scholarly journals Study of the optimum discrete structure configuration in obstructed flow particle heating receivers

2020 ◽  
Author(s):  
Hany Al-Ansary ◽  
Abdelrahman El-Leathy ◽  
Abdulelah Alswaiyd ◽  
Shaker Alaqel ◽  
Nader Saleh ◽  
...  
Keyword(s):  
Discrete Structure ◽  
Particle Heating ◽  
Structure Configuration ◽  
Flow Particle

Preliminary Design of an All-Ceramic Discrete-Structure Particle Heating Receiver

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
George Peters ◽  
Matthew Golob ◽  
Clayton Nguyen ◽  
Sheldon Jeter ◽  
Syed Danish ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Mass Flux ◽  
Metal Wire ◽  
Particle Flow ◽  
Discrete Structure ◽  
Ceramic Tiles ◽  
Particle Mixing ◽  
Particle Heating ◽  
Wire Meshes ◽  
The Impact

Abstract Discrete structure particle heating receivers (DS-PHR), as used in concentrated solar power (CSP) systems, employ suitable discrete porous structures to intermittently halt the falling particles to control the speed and increase the residence time of falling particulates, thereby increasing the temperature rise of particulates exiting the DS-PHR. Previous designs of DS-PHRs have considered both porous foam structures, which have mass flux limits, and metal wire meshes, which are effective but have temperature and other functional limitations. This paper recounts recent studies at Georgia Tech and King Saud University that have investigated the use of ceramic tiles made porous by discrete slot-shaped passages in place of previous metal wire meshes. Currently, for experimental use, the slot-like passages are cut into the tiles by water jet, but operational units are expected to be formed into shape and fired by more economical conventional ceramic techniques. Benefits of ceramic and other refractory materials include higher temperature and heat flux limits at a reasonable cost. The tiles are expected to be installed in chevron configuration, which have been shown by experience to be especially effective, and these so-called ceramic chevrons have been shown to deliver adequate mass flux densities while still removing most of the kinetic energy from the particles. In addition, the thickness of the tile allows the incorporation of angled slots capable of redirecting the particle flow, adding a method to control particle mixing by purposefully directing the particulate streams. These enhanced slots are typically arranged with adequate spacing to allow for increased penetration of concentrated light into the depth of the falling bed of particles and may be angled to redirect hot particles toward the back plane of the DS-PHR. Both of these features should help minimize depthwise temperature variation. The testing reported here will focus on the degree of velocity and flow control that can be achieved by proper design of these ceramic chevrons as well as demonstrate the effectiveness of different designs on light penetration. Prior to this research, the effectiveness of ceramic obstructions might have been properly doubted because of the very high coefficient of restitution (COR) for the impact of ceramic particles on ceramic solids. In reality, it will be shown that a layer of particulates will form on a chevron, which effectively dissipates the kinetic energy of the impacting particles. Overall, this paper will report improvements in DS-PHR designs that can withstand high temperatures and fluxes, achieve additional control of particle flow, enhance particle mixing, and allow deeper penetration of light into the depth of the falling bed.

Measurement of Particulate Flow in Discrete Structure Particle Heating Receivers

2015 ◽  
Author(s):  
A. W. Khayyat ◽  
R. C. Knott ◽  
C. L. Nguyen ◽  
M. C. Golob ◽  
S. I. Abdel-Khalik ◽  
...  
Keyword(s):  
Collection Efficiency ◽  
Vertical Plane ◽  
Perforated Plate ◽  
The Body ◽  
Wire Mesh ◽  
Discrete Structure ◽  
Mesh Material ◽  
Error Propagation Analysis ◽  
Particle Heating ◽  
Wire Meshes

Conventional central receiver power tower plants typically use steam or molten salts as the heat collection medium. Recently, attention has returned to using solid particulates in a particle-heating receiver (PHR). In this project we are interested in discrete structure PHR that includes structures, such as an array of wire mesh protrusions in our current design, to increase the residence time of particles falling through the receiver. The meshes should be sized to accommodate the falling particles without exposing too much mesh to concentrated radiation, which might degrade collection efficiency and expose the mesh material to high temperature thermal degradation. The experiment described in this paper was implemented to measure the appropriate exposed length of such discrete porous structures for a PHR. Particulates are introduced to the model PHR from a perforated plate distributor. As detailed in the body of the paper, a laser and photosensor (responding in units of lux) are used at positions 546 mm and then 1111 mm downstream from the perforated plate to measure the transparency of the flow in a vertical plane across the receiver. The laser light forms a vertical sheet, and its intensity is measured by the photosensor on the opposite side of the receiver. By comparing the lux data with and without particles flowing, the transparency of the particulate curtain can be determined. Different mesh counts have been tested and compared, and plotted for comparison. This research is useful for designers to use when planning a PHR and will inform the proper length of wire meshes to use. This paper reports the results obtained so far including a standard error propagation analysis.

High-resolution electron microscopy of the atomic structure of some grain boundaries in Au

1986 ◽  
Vol 44 ◽  
pp. 414-415
Author(s):  
W. Krakow ◽  
D. A. Smith
Keyword(s):  
Atomic Structure ◽  
High Resolution Electron Microscopy ◽  
Image Features ◽  
Image Feature ◽  
Resolution Electron ◽  
Tilt Boundaries ◽  
Processing Techniques ◽  
Atom Position ◽  
Structure Configuration

The successful determination of the atomic structure of [110] tilt boundaries in Au stems from the investigation of microscope performance at intermediate accelerating voltages (200 and 400kV) as well as a detailed understanding of how grain boundary image features depend on dynamical diffraction processes variation with specimen and beam orientations. This success is also facilitated by improving image quality by digital image processing techniques to the point where a structure image is obtained and each atom position is represented by a resolved image feature. Figure 1 shows an example of a low angle (∼10°) Σ = 129/[110] tilt boundary in a ∼250Å Au film, taken under tilted beam brightfield imaging conditions, to illustrate the steps necessary to obtain the atomic structure configuration from the image. The original image of Fig. 1a shows the regular arrangement of strain-field images associated with the cores of ½ [10] primary dislocations which are separated by ∼15Å.

scholarly journals Stiffness modulation for soft robot joint via lattice structure configuration design

Procedia CIRP ◽  
2021 ◽  
Vol 100 ◽  
pp. 732-737
Author(s):  
Zhiping Wang ◽  
Yicha Zhang ◽  
Gaofeng Li ◽  
Guoqing Jin ◽  
Alain Bernard
Keyword(s):  
Lattice Structure ◽  
Configuration Design ◽  
Soft Robot ◽  
Structure Configuration

Phonological potentials and the lower vocal tract

2019 ◽  
pp. 1-35 ◽  
Author(s):  
Scott R. Moisik ◽  
Ewa Czaykowska-Higgins ◽  
John H. Esling
Keyword(s):  
Theoretical Approach ◽  
Vocal Tract ◽  
Speech Sound ◽  
Physical Nature ◽  
Discrete Structure ◽  
Complex Interactions

This paper outlines a theoretical approach to speech sound systems based on the notion of phonological potentials: physical ‘pressures’ or biases that give rise to discrete structure and the tendencies associated with this structure that arise from the physical nature of speech sound systems. We apply this approach to a poorly understood area of phonology – phenomena of the lower vocal tract (LVT) – through a schematic that encapsulates the complex interactions among the vocal tract structures responsible for producing LVT sounds. With the framework, we provide an account of a range of LVT phenomena from several languages, illustrating how tonal, phonatory, and vowel qualities interact. Finally, we consider how the idea of phonological potentials extends across various physical domains and might exhibit patterns of alignment across these domains, thereby serving to guide the formation of patterns found in speech sound systems.

Potential barrier effect and discrete structure o between 40 and 120 Å in the Rb I absorption spectrum

1975 ◽  
Vol 344 (1637) ◽  
pp. 303-309 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Absorption Maximum ◽  
Random Phase Approximation ◽  
Random Phase ◽  
Particle Model ◽  
Discrete Structure ◽  
Model Calculations ◽  
Hartree Fock ◽  
Independent Particle ◽  
Independent Particle Model

Investigation of the Rb I absorption spectrum between 40 and 120 Å has revealed a broad absorption maximum in the 3d photoionization continuum, as well as discrete features associated with the excitation of a 3d-subshell electron. The discrete structure is identified, Hartree-Fock calculations of the transition energies are given and the absorption maximum is discussed in relation to similar spectra and to recent random phase approximation with exchange (r.p.a.e.) and independent particle model calculations.

Preliminary Techno-Economic Optimization Of 1.3 MWe Particle Heating Receiver Based CSP Power Tower Plant for the MENA Region

2021 ◽  
Author(s):  
Shakir Shakoor Khatti ◽  
Sheldon Jeter ◽  
Hany Al-Ansary
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Energy Demand ◽  
Cost Models ◽  
Low Carbon ◽  
Manufacturing Companies ◽  
Mena Region ◽  
Optical Efficiency ◽  
Central Receiver ◽  
Particle Heating

Abstract Due to increasing energy demand around the globe and potential environmental impacts of fossil fuels, it has become a crucial task for researchers to find alternatives to generate electricity from low-carbon resources at lower costs. Three types of advanced CSP are under consideration: systems heating salt, gas, or particulate. Particle heating receiver (PHR) based central receiver power tower CSP is an emerging technology that promises higher operating temperatures and more cost-effective thermal energy storage (TES) than feasible with existing or alternative CSP systems. For reasons stated above and others, we propose that the particle heating receiver (PHR) based CSP in the classic central receiver power tower (CRPT) configuration will be the most suitable especially in the promising Middle East and North Africa (MENA) region. Specifically, Duba, Al Wajih, and Wa’ad Al-Shamaal regions in Saudi Arabia have high direct normal irradiation (DNI) and represent potential locations. PHR based CSP power tower plant consists of a central receiver power tower with TES and cavity receiver, heliost at field, a high-temperature solar gas turbine with built-in fuel backup to operate in hybrid mode (using both fuel and solar-thermal resources). This study focuses on the optimization of a solar heat supply system (SHSS), consisting of a tower, cavity receiver, and heliostat field. SolarPILOT – Solar Power tower Integrated Layout and Optimization Tool is a field layout optimization tool developed by National Renewable Energy Laboratory (NREL). SolarPILOT is used in this study to generate the field layout of a 1.3 MWe power plant with a solar multiple (SM) of 2, 3, and 4. Cost models for the tower, receiver, and heliostats are developed using the data from research programs, contractors, manufacturing companies, and general cost engineering data and tools. System Advisor Model (SAM) is further used to simulate the annual performance of CSP tower plant including power block (high-temperature gas turbine) and TES using optical efficiency data from SolarPILOT to optimize PHR-based CSP tower plant. The results of this research are fundamental to the techno-economic analysis (TEA) of this and similar smaller-scale systems and will support the TEA of larger grid-connected and smaller off-grid systems operating independently or in conjunction with PV systems.

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