accedaCRIShttps://accedacris.ulpgc.es/jspuiThe accedaCRIS digital repository system captures, stores, indexes, preserves, and distributes digital research material.Mon, 22 Jul 2024 16:33:32 GMT2024-07-22T16:33:32Z5041Local bubble-size distribution in fluidized bedshttp://hdl.handle.net/10553/74150Title: Local bubble-size distribution in fluidized beds
Authors: Santana, D.; Macias-Machin, A.
Abstract: The importance of the rise angle of bubbles on the influence of local bubble-size distribution in fluidized beds was studied. A new method is proposed for transforming chord-length distribution to a local bubble-size distribution, including the effect of the velocity vector direction on the transformation. Monte-Carlo simulation was used to generate bubbles synthetically with several rise angels, based on the fact that the velocity vector direction distribution of bubbles was a Bingham distribution. The transformation of chord-length data obtained by an imaginary probe, using the Parzen window as an estimation of the probability density function, gives a good estimation of the local bubble-size distribution for different rise angles and the new approach offered here, knowing that the direction of the velocity vector direction for any orientation of the bubbles in the fluidized bed gives a superior agreement than the approach where the local bubble-size distribution is estimated from bubbles with vertical rises.
Sat, 01 Jan 2000 00:00:00 GMThttp://hdl.handle.net/10553/741502000-01-01T00:00:00ZAssessment of liquid–liquid equilibrium data by solving the Gibbs-Duhem equationhttp://hdl.handle.net/10553/128103Title: Assessment of liquid–liquid equilibrium data by solving the Gibbs-Duhem equation
Authors: Fernández Suárez, Luis Jesús; Ortega Saavedra, Juan; Wisniak, Jaime
Abstract: A methodology, based on the Gibbs-Duhem equation, is developed to study thethermodynamic consistency of liquid–liquid equilibrium (LLE) data. The methodproposes evaluating the experimental data in two ways: (a) integral-form, veri-fying dependences among variables in the same phase, both for temperatures:bTj¼κTε0T,j Tj,exp Tj,cal, and compositions:bxJ1,j¼κxε0xJ1,j xJ1,j,exp xJ1,j,cal, and(b) differential-form, which validates relationships between the compositions of eachphase bybζj¼κζε0ζ,j ζj,exp ζj,cal. A coverage factorκis introduced in bothapproaches to define the degree of confidence of the evaluation using a database(T,xI1,xII1) of 50 binary systems to define the limits of inconsistency. Withκ=3, morethan 60% of the set is accepted (κ>3 falls to 38%) providing a guarantee of qualityfor LLE data. The results show that the consistency test can detect errors in the set{data+model} under study, although the absence of a reference state for the LLEgives the model a limited sensitivity to systematic errors
Sat, 01 Jan 2022 00:00:00 GMThttp://hdl.handle.net/10553/1281032022-01-01T00:00:00ZExtension of the validation method for vapor–liquid equilibrium data to systems with nonvolatile componentshttp://hdl.handle.net/10553/63414Title: Extension of the validation method for vapor–liquid equilibrium data to systems with nonvolatile components
Authors: Fernández Suárez, Luis Jesús; Ortega Saavedra, Juan; Wisniak, Jaime
Abstract: In this work, a method is proposed to validate the experimental data of solutions of n‐components in vapor–liquid equilibria (VLE) with some nonvolatile component (nv‐VLE). The methodology is based on the resolution of the differential Gibbs–Duhem equation using two forms (differential and integral) described in a previous work. The combination of both forms evaluates as many relationships between the variables that define each data series in equilibrium (p, T, x1, … , n‐1, y1, … , n‐1) as degrees of freedom the problem has, although in this work it is only necessary to use the integral form. The proposed method is applied to 70 experimental data series published in the literature, considering the numerical limits previously assigned to parameters established for the integral‐form, according to the following. (a) A parameter ψ is identified as p or T according to if the data are iso‐T or iso‐p; (b) verification of the data is assessed by the difference urn:x-wiley:00011541:media:aic16628:aic16628-math-0005, with urn:x-wiley:00011541:media:aic16628:aic16628-math-0006 > 0, and urn:x-wiley:00011541:media:aic16628:aic16628-math-0007 is determined by an uncertainty procedure of the inconsistency function urn:x-wiley:00011541:media:aic16628:aic16628-math-0008, being urn:x-wiley:00011541:media:aic16628:aic16628-math-0009; and (c) The parameter κψ depends on the type of equilibrium. With κψ = 5, the rejection ratio of the total analyzed is 12%, this percentage increases as the level of quality required increases above 31% for κψ = 3. The calculations require a precise representation of the binomial {data+model}, which produces excellent results for the treatment of nv‐VLE and the properties of solutions, whose parametrization is achieved by an advanced procedure of combined optimization.
Tue, 01 Jan 2019 00:00:00 GMThttp://hdl.handle.net/10553/634142019-01-01T00:00:00ZA rigorous method to evaluate the consistency of experimental data in phase equilibria. Application to VLE and VLLEhttp://hdl.handle.net/10553/35419Title: A rigorous method to evaluate the consistency of experimental data in phase equilibria. Application to VLE and VLLE
Authors: Fernández, Luis; Ortega, Juan; Wisniak, Jaime
Abstract: This work forms part of a broader study that describes a methodology to validate experimental data of phase equilibria for multicomponent systems from a thermodynamic-mathematical perspective. The goal of this article is to present and justify this method and to study its application to vapor–liquid equilibria (VLE) and vapor–liquid–liquid equilibria (VLLE), obtained under isobaric/isothermal conditions. A procedure based on the Gibbs-Duhem equation is established which presents two independent calculation paths for its resolution: (a) an integral method and (b) a differential method. Functions are generated for both cases that establish the verification or consistency of data, δψ for the integral test and δζ for the differential approach, which are statistically evaluated by their corresponding average values [δψ, δζ], and the standard deviations [s(δψ), s(δζ)]. The evaluation of these parameters for application to real cases is carried out using a set of hypothetical systems (with data generated artificially), for which the values are adequately changed to determine their influence on the method. In this way, the requirements of the proposed method for the data are evaluated and their behavior in response to any disruption in the canonical variables (p,T, phase compositions). The conditions for thermodynamic consistency of data are:δψ<2, s(δψ)<0.2δζ<5. In systems with VLLE, in addition to the previous criteria, must occur that: δXLLE<0.05 and δTLLE<0.5. The new proposed method has been tested with a set of 300 experimental binary systems, biphasic and triphasic, obtained from published bibliography, and the results are compared with those of other tests commonly used for testing thermodynamic consistency. The results show that the greater rigor of the proposed method is mainly due to the simultaneous verification of various independent variables. As a result, the conditions for the new test are verified for fewer systems than using other tests mentioned in the literature (i.e., Fredenslund-test and direct of Van Ness). Its unique application is sufficient to ensure the consistency of experimental data, without using other tests.
Sun, 01 Jan 2017 00:00:00 GMThttp://hdl.handle.net/10553/354192017-01-01T00:00:00Z