Analysis of Flow Maldistribution of Fuel and Oxidant in a PEMFC

2004 ◽  
Vol 126 (4) ◽  
pp. 262-270 ◽  
Author(s):  
Ganesh Mohan ◽  
B. Prabhakara Rao ◽  
Sarit K. Das ◽  
S. Pandiyan ◽  
N. Rajalakshmi ◽  
...  
Keyword(s):  
Porous Medium ◽  
Numerical Modeling ◽  
Analytical Approach ◽  
Flow Distribution ◽  
Close Match ◽  
Large Numbers ◽  
Flow Channeling ◽  
Flow Through ◽  
The Individual ◽  
Flow Maldistribution

The flow of fuel and oxidant through a PEMFC is analyzed for prediction of maldistribution. Flow distribution of both fuel and oxidant from the port to the individual cells critically control the performance of a PEMFC stack in combination. The distribution of fluids was simulated by analytical approach utilizing flow channeling model of a manifold. A detailed numerical modeling is also carried out considering flow in each cell between the electrodes as flow through an equivalent porous medium offering identical resistance. The results show a close match between the analytical and numerical results. The parametric study reveals that flow rate and port size plays major role determining maldistribution of the fluids, which can be considerably skewed when large numbers of cells are stacked for larger power output.

scholarly journals Modeling and Computation of Flow in a Passage With 360° Turning and Multiple Airfoils

1991 ◽  
Author(s):  
W. Shyy ◽  
T. C. Vu
Keyword(s):  
Porous Medium ◽  
Numerical Modeling ◽  
Detailed Analysis ◽  
Flow Condition ◽  
Global Analysis ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Hydraulic Turbine ◽  
The Individual ◽  
Spiral Casing

Numerical modeling of the three-dimensional flows in a spiral casing of a hydraulic turbine, containing a passage of 360-degree turning and multiple elements of airfoils (the so-called distributor), is made. The physical model is based on a novel two-level approach, comprising of (1) a global model that adequately accounts for the geometry of the spiral casing but smears out the details of the distributor and represents the multiple airfoils by a porous medium treatment, and (2) a local model that performs detailed analysis of flow in the distributor region. The global analysis supplies the inlet flow condition for the individual cascade of distributor airfoils, while the distributor analysis yields the information needed for modeling the characteristics of the porous medium. Comparisons of pressure and velocity profiles between measurement and prediction have been made to assess the validity of the present approach. Flow characteristics in the spiral casing are also discussed.

Modelling the flow distribution through automotive catalytic converters

2001 ◽  
Vol 215 (4) ◽  
pp. 379-383 ◽  
Author(s):  
S F Benjamin ◽  
N Haimad ◽  
C A Roberts ◽  
J Wollin
Keyword(s):  
Fluid Dynamics ◽  
Flow Distribution ◽  
Maximum Flow ◽  
One Dimensional ◽  
Exhaust Catalysts ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Through ◽  
Automotive Catalytic Converters ◽  
Flow Maldistribution ◽  
Maximum Flow Velocity

Conventional computational fluid dynamics (CFD) methods for simulating the flow through automotive exhaust catalysts assume a monolith resistance based on one-dimensional laminar flow. This underpredicts the flow maldistribution in the monolith. Incorporation of an additional pressure loss accounting for entrance effects improves predictions for the maximum flow velocity within the substrate.

Optimisation of Header of a Compact Radiator

2018 ◽  
Vol 877 ◽  
pp. 327-334
Author(s):  
Subhadip Roy ◽  
C.S. Vamsi Krishna ◽  
N. Ganesh ◽  
A. Kumarasamy
Keyword(s):  
Heat Transfer ◽  
Hot Spots ◽  
Transfer Rate ◽  
Average Velocity ◽  
Side Pressure ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Through ◽  
The Individual ◽  
Two Parameters ◽  
Flow Maldistribution

The performance of a Plate fin radiator in terms of heat transfer rate and coolant side pressure drop depends significantly on the distribution of coolant through its passages. Uneven flow through the passages i.e. flow maldistribution, can cause local hot spots in the radiator due to high coolant flow in some passages. The flow maldistribution among the passages can be reduced to a large extent by proper optimisation of the header. The present paper investigates the method to optimise the header of a 680 kW radiator to reduce the maldistribution in its passages using Computational Fluid Dynamics (CFD). The analysis was simplified by considering the porous media instead of simulating the exact fin configuration in the radiator. The maximum and absolute values of flow maldistribution factor were considered in this study to determine the effectiveness of the header with respect to flow maldistribution. The flow maldistribution factor was determined based on the individual velocity of coolant in a passage and the average velocity of coolant in all the passages. The methods used for optimisation were rounding the header inlet, tapering the header partially, changing the position of the taper and modifying the end portion of the header. In this paper two parameters, viz., flow maldistribution parameter and absolute maldistribution parameter were considered to measure the maldistribution of a radiator. Due to these optimisations in the header, the maximum and absolute values of maldistribution reduced up to 18% and 45% respectively.

Stochastic homogenization and macroscopic modelling of composites and flow through porous media

2002 ◽  
pp. 337-378 ◽  
Author(s):  
Jozef Telega ◽  
Wlodzimierz Bielski
Keyword(s):  
Porous Medium ◽  
Random Distribution ◽  
Flow Through Porous Media ◽  
Macroscopic Models ◽  
Linear Elastic ◽  
Multi Scale ◽  
Convergence Method ◽  
Flow Through ◽  
The Mean ◽  
Random Porous Medium

The aim of this contribution is mainly twofold. First, the stochastic two-scale convergence in the mean developed by Bourgeat et al. [13] is used to derive the macroscopic models of: (i) diffusion in random porous medium, (ii) nonstationary flow of Stokesian fluid through random linear elastic porous medium. Second, the multi-scale convergence method developed by Allaire and Briane [7] for the case of several microperiodic scales is extended to random distribution of heterogeneities characterized by separated scales (stochastic reiterated homogenization). .

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