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Petkovska, Menka; Petkovska, Ljubica T.

doi:10.1023/a:1024241326422

Cited by 23 publications

(6 citation statements)

References 12 publications

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“…However, several studies have investigated nonlinear kinetic modeling of FR data. [53][54][55][56][57][58][59] The purpose of this work is to utilize concentration-swing frequency response to determine and quantify the appropriate mechanism that describes the mass transport phenomena of condensable vapors in adsorbent particles. This is the first application of concentration-swing frequency response to characterize the diffusion of condensable vapors in adsorbent particles.…”

Section: Introductionmentioning

confidence: 99%

“…The model developed for the concentration swing apparatus is similar to the model used to describe the dynamics of their pressure swing frequency response apparatus. − It should be noted that most of the FR works discussed above assume that small perturbations to the system allow for portions of the kinetic model to be linearized. However, several studies have investigated nonlinear kinetic modeling of FR data. − …”

Section: Introductionmentioning

confidence: 99%

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Diffusion of Condensable Vapors in Single Adsorbent Particles Measured via Concentration-Swing Frequency Response

2008

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A concentration-swing frequency response method is extended to examine mass transfer mechanisms and the concentration dependence of mass transfer rates for adsorption of condensable vapors in single adsorbent particles. The adsorption kinetics of water and hexane in BPL activated carbon and the adsorption of water in silica gel are determined at several different concentrations. The mechanism that best describes the adsorption of water in BPL activated carbon is nanopore diffusion. The diffusivity of water in BPL activated carbon has a clear minimum at approximately P/Po = 0.5, and the concentration dependence of the diffusion data are not described well by the Darken relationship. Both nanopore diffusion and the Glueckauf linear driving force models can be used to describe the diffusion of hexane in BPL activated carbon for the pressure range studied, and the dependence of the diffusivity on concentration can be described approximately using the Darken relationship. However, the diffusion of water in silica gel cannot be described by the nanopore diffusion model and is best characterized by the Glueckauf linear driving force model. The results illustrate the ability of concentration-swing frequency response to accurately determine adsorption rate mechanisms and quantify the complex adsorption kinetics of condensable vapors using small quantities of adsorbent.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Diffusion of Condensable Vapors in Single Adsorbent Particles Measured via Concentration-Swing Frequency Response

2008

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“…The NFR method replaces the nonlinear dynamic model of a weakly nonlinear system with a set of FRFs of the first, second, and higher orders [9,14]. For an exact representation of the nonlinear model, an infinite sequence of FRFs would be needed, but approximations using only the first and second, or eventually third-order FRFs have shown very good results [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

“…These methods can be considered as extensions of the corresponding linear FR methods (classical FR technique for investigating adsorption kinetics, first introduced by Naphtali and Polinski [40], or the classical Electrochemical Impedance Spectroscopy (EIS), first introduced by Epelboin and Loric [41]). The main advantage of our NFR approach is that the second-order FRFs enable mechanism discrimination, based on distinctive shapes of the corresponding amplitude and phase characteristics corresponding to different mechanisms, even in cases when different mechanisms have essentially identical shapes of the first order FRFs [15,16,21,42]. The process mechanism is identified by comparing the FRFs estimated from experimental NFR measurements with the theoretical FRFs corresponding to different mechanisms in consideration.…”

Section: Introductionmentioning

confidence: 99%

Computer-Aided Nonlinear Frequency Response Method for Investigating the Dynamics of Chemical Engineering Systems

2020

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The Nonlinear Frequency Response (NFR) method is a useful Process Systems Engineering tool for developing experimental techniques and periodic processes that exploit the system nonlinearity. The basic and most time-consuming step of the NFR method is the derivation of frequency response functions (FRFs). The computer-aided Nonlinear Frequency Response (cNFR) method, presented in this work, uses a software application for automatic derivation of the FRFs, thus making the NFR analysis much simpler, even for systems with complex dynamics. The cNFR application uses an Excel user-friendly interface for defining the model equations and variables, and MATLAB code which performs analytical derivations. As a result, the cNFR application generates MATLAB files containing the derived FRFs in a symbolic and algebraic vector form. In this paper, the software is explained in detail and illustrated through: (1) analysis of periodic operation of an isothermal continuous stirred-tank reactor with a simple reaction mechanism, and (2) experimental identification of electrochemical oxygen reduction reaction.

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“…In our previous work, we have been using the concept of HFRFs to investigate adsorption kinetics and equilibria. − The most important results of this investigation are that it is possible to discriminate between different kinetic mechanisms reliably using HFRFs 22,24 and that both kinetic and equilibrium parameters, including those which define the system nonlinearity, can be estimated from the same set of experimental data. , The investigation presented in this paper is the first attempt to apply this concept to the estimation of quasi-steady states of periodic processes.…”

Section: Introductionmentioning

confidence: 99%

Fast Estimation of Quasi-Steady States of Cyclic Nonlinear Processes Based on Higher-Order Frequency Response Functions. Case Study: Cyclic Operation of an Adsorption Column

Petkovska

Markovic

2005

Ind. Eng. Chem. Res.

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A new method for fast approximate calculation of quasi-steady states of cyclic processes is presented. The method is based on the concept of higher-order frequency response functions. The system input is represented in the form of Fourier series, whereas the output is presented in the form of Volterra series. For practical applications, both the input and the output series are approximated by finite-length sums. In this way, the approximate periodic quasi-steady state of the system output is calculated directly, without long numerical integrations. Cyclic operation of an adsorption column with periodic fluctuations of the inlet concentration or/and adsorbent temperature is used as a case study for testing the new method. The necessary frequency response functions (FRFs), up to the third order, are derived, based on the equilibrium dispersion model. The method is tested for sinusoidal and rectangular input changes. The approximate solutions based on the FRFs, up to the third order, and a finite number of input harmonics, are calculated for different input frequencies and amplitudes and compared with the numerical solutions. Very good agreement is obtained.

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Cited by 23 publications

References 12 publications

Diffusion of Condensable Vapors in Single Adsorbent Particles Measured via Concentration-Swing Frequency Response

Diffusion of Condensable Vapors in Single Adsorbent Particles Measured via Concentration-Swing Frequency Response

Computer-Aided Nonlinear Frequency Response Method for Investigating the Dynamics of Chemical Engineering Systems

Fast Estimation of Quasi-Steady States of Cyclic Nonlinear Processes Based on Higher-Order Frequency Response Functions. Case Study: Cyclic Operation of an Adsorption Column

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