Assessing the performance of reactant transport layers and flow fields towards oxygen transport: A new imaging method based on chemiluminescence

Lopes, Thiago; Ho, Matthew; Kakati, Biraj Kumar; Kucernak, Anthony

doi:10.1016/j.jpowsour.2014.10.055

Cited by 8 publications

(70 citation statements)

References 20 publications

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“…The geometry used for the simulations follows the one reported for the experimental apparatus [6], and is presented in Figure 1: a single-channel serpentine geometry was used for the flow field; a porous layer for the diffusion media, representing the macroporous carbon paper substrate (MPS); and finally a silica gel based catalytic layer (CL), where the catalyst is assumed homogeneously distributed. The CL includes a surface that follows the middle of the flow channel projection, crossing the entire CL domain thickness, used for probing the model (Fig.…”

Section: Methodsmentioning

confidence: 99%

“…The outlet was defined by a constant pressure, with suppression of backflow, the value of it being supplied by the authors of reference [6]. To allow comparison with different systems, the Reynolds number was calculated using Q, the average kinematic viscosity over the entire flow channel domain, and the hydraulic diameter for rectangular channels, assuming the MPS as a solid wall.…”

Section: Methodsmentioning

confidence: 99%

“…It was proposed that, contrary to what is usually assumed, convection plays a significant role in the distribution of reactants in the porous layers. The unique data reported in [6] is welcome amidst a gap in research of such aspects in the field, providing an opportunity to further refine computational models for fuel cell-like systems, enabling the validation of momentum and species transport in both global and local aspects.…”

Section: Introductionmentioning

confidence: 99%

“…In order to explore the differences between the outlined approaches, a macroscopic, finite elements-based model was assembled to simulate the species and flow dynamics of the system reported in [6]. Using the available data to validate the approach, the intent is to assist in the understanding of the system, and, ultimately, jointly provide a consistent tool to study the dynamics of fuel cell-like systems.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of convective transport in the gas diffusion layer used in polymer electrolyte fuel cells

et al. 2017

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Recent experimental data on a fuel cell-like system revealed insights on the fluid flow in both free and porous media. A computational model is used to investigate the momentum and species transport in such system, solved using the finite elements method. The model consists of a stationary, isothermal, diluted species transport in free and porous media flow. The momentum transport is treated using different formulations, namely Stokes-Darcy, Darcy-Brinkman, and a hybrid StokesBrinkman formulations. The species transport is given by the advection equation for a reactant diluted in air. The formulations are compared to each other and to the available experimental data, where it is concluded that the Darcy-Brinkman formulation reproduces the data appropriately. The validated model is used to investigate the contribution of convection in reactant transport in porous media of fuel cells. Convective transport provides a major contribution to reactant distribution in the so-called diffusion media. For a serpentine channel and flow with Re = 260 to 590, convection accounts for 29 to 58% of total reactant transport to the catalyst

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Investigation of convective transport in the gas diffusion layer used in polymer electrolyte fuel cells

et al. 2017

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“…Notably,5 50 ccm O 2 was chosen because below 450 ccm the catalyst layer is not completely utilised due to an improper distribution of oxygen. [44] Anode and cathode operated at ag auge backpressure of approximately 210/210 kPa (H 2 and O 2 partial pressure at ca. 217 and 244 kPa abs taking into account water vapour) or 65/65 kPa (H 2 and O 2 partial pressure at ca.…”

Section: Membrane Electrode Assembly Preparationpefc Test Conditionsmentioning

confidence: 99%

Mechanistic Insights into the Oxygen Reduction Reaction on Metal–N–C Electrocatalysts under Fuel Cell Conditions

et al. 2016

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Three different transition metal‐C‐N catalysts are tested under a range of fuel cell conditions. It is found that common features of the polarisation curve can be explained by a change in electrocatalytic mechanism. Utilising a simple model to quantify the change in mechanisms, iR‐free results of the fuel cell experiments are fit and found to be represented by a common set of parameters. The change in mechanism is assumed to be a switch from four‐electron reduction of oxygen to water to a two‐electron reduction to hydrogen peroxide followed by disproportionation of the hydrogen peroxide to water and oxygen. The data is used to estimate a mass specific exchange current density towards the oxygen reduction reaction (ORR) to water in the range 10−11–10−13 A g−1 depending on the catalyst. For the reduction of oxygen to hydrogen peroxide, the mass specific exchange current density is estimated to be in the range 10−2–10−3 A g−1. Utilising the electrokinetic model, it is shown how the mass transport losses can be extracted from the polarisation curve. For all three catalyst layers studied, these mass transport losses reach about 100 mV at a current density of 1 A cm−2. Finally a discussion of the performance and site density requirements of the non‐precious metal catalysts are provided, and it is estimated that the activity towards the ORR needs to be increased by an order of magnitude, and the site density by two/three orders of magnitude to compete with platinum as an ORR electrocatalyst.

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Spatially resolved oxygen reaction, water, and temperature distribution: Experimental results as a function of flow field and implications for polymer electrolyte fuel cell operation

et al. 2019

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In situ and ex situ spatially-resolved techniques are employed to investigate reactant distribution and its impacts in a polymer electrolyte fuel cell. Temperature distribution data provides further evidence for secondary flows inferred from reactant imaging data, highlighting the contribution of convection in heat as well as reactant distribution. Water build-up from neutron tomography is linked to component degradation, matching the pattern seen in the reactant distribution and thus suggesting that high, non-uniform local current densities shape degradation patterns in fuel cells. The correlations shown between different techniques confirm the use of the versatile reactant imaging technique, which is used to compare commonly used flow field designs. Among serpentinetype designs, the single serpentine is superior in both equivalent current density and reactant distribution, showing large contributions from convective flow. On the other hand, the interdigitated design is shown to produce larger equivalent current densities, while showing a somewhat poorer reactant distribution. Considering the correlations drawn between the techniques, this suggests that the interdigitated design compromises durability in favour of power output. The results highlight how established techniques provide a robust background for the use of a new and flexible imaging technique toward designing advanced flow fields for practical fuel cell applications.

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Assessing the performance of reactant transport layers and flow fields towards oxygen transport: A new imaging method based on chemiluminescence

Abstract: 30.04.15 KB. Ok to add published ao pape

Cited by 8 publications

References 20 publications

Investigation of convective transport in the gas diffusion layer used in polymer electrolyte fuel cells

Investigation of convective transport in the gas diffusion layer used in polymer electrolyte fuel cells

Mechanistic Insights into the Oxygen Reduction Reaction on Metal–N–C Electrocatalysts under Fuel Cell Conditions

Spatially resolved oxygen reaction, water, and temperature distribution: Experimental results as a function of flow field and implications for polymer electrolyte fuel cell operation

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