A three-dimensional numerical model of a micro laminar flow fuel cell with a bridge-shaped microchannel cross-section

2014 ◽  
Vol 269 ◽  
pp. 542-549 ◽  
Author(s):  
Pedro O. Lopez-Montesinos ◽  
Amit V. Desai ◽  
Paul J.A. Kenis
Keyword(s):  
Fuel Cell ◽  
Numerical Model ◽  
Laminar Flow ◽  
Cross Section ◽  
Three Dimensional

scholarly journals Effects of Bridge-Shaped Microchannel Geometry on the Performance of a Micro Laminar Flow Fuel Cell

Micromachines ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 822
Author(s):  
Muhammad Tanveer ◽  
Kwang-Yong Kim
Keyword(s):  
Fuel Cell ◽  
Numerical Model ◽  
Laminar Flow ◽  
Cross Section ◽  
Cross Sections ◽  
Three Dimensional ◽  
Narrow Channel ◽  
Navier Stokes ◽  
Cross Sectional ◽  
Square Channel

A laminar flow micro fuel cell comprising of bridge-shaped microchannel is investigated to find out the effects of the cross-section shape of the microchannel on the performance. A parametric study is performed by varying the heights and widths of the channel and bridge shape. Nine different microchannel cross-section shapes are evaluated to find effective microchannel cross-sections by combining three bridge shapes with three channel shapes. A three-dimensional fully coupled numerical model is used to calculate the fuel cell’s performance. Navier-Stokes, convection and diffusion, and Butler-Volmer equations are implemented using the numerical model. A narrow channel with a wide bridge shape shows the best performance among the tested nine cross-sectional shapes, which is increased by about 78% compared to the square channel with the square bridge shape.

Heat Transfer for Laminar Flow in Spiral Ducts of Rectangular Cross Section

2005 ◽  
Vol 127 (3) ◽  
pp. 352-356 ◽  
Author(s):  
Michael W. Egner ◽  
Louis C. Burmeister
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Laminar Flow ◽  
Cross Section ◽  
Rectangular Cross Section ◽  
Three Dimensional ◽  
Radius Of Curvature ◽  
Dean Number ◽  
Aspect Ratios ◽  
Small Pitch

Laminar flow and heat transfer in three-dimensional spiral ducts of rectangular cross section with aspect ratios of 1, 4, and 8 were determined by making use of the FLUENT computational fluid dynamics program. The peripherally averaged Nusselt number is presented as a function of distance from the inlet and of the Dean number. Fully developed values of the Nusselt number for a constant-radius-of-curvature duct, either toroidal or helical with small pitch, can be used to predict those quantities for the spiral duct in postentry regions. These results are applicable to spiral-plate heat exchangers.

Numerical Simulation of Vertical Forced Plume in a Crossflow of Stably Stratified Fluid

1995 ◽  
Vol 117 (4) ◽  
pp. 696-705 ◽  
Author(s):  
Robert R. Hwang ◽  
T. P. Chiang
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Cross Section ◽  
Three Dimensional ◽  
Experimental Measurements ◽  
Secondary Vortex ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Vortex Pairs ◽  
Plume Flows

In this study, an investigation using a three-dimensional numerical model, which treats conservation of mass, momentum, and salinity simultaneously, was carried out to study the character of a vertical forced plume in a uniform cross-stream of stably linear stratified environment. A k-ε turbulence model was used to simulate the turbulent phenomena and close the solving problem. The performance of the three-dimensional model is evaluated by comparison of the numerical results with some available experimental measurements. Results indicate that the numerical computation simulates satisfactorily the plume behavior in a stratified crossflow. The secondary vortex pairs in the cross section induced by the primary one change as the plume flows downstream. This denotes the transformation of entrainment mechanism in stratified crossflow.

A Numerical Model to Simulate Diffuse Effects in Microfluidic Fuel Cells

2010 ◽  
Author(s):  
Isaac B. Sprague ◽  
Prashanta Dutta
Keyword(s):  
Fuel Cell ◽  
Numerical Model ◽  
Laminar Flow ◽  
Ion Transport ◽  
Double Layer ◽  
Electric Double Layer ◽  
Double Layers ◽  
Algebraic Equations ◽  
Microfluidic Fuel Cell ◽  
Volume Method

A 2D numerical model is developed for a laminar flow fuel cell considering ion transport and the electric double layer around the electrodes. The Frumkin-Butler-Volmer equation is used for the fuel cell kinetics. The finite volume method is used to form algebraic equations from governing partial differential equations. The numerical solution was obtained using Newton’s method and a block TDMA solver. The model accounts for the coupling of charged ion transport with the electric field and is able to fully resolve the diffuse regions of the electric double layer in both the stream-wise and cross-channel directions. Different operating phenomena, such as laminar flow separation and the development of the depletion boundary layers and electric double layers are obtained. These numerical results demonstrate the model’s ability to capture the complex behavior of a microfluidic fuel cell which has been ignored in previous 1D models.

An Innovative Three Dimensional Numerical Model for Bipolar Plates to Enhance the Efficiency of PEM Fuel Cells

2012 ◽  
Author(s):  
Faraz Arbabi ◽  
Ramin Roshandel
Keyword(s):  
Fuel Cell ◽  
Numerical Model ◽  
Three Dimensional ◽  
Pem Fuel Cell ◽  
Bipolar Plate ◽  
Pem Fuel Cells ◽  
Fuel Cell Performance ◽  
Flow Channels ◽  
Plate Design ◽  
Current Densities

The efficiency of proton exchange membrane (PEM) fuel cell is straightly correlated to the bipolar plate design and fluid channel arrangements. Higher produced energy can be attained by optimal design of type, size, or patterns of the channels. Previous researches showed that the bipolar plate channel design has a considerable effect on reactant distribution uniformity as well as humidity control in PEM fuel cells. This paper concentrates on enhancements in the fuel cell performance by optimization of bipolar plate design and channels configurations. A numerical model of flow distribution based on Navier-Stokes equations using individual computer code is presented. The results gained from this three dimensional, multi-component simulation showed excellent agreement with the existed experimental data in the previous publications. In this paper, a new flow field design inspired from the nature is presented and analyzed. In this work, two mostly used flow channels design — serpentine and parallel — have been studied and compared to the newly introduced bio inspired bipolar plate design. To compare, velocity distributions of fluid, mass fraction of reactant gases and polarization curves for different bipolar plate designs have been analyzed. The key design criteria in this study are based on more homogenous molar spreading of species and more uniform velocity distribution along the flow channels and also higher voltage and power density output in different current densities. By developing a numerical code it was concluded that the bio inspired bipolar plate can enhance the PEM fuel cell performance especially at middle current densities, where the losses caused by mass transport limitations are not significant.

Laminar Flow and Heat Transfer in Spiral Ducts of Rectangular Cross Section

2004 ◽  
Author(s):  
Michael W. Egner ◽  
Louis C. Burmeister
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Cross Section ◽  
Rectangular Cross Section ◽  
Three Dimensional ◽  
Radius Of Curvature ◽  
Dean Number ◽  
Flow And Heat Transfer ◽  
Aspect Ratios ◽  
Small Pitch

Laminar flow and heat transfer in three-dimensional spiral ducts of rectangular cross section with aspect ratios of 1, 4, and 8 were determined with the aide of the FLUENT computational fluid dynamics program. Peripherally-averaged coefficients of friction and Nusselt numbers are presented as a function of distance from the inlet and of the Dean number. Fully-developed values of friction coefficient and Nusselt number for a constant-radius-of-curvature duct, either toroidal or helical with small pitch, can be used to predict those quantities for the spiral duct in post-entry regions. These results are applicable to spiral-plate heat exchangers.

scholarly journals Analysis of Ground Settlement Caused by Double-line TBM Tunnelling under Existing Building

2021 ◽  
Author(s):  
Dongxue Hao ◽  
Renjun Zhu ◽  
Ke Wu ◽  
Rong Chen
Keyword(s):  
Numerical Model ◽  
Cross Section ◽  
Three Dimensional ◽  
Ground Settlement ◽  
Double Line ◽  
Existing Building ◽  
Ground Deformations ◽  
Geological Conditions ◽  
Line Construction ◽  
The Right

Abstract TBM tunnelling is less used in the subway construction in prosperous city due to the limitation of the engineering geological conditions. The studies on the influence of the TBM construction on the existing buildings are also limited. Therefore, based on the engineering case of tunnel crossing existing building in the section of Haiboqiao ~ Xiaocunzhuang station of Qingdao Metro Line 1, the numerical model that simulates the construction process of TBM tunnelling in slightly weathered granite layer is established by three-dimensional finite difference software FLAC3D to analyze the influence of TBM tunneling on ground settlement. The comparisons of ground deformations obtained from FLAC3D and field monitoring in different construction stages of double-line tunnel have been made firstly to validate the numerical model. Then the ground settlement characteristics, differential settlement and the stress distribution of the existing building and the stress of segment structure have been analyzed. Ground settlement groove along the transverse and vertical sections occurs near the building and tunnels, and the settlement becomes smaller with the farther distance from them. The settlement curve on the cross section changes dynamically and is approximately V-shaped, and its width is about 5 ~ 6 times diameter of the tunnel. For the same cross section, the range of the settlement groove after tunnelling right line increases obviously compared with that after tunnelling left line (construction first), the settlement values also increase, and the symmetrical axis of the settlement curve is shifted to the right. This paper can provide important practical reference for relative construction engineering.

Numerical investigation on the effect of tow tension on the geometry of three-dimensional orthogonally woven fabric

2018 ◽  
Vol 89 (18) ◽  
pp. 3779-3791 ◽  
Author(s):  
Zhiping Ying ◽  
Xudong Hu ◽  
Xiaoying Cheng ◽  
Zhenyu Wu
Keyword(s):  
Numerical Model ◽  
Numerical Investigation ◽  
Cross Section ◽  
Mechanical Performance ◽  
Three Dimensional ◽  
Transverse Force ◽  
Woven Fabric ◽  
Textile Composite ◽  
A Chain ◽  
Good Agreement

The fabric geometry determines the mechanical performance of a textile composite. This paper investigates the effect of tow tension on the fabric geometry during the weaving process. A numerical model at the fiber scale was established by representing the fiber as a chain of truss elements connected by fully flexible hinges and having strong tensile modules. Fabric samples were woven on a homemade loom under different tension configurations to verify the numerical model. The model results with respect to the tow cross-section and path are in good agreement with observations of the homemade fabric sample. The tow cross-section deformation is the consequence of fiber rearrangement due to the transverse force originating from Z-binder tension. It is also found that the crimps of weft tows are different to those of warp tows. For weft tows, appreciable crimping is found in the regions of intercrossing with the Z-binder tow. Meanwhile, fibers undulate at the edges and remain straight in the middle of warp tows.

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