Hydrodynamic Predictions of the Ultralight Particle Dispersions in a Bubbling Fluidized Bed
Round 1
Reviewer 1 Report
The paper studies flow behaviors of particles in bubbling fluidized bed, and proposed a prediction method for describing particle dispersion. The topic is interesting to the field. However, the following points should be addressed before it can be accepted for publication in the journal.
1. How would the proposed prediction method be validated against sufficient experimental data?
2. What does the expected data mean in Figure 11? Are that the theoretical result?
3. What can be learnt from the granular temperature? How would the athour quantify the particle dispersion?
4. What would happen if particles with different sizes coexist in the bubbling fluidzed bed?
Author Response
Dear reviewers and editors,
We greatly appreciate your kind comment and help regarding this manuscript. We have carefully addressed all comments in the revised manuscript and the responses point-by-point are given as follows.
Comments of reviewers
Reviewer #1:
- How would the proposed prediction method be validated against sufficient experimental data?
Answer: In the Gera’s experiment and simulation, the quantitative data of particle hydrodynamics, i.e. particle velocity and fluctuation velocity have not been provided. They focus on the comparisons with particle voidage that simulated by TFM and DEM models using snapshots, as well as the experimental observations. Gera et al. compared TFM and DEM simulations and suggested that TFM based simulations are very sensitive to inter-particle friction, incorporated through solid pressure and viscosity, which might obscure observation of true bubbling characteristics of fluidized beds.
By analogue this methodology, the simulated profiles of particle voidage or porosity using the proposed gas-particle second-order moment two-fluid model was validated by Gera’s TFM simulation results in terms of the bubble topology observations. After that, the model, numerical algorithm, and in-house codes are used to predict the ultralight particles.
- What does the expected data mean in Figure 11? Are that the theoretical result?
Answer: The Q-Q(quantile-quantile) plots play an important role to compare the two probability distributions by plotting their quantiles against each other. If they are exactly equal, then the points on the Q-Q plot will perfectly lies on a straight-line y = x. In this figure, it was used to find the type of distribution for a random variable whether it be a Gaussian distribution. Y axis is the quantile of samples and X axis is the quantile of normal distributions. It was updated in the revised manuscript.
- What can be learnt from the granular temperature? How would the author quantify the particle dispersion?
Answer: Granular temperature is determined by the fluctuation velocity of particle, indicating the intensity of particle collisions. In this work, the parameters of distributions of particle velocity, fluctuation velocity, porosity, and granular temperature of particles are used to quantify the particle dispersions at the different heights of central and wall regions. Thus, particle dispersion behaviors are revealed and comparisons with those heavy particles are carried out as well.
- What would happen if particles with different sizes coexist in the bubbling fluidized bed?
Answer：If different sizes of particles exist together, the segregation and mixing characteristics should be occurred. Meanwhile, the model and governing equations should be improved for wider-sizes particles flows. Especially for the closure transportations regarding the interactions between gas and particle, particle-particle collisions. The hydrodynamics of single particle two-phase flow are significantly differently from the multi-particle phase flows.
----------------------------------------------------------------------------------------------------------------------------
Reviewer 2,
- Line 3: bubbling fluidized bed
Answer：It was corrected.
- Line 16: experimental particles -> particles used in experiments
Answer：All of them were updated.
- Line 25: The sentence needs to be improved from the grammatical point of view.
Answer：This sentence was improved.
- Line 29: It is noticeable that… The sentence needs to be improved from the grammatical point of view.
Answer：This sentence was improved.
- Line 35: fluidizations -> fluidization
Answer：It was corrected.
- Line 35: Particle dispersions …. are determined by the hydrodynamic bubbling fluidizations. Please explain this sentence.
Answer：It was updated.
- Line 43: circulated fluid bed -> circulating fluidized bed
Answer：It was corrected.
- Line 41-46: It is quite difficult to agree with this sentence. In fact, there are numerous experimental studies devoted to turbulent mixing and diffusion as well as interaction between gas and particle phases.
Answer: They were corrected.
- Line 51: FOP cannot be used to measure particle size distribution. Resolution of this method is simply too low. PSD can be successfully measured utilizing laser diffraction devices.
Answer：This discussion regarding FOP was corrected according to review’s suggestion.
- Line 53: As examples of the use of non-invasive measurement methods, the authors give only optical methods, the basic limitation of which is the concentration of particles. These methods are rarely used for dense beds (for example bubbling). Please note that there are a large number of publications where column static pressure measurements were used to study the hydrodynamics of bubbling and circulating beds. Many of them deserve quotation. Some of them are listed below:
- Köhler, D. Pallarès, and F. Johnsson, Modeling Axial Mixing of Fuel Particles in the Dense Region of a Fluidized Bed, Energy & Fuels 2020 34 (3), 3294-3304, DOI: 10.1021/acs.energyfuels.9b0419
- Köhler, E. Cano-Pleite, A. Soria-Verdugo, D. Pallarès, F. Johnsson, Modeling the motion of fuel particles in a fluidized bed, Fuel, Volume 305, 2021, 121424, https://doi.org/10.1016/j.fuel.2021.121424
- Mirek, Influence of the model scale on hydrodynamic scaling in CFB boilers, Brazilian Journal of Chemical Engineering 33 (4), pp. 885-896, DOI 10.1590/0104-6632.20160334s20150348
- Djerf, D. Pallarès, F. Johnsson, Solids flow patterns in large-scale circulating fluidised bed boilers: Experimental evaluation under fluid-dynamically down-scaled conditions, Chemical Engineering Science, Volume 231, 2021, 116309, https://doi.org/10.1016/j.ces.2020.116309.
- Mirek, Scaling of flow phenomena in circulating fluidized bed boilers, Chemical and Process Engineering 32 (2), (2011) pp. 91-100, DOI 10.2478/v10176-011-0008-4
- Djerf, D. Pallarès, F. Johnsson, Bottom-bed fluid dynamics – Influence on solids entrainment, Fuel Processing Technology, Volume 173, 2018, Pages 112-118, https://doi.org/10.1016/j.fuproc.2017.12.023.
Answer：The aforementioned and some related references were provided according to the suggestion on the applications of column static pressure measurements in the revised manuscript. In addition, the magnetic particle tracking (MPT) and the radio-frequency identification (RFID) methods were introduced.
- Line 78: The sentence: The findings for the riser…., must be improved.
Answer：This sentence was improved.
- Line 82: Tons -> Numerous studies
Answer：It was corrected.
- Please present the equations in such a way as to reflect the domain of computation. If the case analyzed by the authors is considered in the plane system, what is the point of specifying an additional coordinate k. In such a situation, one should stay only with two coordinates iand j.
Answer：It was corrected and updated in the revised manuscript..
- Line 125: The continuity equations … Please provide two separate equations for gas and particles
Answer：It was updated.
- Line 126: How should the velocity vector in Eq (1) be interpreted - as an average velocity vector? Please explain that.
Answer：It was updated.
- Line 126: What does xjmean in Eq (1)?
Answer：The 2-D coordination is used in this model, and xj represent the x and y, respectively.
- Line 128: Please explain what does (k = g, p) mean?
Answer：g represents the gas phase and p is particle phase.
- Line 130, 131: Please explain why in Eq (1) a different direction (j) is considered than in Eqs (2) and (3) (k)?
Answer：They were updated.
- Eqs. 2 and 3: What does the apostrophe at velocity term mean?
Answer：It means the fluctuation of velocity.
- Line 135: Please explain why the equation for viscous stress tensor for gas was not given?
Answer：The stress tensor of gas was provided.
- Line 141: Please explain in the Nomenclature section, how should the particle diameter to be understood - as the Sauter diameter?
Answer：It was the true diameter of particle.
- In the Nomenclature (greek alphabets) section there is no description for mig
Answer：It was added.
- Eq. 11: Please explain how the notation fi introduced in the single-column matrix (one the right hand side of the equation) should be understood?
Answer: Introduction was provided.
- Line 175: … which can be referred as Ref. 61?
Answer：It was updated.
25 . Figure 1: Instead of Height and Width, please add the symbols from Table 1 - H and D to the diagram.
Answer：Figure 1 was updated including the corrections of “H” and “D” from the Table 1.
- Table 1: Height and width of fluidized bed, H, D should be related to 1.0 and 0.6 and not vice versa..
Answer：They were corrected in the updated Figure 1.
- Table 1: umfseems to be too low. Please check this value. Assuming porosity 0.4 and density 2700 kg.m3 it should be ca. 10 m/s
Answer：It was corrected.
- Figure 1: Free board -> Freeboard
Answer：Figure 1 was updated.
- Line 227: Please explain what the values in brackets refer to? What was the mesh size for the adopted size?
Answer: Detailed illustrations were updated.
- Nothing is mentioned in the paper about the type of computational mesh generated. As this is important in terms of the results obtained, please provide this information.
Answer: This section was updated.
- Figure 3: The figure shows a photograph from experimental research, however, in the body of the text the authors do not mention anything about the conditions for conducting these tests. Since all information should be accurately presented in a scientific article, please fill in this deficiency.
Answer: They were added.
- How do the authors explain the attempt to compare the results obtained on the quasi-flat stand with the results of calculations performed in the 2D domain? The validation of the model based on completely different conditions seems doubtful. Please comment on this.
Answer: Detailed illustrations for experiment performances and conditions were updated.
- Line 242: Does the term 'experimental particles' refer to experimental research? If so, please explain how the results presented in Fig. 5 were obtained experimentally?
Answer: Detailed illustrations for experiment performance and condition were added.
34 Rewritten the conclusions and remarks.
Answer：This section was rewritten and updated.
Thank you again and with my best wishes.
Dr. Yang Liu
July 08, 2022
Author Response File: 
Author Response.docx
Reviewer 2 Report
The article entitled 'Hydrodynamic predictions of the ultralight particle dispersions in bubbling fluidization bed' concerns simulation studies of the behavior of particles of two different densities under the conditions of a bubble fluidized bed. The main problem of the presented work is an attempt to compare the results obtained as a result of numerical simulations and on a laboratory scale. The problem is that the former relate to simulations carried out in a planar system and the latter in a spatial system. The authors do not inform the readers about the parameters of the laboratory experiments carried out. It can be guessed that they were carried out in a quasi-flat system. The question then arises, why were the numerical simulations not carried out in an identical spatial arrangement? Moreover, although the authors indicate a comparison of the obtained results with the results of laboratory tests, the results of the latter have been limited in the text to practically one photo!
I suggest extending the Introduction section to justify the aim of the work, and present the current state of art and novelty of undertaken research in a more structured way. The introduction should briefly place the study in a broad context and highlight why it is important. It should define the purpose of the work and its scientific significance. The current state of the research field should be reviewed. Finally, briefly mention the main aim of the work.
The results obtained by the authors add nothing new to the general state of knowledge. Most of the conclusions drawn during the discussion of the obtained results are obvious and do not require advanced calculations. The article does not clearly emphasize what is the original achievement of the authors. Moreover, the obtained results were not compared with the results of other researchers. In the opinion of the reviewer discussion of the results with up-to-date literature must be added. Please add paragraphs/phrases containing a discussion of the obtained results with literature references. The results section should not only report and summarize the finding but also discuss them with the literature. To discuss the results presented in this paper it is recommended to use up-to-date papers indexed in Scopus and WoS .
The entire section Conclusions and remarks should be rewritten. Authors should include in it very specific conclusions summarizing all work and list their achievements. As it stands, the conclusions drawn are too general. The article requires advanced linguistic correction. Many sentences require grammatical and stylistic improvement. Moreover, the paper contains a lot of ambiguities that need to be clarified. Detailed comments are listed below.
Line 3: bubbling fluidized bed
Line 16: experimental particles -> particles used in experiments
Line 25: The sentence needs to be improved from the grammatical point of view
Line 29: It is noticeable that … The sentence needs to be improved from the grammatical point of view
Line 35: fluidizations -> fluidization
Line 35: Particle dispersions …. are determined by the hydrodynamic bubbling fluidizations. Please explain this sentence.
Line 43: circulated fluid bed -> circulating fluidized bed
Line 41-46: It is quite difficult to agree with this sentence. In fact, there are numerous experimental studies devoted to turbulent mixing and diffusion as well as interaction between gas and particle phases.
Line 51: FOP cannot be used to measure particle size distribution. Resolution of this method is simply too low. PSD can be successfully measured utilizing laser diffraction devices.
Line 53: As examples of the use of non-invasive measurement methods, the authors give only optical methods, the basic limitation of which is the concentration of particles. These methods are rarely used for dense beds (for example bubbling). Please note that there are a large number of publications where column static pressure measurements were used to study the hydrodynamics of bubbling and circulating beds. Many of them deserve quotation. Some of them are listed below:
A. Köhler, D. Pallarès, and F. Johnsson, Modeling Axial Mixing of Fuel Particles in the Dense Region of a Fluidized Bed, Energy & Fuels 2020 34 (3), 3294-3304, DOI: 10.1021/acs.energyfuels.9b0419
A. Köhler, E. Cano-Pleite, A. Soria-Verdugo, D. Pallarès, F. Johnsson, Modeling the motion of fuel particles in a fluidized bed, Fuel, Volume 305, 2021, 121424, https://doi.org/10.1016/j.fuel.2021.121424
P. Mirek, Influence of the model scale on hydrodynamic scaling in CFB boilers, Brazilian Journal of Chemical Engineering 33 (4), pp. 885-896, DOI 10.1590/0104-6632.20160334s20150348
T. Djerf, D. Pallarès, F. Johnsson, Solids flow patterns in large-scale circulating fluidised bed boilers: Experimental evaluation under fluid-dynamically down-scaled conditions, Chemical Engineering Science, Volume 231, 2021, 116309, https://doi.org/10.1016/j.ces.2020.116309.
P. Mirek, Scaling of flow phenomena in circulating fluidized bed boilers, Chemical and Process Engineering 32 (2), (2011) pp. 91-100, DOI 10.2478/v10176-011-0008-4
T. Djerf, D. Pallarès, F. Johnsson, Bottom-bed fluid dynamics – Influence on solids entrainment, Fuel Processing Technology, Volume 173, 2018, Pages 112-118, https://doi.org/10.1016/j.fuproc.2017.12.023.
Line 78: The sentence: The findings for the riser …., must be improved.
Line 82: Tons -> Numerous studies
Section 2 needs to be meticulously organized. The authors cite many equations, the meaning of which should be explained to the readers. Therefore, all equations that do not represent the authors' original achievements should be cited for a better understanding of the individual terms. In addition, all notations used in the equations should be included in the Nomenclature section. Unfortunately, many of them are missing.
Please present the equations in such a way as to reflect the domain of computation. If the case analyzed by the authors is considered in the plane system, what is the point of specifying an additional coordinate k. In such a situation, one should stay only with two coordinates i and j.
Line 125: The continuity equations … Please provide two separate equations for gas and particles
Line 126: How should the velocity vector in Eq (1) be interpreted - as an average velocity vector? Please explain that.
Line 126: What does xj mean in Eq (1)?
Line 128: Please explain what does (k = g, p) mean?
Line 130, 131: Please explain why in Eq (1) a different direction (j) is considered than in Eqs (2) and (3) (k)?
Eqs. 2 and 3: What does the apostrophe at velocity term mean?
Line 135: Please explain why the equation for viscous stress tensor for gas was not given?
Line 141: Please explain in the Nomenclature section, how should the particle diameter to be understood - as the Sauter diameter?
In the Nomenclature (greek alphabets) section there is no description for mig
Eq. 11: Please explain how the notation fi introduced in the single-column matrix (one the right hand side of the equation) should be understood?
Line 175: … which can be referred as Ref. 61?
The article lacks a subsection that presents details on the computation domain. Readers must guess that the calculations are made in a flat system, not a spatial one. I propose to add such a subchapter before the chapter in which the calculation results are discussed.
Figure 1: Instead of Height and Width, please add the symbols from Table 1 - H and D to the diagram.
Table 1: Height and width of fluidized bed, H, D should be related to 1.0 and 0.6 and not vice versa..
Table 1: umf seems to be too low. Please check this value. Assuming porosity 0.4 and density 2700 kg.m3 it should be ca. 10 m/s
Figure 1: Free board -> Freeboard
Line 227: Please explain what the values in brackets refer to? What was the mesh size for the adopted size?
Nothing is mentioned in the paper about the type of computational mesh generated. As this is important in terms of the results obtained, please provide this information.
Figure 3: The figure shows a photograph from experimental research, however, in the body of the text the authors do not mention anything about the conditions for conducting these tests. Since all information should be accurately presented in a scientific article, please fill in this deficiency.
How do the authors explain the attempt to compare the results obtained on the quasi-flat stand with the results of calculations performed in the 2D domain? The validation of the model based on completely different conditions seems doubtful. Please comment on this.
Line 242: Does the term 'experimental particles' refer to experimental research? If so, please explain how the results presented in Fig. 5 were obtained experimentally?
On the whole, the paper should be thoroughly revised. In the revised version, please refer to all comments, not only those listed as detailed comments. In order to speed up the review process and to avoid rejection of the incompletely corrected version of the paper, the authors are asked to scrupulously introduce all corrections.
Author Response
Dear reviewers and editors,
We greatly appreciate your kind comment and help regarding this manuscript. We have carefully addressed all comments in the revised manuscript and the responses point-by-point are given as follows.
Comments of reviewers
Reviewer #1:
- How would the proposed prediction method be validated against sufficient experimental data?
Answer: In the Gera’s experiment and simulation, the quantitative data of particle hydrodynamics, i.e. particle velocity and fluctuation velocity have not been provided. They focus on the comparisons with particle voidage that simulated by TFM and DEM models using snapshots, as well as the experimental observations. Gera et al. compared TFM and DEM simulations and suggested that TFM based simulations are very sensitive to inter-particle friction, incorporated through solid pressure and viscosity, which might obscure observation of true bubbling characteristics of fluidized beds.
By analogue this methodology, the simulated profiles of particle voidage or porosity using the proposed gas-particle second-order moment two-fluid model was validated by Gera’s TFM simulation results in terms of the bubble topology observations. After that, the model, numerical algorithm, and in-house codes are used to predict the ultralight particles.
- What does the expected data mean in Figure 11? Are that the theoretical result?
Answer: The Q-Q(quantile-quantile) plots play an important role to compare the two probability distributions by plotting their quantiles against each other. If they are exactly equal, then the points on the Q-Q plot will perfectly lies on a straight-line y = x. In this figure, it was used to find the type of distribution for a random variable whether it be a Gaussian distribution. Y axis is the quantile of samples and X axis is the quantile of normal distributions. It was updated in the revised manuscript.
- What can be learnt from the granular temperature? How would the author quantify the particle dispersion?
Answer: Granular temperature is determined by the fluctuation velocity of particle, indicating the intensity of particle collisions. In this work, the parameters of distributions of particle velocity, fluctuation velocity, porosity, and granular temperature of particles are used to quantify the particle dispersions at the different heights of central and wall regions. Thus, particle dispersion behaviors are revealed and comparisons with those heavy particles are carried out as well.
- What would happen if particles with different sizes coexist in the bubbling fluidized bed?
Answer：If different sizes of particles exist together, the segregation and mixing characteristics should be occurred. Meanwhile, the model and governing equations should be improved for wider-sizes particles flows. Especially for the closure transportations regarding the interactions between gas and particle, particle-particle collisions. The hydrodynamics of single particle two-phase flow are significantly differently from the multi-particle phase flows.
----------------------------------------------------------------------------------------------------------------------------
Reviewer 2,
- Line 3: bubbling fluidized bed
Answer：It was corrected.
- Line 16: experimental particles -> particles used in experiments
Answer：All of them were updated.
- Line 25: The sentence needs to be improved from the grammatical point of view.
Answer：This sentence was improved.
- Line 29: It is noticeable that… The sentence needs to be improved from the grammatical point of view.
Answer：This sentence was improved.
- Line 35: fluidizations -> fluidization
Answer：It was corrected.
- Line 35: Particle dispersions …. are determined by the hydrodynamic bubbling fluidizations. Please explain this sentence.
Answer：It was updated.
- Line 43: circulated fluid bed -> circulating fluidized bed
Answer：It was corrected.
- Line 41-46: It is quite difficult to agree with this sentence. In fact, there are numerous experimental studies devoted to turbulent mixing and diffusion as well as interaction between gas and particle phases.
Answer: They were corrected.
- Line 51: FOP cannot be used to measure particle size distribution. Resolution of this method is simply too low. PSD can be successfully measured utilizing laser diffraction devices.
Answer：This discussion regarding FOP was corrected according to review’s suggestion.
- Line 53: As examples of the use of non-invasive measurement methods, the authors give only optical methods, the basic limitation of which is the concentration of particles. These methods are rarely used for dense beds (for example bubbling). Please note that there are a large number of publications where column static pressure measurements were used to study the hydrodynamics of bubbling and circulating beds. Many of them deserve quotation. Some of them are listed below:
- Köhler, D. Pallarès, and F. Johnsson, Modeling Axial Mixing of Fuel Particles in the Dense Region of a Fluidized Bed, Energy & Fuels 2020 34 (3), 3294-3304, DOI: 10.1021/acs.energyfuels.9b0419
- Köhler, E. Cano-Pleite, A. Soria-Verdugo, D. Pallarès, F. Johnsson, Modeling the motion of fuel particles in a fluidized bed, Fuel, Volume 305, 2021, 121424, https://doi.org/10.1016/j.fuel.2021.121424
- Mirek, Influence of the model scale on hydrodynamic scaling in CFB boilers, Brazilian Journal of Chemical Engineering 33 (4), pp. 885-896, DOI 10.1590/0104-6632.20160334s20150348
- Djerf, D. Pallarès, F. Johnsson, Solids flow patterns in large-scale circulating fluidised bed boilers: Experimental evaluation under fluid-dynamically down-scaled conditions, Chemical Engineering Science, Volume 231, 2021, 116309, https://doi.org/10.1016/j.ces.2020.116309.
- Mirek, Scaling of flow phenomena in circulating fluidized bed boilers, Chemical and Process Engineering 32 (2), (2011) pp. 91-100, DOI 10.2478/v10176-011-0008-4
- Djerf, D. Pallarès, F. Johnsson, Bottom-bed fluid dynamics – Influence on solids entrainment, Fuel Processing Technology, Volume 173, 2018, Pages 112-118, https://doi.org/10.1016/j.fuproc.2017.12.023.
Answer：The aforementioned and some related references were provided according to the suggestion on the applications of column static pressure measurements in the revised manuscript. In addition, the magnetic particle tracking (MPT) and the radio-frequency identification (RFID) methods were introduced.
- Line 78: The sentence: The findings for the riser…., must be improved.
Answer：This sentence was improved.
- Line 82: Tons -> Numerous studies
Answer：It was corrected.
- Please present the equations in such a way as to reflect the domain of computation. If the case analyzed by the authors is considered in the plane system, what is the point of specifying an additional coordinate k. In such a situation, one should stay only with two coordinates iand j.
Answer：It was corrected and updated in the revised manuscript..
- Line 125: The continuity equations … Please provide two separate equations for gas and particles
Answer：It was updated.
- Line 126: How should the velocity vector in Eq (1) be interpreted - as an average velocity vector? Please explain that.
Answer：It was updated.
- Line 126: What does xjmean in Eq (1)?
Answer：The 2-D coordination is used in this model, and xj represent the x and y, respectively.
- Line 128: Please explain what does (k = g, p) mean?
Answer：g represents the gas phase and p is particle phase.
- Line 130, 131: Please explain why in Eq (1) a different direction (j) is considered than in Eqs (2) and (3) (k)?
Answer：They were updated.
- Eqs. 2 and 3: What does the apostrophe at velocity term mean?
Answer：It means the fluctuation of velocity.
- Line 135: Please explain why the equation for viscous stress tensor for gas was not given?
Answer：The stress tensor of gas was provided.
- Line 141: Please explain in the Nomenclature section, how should the particle diameter to be understood - as the Sauter diameter?
Answer：It was the true diameter of particle.
- In the Nomenclature (greek alphabets) section there is no description for mig
Answer：It was added.
- Eq. 11: Please explain how the notation fi introduced in the single-column matrix (one the right hand side of the equation) should be understood?
Answer: Introduction was provided.
- Line 175: … which can be referred as Ref. 61?
Answer：It was updated.
25 . Figure 1: Instead of Height and Width, please add the symbols from Table 1 - H and D to the diagram.
Answer：Figure 1 was updated including the corrections of “H” and “D” from the Table 1.
- Table 1: Height and width of fluidized bed, H, D should be related to 1.0 and 0.6 and not vice versa..
Answer：They were corrected in the updated Figure 1.
- Table 1: umfseems to be too low. Please check this value. Assuming porosity 0.4 and density 2700 kg.m3 it should be ca. 10 m/s
Answer：It was corrected.
- Figure 1: Free board -> Freeboard
Answer：Figure 1 was updated.
- Line 227: Please explain what the values in brackets refer to? What was the mesh size for the adopted size?
Answer: Detailed illustrations were updated.
- Nothing is mentioned in the paper about the type of computational mesh generated. As this is important in terms of the results obtained, please provide this information.
Answer: This section was updated.
- Figure 3: The figure shows a photograph from experimental research, however, in the body of the text the authors do not mention anything about the conditions for conducting these tests. Since all information should be accurately presented in a scientific article, please fill in this deficiency.
Answer: They were added.
- How do the authors explain the attempt to compare the results obtained on the quasi-flat stand with the results of calculations performed in the 2D domain? The validation of the model based on completely different conditions seems doubtful. Please comment on this.
Answer: Detailed illustrations for experiment performances and conditions were updated.
- Line 242: Does the term 'experimental particles' refer to experimental research? If so, please explain how the results presented in Fig. 5 were obtained experimentally?
Answer: Detailed illustrations for experiment performance and condition were added.
34 Rewritten the conclusions and remarks.
Answer：This section was rewritten and updated.
Thank you again and with my best wishes.
Dr. Yang Liu
July 08, 2022
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The comments have been carefully addressed by the authors. The manuscript can be accepted for publication
Author Response
Dear reviewer and editor,
We greatly appreciate your kind comments. We have carefully addressed all and the following responses point-by-point are given.
Reviewer 1:
The comments have been carefully addressed by the authors. The manuscript can be accepted for publication
Answer：Thank you for your kind suggestions and hard work.
With best wishes.
Dr. Yang LIU
07-10-2022
Author Response File: Author Response.docx
Reviewer 2 Report
Line 47: circulating fluid bed -> circulating fluidized bed
Eqs. (1) and (2): How should the velocity vectors in Eqs (1)-(2) be interpreted - as an average velocity vector? Please explain that.
Table 1: Height and width of fluidized bed, H, D should be related to 1.0 and 0.6 and not vice versa. Please correct it in the third column of the Table
Line 266: Simulated results … Sentence needs to be corrected grammatically
As the authors do not really compare the obtained results of the calculations with the results of laboratory tests, I suggest to remove all information related to this in the body text, e.g. in the abstract of the paper. Please delete the sentence (Predictions are in well ....)
I still suggest to improve the most important part of the paper Conclusions and Remarks section which in its present form is imprecise and does not result directly from the conducted research. For example, look at the conclusion:
Wider bubble size distributions, faster axial velocities, enhanced granular temperatures and anisotropic characteristics are demonstrated.
which raises a number of additional questions:
· - what it refers to: Wider bubble size distributions
· - there is no such thing as: faster axial velocities, maybe you mean higher axial velocities
The sentence ‘Further utilizations for dense particle two-phase flow in spouted bed, circulated fluidized bed, swirling fluidized bed etc. will be conducted in next work’ is not a conclusion from the research, but a statement that may appear at the end of the section.
Please follow the text of the article again and draw from it the most important achievements and conclusions. They should relate to the goals of the thesis set out in the Introduction section.
Please also note that in the section devoted to the analysis of the obtained results, there is still no discussion of the obtained results with the achievements of other researchers.
Author Response
Dear reviewer and editor,
We greatly appreciate your kind comments. We have carefully addressed all and the following responses point-by-point are given.
- Line 47: circulating fluid bed -> circulating fluidized bed.
Answer：It was corrected.
- (1) and (2): How should the velocity vectors in Eqs (1)-(2) be interpreted - as an average velocity vector? Please explain that.
Answer：It was corrected as “velocity components”
- Table 1: Height and width of fluidized bed, H, D should be related to 1.0 and 0.6 and not vice versa. Please correct it in the third column of the Table
Answer：It was corrected as “1.0, 0.6”in Table 1.
- Line 266: Simulated results… Sentence needs to be corrected grammatically
Answer：This sentence was polished and corrected.
- As the authors do not really compare the obtained results of the calculations with the results of laboratory tests, I suggest to remove all information related to this in the body text, e.g. in the 6.
Answer：Related contents were deleted in the revised manuscript.
- I still suggest to improve the most important part of the paper Conclusions and Remarks section which in its present form is imprecise and does not result directly from the conducted research. For example, look at the conclusion:
-Wider bubble size distributions, faster axial velocities, enhanced granular temperatures and anisotropic characteristics are demonstrated. which raises a number of additional questions:
- what it refers to: Wider bubble size distributions
- there is no such thing as: faster axial velocities, maybe you mean higher axial velocities
Answer：The section of conclusion was rewritten, and the improvement of main text was conducted accordingly.
- The sentence ‘Further utilizations for dense particle two-phase flow in spouted bed, circulated fluidized bed, swirling fluidized bed etc. will be conducted in next work’ is not a conclusion from the research, but a statement that may appear at the end of the section.
Answer：This sentence was reorganized at the end of the conclusion section.
- Please follow the text of the article again and draw from it the most important achievements and conclusions. They should relate to the goals of the thesis set out in the Introduction section. Please also note that in the section devoted to the analysis of the obtained results, there is still no discussion of the obtained results with the achievements of other researchers.
Answer：Sections of introduction and conclusion were updated based on the suggestions in the revised manuscript.
Thank you again and with my best wishes.
Dr. Yang Liu
July 10, 2022
Author Response File: Author Response.docx
Round 3
Reviewer 2 Report
Although the authors improved the Conclusion section, there are still many errors in it that should be corrected.
Line 395: Sentence: 'Focusing on gaining a better understanding hydrodynamic behavior carried out' is grammatically incorrect and needs to be corrected.
Line 395: 'It is observed that some distictint dispersion characterisitcs are different from the coventional materials, they are as follows:' -> 'It is observed that some distictint dispersion characterisitcs listed below are different from the coventional materials.'
Line 399: Sentence: 'For axial-averaged particle velcotiy at the heights of 0.5m and 0.24m along central flows, they are almost same, but they are 4.8 times and 2.5 times larger than those of hevay particles' is convoluted and difficult to understanding. Please formulate a more explicit conclusion.
Line 399: particle velcotiy -> particle velocity
Line 400: hevay particles -> heavy particles
Author Response
Dear reviewer,
We greatly appreciate your kind comments regarding my revised manuscript. They have been addressed one-by-one and the answers are given as follows.
Reviewer 2:
- Line 395: Sentence: 'Focusing on gaining a better understanding hydrodynamic behavior carried out' is grammatically incorrect and needs to be corrected.
Answer：Thank you so much. This sentence was improved in the revised manuscript.
- Line 395: 'It is observed that some distictint dispersion characterisitcs are different from the coventional materials, they are as follows:' -> 'It is observed that some distictint dispersion characterisitcs listed below are different from the coventional materials.'
Answer：Thank you for your suggestion, and it was corrected
- Line 399: Sentence: 'For axial-averaged particle velcotiy at the heights of 0.5m and 0.24m along central flows, they are almost same, but they are 4.8 times and 2.5 times larger than those of hevay particles' is convoluted and difficult to Please formulate a more explicit conclusion.
- Answer：Thank you for your comment. This sentence was rewritten, and more illustrations were provided in the section of conclusion. It is “At r/Width=0.5 and heights of 0.5m and 0.24m, the mean values of axial particle velocity are almost equivalent, but they are approximately 4.0 times and 1.5 times larger than those of heavy particles, respectively.” (Please see Figure 6 (c),(d), and Figure 8 (c),(d).)
- Line 399: particle velcotiy -> particle velocity
Answer：Thank you so much. It was corrected.
- Line 400: hevay particles -> heavy particles
Answer：Thank you so much. It was corrected.
Best regards and thank you again.
Dr. Yang
07/13/2002
Author Response File: Author Response.docx
