect the incident illumination refracted by the lens onto a small fixed absorbing area or shelf ~7.6 cm wide resulting in near maximum theoretical concentration ratios for these broad acceptance angles. Nearly 100% of the incident optical rays intercept the absorber shelf. The wide-angle and image collapsing optical properties were confirmed by laser and solar experiments. Rooftop thermal tests on a 30.5 x 30.5-cm collector section using selectively absorbing tubes with water as circulant were conducted that indicate aperture efficiencies of ~60% could be exected on large area collectors based on this design.

A new approach to atmospheric-ion mobility spectrometry

The design of a Gerdien mobility spectrometer using a full intake and divided collector is discussed. A new method for computing mobility spectra from the ion currents collected by each collector section is proposed. Some spectra obtained with the spectrometer are presented, which demonstrate that the spectrum parameters can change significantly over intervals of the order of 100 s.

Contact Problems Of Elastic Shells

In this paper axially symmetric interaction of the shells of rotation made from elastic materials with the rigid bodies of rotation have been considered. For this class of problems the variational statements have been suggested on the basis of mathematical theory of variational inequalities. Large deformations of rubber are described by the constitutive equations of incompressible elastic material. Specific potential energy of the deformation of isotropic material is the function of two invariants of Cauchy-Green's deformations measure. The generalised solution of the contact problems is reduced to the problem of conditional minimisation of the non-linear functional. The solution of the problem of non-linear programming is performed by the method of local variations and when this method is used it is easy to change the form of rigid body and deformations potential view. Numerical solution is performed for rubber shell of the device which disconnects the collector sections. Under the action of the internal pressure the rubber shell expands, makes contact with the cylindrical surface of the collector.

Improved barrier-grid storage tube

The development of a radically new barrier-grid storage tube is described. The tube utilizes a spherically-curved target assembly 4.5 inches in diameter with a 4.5 inch radius of curvature in which the barrier grid is fused to the dielectric surface. The center of deflection of the electrostatically focused and deflected electron gun is essentially coincident with the center of curvature of the target; thus, the beam strikes the target at normal incidence throughout. The total deflection angle of the electron beam is 60° and means are provided for concentrating 10 µa of beam current into an 8-mil spot (measured at the 5% points on the current density distribution curve) and for dynamic focusing of the beam throughout the target area involving dynamic correction of the deflection defocusing. Either collector or target readout may be employed. The collector section of the tube is designed to uniformly and efficiently collect the signal electrons from the target so that the signal shading is negligible. Contact to the collector is made by a coaxial lead through the bulb wall. The target end of the tube is designed so that contact to the target is with a coaxial lead in which the barrier grid is connected to the outer shield of the coax. Techniques for depositing a uniform porcelain enamel layer on the spherically-curved target bowl and for forming and fusing the barrier grid to the insulator surface are described. In addition, the design of the electron gun is described in detail.