Some aspects of photocatalytic reactor modeling using computational fluid dynamics

Boyjoo, Yash; Ang, Ming; Pareek, Vishnu

doi:10.1016/j.ces.2013.06.035

Cited by 109 publications

(67 citation statements)

References 143 publications

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“…The most rigorous methods are described by the Discrete Ordinate Method (DOM) [5,9] commonly included in CFD packages, and by the Monte Carlo (MC) stochastic method which yields an accurate representation of the radiation field [10,11]. Despite the modeling power of the previous methods, these are often mathematically and computationally demanding when applied at the solar dimension scale, which is invariably characterized by atmospheric fluctuations of the boundary conditions (i.e., photon flux), in turn increasing the complexity of the models.…”

Section: Introductionmentioning

confidence: 99%

Coupling the Six Flux Absorption–Scattering Model to the Henyey–Greenstein scattering phase function: Evaluation and optimization of radiation absorption in solar heterogeneous photoreactors

Acosta-Herazo

Monterroza-Romero

Mueses

et al. 2016

Chemical Engineering Journal

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Robust and practical models describing the radiation field in heterogeneous photocatalytic systems, used in emerging environmental, photochemical and renewable energy applications, are fundamental for the further development of these technologies. The sixflux radiation absorption-scattering model (SFM) has shown to be particularly suitable for the modeling of the radiation field in solar pilot-plant photoreactors. In this study, the SFM was coupled to the Henyey-Greenstein (HG) scattering phase function in order to assemble the model with a more accurate description of the scattering phenomenon provided by this IntroductionAs an emerging environmental technology, heterogeneous photocatalysis has received increasing attention in recent years. Its promising applications in air and water remediation[1], clean fuels production [2], green products (e.g. self-cleaning surface [3]) and selective 4 synthesis of organic molecules [4] demonstrates great interest in this technology. The underlying basis of every photocatalytic reaction mechanism is the photoactivation of the semiconductor photocatalyst by absorption of photons with energy higher or equal than the catalyst band-gap. The consequent generation of electron-hole pairs produces a chain of reactions that drive simultaneous oxidation and reduction (redox) reactions.The evaluation of the radiation field and of the spatial distribution of radiation absorption in a photoreactor system, commonly described by the local volumetric rate of photon absorption (LVRPA), is therefore a crucial aspect in the development of efficient photocatalytic processes [5].The LVRPA is the photon equivalent to the concentration of reactant species and is always considered in the description of the kinetics of photochemical reactions and in the optimization of the performance of photoreactors. For instance, several methodologies have been proposed for the determination of the optimum catalyst load or reactor thickness which maximize the absorption of radiation [6,7].The estimation of the LVRPA has been a defiant task within the heterogeneous photocatalysis community, as result of the complex nature of the absorption and scattering radiation phenomenon, which in the most rigorous case is modeled by the Radiative Transfer Equation (RTE). The RTE for a medium that does not emit radiation is [8]: where I λ is the photon irradiance at λ wavelength, s is a spatial coordinate, Ω is the directional solid angle, κ λ is the absorption coefficient and σ λ the scattering coefficient. TheΩ → Ω is the scattering phase function representing the probability of a photon to be redirected by scattering from the direction Ω', in surroundings of the position s, into the direction Ω [8]. A trivial solution for the RTE cannot be achieved and a numerical method is always necessary.Although the precise modeling of the LVRPA and a better understanding of the radiationphotocatalyst-operational conditions nexus still remains a challenge, several approaches have been proposed to solve the RTE. The most rigoro...

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Section: Introductionmentioning

confidence: 99%

Coupling the Six Flux Absorption–Scattering Model to the Henyey–Greenstein scattering phase function: Evaluation and optimization of radiation absorption in solar heterogeneous photoreactors

Acosta-Herazo

Monterroza-Romero

Mueses

et al. 2016

Chemical Engineering Journal

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“…The Beer–Lambert law (Eq. ) was then applied to calculate the light propagation through the photocatalyst film layers.

\frac{d I}{d y} = - α I

…”

Section: Methodsmentioning

confidence: 99%

Intensification of photocatalytic pollutant abatement in microchannel reactor using TiO₂ and TiO₂‐graphene

Padoin¹,

Andrade

Ângelo

et al. 2016

AIChE Journal

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A microfluidic device was applied to the photocatalytic degradation of methylene blue as a model pollutant. Titanium dioxide nanoparticles (TiO2-P25) and a synthesized composite TiO2-graphene catalyst were immobilized on the inner walls of a borosilicate glass microfluidic chip. The deposition evolution of the nanoparticles was evaluated by monitoring the optical profile of the system. It was found that a higher initial reaction rate was obtained in the microreactor containing composite catalyst (TiO2-GR) on the inner walls, but both systems (TiO2 and TiO2-GR) achieved similar reaction rates when the steady-state was reached. Decolorization rate of methylene blue in our microfluidic chips was found to be approximately one order of magnitude higher than equivalent macroscopic systems reported in the literature at similar experimental conditions. Additionally, computational simulations were performed to investigate the physics involved in these processes. The model was experimentally validated for further scale-out studies.

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“…Recently, it was found that the particle concentration gradient could contribute to the overall light absorption in a cylindrical reactor with top irradiation (Cao et al, 2014;Valadés-Pelayo et al, 2015). As for the hydrodynamic properties of the slurry photocatalytic reactor, most studies have used only numerical approaches (Boyjoo et al, 2013;Hatat-Fraile et al, 2013;Qi et al, 2011). Experimental work directly observing and monitoring the dispersion and flow properties of particles in a heterogeneous photocatalytic reactor is rare.…”

Section: Introductionmentioning

confidence: 98%

Insights into the hydrodynamic properties of slurry flow in a tubular photocatalytic reactor by PIV combined with LSIA

Geng

Wang

et al. 2016

Chemical Engineering Science

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Some aspects of photocatalytic reactor modeling using computational fluid dynamics

Cited by 109 publications

References 143 publications

Coupling the Six Flux Absorption–Scattering Model to the Henyey–Greenstein scattering phase function: Evaluation and optimization of radiation absorption in solar heterogeneous photoreactors

Coupling the Six Flux Absorption–Scattering Model to the Henyey–Greenstein scattering phase function: Evaluation and optimization of radiation absorption in solar heterogeneous photoreactors

Intensification of photocatalytic pollutant abatement in microchannel reactor using TiO₂ and TiO₂‐graphene

Insights into the hydrodynamic properties of slurry flow in a tubular photocatalytic reactor by PIV combined with LSIA

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Some aspects of photocatalytic reactor modeling using computational fluid dynamics

Cited by 109 publications

References 143 publications

Coupling the Six Flux Absorption–Scattering Model to the Henyey–Greenstein scattering phase function: Evaluation and optimization of radiation absorption in solar heterogeneous photoreactors

Coupling the Six Flux Absorption–Scattering Model to the Henyey–Greenstein scattering phase function: Evaluation and optimization of radiation absorption in solar heterogeneous photoreactors

Intensification of photocatalytic pollutant abatement in microchannel reactor using TiO2 and TiO2‐graphene

Insights into the hydrodynamic properties of slurry flow in a tubular photocatalytic reactor by PIV combined with LSIA

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Intensification of photocatalytic pollutant abatement in microchannel reactor using TiO₂ and TiO₂‐graphene