The use of the dusty-gas model for the description of mass transport with chemical reaction in porous media

Veldsink, J.W.; Damme, Rudolf M.J. van; Versteeg, Geert; Swaaij, W.P.M. van

doi:10.1016/0923-0467(94)02929-6

Cited by 122 publications

(66 citation statements)

References 17 publications

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“…Transportation of O 2− in traditional SOFC occurs at the electrolyte between anode and cathode. More specifically, ionic conduction can be enhanced and conducted on the particles' surface (Veldsink et al, 1995;Suzuki et al, 2005), which is used in the EFFC device with co-ionic H + /O 2− transport. This device is named as EFFC according to the new principle.…”

Section: Electrolyte (Layer)-free Fuel Cellmentioning

confidence: 99%

Progress in Electrolyte-Free Fuel Cells

Cai

Kim

et al. 2016

Front. Energy Res.

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Solid oxide fuel cell (SOFC) represents a clean electrochemical energy conversion technology with characteristics of high conversion efficiency and low emissions. It is one of the most important new energy technologies in the future. However, the manufacture of SOFCs based on the structure of anode/electrolyte/cathode is complicated and time-consuming. Thus, the cost for the entire fabrication and technology is too high to be affordable, and challenges still hinder commercialization. Recently, a novel type of electrolyte-free fuel cell (EFFC) with single component was invented, which could be the potential candidate for the next generation of advanced fuel cells. This paper briefly introduces the EFFC, working principle, performance, and advantages with updated research progress. A number of key R&D issues about EFFCs have been addressed, and future opportunities and challenges are discussed.

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Section: Electrolyte (Layer)-free Fuel Cellmentioning

confidence: 99%

Progress in Electrolyte-Free Fuel Cells

Cai

Kim

et al. 2016

Front. Energy Res.

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“…The model gives remarkably good coverage of both ultrafiltration of aqueous poly(ethylene glycol) solutions and several gas diffusion phenomena such as the counterdiffusion of He and Ar across porous graphite plugs (Evans et al, 1962(Evans et al, , 1963 and counterdiffusion of various gases in capillaries (Waldmann and Schmitt, 1961). In the process I discovered errors in the basic derivations of the dusty gas model of Mason et al (1967Mason et al ( , 1978Mason et al ( , 1983Mason et al ( , 1985Mason et al ( , 1990, which had been used to explain counterdiffusion phenomena and still finds widespread application, and also in heterogeneous catalysis (Jackson, 1977;Froment and Bischoff, 1979;Veldsink et al, 1995;Keil, 1996) and adsorption (Kä rger and Ruthven, 1992). One of the conclusions from the analysis is that the picture of a simultaneous viscous and diffusive flux of Mason et al, in some regions also paralled by a Knudsen flux, is inherently incorrect and should be replaced by the proper addition of friction forces.…”

Section: Introductionmentioning

confidence: 99%

New Light on Some Old Problems: Revisiting the Stefan Tube, Graham's Law, and the Bosanquet Equation

Kerkhof

1997

Ind. Eng. Chem. Res.

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The Stefan diffusion tube is modeled with the recently developed binary friction model (BFM), and it is shown that this model can describe all kinds of vapor flow regimes from Stefan diffusion to pure pressure-driven flow but also Knudsen and (diffusive) slip flow. From the BFM simple criteria are derived for the transition between various regions, the criteria of which are also relevant to the fields of gas adsorption, heterogeneous catalysis, and drying of porous materials. For isobaric counterdiffusion the BFM shows where the limits of Graham's law are. For equimolar counterdiffusion analogously the area of applicability of the Bosanquet equation is derived from the BFM and an extended equation is given.

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“…16 The mechanisms of the mass transport are closely related to the pore size that partly determines the Knudsen number K n , which will be discussed in the next section. Pore size measurements are often based on the analysis of 2D cross-section images obtained by scanning electron microscopy.…”

mentioning

confidence: 99%

“…12 A considerable amount of work has been reported to measure the diffusivity, such as the experimental methods including diffusion cells, 13 gas chromatography, 14 thermo-gravimetric analysis, 15 as well as theoretical calculations based on the continuum physics, such as the binary diffusivity using Chapman-Enskog theory, the Knudsen diffusion coefficient and the effective diffusion coefficient. 16 The mechanisms of the mass transport are closely related to the pore size that partly determines the Knudsen number K n , which will be discussed in the next section. Pore size measurements are often based on the analysis of 2D cross-section images obtained by scanning electron microscopy.…”

mentioning

confidence: 99%

“…21,22 A considerable amount of work has been reported to measure the pore size distributions, porosity and tortuosity in porous support materials such as SOFC 23 and batteries. 24,25 The reconstructed sample volume can be subsequently used as a real model for the image-based simulation of porous phase tortuosity, 26,27 diffusion flux 16 and electrochemical performance. 9 This study aims to characterize the diffusion regimes in an SOFC anode for different fuel gases using the X-ray nano-CT technique, followed by the quantitative evaluation of the mass transport phenomenon in a binary gas mixture based on a broad distribution of the voxel-basis effective diffusion coefficients.…”

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confidence: 99%

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3D Characterization of Diffusivities and Its Impact on Mass Flux and Concentration Overpotential in SOFC Anode

Tjaden

Bertei

et al. 2017

J. Electrochem. Soc.

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In recent years great effort has been taken to understand the effect of gas transport on the performance of electrochemical devices. This study aims to characterize the diffusion regimes and the possible inaccuracies of the mass transport calculation in Solid Oxide Fuel Cell (SOFC) anodes when a volume-averaged pore diameter is used. 3D pore size distribution is measured based on the extracted pore phase from an X-ray CT scan, which is further used for the calculation of a Knudsen number (K n ) map in the porous medium, followed by the voxel-based distribution of the effective diffusion coefficients for different fuel gases. Diffusion fluxes in a binary gas mixture using the lower boundary, upper boundary and average effective coefficients are compared, and the impact on overpotential is analyzed. The results show that pore diameters from tens to hundreds of nanometers result in a broad range of Knudsen number (1.1 ∼ 4.8 and 0.6 ∼ 3 for H 2 and CH 4 respectively), indicative of the transitional diffusion regime. The results highlight that for a porous material, such as an SOFC anode where Knudsen effects are non-negligible, using a volume-averaged pore size can overestimate the mass flux by ±200% compared to the actual value. The characteristic pore size should be chosen sensibly in order to improve the reliability of the mass transport and electrochemical performance evaluation. Mass transport can significantly limit the reaction rate and lead to concentration polarization in electrochemical devices such as fuel cells, electrolysers and oxygen transport membranes, especially under the conditions of high operating current density and fuel conversion ratios.1 Besides the material-specific transport properties of chemical species (e.g., diffusivity, viscosity, etc.), mass transport is mainly dependent on microstructural parameters of the electrode such as porosity, tortuosity and pore size. [2][3][4] In recent years great effort has been taken to understand the effect of gas transport on the performance of electrochemical devices in terms of electrochemical impedance, 5 concentration polarization loss, 4,6 and electrochemical simulation. 7-10Concentration polarization is caused by the consumption of the fuel gas resulting in a reduction of concentration at the anode/electrolyte interface. In solid oxide fuel cell (SOFC) anodes, concentration polarization is governed by the diffusion of fuel gas (e.g. H 2 ) from the gas inlet to the triple phase boundary. A faster diffusion rate can contribute to a larger partial pressure of the fuel gas within the pores and thus a larger limiting current density, which in turn mitigates the polarization loss. 11The effective diffusivity is closely related to the temperature, pressure, gas species as well as to the microstructure of the porous material.12 A considerable amount of work has been reported to measure the diffusivity, such as the experimental methods including diffusion cells, 13 gas chromatography, 14 thermo-gravimetric analysis, 15 as well as theoretical calculations ...

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The use of the dusty-gas model for the description of mass transport with chemical reaction in porous media

Cited by 122 publications

References 17 publications

Progress in Electrolyte-Free Fuel Cells

Progress in Electrolyte-Free Fuel Cells

New Light on Some Old Problems: Revisiting the Stefan Tube, Graham's Law, and the Bosanquet Equation

3D Characterization of Diffusivities and Its Impact on Mass Flux and Concentration Overpotential in SOFC Anode

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