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Author Maerivoet, S.; Tsonev, I.; Slaets, J.; Reniers, F.; Bogaerts, A.
Title (up) Coupled multi-dimensional modelling of warm plasmas: Application and validation for an atmospheric pressure glow discharge in CO2/CH4/O2 Type A1 Journal Article
Year 2024 Publication Chemical Engineering Journal Abbreviated Journal Chemical Engineering Journal
Volume 492 Issue Pages 152006
Keywords A1 Journal Article; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;
Abstract To support experimental research into gas conversion by warm plasmas, models should be developed to explain the experimental observations. These models need to describe all physical and chemical plasma properties in a coupled way. In this paper, we present a modelling approach to solve the complete set of assumed relevant equations, including gas flow, heat balance and species transport, coupled with a rather extensive chemistry set, consisting of 21 species, obtained by reduction of a more detailed chemistry set, consisting of 41 species. We apply this model to study the combined CO2 and CH4 conversion in the presence of O2, in a direct current atmospheric pressure glow discharge. Our model can predict the experimental trends, and can explain why higher O2 fractions result in higher CH4 conversion, namely due to the higher gas temperature, rather than just by additional chemical reactions. Indeed, our model predicts that when more O2 is added, the energy required to reach any set temperature (i.e., the enthalpy) drops, allowing the system to reach higher temperatures with similar amounts of energy. This is in turn related to the higher H2O fraction and lower H2 fraction formed in the plasma, as demonstrated by our model. Altogether, our new self-consistent model can capture the main physics and chemistry occurring in this warm plasma, which is an important step towards predictive modelling for plasma-based gas conversion.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos Publication Date 2024-05-09
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1385-8947 ISBN Additional Links
Impact Factor 15.1 Times cited Open Access
Notes This research was supported by the Excellence of Science FWO-FNRS project (FWO grant ID G0I1822N; EOS ID 40007511) and the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 810182–SCOPE ERC Synergy project, and grant agreement No. 101081162–PREPARE ERC Proof of Concept project). computational resources and services used in this work were provided by the HPC core facility CalcUA of the Universiteit Antwerpen, and VSC (Flemish Supercomputer Center), funded by the Research Foundation – Flanders (FWO) and the Flemish Government. Approved Most recent IF: 15.1; 2024 IF: 6.216
Call Number PLASMANT @ plasmant @ Serial 9132
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Author Tsonev, I.; Ahmadi Eshtehardi, H.; Delplancke, M.-P.; Bogaerts, A.
Title (up) Importance of geometric effects in scaling up energy-efficient plasma-based nitrogen fixation Type A1 Journal article
Year 2024 Publication Sustainable energy & fuels Abbreviated Journal
Volume Issue Pages 1-19
Keywords A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Despite the recent promising potential of plasma-based nitrogen fixation, the technology faces significant challenges in efficient upscaling. To tackle this challenge, we investigate two reactors, i.e., a small one, operating in a flow rate range of 5-20 ln min-1 and current range of 200-500 mA, and a larger one, operating at higher flow rate (100-300 ln min-1) and current (400-1000 mA). Both reactors operate in a pin-to-pin configuration and are powered by direct current (DC) from the same power supply unit, to allow easy comparison and evaluate the effect of upscaling. In the small reactor, we achieve the lowest energy cost (EC) of 2.8 MJ mol-1, for a NOx concentration of 1.72%, at a flow rate of 20 ln min-1, yielding a production rate (PR) of 33 g h-1. These values are obtained in air; in oxygen-enriched air, the results are typically better, at the cost of producing oxygen-enriched air. In the large reactor, the higher flow rates reduce the NOx concentration due to lower SEI, while maintaining a similar EC. This stresses the important effect of the geometrical configuration of the arc, which is typically concentrated in the center of the reactor, resulting in limited coverage of the reacting gas flow, and this is identified as the limiting factor for upscaling. However, our experiments reveal that by changing the reactor configuration, and thus the plasma geometry and power deposition mechanisms, the amount of gas treated by the plasma can be enhanced, leading to successful upscaling. To obtain more insights in our experiments, we performed thermodynamic equilibrium calculations. First of all, they show that our measured lowest EC closely aligns with the calculated minimum thermodynamic equilibrium at atmospheric pressure. In addition, they reveal that the limited NOx production in the large reactor results from the contracted nature of the plasma. To solve this limitation, we let the large reactor operate in so-called torch configuration. Indeed, the latter enhances the NOx concentrations compared to the pin-to-pin configuration, yielding a PR of 80 g h-1 at an EC of 2.9 MJ mol-1 and NOx concentration of 0.31%. This illustrates the importance of reactor design in upscaling. With the focus on feasibility evaluation of scaling-up plasma-based nitrogen fixation by combined experiments and thermodynamic modelling, we aim to tackle the challenge of design and development of an energy-efficient and scaled-up plasma reactor.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 001203657700001 Publication Date 2024-04-11
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Additional Links UA library record; WoS full record
Impact Factor Times cited Open Access
Notes Approved no
Call Number UA @ admin @ c:irua:205435 Serial 9155
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Author Wang, K.; Ceulemans, S.; Zhang, H.; Tsonev, I.; Zhang, Y.; Long, Y.; Fang, M.; Li, X.; Yan, J.; Bogaerts, A.
Title (up) Inhibiting recombination to improve the performance of plasma-based CO2 conversion Type A1 Journal Article
Year 2024 Publication Chemical Engineering Journal Abbreviated Journal Chemical Engineering Journal
Volume 481 Issue Pages 148684
Keywords A1 Journal Article; Plasma-based CO2 splitting Recombination reactions In-situ gas sampling Fluid dynamics modeling Kinetics modeling Afterglow quenching; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;
Abstract Warm plasma offers a promising route for CO2 splitting into valuable CO, yet recombination reactions of CO with oxygen, forming again CO2, have recently emerged as critical limitation. This study combines experiments and fluid dynamics + chemical kinetics modelling to comprehensively analyse the recombination reactions upon CO2 splitting in an atmospheric plasmatron. We introduce an innovative in-situ gas sampling technique, enabling 2D spatial mapping of gas product compositions and temperatures, experimentally confirming for the first time the substantial limiting effect of CO recombination reactions in the afterglow region. Our results show that the CO mole fraction at a 5 L/min flow rate drops significantly from 11.9 % at a vertical distance of z = 20 mm in the afterglow region to 8.6 % at z = 40 mm. We constructed a comprehensive 2D model that allows for spatial reaction rates analysis incorporating crucial reactions, and we validated it to kinetically elucidate this phenomenon. CO2 +M⇌O+CO+M and CO2 +O⇌CO+O2 are the dominant reactions, with the forward reactions prevailing in the plasma region and the backward reactions becoming prominent in the afterglow region. These results allow us to propose an afterglow quenching strategy for performance enhancement, which is further demonstrated through a meticulously developed plasmatron reactor with two-stage cooling. Our approach substantially increases the CO2 conversion (e.g., from 6.6 % to 19.5 % at 3 L/min flow rate) and energy efficiency (from 13.5 % to 28.5 %, again at 3 L/min) and significantly shortens the startup time (from ~ 150 s to 25 s). Our study underscores the critical role of inhibiting recombination reactions in plasma-based CO2 conversion and offers new avenues for performance enhancement.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 001168999200001 Publication Date 2024-01-10
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1385-8947 ISBN Additional Links UA library record; WoS full record
Impact Factor 15.1 Times cited Open Access Not_Open_Access
Notes Key Research and Development Program of Zhejiang Province, 2023C03129 ; Vlaamse regering; European Research Council; National Natural Science Foundation of China, 51976191 52276214 ; Horizon 2020 Framework Programme; Fonds De La Recherche Scientifique – FNRS; Fonds Wetenschappelijk Onderzoek, 1101524N ; Vlaams Supercomputer Centrum; Horizon 2020, 101081162 810182 ; European Research Council; Approved Most recent IF: 15.1; 2024 IF: 6.216
Call Number PLASMANT @ plasmant @c:irua:204352 Serial 8993
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Author Albrechts, M.; Tsonev, I.; Bogaerts, A.
Title (up) Investigation of O atom kinetics in O2plasma and its afterglow Type A1 Journal Article
Year 2024 Publication Plasma Sources Science and Technology Abbreviated Journal Plasma Sources Sci. Technol.
Volume 33 Issue 4 Pages 045017
Keywords A1 Journal Article; oxygen plasma, pseudo-1D plug-flow kinetic model, O atoms, low-pressure validation, atmospheric pressure microwave torch; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;
Abstract We have developed a comprehensive kinetic model to study the O atom kinetics in an O<sub>2</sub>plasma and its afterglow. By adopting a pseudo-1D plug-flow formalism within the kinetic model, our aim is to assess how far the O atoms travel in the plasma afterglow, evaluating its potential as a source of O atoms for post-plasma gas conversion applications. Since we could not find experimental data for pure O<sub>2</sub>plasma at atmospheric pressure, we first validated our model at low pressure (1–10 Torr) where very good experimental data are available. Good agreement between our model and experiments was achieved for the reduced electric field, gas temperature and the densities of the dominant neutral species, i.e. O<sub>2</sub>(a), O<sub>2</sub>(b) and O. Subsequently, we confirmed that the chemistry set is consistent with thermodynamic equilibrium calculations at atmospheric pressure. Finally, we investigated the O atom densities in the O<sub>2</sub>plasma and its afterglow, for which we considered a microwave O<sub>2</sub>plasma torch, operating at a pressure between 0.1 and 1 atm, for a flow rate of 20 slm and an specific energy input of 1656 kJ mol<sup>−1</sup>. Our results show that for both pressure conditions, a high dissociation degree of ca. 92% is reached within the discharge. However, the O atoms travel much further in the plasma afterglow for<italic>p</italic>= 0.1 atm (9.7 cm) than for<italic>p</italic>= 1 atm (1.4 cm), attributed to the longer lifetime (3.8 ms at 0.1 atm vs 1.8 ms at 1 atm) resulting from slower three-body recombination kinetics, as well as a higher volumetric flow rate.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 001209453500001 Publication Date 2024-04-01
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0963-0252 ISBN Additional Links UA library record; WoS full record
Impact Factor 3.8 Times cited Open Access
Notes This research was supported by the Horizon Europe Framework Program ‘Research and Innovation Actions’ (RIA), Project CANMILK (Grant No. 101069491). Approved Most recent IF: 3.8; 2024 IF: 3.302
Call Number PLASMANT @ plasmant @c:irua:205920 Serial 9125
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Author Tsonev, I.; O’Modhrain, C.; Bogaerts, A.; Gorbanev, Y.
Title (up) Nitrogen Fixation by an Arc Plasma at Elevated Pressure to Increase the Energy Efficiency and Production Rate of NOx Type A1 Journal article
Year 2023 Publication ACS Sustainable Chemistry and Engineering Abbreviated Journal
Volume 11 Issue 5 Pages 1888-1897
Keywords A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Plasma-based nitrogen fixation for fertilizer production is an attractive alternative to the fossil fuel-based industrial processes. However, many factors hinder its applicability, e.g., the commonly observed inverse correlation between energy consumption and production rates or the necessity to enhance the selectivity toward NO2, the desired product for a more facile formation of nitrate-based fertilizers. In this work, we investigated the use of a rotating gliding arc plasma for nitrogen fixation at elevated pressures (up to 3 barg), at different feed gas flow rates and composition. Our results demonstrate a dramatic increase in the amount of NOx produced as a function of increasing pressure, with a record-low EC of 1.8 MJ/(mol N) while yielding a high production rate of 69 g/h and a high selectivity (94%) of NO2. We ascribe this improvement to the enhanced thermal Zeldovich mechanism and an increased rate of NO oxidation compared to the back reaction of NO with atomic oxygen, due to the elevated pressure.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000924366700001 Publication Date 2023-02-06
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2168-0485 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 8.4 Times cited Open Access OpenAccess
Notes Fonds Wetenschappelijk Onderzoek, G0G2322N ; Horizon 2020 Framework Programme, 965546 ; Approved Most recent IF: 8.4; 2023 IF: 5.951
Call Number PLASMANT @ plasmant @c:irua:194281 Serial 7239
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Author Tsonev, I.; Boothroyd, J.; Kolev, S.; Bogaerts, A.
Title (up) Simulation of glow and arc discharges in nitrogen: effects of the cathode emission mechanisms Type A1 Journal Article
Year 2023 Publication PLASMA SOURCES SCIENCE & TECHNOLOGY Abbreviated Journal
Volume 32 Issue 5 Pages 054002
Keywords A1 Journal Article; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;
Abstract Experimental evidence in the literature has shown that low-current direct current nitrogen discharges can exist in both glow and arc regimes at atmospheric pressure. However, modelling investigations of the positive column that include the influence of the cathode phenomena are scarce. In this work we developed a 2D axisymmetric model of a plasma discharge in flowing nitrogen gas, studying the influence of the two cathode emission mechanisms—thermionic field emission and secondary electron emission—on the cathode region and the positive column. We show for an inlet gas flow velocity of 1 m s<sup>−1</sup>in the current range of 80–160 mA, that the electron emission mechanism from the cathode greatly affects the size and temperature of the cathode region, but does not significantly influence the discharge column at atmospheric pressure. We also demonstrate that in the discharge column the electron density balance is local and the electron production and destruction is dominated by volume processes. With increasing flow velocity, the discharge contraction is enhanced due to the increased convective heat loss. The cross sectional area of the conductive region is strongly dependent on the gas velocity and heat conductivity of the gas.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000987841800001 Publication Date 2023-05-01
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0963-0252 ISBN Additional Links UA library record; WoS full record
Impact Factor 3.8 Times cited Open Access Not_Open_Access
Notes This research is financially supported by the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No. 965546. Approved Most recent IF: 3.8; 2023 IF: 3.302
Call Number PLASMANT @ plasmant @c:irua:196972 Serial 8788
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