TY  - CONF
AU  - Marinković, Dalibor
AU  - Nikolić, Daliborka
AU  - Seidel, Carsten
AU  - Seidel-Morgenstern, Andreas
AU  - Kienle, Achim
AU  - Petkovska, Menka
PY  - 2024
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/7459
AB  - The continuous industrial chemical processes are typically designed through steady-state conditions. Nevertheless, there is evidence that processes can be intensified by applying optimized forced periodic operation. Possible improvements in reactor performances caused by the implementation of forced periodic operation (FPO) can be successfully evaluated by applying a nonlinear frequency response (NFR) analysis, before experimental investigation. In this study, we will present the results of two case studies based on heterogeneously catalyzed methanol synthesis in a continuous stirred tank reactor (CSTR). The first is an isothermal case, and the second is a more complicated and more realistic, non-isothermal case.
PB  - Stockholm, Sweden : Scanditale AB
C3  - Energy Proceedings
T1  - Evaluation of possible improvements of forced periodically operated reactor in which methanol synthesis takes place – based on the Nonlinear Frequency Response analysis
IS  - VI
VL  - 43
DO  - 10.46855/energy-proceedings-11025
ER  - 

@conference{
author = "Marinković, Dalibor and Nikolić, Daliborka and Seidel, Carsten and Seidel-Morgenstern, Andreas and Kienle, Achim and Petkovska, Menka",
year = "2024",
abstract = "The continuous industrial chemical processes are typically designed through steady-state conditions. Nevertheless, there is evidence that processes can be intensified by applying optimized forced periodic operation. Possible improvements in reactor performances caused by the implementation of forced periodic operation (FPO) can be successfully evaluated by applying a nonlinear frequency response (NFR) analysis, before experimental investigation. In this study, we will present the results of two case studies based on heterogeneously catalyzed methanol synthesis in a continuous stirred tank reactor (CSTR). The first is an isothermal case, and the second is a more complicated and more realistic, non-isothermal case.",
publisher = "Stockholm, Sweden : Scanditale AB",
journal = "Energy Proceedings",
title = "Evaluation of possible improvements of forced periodically operated reactor in which methanol synthesis takes place – based on the Nonlinear Frequency Response analysis",
number = "VI",
volume = "43",
doi = "10.46855/energy-proceedings-11025"
}

Marinković, D., Nikolić, D., Seidel, C., Seidel-Morgenstern, A., Kienle, A.,& Petkovska, M.. (2024). Evaluation of possible improvements of forced periodically operated reactor in which methanol synthesis takes place – based on the Nonlinear Frequency Response analysis. in Energy Proceedings
Stockholm, Sweden : Scanditale AB., 43(VI).
https://doi.org/10.46855/energy-proceedings-11025

Marinković D, Nikolić D, Seidel C, Seidel-Morgenstern A, Kienle A, Petkovska M. Evaluation of possible improvements of forced periodically operated reactor in which methanol synthesis takes place – based on the Nonlinear Frequency Response analysis. in Energy Proceedings. 2024;43(VI).
doi:10.46855/energy-proceedings-11025 .

Marinković, Dalibor, Nikolić, Daliborka, Seidel, Carsten, Seidel-Morgenstern, Andreas, Kienle, Achim, Petkovska, Menka, "Evaluation of possible improvements of forced periodically operated reactor in which methanol synthesis takes place – based on the Nonlinear Frequency Response analysis" in Energy Proceedings, 43, no. VI (2024),
https://doi.org/10.46855/energy-proceedings-11025 . .

TY  - JOUR
AU  - Seidel, Carsten
AU  - Nikolić, Daliborka
AU  - Felischak, Matthias
AU  - Petkovska, Menka
AU  - Seidel-Morgenstern, Andreas
AU  - Kienle, Achim
PY  - 2022
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/5267
AB  - Methanol synthesis from synthesis gas with heterogeneous Cu/ZnO/Al2O3 catalysts in an isothermal gradientless reactor is described. In a theoretical study, the potential of forced periodic operation (FPO) for improving reactor performance in terms of methanol production rate and methanol yield is explored. The approach is based on a detailed kinetic model and combines nonlinear frequency response (NFR) analysis with rigorous numerical multi-objective optimization. Optimal steady-state operation is compared with optimal forced periodic operation for a given benchmark problem with and without inert nitrogen in the feed. Further, the significant influence of the saturation capacity of the solid phase on the dynamic behavior in response to step changes and periodic input modulations is studied.
PB  - John Wiley and Sons Inc
T2  - Chemical Engineering and Technology
T1  - Forced Periodic Operation of Methanol Synthesis in an Isothermal Gradientless Reactor
DO  - 10.1002/ceat.202200286
ER  - 

@article{
author = "Seidel, Carsten and Nikolić, Daliborka and Felischak, Matthias and Petkovska, Menka and Seidel-Morgenstern, Andreas and Kienle, Achim",
year = "2022",
abstract = "Methanol synthesis from synthesis gas with heterogeneous Cu/ZnO/Al2O3 catalysts in an isothermal gradientless reactor is described. In a theoretical study, the potential of forced periodic operation (FPO) for improving reactor performance in terms of methanol production rate and methanol yield is explored. The approach is based on a detailed kinetic model and combines nonlinear frequency response (NFR) analysis with rigorous numerical multi-objective optimization. Optimal steady-state operation is compared with optimal forced periodic operation for a given benchmark problem with and without inert nitrogen in the feed. Further, the significant influence of the saturation capacity of the solid phase on the dynamic behavior in response to step changes and periodic input modulations is studied.",
publisher = "John Wiley and Sons Inc",
journal = "Chemical Engineering and Technology",
title = "Forced Periodic Operation of Methanol Synthesis in an Isothermal Gradientless Reactor",
doi = "10.1002/ceat.202200286"
}

Seidel, C., Nikolić, D., Felischak, M., Petkovska, M., Seidel-Morgenstern, A.,& Kienle, A.. (2022). Forced Periodic Operation of Methanol Synthesis in an Isothermal Gradientless Reactor. in Chemical Engineering and Technology
John Wiley and Sons Inc..
https://doi.org/10.1002/ceat.202200286

Seidel C, Nikolić D, Felischak M, Petkovska M, Seidel-Morgenstern A, Kienle A. Forced Periodic Operation of Methanol Synthesis in an Isothermal Gradientless Reactor. in Chemical Engineering and Technology. 2022;.
doi:10.1002/ceat.202200286 .

Seidel, Carsten, Nikolić, Daliborka, Felischak, Matthias, Petkovska, Menka, Seidel-Morgenstern, Andreas, Kienle, Achim, "Forced Periodic Operation of Methanol Synthesis in an Isothermal Gradientless Reactor" in Chemical Engineering and Technology (2022),
https://doi.org/10.1002/ceat.202200286 . .

TY  - JOUR
AU  - Nikolic, Daliborka
AU  - Seidel, Carsten
AU  - Felischak, Matthias
AU  - Milicic, Tamara
AU  - Kienle, Achim
AU  - Seidel-Morgenstern, Andreas
AU  - Petkovska, Menka
PY  - 2022
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4989
AB  - In this two-part paper a comprehensive study of the potential to improve performance criteria of a methanol synthesis reactor through forced periodical operations is presented. The study uses the Nonlinear Frequency Response method, a powerful analytical and approximate tool which gives an answer whether and under which conditions certain periodic operation would lead to improvement of process performance. To demonstrate the method, isothermal and isobaric methanol synthesis in a lab-scale CSTR is considered. In Part I, the analysis is performed for single input modulations. Partial pressures of each reactant in the feed stream and the total inlet volumetric flow-rate are considered as possible modulated inputs. The results show that modulations of single inputs essentially do not provide potential for significant improvements. In Part II, the study will be extended to analysis of periodic operations with simultaneous modulations of two inputs and conditions offering significant performance enhancements will be identified.
T2  - Chemical Engineering Science
T1  - Forced periodic operations of a chemical reactor for methanol synthesis - The search for the best scenario based on Nonlinear Frequency Response Method. Part I Single input modulations
VL  - 248
DO  - 10.1016/j.ces.2021.117134
ER  - 

@article{
author = "Nikolic, Daliborka and Seidel, Carsten and Felischak, Matthias and Milicic, Tamara and Kienle, Achim and Seidel-Morgenstern, Andreas and Petkovska, Menka",
year = "2022",
abstract = "In this two-part paper a comprehensive study of the potential to improve performance criteria of a methanol synthesis reactor through forced periodical operations is presented. The study uses the Nonlinear Frequency Response method, a powerful analytical and approximate tool which gives an answer whether and under which conditions certain periodic operation would lead to improvement of process performance. To demonstrate the method, isothermal and isobaric methanol synthesis in a lab-scale CSTR is considered. In Part I, the analysis is performed for single input modulations. Partial pressures of each reactant in the feed stream and the total inlet volumetric flow-rate are considered as possible modulated inputs. The results show that modulations of single inputs essentially do not provide potential for significant improvements. In Part II, the study will be extended to analysis of periodic operations with simultaneous modulations of two inputs and conditions offering significant performance enhancements will be identified.",
journal = "Chemical Engineering Science",
title = "Forced periodic operations of a chemical reactor for methanol synthesis - The search for the best scenario based on Nonlinear Frequency Response Method. Part I Single input modulations",
volume = "248",
doi = "10.1016/j.ces.2021.117134"
}

Nikolic, D., Seidel, C., Felischak, M., Milicic, T., Kienle, A., Seidel-Morgenstern, A.,& Petkovska, M.. (2022). Forced periodic operations of a chemical reactor for methanol synthesis - The search for the best scenario based on Nonlinear Frequency Response Method. Part I Single input modulations. in Chemical Engineering Science, 248.
https://doi.org/10.1016/j.ces.2021.117134

Nikolic D, Seidel C, Felischak M, Milicic T, Kienle A, Seidel-Morgenstern A, Petkovska M. Forced periodic operations of a chemical reactor for methanol synthesis - The search for the best scenario based on Nonlinear Frequency Response Method. Part I Single input modulations. in Chemical Engineering Science. 2022;248.
doi:10.1016/j.ces.2021.117134 .

Nikolic, Daliborka, Seidel, Carsten, Felischak, Matthias, Milicic, Tamara, Kienle, Achim, Seidel-Morgenstern, Andreas, Petkovska, Menka, "Forced periodic operations of a chemical reactor for methanol synthesis - The search for the best scenario based on Nonlinear Frequency Response Method. Part I Single input modulations" in Chemical Engineering Science, 248 (2022),
https://doi.org/10.1016/j.ces.2021.117134 . .

TY  - JOUR
AU  - Nikolic, Daliborka
AU  - Seidel, Carsten
AU  - Felischak, Matthias
AU  - Milicic, Tamara
AU  - Kienle, Achim
AU  - Seidel-Morgenstern, Andreas
AU  - Petkovska, Menka
PY  - 2022
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4973
AB  - The analysis of the potential to improve performance of a methanol synthesis reactor through forced periodical operations by Nonlinear Frequency Response method is presented. The methanol synthesis in an isothermal and isobaric lab-scale CSTR is considered. First, the analysis was performed for single input modulations (in Part I), which showed that significant improvements can't be achieved. Here, the study is extended to analysis of simultaneous modulations of two inputs. All possible input combi-nations (6 cases) are analysed and the optimal forcing parameters, maximizing the time-average metha-nol production, were determined. For all combinations the improvement is possible, but for some cases it is not significant. The highest improvement is predicted for simultaneous modulation of the inlet partial pressure of CO and the inlet volumetric flow rate. This case, for which it is possible to achieve up to 33.51 % of methanol production, is analysed it detail and optimized using multi-objective optimization.
T2  - Chemical Engineering Science
T1  - Forced periodic operations of a chemical reactor for methanol synthesis - The search for the best scenario based on Nonlinear Frequency Response Method. Part II Simultaneous modulation of two inputs
VL  - 248
DO  - 10.1016/j.ces.2021.117133
ER  - 

@article{
author = "Nikolic, Daliborka and Seidel, Carsten and Felischak, Matthias and Milicic, Tamara and Kienle, Achim and Seidel-Morgenstern, Andreas and Petkovska, Menka",
year = "2022",
abstract = "The analysis of the potential to improve performance of a methanol synthesis reactor through forced periodical operations by Nonlinear Frequency Response method is presented. The methanol synthesis in an isothermal and isobaric lab-scale CSTR is considered. First, the analysis was performed for single input modulations (in Part I), which showed that significant improvements can't be achieved. Here, the study is extended to analysis of simultaneous modulations of two inputs. All possible input combi-nations (6 cases) are analysed and the optimal forcing parameters, maximizing the time-average metha-nol production, were determined. For all combinations the improvement is possible, but for some cases it is not significant. The highest improvement is predicted for simultaneous modulation of the inlet partial pressure of CO and the inlet volumetric flow rate. This case, for which it is possible to achieve up to 33.51 % of methanol production, is analysed it detail and optimized using multi-objective optimization.",
journal = "Chemical Engineering Science",
title = "Forced periodic operations of a chemical reactor for methanol synthesis - The search for the best scenario based on Nonlinear Frequency Response Method. Part II Simultaneous modulation of two inputs",
volume = "248",
doi = "10.1016/j.ces.2021.117133"
}

Nikolic, D., Seidel, C., Felischak, M., Milicic, T., Kienle, A., Seidel-Morgenstern, A.,& Petkovska, M.. (2022). Forced periodic operations of a chemical reactor for methanol synthesis - The search for the best scenario based on Nonlinear Frequency Response Method. Part II Simultaneous modulation of two inputs. in Chemical Engineering Science, 248.
https://doi.org/10.1016/j.ces.2021.117133

Nikolic D, Seidel C, Felischak M, Milicic T, Kienle A, Seidel-Morgenstern A, Petkovska M. Forced periodic operations of a chemical reactor for methanol synthesis - The search for the best scenario based on Nonlinear Frequency Response Method. Part II Simultaneous modulation of two inputs. in Chemical Engineering Science. 2022;248.
doi:10.1016/j.ces.2021.117133 .

Nikolic, Daliborka, Seidel, Carsten, Felischak, Matthias, Milicic, Tamara, Kienle, Achim, Seidel-Morgenstern, Andreas, Petkovska, Menka, "Forced periodic operations of a chemical reactor for methanol synthesis - The search for the best scenario based on Nonlinear Frequency Response Method. Part II Simultaneous modulation of two inputs" in Chemical Engineering Science, 248 (2022),
https://doi.org/10.1016/j.ces.2021.117133 . .

TY  - JOUR
AU  - Felischak, Matthias
AU  - Kaps, Lothar
AU  - Hamel, Christof
AU  - Nikolic, Daliborka
AU  - Petkovska, Menka
AU  - Seidel-Morgenstern, Andreas
PY  - 2022
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4995
T2  - Chemical Engineering Journal
T1  - Analysis and experimental demonstration of forced periodic operation of an adiabatic stirred tank reactor: Simultaneous modulation of inlet concentration and total flow-rate (vol 410, 128197, 2021)
VL  - 430
DO  - 10.1016/j.cej.2021.132930
ER  - 

@article{
author = "Felischak, Matthias and Kaps, Lothar and Hamel, Christof and Nikolic, Daliborka and Petkovska, Menka and Seidel-Morgenstern, Andreas",
year = "2022",
journal = "Chemical Engineering Journal",
title = "Analysis and experimental demonstration of forced periodic operation of an adiabatic stirred tank reactor: Simultaneous modulation of inlet concentration and total flow-rate (vol 410, 128197, 2021)",
volume = "430",
doi = "10.1016/j.cej.2021.132930"
}

Felischak, M., Kaps, L., Hamel, C., Nikolic, D., Petkovska, M.,& Seidel-Morgenstern, A.. (2022). Analysis and experimental demonstration of forced periodic operation of an adiabatic stirred tank reactor: Simultaneous modulation of inlet concentration and total flow-rate (vol 410, 128197, 2021). in Chemical Engineering Journal, 430.
https://doi.org/10.1016/j.cej.2021.132930

Felischak M, Kaps L, Hamel C, Nikolic D, Petkovska M, Seidel-Morgenstern A. Analysis and experimental demonstration of forced periodic operation of an adiabatic stirred tank reactor: Simultaneous modulation of inlet concentration and total flow-rate (vol 410, 128197, 2021). in Chemical Engineering Journal. 2022;430.
doi:10.1016/j.cej.2021.132930 .

Felischak, Matthias, Kaps, Lothar, Hamel, Christof, Nikolic, Daliborka, Petkovska, Menka, Seidel-Morgenstern, Andreas, "Analysis and experimental demonstration of forced periodic operation of an adiabatic stirred tank reactor: Simultaneous modulation of inlet concentration and total flow-rate (vol 410, 128197, 2021)" in Chemical Engineering Journal, 430 (2022),
https://doi.org/10.1016/j.cej.2021.132930 . .

TY  - JOUR
AU  - Seidel, Carsten
AU  - Nikolic, Daliborka
AU  - Felischak, Matthias
AU  - Petkovska, Menka
AU  - Seidel-Morgenstern, Andreas
AU  - Kienle, Achim
PY  - 2021
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4938
AB  - Traditionally, methanol is produced in large amounts from synthesis gas with heterogeneous Cu/ZnO/Al2O3 catalysts under steady state conditions. In this paper, the potential of alternative forced periodic operation modes is studied using numerical optimization. The focus is a well-mixed isothermal reactor with two periodic inputs, namely, CO concentration in the feed and total feed flow rate. Exploiting a detailed kinetic model which also describes the dynamics of the catalyst, a sequential NLP optimization approach is applied to compare optimal steady state solutions with optimal periodic regimes. Periodic solutions are calculated using dynamic optimization with a periodicity constraint. The NLP optimization is embedded in a multi-objective optimization framework to optimize the process with respect to two objective functions and generate the corresponding Pareto fronts. The first objective is the methanol outlet flow rate. The second objective is the methanol yield based on the total carbon in the feed. Additional constraints arising from the complex methanol reaction and the practical limitations are introduced step by step. The results show that significant improvements for both objective functions are possible through periodic forcing of the two inputs considered here.
T2  - Processes
T1  - Optimization of Methanol Synthesis under Forced Periodic Operation
IS  - 5
VL  - 9
DO  - 10.3390/pr9050872
ER  - 

@article{
author = "Seidel, Carsten and Nikolic, Daliborka and Felischak, Matthias and Petkovska, Menka and Seidel-Morgenstern, Andreas and Kienle, Achim",
year = "2021",
abstract = "Traditionally, methanol is produced in large amounts from synthesis gas with heterogeneous Cu/ZnO/Al2O3 catalysts under steady state conditions. In this paper, the potential of alternative forced periodic operation modes is studied using numerical optimization. The focus is a well-mixed isothermal reactor with two periodic inputs, namely, CO concentration in the feed and total feed flow rate. Exploiting a detailed kinetic model which also describes the dynamics of the catalyst, a sequential NLP optimization approach is applied to compare optimal steady state solutions with optimal periodic regimes. Periodic solutions are calculated using dynamic optimization with a periodicity constraint. The NLP optimization is embedded in a multi-objective optimization framework to optimize the process with respect to two objective functions and generate the corresponding Pareto fronts. The first objective is the methanol outlet flow rate. The second objective is the methanol yield based on the total carbon in the feed. Additional constraints arising from the complex methanol reaction and the practical limitations are introduced step by step. The results show that significant improvements for both objective functions are possible through periodic forcing of the two inputs considered here.",
journal = "Processes",
title = "Optimization of Methanol Synthesis under Forced Periodic Operation",
number = "5",
volume = "9",
doi = "10.3390/pr9050872"
}

Seidel, C., Nikolic, D., Felischak, M., Petkovska, M., Seidel-Morgenstern, A.,& Kienle, A.. (2021). Optimization of Methanol Synthesis under Forced Periodic Operation. in Processes, 9(5).
https://doi.org/10.3390/pr9050872

Seidel C, Nikolic D, Felischak M, Petkovska M, Seidel-Morgenstern A, Kienle A. Optimization of Methanol Synthesis under Forced Periodic Operation. in Processes. 2021;9(5).
doi:10.3390/pr9050872 .

Seidel, Carsten, Nikolic, Daliborka, Felischak, Matthias, Petkovska, Menka, Seidel-Morgenstern, Andreas, Kienle, Achim, "Optimization of Methanol Synthesis under Forced Periodic Operation" in Processes, 9, no. 5 (2021),
https://doi.org/10.3390/pr9050872 . .

TY  - JOUR
AU  - Felischak, Matthias
AU  - Kaps, Lothar
AU  - Hamel, Christof
AU  - Nikolic, Daliborka
AU  - Petkovska, Menka
AU  - Seidel-Morgenstern, Andreas
PY  - 2021
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4927
AB  - It is well known, that forced periodic operation possesses the potential for process improvements. Nevertheless, only a small number of applications is reported, due to complex realization, limited predictability and high inertia of larger units. Nonlinear frequency response (NFR) analysis has proven to predict efficiently time-averaged performance of reactor effluent streams originating from forced periodic changes of one or several input(s). Focus of this paper was an experimental demonstration of forced periodic operation applied to the hydrolysis of acetic anhydride carried out in an adiabatic CSTR. Theoretical results provided a guideline for experiments exploiting simultaneous sinusoidal modulations of the anhydride inlet concentration and the total volumetric flow-rate. Influences of the forcing parameters (amplitudes and the phase difference) were also studied. Confirming the predictions of NFR analysis a significantly higher time-averaged product yields were experimentally achieved compared to conventional steady-state operation with simultaneous modulation of two inputs using an optimized phase shift.
T2  - Chemical Engineering Journal
T1  - Analysis and experimental demonstration of forced periodic operation of an adiabatic stirred tank reactor: Simultaneous modulation of inlet concentration and total flow-rate
VL  - 410
DO  - 10.1016/j.cej.2020.128197
ER  - 

@article{
author = "Felischak, Matthias and Kaps, Lothar and Hamel, Christof and Nikolic, Daliborka and Petkovska, Menka and Seidel-Morgenstern, Andreas",
year = "2021",
abstract = "It is well known, that forced periodic operation possesses the potential for process improvements. Nevertheless, only a small number of applications is reported, due to complex realization, limited predictability and high inertia of larger units. Nonlinear frequency response (NFR) analysis has proven to predict efficiently time-averaged performance of reactor effluent streams originating from forced periodic changes of one or several input(s). Focus of this paper was an experimental demonstration of forced periodic operation applied to the hydrolysis of acetic anhydride carried out in an adiabatic CSTR. Theoretical results provided a guideline for experiments exploiting simultaneous sinusoidal modulations of the anhydride inlet concentration and the total volumetric flow-rate. Influences of the forcing parameters (amplitudes and the phase difference) were also studied. Confirming the predictions of NFR analysis a significantly higher time-averaged product yields were experimentally achieved compared to conventional steady-state operation with simultaneous modulation of two inputs using an optimized phase shift.",
journal = "Chemical Engineering Journal",
title = "Analysis and experimental demonstration of forced periodic operation of an adiabatic stirred tank reactor: Simultaneous modulation of inlet concentration and total flow-rate",
volume = "410",
doi = "10.1016/j.cej.2020.128197"
}

Felischak, M., Kaps, L., Hamel, C., Nikolic, D., Petkovska, M.,& Seidel-Morgenstern, A.. (2021). Analysis and experimental demonstration of forced periodic operation of an adiabatic stirred tank reactor: Simultaneous modulation of inlet concentration and total flow-rate. in Chemical Engineering Journal, 410.
https://doi.org/10.1016/j.cej.2020.128197

Felischak M, Kaps L, Hamel C, Nikolic D, Petkovska M, Seidel-Morgenstern A. Analysis and experimental demonstration of forced periodic operation of an adiabatic stirred tank reactor: Simultaneous modulation of inlet concentration and total flow-rate. in Chemical Engineering Journal. 2021;410.
doi:10.1016/j.cej.2020.128197 .

Felischak, Matthias, Kaps, Lothar, Hamel, Christof, Nikolic, Daliborka, Petkovska, Menka, Seidel-Morgenstern, Andreas, "Analysis and experimental demonstration of forced periodic operation of an adiabatic stirred tank reactor: Simultaneous modulation of inlet concentration and total flow-rate" in Chemical Engineering Journal, 410 (2021),
https://doi.org/10.1016/j.cej.2020.128197 . .

TY  - JOUR
AU  - Kaps, Lothar
AU  - Felischak, Matthias
AU  - Nikolić, Daliborka
AU  - Petkovska, Menka
AU  - Hamel, Christof
AU  - Seidel-Morgenstern, Andreas
PY  - 2020
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4407
AB  - Continuous chemical reactors are mostly operated under steady-state conditions. However, theoretical studies reveal that forced periodic operation (FPO) can lead to better performance. To predict and optimize FPO, the nonlinear frequency response (NFR) method provides an analytical approach. The presented work is focused on providing theoretical and experimental results devoted to demonstrating both the potential of forced periodic operation and the strength of the NFR method to identify suitable operating conditions. The hydrolysis of acetic anhydride is studied experimentally as a model reaction applying an adiabatic continuous stirred tank reactor (CSTR).
PB  - Wiley-VCH
T2  - Chemie Ingenieur Technik
T1  - Forced periodic reactor operation: Analysis of process and forcing parameters exploiting the nonlinear frequency response method
EP  - 1346
IS  - 9
SP  - 1346
VL  - 92
DO  - 10.1002/cite.202055082
ER  - 

@article{
author = "Kaps, Lothar and Felischak, Matthias and Nikolić, Daliborka and Petkovska, Menka and Hamel, Christof and Seidel-Morgenstern, Andreas",
year = "2020",
abstract = "Continuous chemical reactors are mostly operated under steady-state conditions. However, theoretical studies reveal that forced periodic operation (FPO) can lead to better performance. To predict and optimize FPO, the nonlinear frequency response (NFR) method provides an analytical approach. The presented work is focused on providing theoretical and experimental results devoted to demonstrating both the potential of forced periodic operation and the strength of the NFR method to identify suitable operating conditions. The hydrolysis of acetic anhydride is studied experimentally as a model reaction applying an adiabatic continuous stirred tank reactor (CSTR).",
publisher = "Wiley-VCH",
journal = "Chemie Ingenieur Technik",
title = "Forced periodic reactor operation: Analysis of process and forcing parameters exploiting the nonlinear frequency response method",
pages = "1346-1346",
number = "9",
volume = "92",
doi = "10.1002/cite.202055082"
}

Kaps, L., Felischak, M., Nikolić, D., Petkovska, M., Hamel, C.,& Seidel-Morgenstern, A.. (2020). Forced periodic reactor operation: Analysis of process and forcing parameters exploiting the nonlinear frequency response method. in Chemie Ingenieur Technik
Wiley-VCH., 92(9), 1346-1346.
https://doi.org/10.1002/cite.202055082

Kaps L, Felischak M, Nikolić D, Petkovska M, Hamel C, Seidel-Morgenstern A. Forced periodic reactor operation: Analysis of process and forcing parameters exploiting the nonlinear frequency response method. in Chemie Ingenieur Technik. 2020;92(9):1346-1346.
doi:10.1002/cite.202055082 .

Kaps, Lothar, Felischak, Matthias, Nikolić, Daliborka, Petkovska, Menka, Hamel, Christof, Seidel-Morgenstern, Andreas, "Forced periodic reactor operation: Analysis of process and forcing parameters exploiting the nonlinear frequency response method" in Chemie Ingenieur Technik, 92, no. 9 (2020):1346-1346,
https://doi.org/10.1002/cite.202055082 . .

TY  - JOUR
AU  - Nikolić-Paunić, Daliborka
AU  - Seidel-Morgenstern, Andreas
AU  - Petkovska, Menka
PY  - 2020
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4360
AB  - Nonlinear frequency response (NFR) method was used to evaluate the forced periodic operations and their potential for improving the system performance compared to steady-state operations. The NFR method was used to evaluate the time-average performances of forced periodically operated systems subjected to simultaneous periodic modulation of two-inputs of general waveforms. As an example, a forced periodically operated adiabatic CSTR with simple nth order reaction A - gt  v(p)P and square-wave modulation of two pairs of inputs were analyzed in detail. The theory is illustrated analyzing the hydrolysis of acetic acid anhydride performed in a laboratory scale adiabatic CSTR. The results showed that significant improvements could be achieved by simultaneous modulation of both pairs of inputs. Comparison with the results of numerical integration showed that the approximation using only the asymmetrical second order FRFs and the first three harmonics of the inputs provide very reliable predictions of the DC component.
PB  - Pergamon-Elsevier Science Ltd, Oxford
T2  - Chemical Engineering Science
T1  - Nonlinear frequency response analysis of forced periodic operations with simultaneous modulation of two general waveform inputs with applications on adiabatic CSTR with square-wave modulations
VL  - 226
DO  - 10.1016/j.ces.2020.115842
ER  - 

@article{
author = "Nikolić-Paunić, Daliborka and Seidel-Morgenstern, Andreas and Petkovska, Menka",
year = "2020",
abstract = "Nonlinear frequency response (NFR) method was used to evaluate the forced periodic operations and their potential for improving the system performance compared to steady-state operations. The NFR method was used to evaluate the time-average performances of forced periodically operated systems subjected to simultaneous periodic modulation of two-inputs of general waveforms. As an example, a forced periodically operated adiabatic CSTR with simple nth order reaction A - gt  v(p)P and square-wave modulation of two pairs of inputs were analyzed in detail. The theory is illustrated analyzing the hydrolysis of acetic acid anhydride performed in a laboratory scale adiabatic CSTR. The results showed that significant improvements could be achieved by simultaneous modulation of both pairs of inputs. Comparison with the results of numerical integration showed that the approximation using only the asymmetrical second order FRFs and the first three harmonics of the inputs provide very reliable predictions of the DC component.",
publisher = "Pergamon-Elsevier Science Ltd, Oxford",
journal = "Chemical Engineering Science",
title = "Nonlinear frequency response analysis of forced periodic operations with simultaneous modulation of two general waveform inputs with applications on adiabatic CSTR with square-wave modulations",
volume = "226",
doi = "10.1016/j.ces.2020.115842"
}

Nikolić-Paunić, D., Seidel-Morgenstern, A.,& Petkovska, M.. (2020). Nonlinear frequency response analysis of forced periodic operations with simultaneous modulation of two general waveform inputs with applications on adiabatic CSTR with square-wave modulations. in Chemical Engineering Science
Pergamon-Elsevier Science Ltd, Oxford., 226.
https://doi.org/10.1016/j.ces.2020.115842

Nikolić-Paunić D, Seidel-Morgenstern A, Petkovska M. Nonlinear frequency response analysis of forced periodic operations with simultaneous modulation of two general waveform inputs with applications on adiabatic CSTR with square-wave modulations. in Chemical Engineering Science. 2020;226.
doi:10.1016/j.ces.2020.115842 .

Nikolić-Paunić, Daliborka, Seidel-Morgenstern, Andreas, Petkovska, Menka, "Nonlinear frequency response analysis of forced periodic operations with simultaneous modulation of two general waveform inputs with applications on adiabatic CSTR with square-wave modulations" in Chemical Engineering Science, 226 (2020),
https://doi.org/10.1016/j.ces.2020.115842 . .

TY  - CONF
AU  - Seidel, Carsten
AU  - Felischak, Matthias
AU  - Nikolić, Daliborka
AU  - Seidel-Morgenstern, Andreas
AU  - Petkovska, Menka
AU  - Kienle, Achim
PY  - 2020
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4412
AB  - Methanol is an essential primary chemical in the chemical industry. Further, there is a growing interest in using methanol also for chemical energy storage. Excess electrical wind or solar energy can be converted to hydrogen and react with CO and CO2 from biogas or waste streams to methanol. Suitable kinetic models are required for designing such processes. Established kinetics need to be extended to account for strongly varying input ratios of H2, CO, and CO2 in such applications leading to the need for dynamic process operation. Kinetic models for methanol synthesis accounting for dynamic changes of the catalyst morphology were proposed recently [1]. For the implementation and evaluation of the dynamic operation, a novel reactor concept, incorporating a micro-berty reactor, is established. The configuration allows the modulation of single and multiple input parameters simultaneously, such as partial pressure, total flow-rate, and total pressure. Periodic variation of the inputs results in fluctuating outputs. For the analysis of these changes, an online mass spectrometer (MS) and a micro-gas chromatograph (GC) are implemented for time-resolved concentration profiles, as well as the analysis of collected samples of multiple fluctuation periods. A set of dynamic experiments is determined by optimal experimental design that improves the parameter sensitivity by solving optimal control problems to identify an optimal parameter set. Additionally, it is analyzed what kind of additional measurement is required for further improvement of the identifiability of the kinetic model [2]. The nonlinear dynamic behavior of the methanol synthesis can be exploited by a forced periodic modulation of different feed streams and total flow-rate (separately of simultaneously) that result in improvements of the time-average output, in comparison to the steady-state process, concerning different objective functions. The nonlinear frequency response (NFR) analysis [3] is used to estimate suitable input variations and the corresponding optimal dynamic parameters (forcing frequency, amplitudes, and phase difference). The NFR method was already applied in various cases [4–6], and it represents promising starting points for rigorous dynamic optimization. The selection of the objective functions for single- and multi-objective optimization of forced periodic operations is critically discussed.
PB  - Max Planck Institute
C3  - 4th Indo-German Workshop on Advances in Materials, Reaction& Separation Processes, Berlin, Germany
T1  - Optimization of methanol synthesis under forced dynamic operation
UR  - https://hdl.handle.net/21.15107/rcub_technorep_4412
ER  - 

@conference{
author = "Seidel, Carsten and Felischak, Matthias and Nikolić, Daliborka and Seidel-Morgenstern, Andreas and Petkovska, Menka and Kienle, Achim",
year = "2020",
abstract = "Methanol is an essential primary chemical in the chemical industry. Further, there is a growing interest in using methanol also for chemical energy storage. Excess electrical wind or solar energy can be converted to hydrogen and react with CO and CO2 from biogas or waste streams to methanol. Suitable kinetic models are required for designing such processes. Established kinetics need to be extended to account for strongly varying input ratios of H2, CO, and CO2 in such applications leading to the need for dynamic process operation. Kinetic models for methanol synthesis accounting for dynamic changes of the catalyst morphology were proposed recently [1]. For the implementation and evaluation of the dynamic operation, a novel reactor concept, incorporating a micro-berty reactor, is established. The configuration allows the modulation of single and multiple input parameters simultaneously, such as partial pressure, total flow-rate, and total pressure. Periodic variation of the inputs results in fluctuating outputs. For the analysis of these changes, an online mass spectrometer (MS) and a micro-gas chromatograph (GC) are implemented for time-resolved concentration profiles, as well as the analysis of collected samples of multiple fluctuation periods. A set of dynamic experiments is determined by optimal experimental design that improves the parameter sensitivity by solving optimal control problems to identify an optimal parameter set. Additionally, it is analyzed what kind of additional measurement is required for further improvement of the identifiability of the kinetic model [2]. The nonlinear dynamic behavior of the methanol synthesis can be exploited by a forced periodic modulation of different feed streams and total flow-rate (separately of simultaneously) that result in improvements of the time-average output, in comparison to the steady-state process, concerning different objective functions. The nonlinear frequency response (NFR) analysis [3] is used to estimate suitable input variations and the corresponding optimal dynamic parameters (forcing frequency, amplitudes, and phase difference). The NFR method was already applied in various cases [4–6], and it represents promising starting points for rigorous dynamic optimization. The selection of the objective functions for single- and multi-objective optimization of forced periodic operations is critically discussed.",
publisher = "Max Planck Institute",
journal = "4th Indo-German Workshop on Advances in Materials, Reaction& Separation Processes, Berlin, Germany",
title = "Optimization of methanol synthesis under forced dynamic operation",
url = "https://hdl.handle.net/21.15107/rcub_technorep_4412"
}

Seidel, C., Felischak, M., Nikolić, D., Seidel-Morgenstern, A., Petkovska, M.,& Kienle, A.. (2020). Optimization of methanol synthesis under forced dynamic operation. in 4th Indo-German Workshop on Advances in Materials, Reaction& Separation Processes, Berlin, Germany
Max Planck Institute..
https://hdl.handle.net/21.15107/rcub_technorep_4412

Seidel C, Felischak M, Nikolić D, Seidel-Morgenstern A, Petkovska M, Kienle A. Optimization of methanol synthesis under forced dynamic operation. in 4th Indo-German Workshop on Advances in Materials, Reaction& Separation Processes, Berlin, Germany. 2020;.
https://hdl.handle.net/21.15107/rcub_technorep_4412 .

Seidel, Carsten, Felischak, Matthias, Nikolić, Daliborka, Seidel-Morgenstern, Andreas, Petkovska, Menka, Kienle, Achim, "Optimization of methanol synthesis under forced dynamic operation" in 4th Indo-German Workshop on Advances in Materials, Reaction& Separation Processes, Berlin, Germany (2020),
https://hdl.handle.net/21.15107/rcub_technorep_4412 .

TY  - CONF
AU  - Petkovska, Menka
AU  - Kienle, Achim
AU  - Nikolić, Daliborka
AU  - Seidel, Carsten
AU  - Felischak, Matthias
AU  - Seidel-Morgenstern, Andreas
PY  - 2020
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4411
AB  - We used the nonlinear frequency response (NFR) method in order to identify forced periodic conditions under which the acetic acid anhydride hydrolysis (chosen as a test reaction) can be favorably performed in a CSTR. Based on the results of the theoretical analysis, experimental investigations were performed using a lab-scale reactor exposed to two fluctuating inlet streams (water and acetic anhydride) with adjustable flow-rates, which enables modulation of the inlet reactant concentrations or/and total flow-rates in a flexible manner. The concentration of acetic acid formed is measured in the reactor online and used to monitor the process dynamics. Averaged values of the product outlet stream serve to validate the mean values predicted by NFR analysis and to evaluate the potential of this flexible forcing strategy. Recently we started to analyze both theoretically and experimentally the potential of applying a forced periodic operation to improve the methanol synthesis from CO, CO2 and H2 using the conventional Cu/ZnO/Al2O3 catalysts. This work is based on a recently published detailed model of this reaction, which is capable to quantify the rates under dynamic conditions (C. Seidel, A. Jörke, B. Vollbrecht, A. Seidel-Morgenstern, A. Kienle, Chem. Eng. Sci. 175 (2917) 130–138).
PB  - Max Planck Institute
C3  - 4th Indo-German Workshop on Advances in Materials, Reaction& Separation Processes, Berlin, Germany
T1  - Forced periodic reactor operation
UR  - https://hdl.handle.net/21.15107/rcub_technorep_4411
ER  - 

@conference{
author = "Petkovska, Menka and Kienle, Achim and Nikolić, Daliborka and Seidel, Carsten and Felischak, Matthias and Seidel-Morgenstern, Andreas",
year = "2020",
abstract = "We used the nonlinear frequency response (NFR) method in order to identify forced periodic conditions under which the acetic acid anhydride hydrolysis (chosen as a test reaction) can be favorably performed in a CSTR. Based on the results of the theoretical analysis, experimental investigations were performed using a lab-scale reactor exposed to two fluctuating inlet streams (water and acetic anhydride) with adjustable flow-rates, which enables modulation of the inlet reactant concentrations or/and total flow-rates in a flexible manner. The concentration of acetic acid formed is measured in the reactor online and used to monitor the process dynamics. Averaged values of the product outlet stream serve to validate the mean values predicted by NFR analysis and to evaluate the potential of this flexible forcing strategy. Recently we started to analyze both theoretically and experimentally the potential of applying a forced periodic operation to improve the methanol synthesis from CO, CO2 and H2 using the conventional Cu/ZnO/Al2O3 catalysts. This work is based on a recently published detailed model of this reaction, which is capable to quantify the rates under dynamic conditions (C. Seidel, A. Jörke, B. Vollbrecht, A. Seidel-Morgenstern, A. Kienle, Chem. Eng. Sci. 175 (2917) 130–138).",
publisher = "Max Planck Institute",
journal = "4th Indo-German Workshop on Advances in Materials, Reaction& Separation Processes, Berlin, Germany",
title = "Forced periodic reactor operation",
url = "https://hdl.handle.net/21.15107/rcub_technorep_4411"
}

Petkovska, M., Kienle, A., Nikolić, D., Seidel, C., Felischak, M.,& Seidel-Morgenstern, A.. (2020). Forced periodic reactor operation. in 4th Indo-German Workshop on Advances in Materials, Reaction& Separation Processes, Berlin, Germany
Max Planck Institute..
https://hdl.handle.net/21.15107/rcub_technorep_4411

Petkovska M, Kienle A, Nikolić D, Seidel C, Felischak M, Seidel-Morgenstern A. Forced periodic reactor operation. in 4th Indo-German Workshop on Advances in Materials, Reaction& Separation Processes, Berlin, Germany. 2020;.
https://hdl.handle.net/21.15107/rcub_technorep_4411 .

Petkovska, Menka, Kienle, Achim, Nikolić, Daliborka, Seidel, Carsten, Felischak, Matthias, Seidel-Morgenstern, Andreas, "Forced periodic reactor operation" in 4th Indo-German Workshop on Advances in Materials, Reaction& Separation Processes, Berlin, Germany (2020),
https://hdl.handle.net/21.15107/rcub_technorep_4411 .

TY  - CONF
AU  - Felischak, Matthias
AU  - Nikolić, Daliborka
AU  - Petkovska, Menka
AU  - Hamel, Christof
AU  - Seidel-Morgenstern, Andreas
PY  - 2019
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4152
AB  - The classical design of continuous chemical reactors exploits steady-state operation, which is optimized and maintained by appropriate control systems. Nevertheless, it is well-known that the reactor performance can be enhanced by applying periodic regimes, like forced modulations of input parameters.The identification and evaluation of suitable periodic operation conditions is challenging. One approach that can be used is based on nonlinear frequency response (NFR) analysis. The focus of this work is the experimental analysis of shapes for two simultaneously imposed modulations (sinusoidal and square) in comparison to results predicted by the NFR method. The acetic anhydride hydrolysis was studied in an adiabatic CSTR exploiting a periodic operation mode, which was found to be superior to the corresponding steady-state operation.
C3  - German reaction Engineering Meeting (DECHEMA), Wuerzburg, Germany
T1  - Forced Periodic Operation: Effect of shapes for two simultaneously imposed modulations
UR  - https://hdl.handle.net/21.15107/rcub_technorep_4152
ER  - 

@conference{
author = "Felischak, Matthias and Nikolić, Daliborka and Petkovska, Menka and Hamel, Christof and Seidel-Morgenstern, Andreas",
year = "2019",
abstract = "The classical design of continuous chemical reactors exploits steady-state operation, which is optimized and maintained by appropriate control systems. Nevertheless, it is well-known that the reactor performance can be enhanced by applying periodic regimes, like forced modulations of input parameters.The identification and evaluation of suitable periodic operation conditions is challenging. One approach that can be used is based on nonlinear frequency response (NFR) analysis. The focus of this work is the experimental analysis of shapes for two simultaneously imposed modulations (sinusoidal and square) in comparison to results predicted by the NFR method. The acetic anhydride hydrolysis was studied in an adiabatic CSTR exploiting a periodic operation mode, which was found to be superior to the corresponding steady-state operation.",
journal = "German reaction Engineering Meeting (DECHEMA), Wuerzburg, Germany",
title = "Forced Periodic Operation: Effect of shapes for two simultaneously imposed modulations",
url = "https://hdl.handle.net/21.15107/rcub_technorep_4152"
}

Felischak, M., Nikolić, D., Petkovska, M., Hamel, C.,& Seidel-Morgenstern, A.. (2019). Forced Periodic Operation: Effect of shapes for two simultaneously imposed modulations. in German reaction Engineering Meeting (DECHEMA), Wuerzburg, Germany.
https://hdl.handle.net/21.15107/rcub_technorep_4152

Felischak M, Nikolić D, Petkovska M, Hamel C, Seidel-Morgenstern A. Forced Periodic Operation: Effect of shapes for two simultaneously imposed modulations. in German reaction Engineering Meeting (DECHEMA), Wuerzburg, Germany. 2019;.
https://hdl.handle.net/21.15107/rcub_technorep_4152 .

Felischak, Matthias, Nikolić, Daliborka, Petkovska, Menka, Hamel, Christof, Seidel-Morgenstern, Andreas, "Forced Periodic Operation: Effect of shapes for two simultaneously imposed modulations" in German reaction Engineering Meeting (DECHEMA), Wuerzburg, Germany (2019),
https://hdl.handle.net/21.15107/rcub_technorep_4152 .

TY  - CONF
AU  - Nikolić, Daliborka
AU  - Seidel, Carsten
AU  - Kienle, Achim
AU  - Seidel-Morgenstern, Andreas
AU  - Petkovska, Menka
PY  - 2019
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4159
AB  - In this work, the NFR method is implemented for evaluation of possible improvement for the reaction of methanol synthesis by hydrogenation of CO and CO2, using a standard Cu/ZnO/Al2O3 catalyst. For start, a forced periodically operated isothermal continuous-stirred tank reactor (CSTR) is considered. A simplified (lumped) kinetic model of methanol synthesis with 14 parameters which were estimated from the results of an extensive experimental investigation is used. The NFR method is performed for evaluation of possible increase of methanol production by modulating the mole fractions of CO and CO2 in the feed stream, as well as their simultaneous modulation. The necessary asymmetrical second order frequency response functions correlating the methanol production with the modulated inputs are derived and the forcing parameters leading to improvement of the reactor performance are determined. The results of the NFR analysis will further be used for rigorous optimisation of the forced periodic operations and planning the best experimental scenarios. The final step will be experimental investigation and confirmation on a laboratory scale reactor.
C3  - 2nd International Process Intensification Conference, Leuven, Belgium
T1  - Intensification of a chemical reactor for methanol synthesis through forced periodic operations- Evaluation based on Nonlinear Frequency Response Analysis
UR  - https://hdl.handle.net/21.15107/rcub_technorep_4159
ER  - 

@conference{
author = "Nikolić, Daliborka and Seidel, Carsten and Kienle, Achim and Seidel-Morgenstern, Andreas and Petkovska, Menka",
year = "2019",
abstract = "In this work, the NFR method is implemented for evaluation of possible improvement for the reaction of methanol synthesis by hydrogenation of CO and CO2, using a standard Cu/ZnO/Al2O3 catalyst. For start, a forced periodically operated isothermal continuous-stirred tank reactor (CSTR) is considered. A simplified (lumped) kinetic model of methanol synthesis with 14 parameters which were estimated from the results of an extensive experimental investigation is used. The NFR method is performed for evaluation of possible increase of methanol production by modulating the mole fractions of CO and CO2 in the feed stream, as well as their simultaneous modulation. The necessary asymmetrical second order frequency response functions correlating the methanol production with the modulated inputs are derived and the forcing parameters leading to improvement of the reactor performance are determined. The results of the NFR analysis will further be used for rigorous optimisation of the forced periodic operations and planning the best experimental scenarios. The final step will be experimental investigation and confirmation on a laboratory scale reactor.",
journal = "2nd International Process Intensification Conference, Leuven, Belgium",
title = "Intensification of a chemical reactor for methanol synthesis through forced periodic operations- Evaluation based on Nonlinear Frequency Response Analysis",
url = "https://hdl.handle.net/21.15107/rcub_technorep_4159"
}

Nikolić, D., Seidel, C., Kienle, A., Seidel-Morgenstern, A.,& Petkovska, M.. (2019). Intensification of a chemical reactor for methanol synthesis through forced periodic operations- Evaluation based on Nonlinear Frequency Response Analysis. in 2nd International Process Intensification Conference, Leuven, Belgium.
https://hdl.handle.net/21.15107/rcub_technorep_4159

Nikolić D, Seidel C, Kienle A, Seidel-Morgenstern A, Petkovska M. Intensification of a chemical reactor for methanol synthesis through forced periodic operations- Evaluation based on Nonlinear Frequency Response Analysis. in 2nd International Process Intensification Conference, Leuven, Belgium. 2019;.
https://hdl.handle.net/21.15107/rcub_technorep_4159 .

Nikolić, Daliborka, Seidel, Carsten, Kienle, Achim, Seidel-Morgenstern, Andreas, Petkovska, Menka, "Intensification of a chemical reactor for methanol synthesis through forced periodic operations- Evaluation based on Nonlinear Frequency Response Analysis" in 2nd International Process Intensification Conference, Leuven, Belgium (2019),
https://hdl.handle.net/21.15107/rcub_technorep_4159 .

TY  - CONF
AU  - Felischak, Matthias
AU  - Nikolić, Daliborka
AU  - Petkovska, Menka
AU  - Seidel-Morgenstern, Andreas
PY  - 2018
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3763
AB  - Theoretical evaluation of possible reactor improvement for periodic operation. Automated experimental setup was built, with a lab-scale CSTR and adjustable flow-rates, in which periodic operations can be conducted. The concept was implemented for the hydrolysis of acetic anhydride as a model reaction.
C3  - The 25th International Symposium of Chemical Reaction Engineering (ISCRE 25), Florance, Italy
T1  - Forced periodic reactor operation with simultaneous modulation of two inputs: Experimental investigation based on Nonlinear Frequency Response Analysis
UR  - https://hdl.handle.net/21.15107/rcub_technorep_3763
ER  - 

@conference{
author = "Felischak, Matthias and Nikolić, Daliborka and Petkovska, Menka and Seidel-Morgenstern, Andreas",
year = "2018",
abstract = "Theoretical evaluation of possible reactor improvement for periodic operation. Automated experimental setup was built, with a lab-scale CSTR and adjustable flow-rates, in which periodic operations can be conducted. The concept was implemented for the hydrolysis of acetic anhydride as a model reaction.",
journal = "The 25th International Symposium of Chemical Reaction Engineering (ISCRE 25), Florance, Italy",
title = "Forced periodic reactor operation with simultaneous modulation of two inputs: Experimental investigation based on Nonlinear Frequency Response Analysis",
url = "https://hdl.handle.net/21.15107/rcub_technorep_3763"
}

Felischak, M., Nikolić, D., Petkovska, M.,& Seidel-Morgenstern, A.. (2018). Forced periodic reactor operation with simultaneous modulation of two inputs: Experimental investigation based on Nonlinear Frequency Response Analysis. in The 25th International Symposium of Chemical Reaction Engineering (ISCRE 25), Florance, Italy.
https://hdl.handle.net/21.15107/rcub_technorep_3763

Felischak M, Nikolić D, Petkovska M, Seidel-Morgenstern A. Forced periodic reactor operation with simultaneous modulation of two inputs: Experimental investigation based on Nonlinear Frequency Response Analysis. in The 25th International Symposium of Chemical Reaction Engineering (ISCRE 25), Florance, Italy. 2018;.
https://hdl.handle.net/21.15107/rcub_technorep_3763 .

Felischak, Matthias, Nikolić, Daliborka, Petkovska, Menka, Seidel-Morgenstern, Andreas, "Forced periodic reactor operation with simultaneous modulation of two inputs: Experimental investigation based on Nonlinear Frequency Response Analysis" in The 25th International Symposium of Chemical Reaction Engineering (ISCRE 25), Florance, Italy (2018),
https://hdl.handle.net/21.15107/rcub_technorep_3763 .

TY  - JOUR
AU  - Petkovska, Menka
AU  - Nikolić-Paunić, Daliborka
AU  - Seidel-Morgenstern, Andreas
PY  - 2018
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3878
AB  - Nonlinear Frequency Response (NFR) method is a relatively new method which can be used for fast evaluation of possible process improvements through periodic operations. The method is analytical and approximate. Its main task is to give an answer whether periodic modulation of one or more process inputs can result in improved process performance. The method is explained in brief and an overview of the existing applications is given. The review covers simple reactions performed in isothermal and non-isothermal stirred tank reactors exposed to different modulated inputs (inlet concentration, flow-rate, inlet temperature, temperature of the heating/cooling medium). Processes with two simultaneously modulated inputs and different shapes of the periodic input are also considered. The results of the NFR method are compared with the results of numerical simulation and a critical evaluation of the method is given.
PB  - Wiley-VCH Verlag Gmbh, Weinheim
T2  - Israel Journal of Chemistry
T1  - Nonlinear Frequency Response Method for Evaluating Forced Periodic Operations of Chemical Reactors
EP  - 681
IS  - 6-7
SP  - 663
VL  - 58
DO  - 10.1002/ijch.201700132
ER  - 

@article{
author = "Petkovska, Menka and Nikolić-Paunić, Daliborka and Seidel-Morgenstern, Andreas",
year = "2018",
abstract = "Nonlinear Frequency Response (NFR) method is a relatively new method which can be used for fast evaluation of possible process improvements through periodic operations. The method is analytical and approximate. Its main task is to give an answer whether periodic modulation of one or more process inputs can result in improved process performance. The method is explained in brief and an overview of the existing applications is given. The review covers simple reactions performed in isothermal and non-isothermal stirred tank reactors exposed to different modulated inputs (inlet concentration, flow-rate, inlet temperature, temperature of the heating/cooling medium). Processes with two simultaneously modulated inputs and different shapes of the periodic input are also considered. The results of the NFR method are compared with the results of numerical simulation and a critical evaluation of the method is given.",
publisher = "Wiley-VCH Verlag Gmbh, Weinheim",
journal = "Israel Journal of Chemistry",
title = "Nonlinear Frequency Response Method for Evaluating Forced Periodic Operations of Chemical Reactors",
pages = "681-663",
number = "6-7",
volume = "58",
doi = "10.1002/ijch.201700132"
}

Petkovska, M., Nikolić-Paunić, D.,& Seidel-Morgenstern, A.. (2018). Nonlinear Frequency Response Method for Evaluating Forced Periodic Operations of Chemical Reactors. in Israel Journal of Chemistry
Wiley-VCH Verlag Gmbh, Weinheim., 58(6-7), 663-681.
https://doi.org/10.1002/ijch.201700132

Petkovska M, Nikolić-Paunić D, Seidel-Morgenstern A. Nonlinear Frequency Response Method for Evaluating Forced Periodic Operations of Chemical Reactors. in Israel Journal of Chemistry. 2018;58(6-7):663-681.
doi:10.1002/ijch.201700132 .

Petkovska, Menka, Nikolić-Paunić, Daliborka, Seidel-Morgenstern, Andreas, "Nonlinear Frequency Response Method for Evaluating Forced Periodic Operations of Chemical Reactors" in Israel Journal of Chemistry, 58, no. 6-7 (2018):663-681,
https://doi.org/10.1002/ijch.201700132 . .

TY  - CONF
AU  - Felischak, Matthias
AU  - Nikolić, Daliborka
AU  - Petkovska, Menka
AU  - Seidel-Morgenstern, Andreas
PY  - 2018
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3787
AB  - The classical design of continuously operated chemical reactors assumes that they are operated in a steady-state which is usually optimized and maintained by using appropriate control systems. Nevertheless, it has been known for quite some time that, in some cases, better performance can be achieved by applying a periodic regime exploiting forced modulations of one or more inputs to the reactor [1,2]. Finding out whether, at which conditions and to which extent periodic operation can be superior to the optimal steady-state is difficult. One approach that can be used is an approximate, analytical method called nonlinear frequency response (NFR) method [3].  The NFR method is based on the concept of higher order frequency response functions (FRFs) and applicable for weakly nonlinear systems [3]. Frequency response of a weakly nonlinear system, in addition to the basic harmonic, contains a non-periodic (DC) term and, theoretically, an infinite sequence of higher harmonics. The DC component of the output is responsible for the average performance of the periodically operated reactor, and its sign and value define whether, and to which extent, the periodic operation leads to process improvement. Using the NFR method, this DC component can be approximately estimated from a single asymmetrical second order FRF (for modulation of a single input) or from several single input and cross- asymmetrical second order FRFs (for multiple-input modulation). For the case of multiple modulated inputs, the optimal phase difference between the modulated inputs, which is an essential parameter, can be directly determined [4,5]. Promising parameters to be periodically modulated separately or simultaneously are clearly the reactant inlet concentrations, the flow-rates and the feed temperatures.   We used the NFR method in order to identify forced periodic conditions under which the acetic acid anhydride hydrolysis (chosen as a test reaction) can be favorably performed in a CSTR. Based on the results of the theoretical analysis, experimental investigations were performed using a lab-scale reactor exposed to two fluctuating inlet streams (water and acetic anhydride) with adjustable flow-rates, which enables modulation of the inlet reactant concentrations or/and total flow-rates in a flexible manner. The concentration of the acetic acid formed is measured in the reactor online and used to monitor the process dynamics. Averaged values of the product outlet stream serve to validate the mean values predicted by NFR analysis and to evaluate the potential of this flexible forcing strategy.
C3  - American Institute of Chemical Engineers Annual Meeting (AIChE Annual Meeting), Pittsburgh, USA
T1  - Forced periodic reactor operation with simultaneous modulation of two inputs: Nonlinear frequency response analysis  and experimental demonstration
UR  - https://hdl.handle.net/21.15107/rcub_technorep_3787
ER  - 

@conference{
author = "Felischak, Matthias and Nikolić, Daliborka and Petkovska, Menka and Seidel-Morgenstern, Andreas",
year = "2018",
abstract = "The classical design of continuously operated chemical reactors assumes that they are operated in a steady-state which is usually optimized and maintained by using appropriate control systems. Nevertheless, it has been known for quite some time that, in some cases, better performance can be achieved by applying a periodic regime exploiting forced modulations of one or more inputs to the reactor [1,2]. Finding out whether, at which conditions and to which extent periodic operation can be superior to the optimal steady-state is difficult. One approach that can be used is an approximate, analytical method called nonlinear frequency response (NFR) method [3].  The NFR method is based on the concept of higher order frequency response functions (FRFs) and applicable for weakly nonlinear systems [3]. Frequency response of a weakly nonlinear system, in addition to the basic harmonic, contains a non-periodic (DC) term and, theoretically, an infinite sequence of higher harmonics. The DC component of the output is responsible for the average performance of the periodically operated reactor, and its sign and value define whether, and to which extent, the periodic operation leads to process improvement. Using the NFR method, this DC component can be approximately estimated from a single asymmetrical second order FRF (for modulation of a single input) or from several single input and cross- asymmetrical second order FRFs (for multiple-input modulation). For the case of multiple modulated inputs, the optimal phase difference between the modulated inputs, which is an essential parameter, can be directly determined [4,5]. Promising parameters to be periodically modulated separately or simultaneously are clearly the reactant inlet concentrations, the flow-rates and the feed temperatures.   We used the NFR method in order to identify forced periodic conditions under which the acetic acid anhydride hydrolysis (chosen as a test reaction) can be favorably performed in a CSTR. Based on the results of the theoretical analysis, experimental investigations were performed using a lab-scale reactor exposed to two fluctuating inlet streams (water and acetic anhydride) with adjustable flow-rates, which enables modulation of the inlet reactant concentrations or/and total flow-rates in a flexible manner. The concentration of the acetic acid formed is measured in the reactor online and used to monitor the process dynamics. Averaged values of the product outlet stream serve to validate the mean values predicted by NFR analysis and to evaluate the potential of this flexible forcing strategy.",
journal = "American Institute of Chemical Engineers Annual Meeting (AIChE Annual Meeting), Pittsburgh, USA",
title = "Forced periodic reactor operation with simultaneous modulation of two inputs: Nonlinear frequency response analysis  and experimental demonstration",
url = "https://hdl.handle.net/21.15107/rcub_technorep_3787"
}

Felischak, M., Nikolić, D., Petkovska, M.,& Seidel-Morgenstern, A.. (2018). Forced periodic reactor operation with simultaneous modulation of two inputs: Nonlinear frequency response analysis  and experimental demonstration. in American Institute of Chemical Engineers Annual Meeting (AIChE Annual Meeting), Pittsburgh, USA.
https://hdl.handle.net/21.15107/rcub_technorep_3787

Felischak M, Nikolić D, Petkovska M, Seidel-Morgenstern A. Forced periodic reactor operation with simultaneous modulation of two inputs: Nonlinear frequency response analysis  and experimental demonstration. in American Institute of Chemical Engineers Annual Meeting (AIChE Annual Meeting), Pittsburgh, USA. 2018;.
https://hdl.handle.net/21.15107/rcub_technorep_3787 .

Felischak, Matthias, Nikolić, Daliborka, Petkovska, Menka, Seidel-Morgenstern, Andreas, "Forced periodic reactor operation with simultaneous modulation of two inputs: Nonlinear frequency response analysis  and experimental demonstration" in American Institute of Chemical Engineers Annual Meeting (AIChE Annual Meeting), Pittsburgh, USA (2018),
https://hdl.handle.net/21.15107/rcub_technorep_3787 .

TY  - CONF
AU  - Nikolić, Daliborka
AU  - Felischak, Matthias
AU  - Seidel-Morgenstern, Andreas
AU  - Petkovska, Menka
PY  - 2017
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3503
AB  - Deliberate periodic operations have been recognized as one way of process intensification for several decades. Special attention has been dedicated to possible improvements of chemical reactor performance through periodic modulation of one or more inputs. In our previous investigations we have developed a new, nonlinear frequency response (NFR) method, as a fast and easy analytical method for evaluating the performance of forced periodically operated chemical reactors. The NFR method is based on nonlinear frequency response analysis and the concept of higher order frequency response function (FRFs) [1]. In its essence the method is approximate and it is limited to analysis of stable, weakly nonlinear systems. The method gives an answer whether, and in which cases, it is possible to obtain process improvement through periodic operation. It also gives an approximate quantitative estimate of the improvement. In addition, the method enables choosing the best forcing parameters of the modulated input(s) (frequency, amplitude and, for multiple input modulation, the phase difference between the input waves). The NFR method was originally developed for sinusoidal forcing function(s) [1]. Recently, it was extended to a general case which is applicable for any shape of the periodic input modulation, by expanding the input function into Fourier series and taking into account only a finite number of harmonics [2]. This opens a new possibility of choosing the best shape of the input wave, as well. In this paper, the NFR method is used to evaluate the performance of a forced periodically operated adiabatic continuous stirred tank reactor (CSTR) in which an exothermal reaction of hydrolysis of acetic acid anhydride to acetic acid takes place [3]. The analysisis performed for periodic modulations of the acetic anhydride concentration in the feed stream, around a previously established optimal steady state. Different shapes of the input forcing function (sinusoidal, square-wave, triangle, saw-tooth,…) were analyzed, in order to determine the best strategy of performing periodic operation. The acetic acid yield is used as a measure of the reactor performance. The increases of the product yield (relative to the steady-state value) for different shapes of the forcing function are compared. Finally, the best forcing strategy (regarding the shape, frequency and amplitude of the input wave) is chosen to be applied for experimental investigation in a lab-scale adiabatic CSTR.
C3  - 10th World Congress of Chemical Engineering (WCCE10), Barcelona, Spain
T1  - Comparison of possible improvements of a periodically operated adiabatic CSTR with inlet concentration modulation for different shapes of the forcing function
UR  - https://hdl.handle.net/21.15107/rcub_technorep_3503
ER  - 

@conference{
author = "Nikolić, Daliborka and Felischak, Matthias and Seidel-Morgenstern, Andreas and Petkovska, Menka",
year = "2017",
abstract = "Deliberate periodic operations have been recognized as one way of process intensification for several decades. Special attention has been dedicated to possible improvements of chemical reactor performance through periodic modulation of one or more inputs. In our previous investigations we have developed a new, nonlinear frequency response (NFR) method, as a fast and easy analytical method for evaluating the performance of forced periodically operated chemical reactors. The NFR method is based on nonlinear frequency response analysis and the concept of higher order frequency response function (FRFs) [1]. In its essence the method is approximate and it is limited to analysis of stable, weakly nonlinear systems. The method gives an answer whether, and in which cases, it is possible to obtain process improvement through periodic operation. It also gives an approximate quantitative estimate of the improvement. In addition, the method enables choosing the best forcing parameters of the modulated input(s) (frequency, amplitude and, for multiple input modulation, the phase difference between the input waves). The NFR method was originally developed for sinusoidal forcing function(s) [1]. Recently, it was extended to a general case which is applicable for any shape of the periodic input modulation, by expanding the input function into Fourier series and taking into account only a finite number of harmonics [2]. This opens a new possibility of choosing the best shape of the input wave, as well. In this paper, the NFR method is used to evaluate the performance of a forced periodically operated adiabatic continuous stirred tank reactor (CSTR) in which an exothermal reaction of hydrolysis of acetic acid anhydride to acetic acid takes place [3]. The analysisis performed for periodic modulations of the acetic anhydride concentration in the feed stream, around a previously established optimal steady state. Different shapes of the input forcing function (sinusoidal, square-wave, triangle, saw-tooth,…) were analyzed, in order to determine the best strategy of performing periodic operation. The acetic acid yield is used as a measure of the reactor performance. The increases of the product yield (relative to the steady-state value) for different shapes of the forcing function are compared. Finally, the best forcing strategy (regarding the shape, frequency and amplitude of the input wave) is chosen to be applied for experimental investigation in a lab-scale adiabatic CSTR.",
journal = "10th World Congress of Chemical Engineering (WCCE10), Barcelona, Spain",
title = "Comparison of possible improvements of a periodically operated adiabatic CSTR with inlet concentration modulation for different shapes of the forcing function",
url = "https://hdl.handle.net/21.15107/rcub_technorep_3503"
}

Nikolić, D., Felischak, M., Seidel-Morgenstern, A.,& Petkovska, M.. (2017). Comparison of possible improvements of a periodically operated adiabatic CSTR with inlet concentration modulation for different shapes of the forcing function. in 10th World Congress of Chemical Engineering (WCCE10), Barcelona, Spain.
https://hdl.handle.net/21.15107/rcub_technorep_3503

Nikolić D, Felischak M, Seidel-Morgenstern A, Petkovska M. Comparison of possible improvements of a periodically operated adiabatic CSTR with inlet concentration modulation for different shapes of the forcing function. in 10th World Congress of Chemical Engineering (WCCE10), Barcelona, Spain. 2017;.
https://hdl.handle.net/21.15107/rcub_technorep_3503 .

Nikolić, Daliborka, Felischak, Matthias, Seidel-Morgenstern, Andreas, Petkovska, Menka, "Comparison of possible improvements of a periodically operated adiabatic CSTR with inlet concentration modulation for different shapes of the forcing function" in 10th World Congress of Chemical Engineering (WCCE10), Barcelona, Spain (2017),
https://hdl.handle.net/21.15107/rcub_technorep_3503 .

TY  - CONF
AU  - Petkovska, Menka
AU  - Nikolić, Daliborka
AU  - Seidel-Morgenstern, Andreas
PY  - 2016
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3182
AB  - One way to achieve process intensification is to operate the process in a periodic way, by cycling one or more input variables, in order to obtain better average performance compared to the optimal steady-state operation. The source of the possible improvement lies in the process nonlinearity. Nevertheless, the improvement is obtained only in some cases, while in some others the periodic operation can result in deterioration. Periodic operations of chemical reactors have been attracting attention of a number of research groups, since the pioneering works of, e.g., Douglas and Rippin [1] and Bailey [2]. A review of the recent research in this area can be found in a book by Silveston and Hudgins [3]. Testing whether a potential periodic process is favourable or unfavourable generally demands long and tedious experimental and/or numerical work. In this work we present an alternative approach, based on the nonlinear frequency response (NFR) analysis, which gives an approximate value of the average process performance directly, without numerical simulation. The method is applicable for stable, weakly nonlinear systems.  The mathematical foundations of the nonlinear frequency response method are based on Volterra series and the resulting concept of higher order frequency response functions (FRFs). The method is based on the following facts: •	Frequency response (periodic steady-state) of a weakly nonlinear system consists of a non-periodic (DC) term, the basic and indefinite number of higher harmonics, where only the non-periodic term is responsible for the average process performance during the periodic process. •	The nonlinear model of a weakly nonlinear system can be replaced with an indefinite sequence of frequency response functions of different orders. •	The non-periodic term of the frequency response can be approximated by its dominant term which is proportional to the asymmetrical second order FRF. The nonlinear frequency response method has been applied for analysis of periodic operations of isothermal and non-isothermal CSTRs with simple reaction mechanisms. Modulation strategies with one modulated input and with simultaneous modulation of two inputs have been analysed. Periodic operations with sinusoidal or any other shape of periodic modulation can be considered. The NFR method gives answers to the following questions: •	Is it possible to improve the performance of a particular reactor by periodic modulation of one or more inputs? •	Which range of frequencies of the input modulation(s) should be used in order to get the improvement? •	If simultaneous modulation of two inputs is used, what is the optimal phase difference between them? •	Are there some optimal values of the input amplitudes that should be used, and if there are, how to determine them? •	What is the approximate extent of the performance improvement for a particular periodic operation, for a chosen set of forcing parameters (frequency, amplitude(s) and phase difference). The purpose of the method is fast evaluation of periodic operations, with the aim of selecting the cases and conditions which have a potential for improvement and are, therefore, worth of further, detailed numerical and experimental investigation.
C3  - XXII International Conference on Chemical Reactors (CHEMREACTOR-22), London, UK
T1  - Evaluating the Potential of Forced Periodic Operations of Chemical Reactors- The Nonlinear Frequency Response Approach
UR  - https://hdl.handle.net/21.15107/rcub_technorep_3182
ER  - 

@conference{
author = "Petkovska, Menka and Nikolić, Daliborka and Seidel-Morgenstern, Andreas",
year = "2016",
abstract = "One way to achieve process intensification is to operate the process in a periodic way, by cycling one or more input variables, in order to obtain better average performance compared to the optimal steady-state operation. The source of the possible improvement lies in the process nonlinearity. Nevertheless, the improvement is obtained only in some cases, while in some others the periodic operation can result in deterioration. Periodic operations of chemical reactors have been attracting attention of a number of research groups, since the pioneering works of, e.g., Douglas and Rippin [1] and Bailey [2]. A review of the recent research in this area can be found in a book by Silveston and Hudgins [3]. Testing whether a potential periodic process is favourable or unfavourable generally demands long and tedious experimental and/or numerical work. In this work we present an alternative approach, based on the nonlinear frequency response (NFR) analysis, which gives an approximate value of the average process performance directly, without numerical simulation. The method is applicable for stable, weakly nonlinear systems.  The mathematical foundations of the nonlinear frequency response method are based on Volterra series and the resulting concept of higher order frequency response functions (FRFs). The method is based on the following facts: •	Frequency response (periodic steady-state) of a weakly nonlinear system consists of a non-periodic (DC) term, the basic and indefinite number of higher harmonics, where only the non-periodic term is responsible for the average process performance during the periodic process. •	The nonlinear model of a weakly nonlinear system can be replaced with an indefinite sequence of frequency response functions of different orders. •	The non-periodic term of the frequency response can be approximated by its dominant term which is proportional to the asymmetrical second order FRF. The nonlinear frequency response method has been applied for analysis of periodic operations of isothermal and non-isothermal CSTRs with simple reaction mechanisms. Modulation strategies with one modulated input and with simultaneous modulation of two inputs have been analysed. Periodic operations with sinusoidal or any other shape of periodic modulation can be considered. The NFR method gives answers to the following questions: •	Is it possible to improve the performance of a particular reactor by periodic modulation of one or more inputs? •	Which range of frequencies of the input modulation(s) should be used in order to get the improvement? •	If simultaneous modulation of two inputs is used, what is the optimal phase difference between them? •	Are there some optimal values of the input amplitudes that should be used, and if there are, how to determine them? •	What is the approximate extent of the performance improvement for a particular periodic operation, for a chosen set of forcing parameters (frequency, amplitude(s) and phase difference). The purpose of the method is fast evaluation of periodic operations, with the aim of selecting the cases and conditions which have a potential for improvement and are, therefore, worth of further, detailed numerical and experimental investigation.",
journal = "XXII International Conference on Chemical Reactors (CHEMREACTOR-22), London, UK",
title = "Evaluating the Potential of Forced Periodic Operations of Chemical Reactors- The Nonlinear Frequency Response Approach",
url = "https://hdl.handle.net/21.15107/rcub_technorep_3182"
}

Petkovska, M., Nikolić, D.,& Seidel-Morgenstern, A.. (2016). Evaluating the Potential of Forced Periodic Operations of Chemical Reactors- The Nonlinear Frequency Response Approach. in XXII International Conference on Chemical Reactors (CHEMREACTOR-22), London, UK.
https://hdl.handle.net/21.15107/rcub_technorep_3182

Petkovska M, Nikolić D, Seidel-Morgenstern A. Evaluating the Potential of Forced Periodic Operations of Chemical Reactors- The Nonlinear Frequency Response Approach. in XXII International Conference on Chemical Reactors (CHEMREACTOR-22), London, UK. 2016;.
https://hdl.handle.net/21.15107/rcub_technorep_3182 .

Petkovska, Menka, Nikolić, Daliborka, Seidel-Morgenstern, Andreas, "Evaluating the Potential of Forced Periodic Operations of Chemical Reactors- The Nonlinear Frequency Response Approach" in XXII International Conference on Chemical Reactors (CHEMREACTOR-22), London, UK (2016),
https://hdl.handle.net/21.15107/rcub_technorep_3182 .

TY  - CONF
AU  - Petkovska, Menka
AU  - Nikolić, Daliborka
AU  - Felischak, Matthias
AU  - Seidel-Morgenstern, Andreas
PY  - 2016
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3177
AB  - Forced periodic operations of chemical reactors possess significant potential to improve numerous performance criteria. The corresponding analysis of reaction systems and the estimation of the magnitude of possible performance improvements have occupied many researchers since the earliest explorations by Douglas and Rippin (1966), Horn and Lin (1967) and Bailey (1973). Theoretical problems related to identification and estimation of the enhancement were typically analyzed evaluating suitable control criteria and applying four major approaches described by Watanabe et al. (1981) and Parulekar (2003). However, there are hardly industrial applications of this promising concept and there is still a need for developing generally applicable methods for identifying and analyzing promising reaction systems. NEW APPROACH We suggest applying the nonlinear frequency response (NFR) method to predict the outcome of perturbing periodically one or several input variables. Applying the concept of higher order frequency response functions (FRFs) weakly nonlinear systems can be described analytically (Petkovska and Seidel-Morgenstern, 2013). The response of a weakly nonlinear system to periodic input change(s) contains a periodic term, consisting of the basic and a number of higher harmonics, and a non-periodic (DC) component. The value and sign of the DC component of the outlet  can be used as an indicator for the mean performance of the forced periodic operation, as it  gives insight whether and  to which extent improvements can be expected as a result of forced periodic modulation(s) of the input(s). Applying the NRF method, the non-periodic term can be efficiently estimated for modulation of  single or multiple inputs. To demonstrate the strength of the theoretical concept the model of an adiabatic CSTR was analyzed considering reactions of different orders. Estimates are provided for different frequencies of sinusoidal changes of the inlet composition, the total inlet flow-rate and the feed temperature. It will be shown that it is in particular attractive to perturb simultaneously two input variables using the optimal phase shift, which can be determined using our method (Nikolic et al., 2015). EXPERIMENTAL To validate the theoretical predictions we carried out experiments in a laboratory scale CSTR using hydrolysis of acetic anhydride as a test reaction. The performance of the reaction system was evaluated with respect to different objectives under various steady state conditions, including theoretically optimal ones, and for various types of single and binary input perturbations.
C3  - American Institute of Chemical Engineers Annual Meeting (AIChE Annual Meeting), San Francisco, USA
T1  - Exploiting the Nonlinear Frequency Response Method to Evaluate the Potential of Forced Periodic Operation of Reactors
UR  - https://hdl.handle.net/21.15107/rcub_technorep_3177
ER  - 

@conference{
author = "Petkovska, Menka and Nikolić, Daliborka and Felischak, Matthias and Seidel-Morgenstern, Andreas",
year = "2016",
abstract = "Forced periodic operations of chemical reactors possess significant potential to improve numerous performance criteria. The corresponding analysis of reaction systems and the estimation of the magnitude of possible performance improvements have occupied many researchers since the earliest explorations by Douglas and Rippin (1966), Horn and Lin (1967) and Bailey (1973). Theoretical problems related to identification and estimation of the enhancement were typically analyzed evaluating suitable control criteria and applying four major approaches described by Watanabe et al. (1981) and Parulekar (2003). However, there are hardly industrial applications of this promising concept and there is still a need for developing generally applicable methods for identifying and analyzing promising reaction systems. NEW APPROACH We suggest applying the nonlinear frequency response (NFR) method to predict the outcome of perturbing periodically one or several input variables. Applying the concept of higher order frequency response functions (FRFs) weakly nonlinear systems can be described analytically (Petkovska and Seidel-Morgenstern, 2013). The response of a weakly nonlinear system to periodic input change(s) contains a periodic term, consisting of the basic and a number of higher harmonics, and a non-periodic (DC) component. The value and sign of the DC component of the outlet  can be used as an indicator for the mean performance of the forced periodic operation, as it  gives insight whether and  to which extent improvements can be expected as a result of forced periodic modulation(s) of the input(s). Applying the NRF method, the non-periodic term can be efficiently estimated for modulation of  single or multiple inputs. To demonstrate the strength of the theoretical concept the model of an adiabatic CSTR was analyzed considering reactions of different orders. Estimates are provided for different frequencies of sinusoidal changes of the inlet composition, the total inlet flow-rate and the feed temperature. It will be shown that it is in particular attractive to perturb simultaneously two input variables using the optimal phase shift, which can be determined using our method (Nikolic et al., 2015). EXPERIMENTAL To validate the theoretical predictions we carried out experiments in a laboratory scale CSTR using hydrolysis of acetic anhydride as a test reaction. The performance of the reaction system was evaluated with respect to different objectives under various steady state conditions, including theoretically optimal ones, and for various types of single and binary input perturbations.",
journal = "American Institute of Chemical Engineers Annual Meeting (AIChE Annual Meeting), San Francisco, USA",
title = "Exploiting the Nonlinear Frequency Response Method to Evaluate the Potential of Forced Periodic Operation of Reactors",
url = "https://hdl.handle.net/21.15107/rcub_technorep_3177"
}

Petkovska, M., Nikolić, D., Felischak, M.,& Seidel-Morgenstern, A.. (2016). Exploiting the Nonlinear Frequency Response Method to Evaluate the Potential of Forced Periodic Operation of Reactors. in American Institute of Chemical Engineers Annual Meeting (AIChE Annual Meeting), San Francisco, USA.
https://hdl.handle.net/21.15107/rcub_technorep_3177

Petkovska M, Nikolić D, Felischak M, Seidel-Morgenstern A. Exploiting the Nonlinear Frequency Response Method to Evaluate the Potential of Forced Periodic Operation of Reactors. in American Institute of Chemical Engineers Annual Meeting (AIChE Annual Meeting), San Francisco, USA. 2016;.
https://hdl.handle.net/21.15107/rcub_technorep_3177 .

Petkovska, Menka, Nikolić, Daliborka, Felischak, Matthias, Seidel-Morgenstern, Andreas, "Exploiting the Nonlinear Frequency Response Method to Evaluate the Potential of Forced Periodic Operation of Reactors" in American Institute of Chemical Engineers Annual Meeting (AIChE Annual Meeting), San Francisco, USA (2016),
https://hdl.handle.net/21.15107/rcub_technorep_3177 .

TY  - JOUR
AU  - Nikolić-Paunić, Daliborka
AU  - Seidel-Morgenstern, Andreas
AU  - Petkovska, Menka
PY  - 2016
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3299
AB  - The nonlinear frequency response (NFR) method, which is an analytical, fast, and easy method for evaluating the performance of forced periodically operated chemical reactors, was used to investigate possible improvements to a nonisothermal continuous stirred tank reactor (CSTR) when inlet concentration and/or flow rate is periodically modulated. The product yield corresponding to periodic operation is defined, expressions for its estimation, based on the NFR method, are derived, and it is used to evaluate the performance improvements due to periodic operation. Part I considers the general nonisothermal case. In Part II, these results are applied to an adiabatic CSTR and used to evaluate possible improvements for the case of the hydrolysis reaction of acetic anhydride.
PB  - Wiley-VCH Verlag Gmbh, Weinheim
T2  - Chemical Engineering & Technology
T1  - Periodic Operation with Modulation of Inlet Concentration and Flow Rate Part I: Nonisothermal Continuous Stirred-Tank Reactor
EP  - 2028
IS  - 11
SP  - 2020
VL  - 39
DO  - 10.1002/ceat.201600185
ER  - 

@article{
author = "Nikolić-Paunić, Daliborka and Seidel-Morgenstern, Andreas and Petkovska, Menka",
year = "2016",
abstract = "The nonlinear frequency response (NFR) method, which is an analytical, fast, and easy method for evaluating the performance of forced periodically operated chemical reactors, was used to investigate possible improvements to a nonisothermal continuous stirred tank reactor (CSTR) when inlet concentration and/or flow rate is periodically modulated. The product yield corresponding to periodic operation is defined, expressions for its estimation, based on the NFR method, are derived, and it is used to evaluate the performance improvements due to periodic operation. Part I considers the general nonisothermal case. In Part II, these results are applied to an adiabatic CSTR and used to evaluate possible improvements for the case of the hydrolysis reaction of acetic anhydride.",
publisher = "Wiley-VCH Verlag Gmbh, Weinheim",
journal = "Chemical Engineering & Technology",
title = "Periodic Operation with Modulation of Inlet Concentration and Flow Rate Part I: Nonisothermal Continuous Stirred-Tank Reactor",
pages = "2028-2020",
number = "11",
volume = "39",
doi = "10.1002/ceat.201600185"
}

Nikolić-Paunić, D., Seidel-Morgenstern, A.,& Petkovska, M.. (2016). Periodic Operation with Modulation of Inlet Concentration and Flow Rate Part I: Nonisothermal Continuous Stirred-Tank Reactor. in Chemical Engineering & Technology
Wiley-VCH Verlag Gmbh, Weinheim., 39(11), 2020-2028.
https://doi.org/10.1002/ceat.201600185

Nikolić-Paunić D, Seidel-Morgenstern A, Petkovska M. Periodic Operation with Modulation of Inlet Concentration and Flow Rate Part I: Nonisothermal Continuous Stirred-Tank Reactor. in Chemical Engineering & Technology. 2016;39(11):2020-2028.
doi:10.1002/ceat.201600185 .

Nikolić-Paunić, Daliborka, Seidel-Morgenstern, Andreas, Petkovska, Menka, "Periodic Operation with Modulation of Inlet Concentration and Flow Rate Part I: Nonisothermal Continuous Stirred-Tank Reactor" in Chemical Engineering & Technology, 39, no. 11 (2016):2020-2028,
https://doi.org/10.1002/ceat.201600185 . .

TY  - CONF
AU  - Petkovska, Menka
AU  - Nikolić, Daliborka
AU  - Felischak, Matthias
AU  - Seidel-Morgenstern, Andreas
PY  - 2016
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3185
AB  - Forced periodic operation of chemical reactors possess significant potential to improve numerous performance criteria. The corresponding analysis of reaction systems and the estimation of the magnitude of possible performance improvements have occupied many researchers since the earlier explorations by Douglas and Rippin (1966), Horn and Lin (1967) and Bailey (1973). Theoretical problems related to identification and estimation of enhancement were typically analyzed evaluating suitable control criteria applying four major approaches described by Watanabe et al. (1981) and Parulekar (2003). However, there are hardly industrial applications of the promising concept and there is still a need in generally applicable methods for identifying and analyzing promising reaction systems.   New Approach  We suggest applying the nonlinear frequency response (NFR) method to predict the outcome of perturbing periodically one or several input variables. Applying the concept of higher order frequency response functions (FRFs) weakly nonlinear systems can be described analytically (Petkovska and Seidel-Morgenstern, 2013). Those systems contain a harmonic and a non-periodic (DC) term. As an indicator for the mean performance of the forced periodic operation the value and sign of the DC component of the outlet give insight up to which extent improvements can be expected by the forced input changes. Applying the NRF method the non-periodic term can be efficiently estimated for the modulation of a single input and also for multiple inputs. To demonstrate the strength of the theoretical concept the model of an adiabatic CSTR was analyzed considering reactions of different order. Estimates are provided for different frequencies of sinusoidal changes of the inlet composition, the total inlet flow and the feed temperature. It will be shown, that it is in particular attractive to perturb simultaneously two input variables using an optimal phase shift, which can be determined using our method (Nikolic et al., 2015).   Experimental  To validate theoretical predictions we carried out experiments in a laboratory scale CSTR considering the hydrolysis of acetic anhydride as a test reaction. The performance of the reaction system was evaluated with respect to different objectives under various steady state conditions, including theoretically optimal ones,  and for various types of single and binary input perturbations.
C3  - German reaction Engineering Meeting (DECHEMA), Wuerzburg, Germany
T1  - Exploiting the Nonlinear Frequency Response Method to Evaluate the Potential of Forced Periodic Operation of Reactors
UR  - https://hdl.handle.net/21.15107/rcub_technorep_3185
ER  - 

@conference{
author = "Petkovska, Menka and Nikolić, Daliborka and Felischak, Matthias and Seidel-Morgenstern, Andreas",
year = "2016",
abstract = "Forced periodic operation of chemical reactors possess significant potential to improve numerous performance criteria. The corresponding analysis of reaction systems and the estimation of the magnitude of possible performance improvements have occupied many researchers since the earlier explorations by Douglas and Rippin (1966), Horn and Lin (1967) and Bailey (1973). Theoretical problems related to identification and estimation of enhancement were typically analyzed evaluating suitable control criteria applying four major approaches described by Watanabe et al. (1981) and Parulekar (2003). However, there are hardly industrial applications of the promising concept and there is still a need in generally applicable methods for identifying and analyzing promising reaction systems.   New Approach  We suggest applying the nonlinear frequency response (NFR) method to predict the outcome of perturbing periodically one or several input variables. Applying the concept of higher order frequency response functions (FRFs) weakly nonlinear systems can be described analytically (Petkovska and Seidel-Morgenstern, 2013). Those systems contain a harmonic and a non-periodic (DC) term. As an indicator for the mean performance of the forced periodic operation the value and sign of the DC component of the outlet give insight up to which extent improvements can be expected by the forced input changes. Applying the NRF method the non-periodic term can be efficiently estimated for the modulation of a single input and also for multiple inputs. To demonstrate the strength of the theoretical concept the model of an adiabatic CSTR was analyzed considering reactions of different order. Estimates are provided for different frequencies of sinusoidal changes of the inlet composition, the total inlet flow and the feed temperature. It will be shown, that it is in particular attractive to perturb simultaneously two input variables using an optimal phase shift, which can be determined using our method (Nikolic et al., 2015).   Experimental  To validate theoretical predictions we carried out experiments in a laboratory scale CSTR considering the hydrolysis of acetic anhydride as a test reaction. The performance of the reaction system was evaluated with respect to different objectives under various steady state conditions, including theoretically optimal ones,  and for various types of single and binary input perturbations.",
journal = "German reaction Engineering Meeting (DECHEMA), Wuerzburg, Germany",
title = "Exploiting the Nonlinear Frequency Response Method to Evaluate the Potential of Forced Periodic Operation of Reactors",
url = "https://hdl.handle.net/21.15107/rcub_technorep_3185"
}

Petkovska, M., Nikolić, D., Felischak, M.,& Seidel-Morgenstern, A.. (2016). Exploiting the Nonlinear Frequency Response Method to Evaluate the Potential of Forced Periodic Operation of Reactors. in German reaction Engineering Meeting (DECHEMA), Wuerzburg, Germany.
https://hdl.handle.net/21.15107/rcub_technorep_3185

Petkovska M, Nikolić D, Felischak M, Seidel-Morgenstern A. Exploiting the Nonlinear Frequency Response Method to Evaluate the Potential of Forced Periodic Operation of Reactors. in German reaction Engineering Meeting (DECHEMA), Wuerzburg, Germany. 2016;.
https://hdl.handle.net/21.15107/rcub_technorep_3185 .

Petkovska, Menka, Nikolić, Daliborka, Felischak, Matthias, Seidel-Morgenstern, Andreas, "Exploiting the Nonlinear Frequency Response Method to Evaluate the Potential of Forced Periodic Operation of Reactors" in German reaction Engineering Meeting (DECHEMA), Wuerzburg, Germany (2016),
https://hdl.handle.net/21.15107/rcub_technorep_3185 .

TY  - JOUR
AU  - Nikolić-Paunić, Daliborka
AU  - Felischak, Matthias
AU  - Seidel-Morgenstern, Andreas
AU  - Petkovska, Menka
PY  - 2016
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3308
AB  - The nonlinear frequency response (NFR) method, which is an analytical, fast, and easy method for evaluating the performance of forced periodically operated chemical reactors, was used to investigate possible improvements to a nonisothermal continuous stirred-tank reactor (CSTR) when inlet concentration and/or flow rate are periodically modulated. The product yield was used for evaluating the performance improvements. Part I of this paper considered the general nonisothermal case. In this part, the results are applied to an adiabatic CSTR. A laboratory-scale adiabatic CSTR was analyzed by applying kinetic parameters for the hydrolysis of acetic anhydride. It is shown that improvement can be obtained for simultaneous modulation of the two inputs with appropriately chosen forcing parameters.
PB  - Wiley-VCH Verlag Gmbh, Weinheim
T2  - Chemical Engineering & Technology
T1  - Periodic Operation with Modulation of Inlet Concentration and Flow Rate Part II: Adiabatic Continuous Stirred-Tank Reactor
EP  - 2134
IS  - 11
SP  - 2126
VL  - 39
DO  - 10.1002/ceat.201600187
ER  - 

@article{
author = "Nikolić-Paunić, Daliborka and Felischak, Matthias and Seidel-Morgenstern, Andreas and Petkovska, Menka",
year = "2016",
abstract = "The nonlinear frequency response (NFR) method, which is an analytical, fast, and easy method for evaluating the performance of forced periodically operated chemical reactors, was used to investigate possible improvements to a nonisothermal continuous stirred-tank reactor (CSTR) when inlet concentration and/or flow rate are periodically modulated. The product yield was used for evaluating the performance improvements. Part I of this paper considered the general nonisothermal case. In this part, the results are applied to an adiabatic CSTR. A laboratory-scale adiabatic CSTR was analyzed by applying kinetic parameters for the hydrolysis of acetic anhydride. It is shown that improvement can be obtained for simultaneous modulation of the two inputs with appropriately chosen forcing parameters.",
publisher = "Wiley-VCH Verlag Gmbh, Weinheim",
journal = "Chemical Engineering & Technology",
title = "Periodic Operation with Modulation of Inlet Concentration and Flow Rate Part II: Adiabatic Continuous Stirred-Tank Reactor",
pages = "2134-2126",
number = "11",
volume = "39",
doi = "10.1002/ceat.201600187"
}

Nikolić-Paunić, D., Felischak, M., Seidel-Morgenstern, A.,& Petkovska, M.. (2016). Periodic Operation with Modulation of Inlet Concentration and Flow Rate Part II: Adiabatic Continuous Stirred-Tank Reactor. in Chemical Engineering & Technology
Wiley-VCH Verlag Gmbh, Weinheim., 39(11), 2126-2134.
https://doi.org/10.1002/ceat.201600187

Nikolić-Paunić D, Felischak M, Seidel-Morgenstern A, Petkovska M. Periodic Operation with Modulation of Inlet Concentration and Flow Rate Part II: Adiabatic Continuous Stirred-Tank Reactor. in Chemical Engineering & Technology. 2016;39(11):2126-2134.
doi:10.1002/ceat.201600187 .

Nikolić-Paunić, Daliborka, Felischak, Matthias, Seidel-Morgenstern, Andreas, Petkovska, Menka, "Periodic Operation with Modulation of Inlet Concentration and Flow Rate Part II: Adiabatic Continuous Stirred-Tank Reactor" in Chemical Engineering & Technology, 39, no. 11 (2016):2126-2134,
https://doi.org/10.1002/ceat.201600187 . .

TY  - CONF
AU  - Felischak, Matthias
AU  - Nikolić, Daliborka
AU  - Petkovska, Menka
AU  - Christof, Hamel
AU  - Seidel-Morgenstern, Andreas
PY  - 2016
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3183
AB  - The method of nonlinear frequency response (NFR) attempts to predict the outcome of perturbation for the instructive input variables using nonlinear functions within the model equations. The aim of the derived models is the estimation of optimal frequencies and amplitudes for sinusoidal changes of the total inlet flow, concentration, temperature and the cooling temperature, as well as combinations of several of these inputs. As a model reaction the hydrolysis of acetic anhydride in a continuously stirred tank reactor (CSTR) has been chosen. This exothermal reaction is investigated for the cases of separately and simultaneously modulated inlet concentrations and feed flow rates. For the experimental validation of predicted model-based results at first a verification and adjustment of the kinetic parameters is performed. Based on these results an optimal steady-state is calculated, which is used as an initial state of periodic operations. To estimate the performance of the reaction system mean values of the conversion of acetic anhydride and the yield of acetic acid are compared to the corresponding steady-state values of the reactor. Different forcing frequencies, input amplitudes and, for multiple input parameter, phase shift between them are investigated. The theoretical foundation as well as systematic exploration of the experimental possibilities will be presented.
C3  - 22nd International Congress of Chemical and Process Engineering (CHISA 2016), Prague, Czech Republic
T1  - Evaluation of nonlinear frequency response method for the hydrolysis of acetic anhydride
UR  - https://hdl.handle.net/21.15107/rcub_technorep_3183
ER  - 

@conference{
author = "Felischak, Matthias and Nikolić, Daliborka and Petkovska, Menka and Christof, Hamel and Seidel-Morgenstern, Andreas",
year = "2016",
abstract = "The method of nonlinear frequency response (NFR) attempts to predict the outcome of perturbation for the instructive input variables using nonlinear functions within the model equations. The aim of the derived models is the estimation of optimal frequencies and amplitudes for sinusoidal changes of the total inlet flow, concentration, temperature and the cooling temperature, as well as combinations of several of these inputs. As a model reaction the hydrolysis of acetic anhydride in a continuously stirred tank reactor (CSTR) has been chosen. This exothermal reaction is investigated for the cases of separately and simultaneously modulated inlet concentrations and feed flow rates. For the experimental validation of predicted model-based results at first a verification and adjustment of the kinetic parameters is performed. Based on these results an optimal steady-state is calculated, which is used as an initial state of periodic operations. To estimate the performance of the reaction system mean values of the conversion of acetic anhydride and the yield of acetic acid are compared to the corresponding steady-state values of the reactor. Different forcing frequencies, input amplitudes and, for multiple input parameter, phase shift between them are investigated. The theoretical foundation as well as systematic exploration of the experimental possibilities will be presented.",
journal = "22nd International Congress of Chemical and Process Engineering (CHISA 2016), Prague, Czech Republic",
title = "Evaluation of nonlinear frequency response method for the hydrolysis of acetic anhydride",
url = "https://hdl.handle.net/21.15107/rcub_technorep_3183"
}

Felischak, M., Nikolić, D., Petkovska, M., Christof, H.,& Seidel-Morgenstern, A.. (2016). Evaluation of nonlinear frequency response method for the hydrolysis of acetic anhydride. in 22nd International Congress of Chemical and Process Engineering (CHISA 2016), Prague, Czech Republic.
https://hdl.handle.net/21.15107/rcub_technorep_3183

Felischak M, Nikolić D, Petkovska M, Christof H, Seidel-Morgenstern A. Evaluation of nonlinear frequency response method for the hydrolysis of acetic anhydride. in 22nd International Congress of Chemical and Process Engineering (CHISA 2016), Prague, Czech Republic. 2016;.
https://hdl.handle.net/21.15107/rcub_technorep_3183 .

Felischak, Matthias, Nikolić, Daliborka, Petkovska, Menka, Christof, Hamel, Seidel-Morgenstern, Andreas, "Evaluation of nonlinear frequency response method for the hydrolysis of acetic anhydride" in 22nd International Congress of Chemical and Process Engineering (CHISA 2016), Prague, Czech Republic (2016),
https://hdl.handle.net/21.15107/rcub_technorep_3183 .

TY  - JOUR
AU  - Nikolić-Paunić, Daliborka
AU  - Seidel-Morgenstern, Andreas
AU  - Petkovska, Menka
PY  - 2015
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3144
AB  - The nonlinear frequency response (NFR) method is applied for evaluation of possible improvement through simultaneous periodic modulation of two inputs of a non-isothermal continuously stirred tank reactor (CSTR) in which homogeneous nth order reaction A - gt  product(s) takes place. The two modulated inputs are the concentration of the reactant in the feed steam and the temperature of the feed stream. The cross asymmetrical second order FRF which correlates the outlet concentration with both modulated inputs is derived and analyzed. The optimal phase difference which should be used in order to maximize the conversion is determined. The method is tested on three numerical examples of non-isothermal CSTRs: (a) one which is oscillatory stable with strong resonant behavior, (b) one which is oscillatory stable with weak resonant behavior and
PB  - Pergamon-Elsevier Science Ltd, Oxford
T2  - Chemical Engineering Science
T1  - Nonlinear frequency response analysis of forced periodic operation of non-isothermal CSTR with simultaneous modulation of inlet concentration and inlet temperature
EP  - 58
SP  - 40
VL  - 137
DO  - 10.1016/j.ces.2015.06.018
ER  - 

@article{
author = "Nikolić-Paunić, Daliborka and Seidel-Morgenstern, Andreas and Petkovska, Menka",
year = "2015",
abstract = "The nonlinear frequency response (NFR) method is applied for evaluation of possible improvement through simultaneous periodic modulation of two inputs of a non-isothermal continuously stirred tank reactor (CSTR) in which homogeneous nth order reaction A - gt  product(s) takes place. The two modulated inputs are the concentration of the reactant in the feed steam and the temperature of the feed stream. The cross asymmetrical second order FRF which correlates the outlet concentration with both modulated inputs is derived and analyzed. The optimal phase difference which should be used in order to maximize the conversion is determined. The method is tested on three numerical examples of non-isothermal CSTRs: (a) one which is oscillatory stable with strong resonant behavior, (b) one which is oscillatory stable with weak resonant behavior and",
publisher = "Pergamon-Elsevier Science Ltd, Oxford",
journal = "Chemical Engineering Science",
title = "Nonlinear frequency response analysis of forced periodic operation of non-isothermal CSTR with simultaneous modulation of inlet concentration and inlet temperature",
pages = "58-40",
volume = "137",
doi = "10.1016/j.ces.2015.06.018"
}

Nikolić-Paunić, D., Seidel-Morgenstern, A.,& Petkovska, M.. (2015). Nonlinear frequency response analysis of forced periodic operation of non-isothermal CSTR with simultaneous modulation of inlet concentration and inlet temperature. in Chemical Engineering Science
Pergamon-Elsevier Science Ltd, Oxford., 137, 40-58.
https://doi.org/10.1016/j.ces.2015.06.018

Nikolić-Paunić D, Seidel-Morgenstern A, Petkovska M. Nonlinear frequency response analysis of forced periodic operation of non-isothermal CSTR with simultaneous modulation of inlet concentration and inlet temperature. in Chemical Engineering Science. 2015;137:40-58.
doi:10.1016/j.ces.2015.06.018 .

Nikolić-Paunić, Daliborka, Seidel-Morgenstern, Andreas, Petkovska, Menka, "Nonlinear frequency response analysis of forced periodic operation of non-isothermal CSTR with simultaneous modulation of inlet concentration and inlet temperature" in Chemical Engineering Science, 137 (2015):40-58,
https://doi.org/10.1016/j.ces.2015.06.018 . .

TY  - CONF
AU  - Nikolić, Daliborka
AU  - Seidel-Morgenstern, Andreas
AU  - Petkovska, Menka
PY  - 2015
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/2874
AB  - Possible improvements of chemical reactor performance through periodic modulation of one or more inputs have been investigated for several decades. In our previous investigations we have introduced the nonlinear frequency response (NFR) method, as a fast and easy, analytical method for evaluating the performance of forced periodically operated chemical reactors, which is based on nonlinear frequency response analysis and the concept of higher order frequency response function (FRFs).[1] The method gives an answer whether, and in which cases, it is possible to obtain process improvement through periodic operation and gives an approximate quantitative estimate of the improvement. For the case of multiple input modulations, it also gives the value of the optimal phase shift between the modulated inputs which maximizes the improvement, which, in principle, depends on the forcing frequency [2]. 	In this work, the NFR method is used for evaluation of forced periodically operated isothermal and non-isothermal CSTRs with simple reaction mechanism A→P, for simultaneous modulation of the inlet concentration of the reactant and flow-rate. The second order asymmetrical FRFs, corresponding to the single input modulations of the inlet concentration and flow-rate, and the cross second order asymmetrical FRFs, corresponding to simultaneous modulation of both inputs, are derived and analyzed.  	In principle, the reactor performance can be evaluated through reactant conversion and/or product yield. For steady-state operations and simple reactions, these two performance criteria are equal. It can easily be shown that the same is valid for periodic operations with modulations of single inputs. Nevertheless, for the case of simultaneous modulation of the inlet concentration of the reactant and flow rate, an unexpected result is obtained that the changes of the reactant conversion and product yield differ. This difference is most significant at high frequencies and becomes negligible at low frequencies. As a consequence, the optimal phase difference that maximizes the reactant conversion is different from the one that maximizes the product yield.  	The expression for this difference is derived from the cross asymmetrical second order FRFs and it depends only on the forcing parameters (input amplitudes, forcing frequency and the phase difference between the modulated inputs). It is important to notice that this expression is the same, both for the isothermal and non-isothermal CSTR. 	These results are illustrated on two numerical examples of periodic operations of an isothermal and a non-isothermal CSTR around their optimal steady-states. The results were also proven by numerical integration of the model equations.
C3  - 10th European Congress of Chemical Engineering (ECCE 10), Nice, France
T1  - Periodically operated CSTRs with simultaneous modulation of feed concentration and flow-rate- Nonlinear frequency response approach
UR  - https://hdl.handle.net/21.15107/rcub_technorep_2874
ER  - 

@conference{
author = "Nikolić, Daliborka and Seidel-Morgenstern, Andreas and Petkovska, Menka",
year = "2015",
abstract = "Possible improvements of chemical reactor performance through periodic modulation of one or more inputs have been investigated for several decades. In our previous investigations we have introduced the nonlinear frequency response (NFR) method, as a fast and easy, analytical method for evaluating the performance of forced periodically operated chemical reactors, which is based on nonlinear frequency response analysis and the concept of higher order frequency response function (FRFs).[1] The method gives an answer whether, and in which cases, it is possible to obtain process improvement through periodic operation and gives an approximate quantitative estimate of the improvement. For the case of multiple input modulations, it also gives the value of the optimal phase shift between the modulated inputs which maximizes the improvement, which, in principle, depends on the forcing frequency [2]. 	In this work, the NFR method is used for evaluation of forced periodically operated isothermal and non-isothermal CSTRs with simple reaction mechanism A→P, for simultaneous modulation of the inlet concentration of the reactant and flow-rate. The second order asymmetrical FRFs, corresponding to the single input modulations of the inlet concentration and flow-rate, and the cross second order asymmetrical FRFs, corresponding to simultaneous modulation of both inputs, are derived and analyzed.  	In principle, the reactor performance can be evaluated through reactant conversion and/or product yield. For steady-state operations and simple reactions, these two performance criteria are equal. It can easily be shown that the same is valid for periodic operations with modulations of single inputs. Nevertheless, for the case of simultaneous modulation of the inlet concentration of the reactant and flow rate, an unexpected result is obtained that the changes of the reactant conversion and product yield differ. This difference is most significant at high frequencies and becomes negligible at low frequencies. As a consequence, the optimal phase difference that maximizes the reactant conversion is different from the one that maximizes the product yield.  	The expression for this difference is derived from the cross asymmetrical second order FRFs and it depends only on the forcing parameters (input amplitudes, forcing frequency and the phase difference between the modulated inputs). It is important to notice that this expression is the same, both for the isothermal and non-isothermal CSTR. 	These results are illustrated on two numerical examples of periodic operations of an isothermal and a non-isothermal CSTR around their optimal steady-states. The results were also proven by numerical integration of the model equations.",
journal = "10th European Congress of Chemical Engineering (ECCE 10), Nice, France",
title = "Periodically operated CSTRs with simultaneous modulation of feed concentration and flow-rate- Nonlinear frequency response approach",
url = "https://hdl.handle.net/21.15107/rcub_technorep_2874"
}

Nikolić, D., Seidel-Morgenstern, A.,& Petkovska, M.. (2015). Periodically operated CSTRs with simultaneous modulation of feed concentration and flow-rate- Nonlinear frequency response approach. in 10th European Congress of Chemical Engineering (ECCE 10), Nice, France.
https://hdl.handle.net/21.15107/rcub_technorep_2874

Nikolić D, Seidel-Morgenstern A, Petkovska M. Periodically operated CSTRs with simultaneous modulation of feed concentration and flow-rate- Nonlinear frequency response approach. in 10th European Congress of Chemical Engineering (ECCE 10), Nice, France. 2015;.
https://hdl.handle.net/21.15107/rcub_technorep_2874 .

Nikolić, Daliborka, Seidel-Morgenstern, Andreas, Petkovska, Menka, "Periodically operated CSTRs with simultaneous modulation of feed concentration and flow-rate- Nonlinear frequency response approach" in 10th European Congress of Chemical Engineering (ECCE 10), Nice, France (2015),
https://hdl.handle.net/21.15107/rcub_technorep_2874 .