Simulation of Multi-Phase Flow in Autoclaves Using a Coupled CFD-DPM Approach

Round 1

Reviewer 1 Report

The autoclave is widely used in metallurgy in the production and the purification of metals. The research topic is relevant because it covers a multiphase motion in autoclave, for evaluation of solid holdup, critical suspension speed, nonuniformity of solid suspension, gas holdup distribution, bubble tracks, and residence time during stirring leaching. Optimal parameters for these processes have been determined.

In the research the authors use a combination of CFD-DPM approach and Particle Image Velocimetry methods, which is a fairly reliable combination. The research methods are reasonable and exhaustive for the set research goals. The mathematical model and solution strategy are well described.  The conclusions match the results of the study. The method of presentation is concise and the text is in a scientific style.

The article looks like a completed scientific study, but recommendations are offered to clarify some points and to strengthen the article:

1.   In section “2. Mathematical model” you can expand information about different ways of the description of the turbulent flow characteristics in multiphase flow (Eulerian-Eulerian, Lagrange-Eulerian) with strong shear flow and to add the newest literature sources (last 5 years), where authors use approaches with:

- DNS

https://doi.org/10.1016/j.ijmultiphaseflow.2023.104388

https://doi.org/10.1080/19942060.2021.2024451

-LES

https://doi.org/10.1017/flo.2022.24

https://doi.org/10.1002/bit.27815

- k-e

https://doi.org/10.1016/j.mineng.2020.106418

https://doi.org/10.1007/978-981-16-6928-6_5

- SST k-w:

https://doi.org/10.1016/j.jtice.2022.104578

https://doi.org/10.1016/j.applthermaleng.2022.119848

https://doi.org/10.1016/j.ces.2020.115554

- RSM

https://doi.org/10.3390/separations9030074
https://doi.org/10.3390/pr9111921

2.    How have you taken into account in your simulation the interaction of the solids with each other and with the autoclave wall? What about bubbles interaction?

3.    In section “3.2 Boundary conditions” better to clarify: “In this work, the multiple reference frame (MRF) method is used [27, 28]”, because the abbreviation MDF can be unfamiliar to the reader.

4.    How have you determined the volume fraction of the solid phase in Figure 6?

5.    In section “4.4. Critical suspension speed” you have mentioned: “Then make the maximum slope and the minimum slope tangent, and from the figure, it can be found that the abscissa of the intersection point is O (406. 0.0322).” in my humble opinion better: “that the coordinates/values of the intersection point O is (406. 0.0322).” because abscissa = 406, and ordinate = 0.0322.

6.    In equation (14) please explain, what are mean a, ai?

 

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

The authors presented a numerical study on the multi-phase flow in autoclaves using a coupled CFD-DPM approach.

The novelty of the paper is to be clearly stated.

The used turbulence model is to be justified.

What is the range of Reynolds number corresponding to the considered cases.

The boundary conditions are to be expressed mathematically.

The 3D mesh is to be presented.

The parameter fixed in the grid sensitivity test are to be mentioned.

In the grid sensitivity test, what do you mean by ‘’flow field velocity’’ ? is it the average velocity on the whole domain? To be explained.

Have you used a moving mesh? How are the rotating domains treated? To be explained.

The characteristics of the computer used for the simulation are to be mentioned.

Some figures have low resolution.

The sub-figures 2a and 2b are not similar, also it seems that the considered configurations are not same. It is better to verify the validity of the numerical model by comparing with earlier published numerical results.

Why is the time limited to 10 s for the presented results? What is the time needed to reach the stationary state?

The English level is relatively low.

 

 

Author Response

Please see the attachment

 

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

 Accept in present form