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Arias Zugasti, Manuel

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0000-0002-0408-2379
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Arias Zugasti
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Manuel
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2022 - 20253
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Mostrando 1 - 3 de 3
  • Miniatura
    Publicación
    Accurate and efficient calculation of multicomponent thermal diffusion coefficients and partial thermal conductivity based on kinetic theory
    (Elsevier, 2022-03-25) Córdoba, Oscar; Arias Zugasti, Manuel
    The calculation of the multicomponent thermal diffusion coefficients and partial thermal conductivity of polyatomic gas mixtures, with large numbers of components, based on the Kinetic Theory of Gases is revisited. The terms involving inelastic collisions and relaxation times for various internal degrees of freedom are considered, in addition to the classical Chapman-Enskog expressions. For polar gases, the resonant exchange of rotational energy is also accounted for. The present work is the natural extension of the algorithms shown in Combust. and Flame 163 (2016) 540-55 for the calculation of the Fick’s law multicomponent diffusion coefficients, of which it makes use. This work presents a new iterative algorithm for the calculation of the multicomponent thermal diffusion coefficients and partial thermal conductivity. This new algorithm has been implemented in the C++ library MuTLib (Multicomponent Transport Library), available for the transport properties calculations in third party applications and included in the additional material of this publication. The algorithm performance improvements are shown in two different flames: a hydrogen premixed flame and a methane diffusion flame. The results are successfully compared against the library package EGLib (Ern-Giovangigli Library, which considers the same physical effects as this work), and to the well known mixture averaged approximation.
  • Miniatura
    Publicación
    Multi-mechanism theory of aerosol capture by fibrous filters, including fiber diameter/orientation dispersity and particle morphology effects. Preliminary tests vs. data for mobility-selected submicron particles
    (Elsevier, 2022-04-09) Rosner, Daniel E.; Arias Zugasti, Manuel
    In Paper I (Sep. Purif. Technol. 257 (2021) 117676) we showed that a semi-analytic, multi-mechanism expression for the single-fiber capture fraction, cap,SF, (derived using asymptotically valid approximations: Ref < 0.4, Pef 1, R 1, R·Pe1/3 f arbitrary and Stkp Stkpcrit), facilitates a deterministic-, pseudo-continuum aerosol population-balance (PB-) approach to predicting fibrous filter performance. There we explicitly considered “deep” (Lf/df,g 1), low solidity idealized fibrous filters (FFs) challenged by polydispersed aerosols—especially single-mode log-normal (LN) ASDs of modest spread captured by a spatially uniform array of fibers of a single diameter in crossflow. However, realistic fibrous filter media often possess a LN distribution of fiber diameters, as well as a near-Gaussian orientation distribution narrowly spread about normal incidence ( = /2). Moreover, even if this were not so, there would be meso-scale departures from a uniform average fiber solid fraction. We show here that our tractable aerosol PBE-approach to idealized FF performance (Paper I) can be generalized to incorporate these particular structural features of commercially available fibrous filter media. But, to clarify whether these generalizations are likely to be useful, if not fully sufficient, for practical circumstances, it is also necessary to compare such methods/predictions against selected sets of well-defined experimental results. We initiate this program here, having chosen the recent experiments of Kang et al. (Sep. Purif. Technol. 209 (2019) 461–469) carried out using a commercially available fiberglass filter with Lf/df,g ' 300, mean solid fraction of 0.039, and df,g = 2.5 μm, successively challenged by mobility-selected KCl(s) particles (with diameters between ca. 20 and 600 nm) at the carrier gas velocities of 15 and 10 cm/s—capture conditions dominated by the transport mechanism of Brownian diffusion and convection, with “interception” (associated with non-negligible dp/df ) becoming important above ca. dp = 100 nm. We conclude from these data that the effective interception diameter, dp,icpt,eff, of the particles studied is systematically larger than their stated mobility diameters—a situation which will deserve further attention in future studies. Encouraged by these preliminary but instructive comparisons, we expect that, for many current and future design purposes, our present class of semi-analytic/non-stochastic/multi-mechanism methods will provide a welcome complement, if not alternative, to much more computationally-intensive simulation methods for realistic fibrous media that have been described and implemented in the recent aerosol filtration literature. The consequences of including these structural features of fibrous filters in the presence of aerosol size- and shape polydispersity will be the subject of future studies, based on the generalized Population Balance Equation developed/proposed in Section 3.3.
  • Miniatura
    Publicación
    Complete multicomponent versus mixture-averaged calculations of a laminar H2/N2 diffusion flame including heattransfer at the burner and Soret effects
    (Elsevier, 2025-01-09) Arias Zugasti, Manuel; Naud, Bertrand; Cuoci, Alberto; Elsevier; https://orcid.org/0000-0002-1882-0299
    The implementation of full multicomponent treatment of diffusion fluxes in the CFD solver for laminar reacting flows with detailed kinetic mechanisms laminarSMOKE++ is presented. The optimised 1+𝑀 multicomponent formulation (including Fick diffusion and Soret effects) derived from the Kinetic Theory of Gases, with a similar computational cost as mixture-averaged, is considered. Results are presented for a H2/N2 laminar coflow diffusion flame, where either heat transfer at the burner wall is included, either the wall is considered adiabatic. We observe that full multicomponent and mixture-averaged results are very similar when Soret effects are neglected. However, differences are observed when including thermodiffusion. In particular with heat transfer at the wall, large differences are observed whether thermodiffusion is neglected or included. In this case, the mixture-averaged approximation used for the thermal diffusion coefficients leads to significant differences in the results compared to the full multicomponent 1+𝑀 formulation.