Image Processing and Measurement of the Bubble Properties in a Bubbling Fluidized Bed Reactor
The efficiency of a fluidized bed reactor depends on the bed fluid dynamic behavior, which is significantly influenced by the bubble properties. This work investigates the bubble properties of a bubbling fluidized bed reactor using computational particle fluid dynamic (CPFD) simulations and electric...
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MDPI AG
2022-10-01
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| Series: | Energies |
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| Online Access: | https://www.mdpi.com/1996-1073/15/21/7828 |
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| author | Rajan Jaiswal Britt. M. E. Moldestad Marianne S. Eikeland Henrik K. Nielsen Rajan Kumar Thapa |
| author_facet | Rajan Jaiswal Britt. M. E. Moldestad Marianne S. Eikeland Henrik K. Nielsen Rajan Kumar Thapa |
| author_sort | Rajan Jaiswal |
| collection | DOAJ |
| description | The efficiency of a fluidized bed reactor depends on the bed fluid dynamic behavior, which is significantly influenced by the bubble properties. This work investigates the bubble properties of a bubbling fluidized bed reactor using computational particle fluid dynamic (CPFD) simulations and electrical capacitance tomography (ECT) measurements. The two-dimensional images (along the reactor horizontal and vertical planes) of the fluidized bed are obtained from the CPFD simulations at different operating conditions. The CPFD model was developed in a commercial CPFD software Barracuda Virtual Reactor 20.0.1. The bubble behavior and bed fluidization behavior are characterized form the bubble properties: average bubble diameter, bubble rise velocity, and bubble frequency. The bubble properties were determined by processing the extracted images with script developed in MATLAB. The CPFD simulation results are compared with experimental data (obtained from the ECT sensors) and correlations in the literature. The results from the CPFD model and experimental measurement depicted that the average bubble diameter increased with an increase in superficial gas velocities up to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>4.2</mn><mo> </mo><msub><mi>U</mi><mrow><mi>m</mi><mi>f</mi></mrow></msub></mrow></semantics></math></inline-formula> and decreased with a further increase in gas velocities due to the onset of large bubbles (potential slugging regime). The bubble rise velocity increased as it moved from the lower region to the bed surface. The Fourier transform of the transient solid volume fraction illustrated that multiple bubbles pass the plane with varying amplitude and frequency in the range of 1–6 Hz. Further, the bubble frequency increased with an increase in superficial gas velocity up to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>2.5</mn><msub><mi>U</mi><mrow><mi>m</mi><mi>f</mi></mrow></msub></mrow></semantics></math></inline-formula> and decreased with a further increase in gas velocity. The CPFD model and method employed in this work can be useful for studying the influence of bubble properties on conversion efficiency of a gasification reactor operating at high temperatures. |
| first_indexed | 2024-03-09T19:07:10Z |
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| id | doaj.art-23a0f881e5c34bf08df7e13efc0cad79 |
| institution | Directory Open Access Journal |
| issn | 1996-1073 |
| language | English |
| last_indexed | 2024-03-09T19:07:10Z |
| publishDate | 2022-10-01 |
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| series | Energies |
| spelling | doaj.art-23a0f881e5c34bf08df7e13efc0cad792023-11-24T04:27:17ZengMDPI AGEnergies1996-10732022-10-011521782810.3390/en15217828Image Processing and Measurement of the Bubble Properties in a Bubbling Fluidized Bed ReactorRajan Jaiswal0Britt. M. E. Moldestad1Marianne S. Eikeland2Henrik K. Nielsen3Rajan Kumar Thapa4Department of Process, Energy and Environmental Technology, Faculty of Technology, Natural Sciences and Maritime Sciences, Campus Porsgrunn, University of South-Eastern Norway, Kjølnes 56, 3918 Porsgrunn, NorwayDepartment of Process, Energy and Environmental Technology, Faculty of Technology, Natural Sciences and Maritime Sciences, Campus Porsgrunn, University of South-Eastern Norway, Kjølnes 56, 3918 Porsgrunn, NorwayDepartment of Process, Energy and Environmental Technology, Faculty of Technology, Natural Sciences and Maritime Sciences, Campus Porsgrunn, University of South-Eastern Norway, Kjølnes 56, 3918 Porsgrunn, NorwayDepartment of engineering sciences, Faculty of engineering and science, University of Agder, Jon Lilletuns vei 9, 4879 Grimstad, NorwayDepartment of Process, Energy and Environmental Technology, Faculty of Technology, Natural Sciences and Maritime Sciences, Campus Porsgrunn, University of South-Eastern Norway, Kjølnes 56, 3918 Porsgrunn, NorwayThe efficiency of a fluidized bed reactor depends on the bed fluid dynamic behavior, which is significantly influenced by the bubble properties. This work investigates the bubble properties of a bubbling fluidized bed reactor using computational particle fluid dynamic (CPFD) simulations and electrical capacitance tomography (ECT) measurements. The two-dimensional images (along the reactor horizontal and vertical planes) of the fluidized bed are obtained from the CPFD simulations at different operating conditions. The CPFD model was developed in a commercial CPFD software Barracuda Virtual Reactor 20.0.1. The bubble behavior and bed fluidization behavior are characterized form the bubble properties: average bubble diameter, bubble rise velocity, and bubble frequency. The bubble properties were determined by processing the extracted images with script developed in MATLAB. The CPFD simulation results are compared with experimental data (obtained from the ECT sensors) and correlations in the literature. The results from the CPFD model and experimental measurement depicted that the average bubble diameter increased with an increase in superficial gas velocities up to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>4.2</mn><mo> </mo><msub><mi>U</mi><mrow><mi>m</mi><mi>f</mi></mrow></msub></mrow></semantics></math></inline-formula> and decreased with a further increase in gas velocities due to the onset of large bubbles (potential slugging regime). The bubble rise velocity increased as it moved from the lower region to the bed surface. The Fourier transform of the transient solid volume fraction illustrated that multiple bubbles pass the plane with varying amplitude and frequency in the range of 1–6 Hz. Further, the bubble frequency increased with an increase in superficial gas velocity up to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>2.5</mn><msub><mi>U</mi><mrow><mi>m</mi><mi>f</mi></mrow></msub></mrow></semantics></math></inline-formula> and decreased with a further increase in gas velocity. The CPFD model and method employed in this work can be useful for studying the influence of bubble properties on conversion efficiency of a gasification reactor operating at high temperatures.https://www.mdpi.com/1996-1073/15/21/7828fluidized bedbubble diameterbubble rise velocitybubble frequencycomputational particle fluid dynamicimage processing |
| spellingShingle | Rajan Jaiswal Britt. M. E. Moldestad Marianne S. Eikeland Henrik K. Nielsen Rajan Kumar Thapa Image Processing and Measurement of the Bubble Properties in a Bubbling Fluidized Bed Reactor Energies fluidized bed bubble diameter bubble rise velocity bubble frequency computational particle fluid dynamic image processing |
| title | Image Processing and Measurement of the Bubble Properties in a Bubbling Fluidized Bed Reactor |
| title_full | Image Processing and Measurement of the Bubble Properties in a Bubbling Fluidized Bed Reactor |
| title_fullStr | Image Processing and Measurement of the Bubble Properties in a Bubbling Fluidized Bed Reactor |
| title_full_unstemmed | Image Processing and Measurement of the Bubble Properties in a Bubbling Fluidized Bed Reactor |
| title_short | Image Processing and Measurement of the Bubble Properties in a Bubbling Fluidized Bed Reactor |
| title_sort | image processing and measurement of the bubble properties in a bubbling fluidized bed reactor |
| topic | fluidized bed bubble diameter bubble rise velocity bubble frequency computational particle fluid dynamic image processing |
| url | https://www.mdpi.com/1996-1073/15/21/7828 |
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