Boundary conditions and phase functions in a Photo-CREC Water-II reactor radiation field

Valadés-Pelayo, Patricio J.; Moreira, Jesús; Serrano, Benito; Lasa, Hugo de

doi:10.1016/j.ces.2013.12.013

Cited by 32 publications

(30 citation statements)

References 28 publications

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“…As the optical thickness increases (at the same loading of the catalyst) the optical shielding of light overlap the scattering effects and the absorption of the radiant energy radically reduces [8,9,25,26].…”

Section: Radiation Field Simulationmentioning

confidence: 99%

“…Its mathematical structure is of algebraic nature, therefore, its implementation in reactors to different scales and radiation sources is practical, with a low complexity in numeric procedures and short computational times [36]. Nevertheless, the presence of a diffuse phase function may cause the method to fail in correctly predict radiant field performances generated by simulation through the solution of Mie theoretical equation [9].…”

Section: Introductionmentioning

confidence: 99%

“…In the presence of a radiation field made of photons of wavelength with energy higher than the band-gap of the semiconductor photocatalyst electronhole pairs can be generated, which in turn trigger reduction and oxidation reactions at the surface of the photocatalyst. Highly reactive radical species such as hydroxyl, peroxyl, radicals and superoxide anion, [9,10] are often produced which can then oxidize or reduce organic and inorganic contaminants. There is consensus among the scientific community that the evaluation and optimization of the radiation absorption in solar photoreactors is a very important step, in order to realize a wider application of photocatalytic processes [2,8,11].…”

Section: Introductionmentioning

confidence: 99%

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Effective radiation field model to scattering – Absorption applied in heterogeneous photocatalytic reactors

Mueses

Martínez

Hernández‐Ramírez

et al. 2015

Chemical Engineering Journal

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Abstract:A new mathematical model for the calculation of the radiation field in heterogeneous photocatalytic reactors using the new concept of "Effective radiation field model" or ERFM is proposed. In this concept, the incident radiation associated to the photons flow is an energy cloud. The generated space-phase and the properties of the cloud are considered to be isotropic and independent of the propagation angle and photon frequency. The isotropic nature of the ERFM concept provides a simpler estimation of the radiation field of a photocatalyst suspension (particles and fluid) for polychromatic radiation spectra such as the solar spectrum.The ERFM is an alternative for the calculus of the spatial distribution of the radiant energy in heterogeneous photocatalytic reactors as an extension of the concept associated to the overall volumetric rate photon absorption -OVRPA. The local volumetric rate of photon absorption (LVRPA) predicted by the ERFM were compared with the predictons from the Six Flux Model (SFM) and the rigorous solution of the radiative transfer equation (RTE).The LVRPA calculated with the ERFM was found to be closer to the solution of the RTE by the Discrete Ordinate Method (DOM). This was attributed to the isotropic phase function which was adopted in both models (ERFM and RTE-DOM).

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Section: Radiation Field Simulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effective radiation field model to scattering – Absorption applied in heterogeneous photocatalytic reactors

Mueses

Martínez

Hernández‐Ramírez

et al. 2015

Chemical Engineering Journal

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“…The impact of different phase functions on the radiation field of photoreactors has recently been investigated in literature [16,17], however, there is a lack of information on its significance with regards to the optimization of radiation absorption is solar photoreactors.…”

Section: Phase Functions and Their Impact On The Optimization Of Radimentioning

confidence: 99%

“…Albeit remains unclear which scattering phase function is the most adequate to model the radiation field in heterogeneous photocatalytic reactors, the determining role played by different formulations of these on the radiation field calculations has been shown [16], which makes its determination a significant step, as relevant as the prior knowledge of the absorption and scattering coefficients of the photocatalyst [17]. Table 1 lists the most common scattering phase functions used in photocatalysis and some of the most relevant studies in which were adopted.…”

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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Simulation of Photocatalytic Reactors

Akach¹,

Kabuba²,

Ochieng³

2023

Photoreactors in Advanced Oxidation Processes

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Boundary conditions and phase functions in a Photo-CREC Water-II reactor radiation field

Cited by 32 publications

References 28 publications

Effective radiation field model to scattering – Absorption applied in heterogeneous photocatalytic reactors

Effective radiation field model to scattering – Absorption applied in heterogeneous photocatalytic reactors

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

Simulation of Photocatalytic Reactors

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