CFD Analysis of PEMFC Flow Channel Cross Sections

This contribution presents the results of parametrical studies focused on the mixing process in a small rectangular duct within a biomass boiler. The first study investigates the influence of a local narrowing located in the central part of the duct. This narrowing works as an orifice with very simple rectangular geometry. Four different free cross sections of the orifice were considered in the center of the duct, namely 100%, 70%, 50%, 30% of free cross section area in the duct. The second study is focused on the investigation of the influence of secondary air distribution pipe diameter on the mixing process in a flue gas duct without a narrowing.

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Research on the Physical Modelling for the Subchannel Analysis of PWR Core

Volume 6A: Thermal-Hydraulics and Safety Analyses ◽

10.1115/icone26-81231 ◽

2018 ◽

Author(s):

Guangliang Chen ◽

Xiaomeng Dong ◽

Lei Li ◽

Peizheng Hu ◽

Thompson Appah ◽

...

Keyword(s):

Physical Mechanism ◽

Physical Modelling ◽

Flow Channel ◽

Analysis Tool ◽

Cfd Analysis ◽

Subchannel Analysis

To obtain a better subchannel analysis tool for PWR core, an investigation on the physical modelling was done via CFD analysis in this paper. A detailed discussion on the TH status was carried out to consider the suitability of the physical modelling in the subchannel analysis. The counteracted effect on the balance of the mass, momentum, and energy was found. Its influence on the physical mechanism was analyzed for the TH status in PWR core. Then it was found that the subchannel analysis based on each flow channel is very necessary for the accuracy of the 3D engineering TH analysis for the whole PWR core.

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Predicting the Effect of Gas-Flow Channel Spacing on Current Density in PEM Fuel Cells

10.1115/imece1999-0843 ◽

1999 ◽

Author(s):

Hamid Naseri-Neshat ◽

Sirivatch Shimpalee ◽

Sandip Dutta ◽

Woo-kum Lee ◽

J. W. Van Zee

Keyword(s):

Fuel Cell ◽

Cross Sections ◽

Diffusion Layer ◽

Current Density ◽

Gas Flow ◽

Channel Model ◽

Three Dimensional ◽

Pem Fuel Cell ◽

Flow Channel ◽

Straight Channel

Abstract The effects of change in diffusion layer width for constant diffusion layer thickness and constant gas-flow channel width are investigated with a straight channel model of a Proton Exchange Membrane (PEM) fuel cell. A three-dimensional 10-cm long straight channel model of the PEM fuel cell is presented. The geometrical model includes diffusion layers on both the anode and cathode sides and the numerical model couples three-dimensional Navier-Stokes flow with electro-chemical reactions occurring in the fuel cell. Contours of the current density, anode water vapor concentration, anode water activity, water molecules per proton flux, and secondary flow velocity vectors at different cross sections are presented for the two diffusion layer widths. For the particular conditions and properties used for this study, the results show a marked difference between the base case (0.16-cm) and the wide (0.72-cm) diffusion layer. The current density is quite uniform at different axial cross sections and cross-flow sections for the 0.16-cm wide diffusion layer. However, for the 0.72-cm wide diffusion layer, the current density decreases more significantly in the axial direction near the edges of the diffusion layer. Numerical predictions of the water transport between cathode and anode across the width of the MEA show the delicate balance of diffusion and electro-osmosis and their effect on the current distribution along channel.

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CFD Assisted Design Optimization of a Flow Distributor for Uniform Fluid Distribution

Volume 6: Fluids and Thermal Systems; Advances for Process Industries, Parts A and B ◽

10.1115/imece2011-65344 ◽

2011 ◽

Cited By ~ 2

Author(s):

Hong Liu ◽

Peiwen Li

Keyword(s):

Flow Distribution ◽

Basic Mechanism ◽

Flow Channel ◽

Fluid Distribution ◽

Cfd Analysis ◽

High Uniformity ◽

Uniform Flow Distribution ◽

Distribution Uniformity ◽

Flow Distributor ◽

Uniform Fluid

This study addresses a fundamental issue of distributing a fluid flow into a number of flow channels uniformly. A basic mechanism of flow distribution is accomplished through a channel bifurcation that symmetrically split one flow channel into two downstream channels. Applying the basic mechanism, cascades flow distributions are designed to split one flow into a large number of downstream flows uniformly. Some key parameters decisive to the flow distribution uniformity in such a system have been recognized, and the flow distribution uniformity was studied for several versions of flow distributor designs using CFD analysis. The effect of the key parameters of the flow channel designs to the flow distribution uniformity was investigated. As an example of industrial application, a novel fluid packaging device was proposed and some CFD analysis results for the device were provided. The optimized flow distributor makes a very good uniform flow distribution which will significantly improve the efficiency of fluid packaging. The technology is expected to be of great significance to many industrial devices that require high uniformity of flow distribution.

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Shape Optimization of PEMFC Flow-channel Cross-Sections

Fuel Cells ◽

10.1002/fuce.201700168 ◽

2017 ◽

Vol 17 (6) ◽

pp. 809-815 ◽

Cited By ~ 5

Author(s):

I. Korkischko ◽

B. S. Carmo ◽

F. C. Fonseca

Keyword(s):

Shape Optimization ◽

Cross Sections ◽

Flow Channel

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Analysis of STEM micrographs of thick objects

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100081395 ◽

1978 ◽

Vol 36 (2) ◽

pp. 106-107

Author(s):

S. Golladay

Keyword(s):

Inelastic Scattering ◽

Multiple Scattering ◽

Mass Distribution ◽

Cross Sections ◽

Phase Contrast ◽

Image Point ◽

Contrast Effects ◽

Total Cross Sections ◽

Elastic And Inelastic Scattering

The theory of multiple scattering has been worked out by Groves and comparisons have been made between predicted and observed signals for thick specimens observed in a STEM under conditions where phase contrast effects are unimportant. Independent measurements of the collection efficiencies of the two STEM detectors, calculations of the ratio σe/σi = R, where σe, σi are the total cross sections for elastic and inelastic scattering respectively, and a model of the unknown mass distribution are needed for these comparisons. In this paper an extension of this work will be described which allows the determination of the required efficiencies, R, and the unknown mass distribution from the data without additional measurements or models. Essential to the analysis is the fact that in a STEM two or more signal measurements can be made simultaneously at each image point.

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Direct Observation of Heat Exchanger Deposits by Cross Sectioning

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100061835 ◽

1967 ◽

Vol 25 ◽

pp. 364-365

Author(s):

R. W. Anderson ◽

D. L. Senecal

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Heat Exchanger ◽

Direct Observation ◽

Cross Sections ◽

Preparation Method ◽

Specimen Preparation ◽

Flowing Water ◽

Transmission Electron ◽

Deposit Layer

A problem was presented to observe the packing densities of deposits of sub-micron corrosion product particles. The deposits were 5-100 mils thick and had formed on the inside surfaces of 3/8 inch diameter Zircaloy-2 heat exchanger tubes. The particles were iron oxides deposited from flowing water and consequently were only weakly bonded. Particular care was required during handling to preserve the original formations of the deposits. The specimen preparation method described below allowed direct observation of cross sections of the deposit layers by transmission electron microscopy.The specimens were short sections of the tubes (about 3 inches long) that were carefully cut from the systems. The insides of the tube sections were first coated with a thin layer of a fluid epoxy resin by dipping. This coating served to impregnate the deposit layer as well as to protect the layer if subsequent handling were required.

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An Analysis of Dissociation of Molecules in a High Resolution Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100072873 ◽

1973 ◽

Vol 31 ◽

pp. 486-487

Author(s):

Mihir Parikh

Keyword(s):

Electron Microscope ◽

High Resolution ◽

Cross Sections ◽

Resolving Power ◽

Peak Intensity ◽

Molecular Film ◽

Resolution Electron ◽

Dissociation Cross Section ◽

High Resolution Electron Microscope ◽

The Stability

It is well known that the resolution of bio-molecules in a high resolution electron microscope depends not just on the physical resolving power of the instrument, but also on the stability of these molecules under the electron beam. Experimentally, the damage to the bio-molecules is commo ly monitored by the decrease in the intensity of the diffraction pattern, or more quantitatively by the decrease in the peaks of an energy loss spectrum. In the latter case the exposure, EC, to decrease the peak intensity from IO to I’O can be related to the molecular dissociation cross-section, σD, by EC = ℓn(IO /I’O) /ℓD. Qu ntitative data on damage cross-sections are just being reported, However, the microscopist needs to know the explicit dependence of damage on: (1) the molecular properties, (2) the density and characteristics of the molecular film and that of the support film, if any, (3) the temperature of the molecular film and (4) certain characteristics of the electron microscope used

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Surface ultrastructure of danazol treated rat endometrium: A SEM study

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010007641x ◽

1983 ◽

Vol 41 ◽

pp. 556-557

Author(s):

R.P. Apkarian ◽

J.S. Sanfilippo

Keyword(s):

Cross Sections ◽

Reproductive Tract ◽

Preliminary Investigation ◽

Breast Disease ◽

Distal Segment ◽

Uterine Horn ◽

Female Reproductive Tract ◽

Ultrastructural Changes ◽

Cycle Phase ◽

Sprague Dawley

The synthetic androgen danazol, is an isoxazol derivative of ethisterone. It is utilized in the treatment of endometriosis, fibrocystic breast disease, and has a potential use as a contraceptive. A study was designed to evaluate the ultrastructural changes associated with danazol therapy in a rat model. The preliminary investigation of the distal segment of the rat uterine horn was undertaken as part of a larger study intended to elucidate the effects of danazol on the female reproductive tract.Cross-sections (2-3 mm in length) of the distal segment of the uterine horn from sixteen Sprague-Dawley rats were prepared for SEM. Ten rats in estrus served as controls and six danazol treated rats were noted to have alterations of the estrus cycle i.e. a lag in cycle phase or noncycling patterns. Specimens were fixed in 3% glutaraldehyde in 0.05M phosphate buffer containing CaCl2 at pH 7.0-7.4 and chilled to 4°C. After a brief wash in distilled water, specimens were passed through a graded series of ethanol, critical point dryed in CO2 from absolute ethanol, and coated with 6nm Au. Observations were made with an IS1-40 SEM operated at 15kV.

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Electron Irradiation Effects in Polyoxymethylene Crystals Grown Inside Trioxane Crystals

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010006444x ◽

1971 ◽

Vol 29 ◽

pp. 78-79

Author(s):

J. P. Colson ◽

D. H. Reneker

Keyword(s):

Cross Section ◽

Cross Sections ◽

Detailed Examination ◽

The Other ◽

Electron Micrograph ◽

Irradiation Effects ◽

Threefold Axis ◽

Typical Sample ◽

Polymer Crystals ◽

Chain Axis

Polyoxymethylene (POM) crystals grow inside trioxane crystals which have been irradiated and heated to a temperature slightly below their melting point. Figure 1 shows a low magnification electron micrograph of a group of such POM crystals. Detailed examination at higher magnification showed that three distinct types of POM crystals grew in a typical sample. The three types of POM crystals were distinguished by the direction that the polymer chain axis in each crystal made with respect to the threefold axis of the trioxane crystal. These polyoxymethylene crystals were described previously.At low magnifications the three types of polymer crystals appeared as slender rods. One type had a hexagonal cross section and the other two types had rectangular cross sections, that is, they were ribbonlike.

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