Polymer Electrolyte Membrane (PEM) fuel cell is a promising energy conversion device with applications involving rapid start-up and low operating temperature. Proper cooling of PEM fuel cell stack is an essential requirement in ensuring its durability for which separate cooling channels between each cell are often used. This study involves a detailed three-dimensional numerical investigation on cooling channel designs based on traditional serpentine and spiral designs. Four new designs - divided serpentine, divided spiral, distributed serpentine and distributed spiral are proposed to predict the fluid flow and thermal characteristics. An in-house code based on Streamline upwind/Petrov Galerkin finite element method is used to solve the three-dimensional governing equations. Simulations are carried out for Reynolds number ranging from 415 to 1247. Results indicate that the novel designs have better performance compared to serpentine in terms of uniformity in temperature distribution at all Re. The merits and demerits of all the designs in terms of maximum and average temperature on the cooling plate is also discussed. The pressure drop required to drive the flow is higher in the spiral and new designs compared to serpentine due to the presence of complex turns. © 2014 Elsevier Ltd. All rights reserved.

Arul Prakash Karaiyan

Department of Applied Mechanics

S. Ravishankar

COOLING PLATES

ENERGY CONVERSION DEVICES

GALERKIN FINITE ELEMENT METHODS

LOW OPERATING TEMPERATURE

Numerical investigations

POLYMER ELECTROLYTE MEMBRANES

SERPENTINE FLOW FIELDS

Thermal characteristics

Cooling

Electrolytes

Energy conversion

Polymers

Proton exchange membrane fuel cells (PEMFC)

Reynolds number

Serpentine

three dimensional

Design

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Applied Thermal Engineering

Numerical studies on fluid flow and heat transfer through a two-dimensional 180-degree sharp bend are performed using an in-house code based on streamline upwind Petrov-Galerkin finite element method. A new geometric parameter called inlet height to outlet height ratio (IOR) is defined to assess the heat transfer performance. Parametric analyses are carried out by varying the Reynolds number (Re) from 100 to 900 for five IORs (1:2, 1:1.5, 1:1, 1.5:1, 2:1). The fluid flow changes from steady to unsteady for all IORs with increasing Re. The critical Reynolds number range is identified for each IOR and is found to be lower for IOR < 1 or IOR > 1 when compared with IOR 1:1, thus enhancing the heat transfer due to unsteadiness. IOR also influences the rate of generation of the vortices and the vortex interactions, which emphasize the enhancement in heat transfer. Nusselt number (Nu) and thermal performance factor (TPF) for the domain are calculated and it is observed that though there is an increase of 20%–40% in Nu for IOR 2:1 configuration with respect to IOR 1:1, the TPF predicts that IOR 1:1.5 is an overall good domain for heat transfer and pressure drop considerations. © 2019, © 2019 Taylor & Francis Group, LLC.

Heat Transfer Engineering

Steady and Unsteady Forced Convective Heat Transfer Analysis in 180 Degree Bend

In this study, the effect of splitter plate on fluid flow characteristics past an elliptic cylinder of different axis ratios (AR=1.0−0.5) is numerically investigated for various Reynolds number (Re = 50–200). The equations governing fluid flow are discretized using Streamline Upwind/Petrov-Galerkin (SUPG) based finite element method (FEM). The presence of a splitter plate alters the wake region where vortex shedding is suppressed. Depending on AR and Re two critical lengths of splitter plate are defined, one for suppression of vortex shedding and the other when shear layer interaction in the wake is inhibited. The correlations for the critical lengths of splitter plate as a function of AR and Re are derived using regression analysis. It is observed that, the variation of integral parameters like drag, lift and St are not monotonic with increasing plate length. From the results it is concluded that for a particular combination of Re and AR with suitable splitter plate length, the total drag is minimized approximately from 2% to 38%. Finally, Cd_avg is selected as an objective function and modelled using Response Surface Approximation (RSA). Furthermore, a single-objective Genetic algorithm has been implemented to obtain optimum configuration for minimum Cd_avg. © 2017 Elsevier Ltd

Ocean Engineering

Effect of splitter plate on passive control and drag reduction for fluid flow past an elliptic cylinder

The design of optimum spiral casing configuration is a difficult task and a big challenge in the field of turbomachinery. Computational fluid dynamics (CFD) analysis of fluid flow characteristics in a 360◦ turn around spiral casing plays an important role in its design. The objective in this study is to propose an optimum spiral casing configuration by reducing the total pressure loss and increasing the spiral velocity coefficient and average radial velocity at the exit of spiral casing. For this, three different configurations of spiral casing, viz. accelerated, decelerated and free vortex type, with different aspect ratios (ARs) are numerically simulated. A Eulerian velocity-correction method based on the streamline upwind Petrov–Galerkin (SUPG) finite-element method is employed to solve complete Reynolds-averaged Navier–Stokes (RANS) equations governing fluid flow characteristics. The results show that the average radial velocity along the exit of spiral casings is more for elliptical crosssectional spiral casings of AR>1 when compared to circular cross-sectional spiral casings. The total pressure loss is found to be at minimum for decelerated spiral casings. In the case of decelerated spiral casings, a further reduction in total pressure loss is obtained with elliptical cross-sections of AR>1. The spiral velocity coefficient is found to be at maximum for decelerated spiral casings with AR>1. © 2016 The Author(s).

Fulltext

Engineering Applications of Computational Fluid Mechanics

Numerical studies on fluid flow characteristics through different configurations of spiral casing

In the present study, fluid flow and thermal characteristics associated with forced convection cooling of an array of discrete protruding heat sources mounted on impingement plate of channel by an impinging laminar jet is investigated for various Reynolds number (Re) and channel height (H/L). It is observed that, the magnitude of average Nusselt number for all heat sources increases with increasing Re and decreasing H/L, except the regions of heat sources covered by recirculation bubbles which may be due to accumulation of heat resulting in hot spots. In order to eliminate these hot spots, a porous layer is attached to the impingement plate. A parametric study is conducted to predict the performance of porous layer on fluid flow pattern, heat transfer and entropy generation for various values of Darcy number (Da), Reynolds number (Re), channel height (H/L), porosity (∈) and porous layer thickness (h/H). For the purpose, equations governing two-dimensional, time-dependent, incompressible and laminar flow are solved in a Cartesian framework by using Streamline Upwind Petrov-Galerkin (SUPG) Finite Element (FE) method. The generalized Darcy-Forchheimer-Brinkman model is adopted to model the flow in porous medium. The recirculation bubbles on heat sources are completely eliminated with the inclusion of porous layer at Darcy number, Da=10-2. The magnitude of overall Nusselt number and global entropy generation due to heat transfer (Sθ,Ω¯) and fluid friction (Sψ,Ω¯) increases with increasing Da,Re,h/H and decreasing ∈ and H/L. The optimum configuration for maximum heat transfer and minimum entropy generation is observed at Da=10-2,Re=1000,H/L=1.0,h/H=0.75 and ∈=0.5. © 2014 Elsevier Ltd. All rights reserved.

Energy Conversion and Management

A numerical investigation of heat transfer and entropy generation during jet impingement cooling of protruding heat sources without and with porous medium

Single U- and Z-type parallel-channel configurations for gas distributor plates in planar fuel cells reduce the pressure drop but give rise to the problem of severe flow maldistribution wherein some of the channels may be starved of the reactants. In this paper, previous analytical solutions obtained for single U- and Z-type flow configurations are extended to multiple U- and multiple Z-type flow configurations of interest to fuel cell applications. Algorithms to calculate flow distribution and pressure drop in multiple U- and Z-type flow configurations are developed. The results are validated by comparison with those obtained from three-dimensional computational fluid dynamics (CFD) simulations. It is found that there is a significant improvement in the flow distribution in some configurations without paying for extra pressure drop. The possibility of unmatched distribution on the cathode and the anodes sides is also highlighted. Careful design of the flow configuration is therefore necessary for optimum performance. © 2005 Elsevier B.V. All rights reserved.

Journal of Power Sources

Pressure drop and flow distribution in multiple parallel-channel configurations used in proton-exchange membrane fuel cell stacks

Fuel Cell Fundamentals

International Journal of Hydrogen Energy

Influence of geometric parameters of the flow fields on the performance of a PEM fuel cell. A review

A critical review of cooling techniques in proton exchange membrane fuel cell stacks

Renewable and Sustainable Energy Reviews

Comparative study of different fuel cell technologies

Numerical studies on thermal performance of novel cooling plate designs in polymer electrolyte membrane fuel cell stacks

Journal	Applied Thermal Engineering
ISSN	13594311
Open Access	No