Investigation of Liquid Water Content of a Compressed PEMFC GDL Using Micro-Computed Tomography

2012 ◽  
Author(s):  
Ronnie Yip ◽  
Aimy Bazylak
Keyword(s):  
Computed Tomography ◽  
Water Content ◽  
Liquid Water ◽  
Water Injection ◽  
Three Dimensional ◽  
Liquid Water Content ◽  
Gas Diffusion ◽  
Ex Situ ◽  
Micro Ct ◽  
Micro Computed Tomography

With the current lack of understanding of the water transport phenomenon in the porous gas diffusion layers (GDLs) of the polymer electrolyte membrane fuel cells (PEMFCs), GDL designs are primarily implemented on a costly trial-and-error basis. In this work, an ex-situ device, suitable for micro-computed tomography (micro-CT) imaging, was designed to facilitate liquid water invasion of a GDL sample under flow field compression. The millimeter-scale apparatus allows for water injection from a point source with an opening diameter of 0.8 mm. A sample of felt-based Freudenberg GDL (H2315) was examined for the current study. Using micro-CT, the sample was scanned, before and after water invasion, to obtain high resolution, three-dimensional reconstructions of the dry GDL microstructures, as well as the liquid water patterns after breakthrough. These results were used to find the effect of liquid water content on the effective through-plane porosity for the felt-based Freudenberg GDL.

Comparison of Water Thickness Profiles of Compressed PEMFC GDLs

2011 ◽  
Author(s):  
Pradyumna Challa ◽  
James Hinebaugh ◽  
A. Bazylak
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Water Distribution ◽  
Polymer Electrolyte Membrane ◽  
Water Injection ◽  
Liquid Water Content ◽  
Gas Diffusion ◽  
Injection Rate ◽  
Water Levels ◽  
Ex Situ

In this paper, through-plane liquid water distribution is analyzed for two polymer electrolyte membrane fuel cell (PEMFC) gas diffusion layers (GDLs). The experiments were conducted in an ex situ flow field apparatus with 1 mm square channels at two distinct flow rates to mimic water production rates of 0.2 and 1.5 A/cm2 in a PEMFC. Synchrotron radiography, which involves high intensity monochromatic X-ray beams, was used to obtain images with a spatial and temporal resolution of 20–25 μm and 0.9 s, respectively. Freudenberg H2315 I6 exhibited significantly higher amounts of water than Toray TGP-H-090 at the instance of breakthrough, where breakthrough describes the event in which liquid water reaches the flow fields. While Freudenberg H2315 I6 exhibited a significant overall decrease in liquid water content throughout the GDL shortly after breakthrough, Toray TGP-H-090 appeared to retain breakthrough water-levels post-breakthrough. It was also observed that the amount of liquid water content in Toray TGP-H-090 (10%.wt PTFE) decreased significantly when the liquid water injection rate increased from 1 μL/min to 8 μL/min.

Proton transport resistance correlated to liquid water content of gas diffusion layers

2012 ◽  
Vol 209 ◽  
pp. 147-151 ◽  
Author(s):  
Jon P. Owejan ◽  
Jeffrey J. Gagliardo ◽  
Robert C. Reid ◽  
Thomas A. Trabold
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Proton Transport ◽  
Liquid Water Content ◽  
Gas Diffusion ◽  
Gas Diffusion Layers ◽  
Diffusion Layers

scholarly journals Evaluation of Orographic Cloud Seeding Using a Bin Microphysics Scheme: Three-Dimensional Simulation of Real Cases

2020 ◽  
Vol 59 (9) ◽  
pp. 1537-1555
Author(s):  
István Geresdi ◽  
Lulin Xue ◽  
Noémi Sarkadi ◽  
Roy Rasmussen
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Cloud Condensation Nuclei ◽  
Three Dimensional ◽  
Liquid Water Content ◽  
Weather Modification ◽  
Diffusional Growth ◽  
Surface Precipitation ◽  
Orographic Clouds ◽  
The Impact

AbstractThe University of Pécs and NCAR Bin (UPNB) microphysical scheme was implemented into the mesoscale Weather Research and Forecast (WRF) Model that was used to study the impact of silver iodide (AgI) seeding on precipitation formation in winter orographic clouds. Four different experimental units were chosen from the Wyoming Weather Modification Pilot Project to simulate the seeding effect. The results of the numerical experiments show the following: (i) Comparisons with the soundings, snow gauges, and microwave radiometer data indicate that the three-dimensional simulations with detailed microphysics reasonably represent both the dynamics and the microphysics of real clouds. (ii) The dispersion of the AgI particles from the simulated ground-based seeding was effective because of turbulent mixing. (iii) In the investigated cases (surface temperature is less than 0°C), surface precipitation and precipitation efficiency show low susceptibility to the concentrations of cloud condensation nuclei and natural ice nucleating particles. (iv) If the available liquid water content promotes the enhancement of the number of snowflakes by diffusional growth, the surface precipitation can be increased by more than 5%. A novel parameter relevant to orographic clouds, horizontally integrated liquid water path (LWP), was evaluated to find the relation between seeding efficiency and liquid water content. The impact of seeding is negligible if the horizontal LWP is less than 0.1 mm and is apparent if the horizontal LWP is larger than 1 mm, as based on the cases investigated in this study.

scholarly journals Micro-CT study of Middle Ordovician Spumellaria (radiolarians) from western Newfoundland, Canada

2020 ◽  
Vol 94 (3) ◽  
pp. 417-435 ◽  
Author(s):  
Sarah Kachovich ◽  
Jonathan C. Aitchison
Keyword(s):  
Computed Tomography ◽  
Three Dimensional ◽  
Detailed Examination ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Lower Paleozoic ◽  
X Ray ◽  
Middle Ordovician ◽  
Radiolarian Assemblage ◽  
Taxonomic Groups

AbstractA new, previously undescribed Middle Ordovician (middle Darriwilian: Dw2) radiolarian assemblage has been recovered from the Table Cove Formation at Piccadilly Quarry, western Newfoundland. Constituents of the fauna described herein are both distinctive and exceptionally well preserved. Three-dimensional X-ray micro-computed tomography (μ-CT) is used to make a detailed examination of four key spumellarian specimens. This technology enables visualization of hitherto ambiguous details of the internal morphologies of key lower Paleozoic taxonomic groups, among which a lack of knowledge has impeded resolution of higher taxonomic rankings.

Pore Space Characterization of Compressed PEMFC GDLs Using 3D Micro-Computed Tomography

2012 ◽  
Author(s):  
Pradyumna R. Challa ◽  
A. Bazylak
Keyword(s):  
Computed Tomography ◽  
Pore Space ◽  
Polymer Electrolyte Membrane ◽  
Gas Diffusion ◽  
Ex Situ ◽  
Micro Computed Tomography ◽  
Porous Layers ◽  
Electrolyte Membrane ◽  
Diffusion Layers

In this work, micro-computed tomography was employed to characterize the effect of rib and channel compression on the through-plane porosity distributions of polymer electrolyte membrane fuel cell (PEMFC) gas diffusion layers (GDLs). Two GDLs with micro-porous layers (MPLs): a paper based GDL (GDL A), and a felt GDL (GDL B) were compressed at 1.2 MPa in an ex situ flow field apparatus with 1mm × 1mm channels. Porosity distributions of compressed GDLs were compared with those of uncompressed GDLs, and the microstructural differences caused during the manufacturing of paper, felt, and cloth GDLs are discussed. The results of this study will aid modellers in generating realistic stochastic GDL pore structures for multiphase flow simulations.

scholarly journals Micro-computed tomography: A novel diagnostic technique for the evaluation of gastrointestinal specimens

2021 ◽  
Vol 09 (12) ◽  
pp. E1886-E1889
Author(s):  
Noboru Kawata ◽  
Alexei Teplov ◽  
Peter Ntiamoah ◽  
Jinru Shia ◽  
Meera Hameed ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Three Dimensional ◽  
Diagnostic Technique ◽  
Human Colon ◽  
Ffpe Tissue ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Cross Sectional ◽  
Tissue Samples ◽  
Formalin Fixed Paraffin Embedded

AbstractMicro-computed tomography (micro-CT) is a non-destructive modality that can be used to obtain high-resolution three-dimensional (3 D) images of the whole sample tissue; the usefulness of micro-CT has been reported for evaluation of breast cancer and lung cancer. However, this novel diagnostic technique has never been used for evaluating endoscopically resected gastrointestinal specimens. In the present study, we scanned 13 formalin-fixed paraffin-embedded (FFPE) tissue blocks of a normal human colon and gastric tissue samples using micro-CT. The evaluation comprised a comparison of the acquired whole block images with the images of the corresponding cross-sectional slice of the hematoxylin and eosin-stained slide. Micro-CT was able to produce images of the whole sample and clearly depict tissues such as glandular structures, muscularis mucosae, and blood vessels in the FFPE tissue blocks of normal gastrointestinal samples. Furthermore, the 3 D reconstructed could be used to create a cross-sectional image and reflected the surface structure of samples obtained from any site. Micro-CT has the potential to become a highly promising pathological diagnostic assistance tool for endoscopically resected gastrointestinal specimens in combination with conventional microscopic examination.

Effect of Liquid Water Saturation on Oxygen Transport in Gas Diffusion Layers of Polymer Electrolyte Fuel Cells

2010 ◽  
Author(s):  
Takeshi Shiomi ◽  
Richard S. Fu ◽  
Ugur Pasaogullari ◽  
Yuichiro Tabuchi ◽  
Shinichi Miyazaki ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Water Content ◽  
Polymer Electrolyte ◽  
Liquid Water ◽  
Water Saturation ◽  
Liquid Water Content ◽  
Gas Diffusion ◽  
Polymer Electrolyte Fuel Cells ◽  
Oxygen Diffusivity ◽  
Liquid Saturation

Improved oxygen diffusivity is essential for reducing mass transport losses in polymer electrolyte fuel cells (PEFCs). In this work, effective oxygen diffusivity in the presence of liquid water inside a gas diffusion layer (GDL) was investigated by means of coupled experimental and numerical analyses. In order to control the liquid water content inside the GDL, a temperature gradient method was developed. In a separate experiment liquid water content inside the GDL was measured by neutron radiography (NR) and analyzed by using a two-phase, non-isothermal numerical model. The model accurately reproduced the total liquid water content and was in qualitative agreement with the liquid saturation trend as obtained from the NR experiments, which was utilized to estimate the liquid saturation in the limiting current experiment. Based on the predicted liquid water profile, the dependence of effective oxygen diffusivity on the liquid water saturation is deduced. It is found that the Bruggeman exponent factor is much larger than the predictions from network models and this suggests that the understanding of the relationship between liquid water transport and the GDL local structure is important.

Upscaling Reservoir Rock Porosity by Fractal Dimension Using Three-Dimensional Micro-Computed Tomography and Two-Dimensional Scanning Electron Microscope Images

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Muhammad Jawad Munawar ◽  
Sandra Vega ◽  
Chengyan Lin ◽  
Mohammad Alsuwaidi ◽  
Naveed Ahsan ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Three Dimensional ◽  
Fractal Dimensions ◽  
Two Dimensional ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Sandstone Sample ◽  
The Core ◽  
Carbonate Sample ◽  
Scanning Electron

Abstract Scaling porosity of sedimentary rocks from the scale of measurement to the scale of interest is still a challenge. Upscaling of porosity can assist to accurately predict other petrophysical properties of rock at multiple scales. In this study, we use the two-dimensional (2D) scanning electron microscope (SEM) and three-dimensional (3D) X-ray micro-computed tomography (micro-CT) image to upscale porosity from the image scale to the core plug scale. A systematic imaging plan is deployed to capture rock properties of a carbonate and a sandstone sample, which are sensitive to the fractal nature of these rocks. Image analysis records wider pore spectrum (0.12–50 µm) in the carbonate sample than in sandstone (0.12–30 µm). The fractal dimensions are also higher in the carbonate than in the sandstone sample. Median, volume-weighted average of pore radius, and fractal dimensions derived from the image analysis are used as inputs in this equation. The results of the present study using this equation yielded to the best results on a resolution of 2.5 µm/voxel in the sandstone and 2.01 µm/voxel resolution in the carbonate sample for 3D micro-CT images, where fractal-scaling porosity matches well with the porosity measured at the core plug scale. The 2D SEM images provided a good estimation of porosity in the sandstone sample, where micro-CT imaging techniques could not capture the full pore spectrum. The fractal porosity equation showed promising results and offers a potential alternative way to estimate porosity when there are no routine core measurements available.

scholarly journals Evaluation of scaffold microstructure and comparison of cell seeding methods using micro-computed tomography-based tools

2020 ◽  
Vol 17 (165) ◽  
pp. 20200102
Author(s):  
Aleksi Palmroth ◽  
Sanna Pitkänen ◽  
Markus Hannula ◽  
Kaarlo Paakinaho ◽  
Jari Hyttinen ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Three Dimensional ◽  
3D Cell Culture ◽  
Adipose Derived Stem Cells ◽  
Micro Ct ◽  
Cell Seeding ◽  
Micro Computed Tomography ◽  
Tissue Engineering Scaffolds ◽  
Scaffold Architecture ◽  
Static Seeding

Micro-computed tomography (micro-CT) provides a means to analyse and model three-dimensional (3D) tissue engineering scaffolds. This study proposes a set of micro-CT-based tools firstly for evaluating the microstructure of scaffolds and secondly for comparing different cell seeding methods. The pore size, porosity and pore interconnectivity of supercritical CO 2 processed poly( l -lactide-co- ɛ -caprolactone) (PLCL) and PLCL/β-tricalcium phosphate scaffolds were analysed using computational micro-CT models. The models were supplemented with an experimental method, where iron-labelled microspheres were seeded into the scaffolds and micro-CT imaged to assess their infiltration into the scaffolds. After examining the scaffold architecture, human adipose-derived stem cells (hASCs) were seeded into the scaffolds using five different cell seeding methods. Cell viability, number and 3D distribution were evaluated. The distribution of the cells was analysed using micro-CT by labelling the hASCs with ultrasmall paramagnetic iron oxide nanoparticles. Among the tested seeding methods, a forced fluid flow-based technique resulted in an enhanced cell infiltration throughout the scaffolds compared with static seeding. The current study provides an excellent set of tools for the development of scaffolds and for the design of 3D cell culture experiments.

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