Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors presented the results of the investigation in which the influence of varying cylinder to particle size ratios and particle temperatures on heat and moisture transfer during soybean drying are presented. The presented results of DEM simulation may motivate investigators to investigate the obtained results in a real experiment. Beside people from academia, the results are interesting also for people dealing with grain storage.

The layout of the paper is sufficiently good as well as the English language. The presented methodology is detailed and clear. My suggestion would be that authors give explanation of each abbreviation presented in title of Figures, so that readers can understand the Figure as a whole, without need to go through the text. The presented results back up the conclusions and they are given in a manner that can be easily understood.

Comments on the Quality of English Language

Minor editing of English language required

Author Response

Please see attached

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The submitted manuscript is entitled "Investigation of the heat and moisture transfer during the drying of packed-bed porous media in soybeans." The objective of this study is to examine how different ratios of cylinder to particle sizes and varying particle temperatures affect heat and moisture transfer in the context of soybean drying. Utilizing the Discrete Element Method, the authors developed a conjugate transfer model to simulate the fixed bed drying process. The authors examine the flow field, pressure drop, and heat and moisture transfer mechanisms within the fixed bed under varying cylinder-to-particle size ratios. Furthermore, the study investigates how particle temperature influences heat and mass transfer parameters throughout the drying process.

The presented study is interesting, however, the manuscript needs review considering the following points:

1. Figure 17 shows the fluctuation of the average moisture content of the particle bed at various particle temperatures. The authors found that at temperature 288 K, the moisture content of soybean particles undergoes the most rapid change, exhibiting the highest water transfer rate and reaching the safe moisture content first. This phenomenon shows that an increase in particle temperature enhances the water transfer rate in the packed bed. This process should explained in more detail. In which temperature range the enhance the water transfer rate is expected?

2. The authors should support their results by referring to some experimental studies in the field. A more in-depth discussion should be provided.

3. The particle size scale should be displayed in the schematic diagram in Figure 3.

4. The units should be displayed in the same manner in Figures, e.g. revise Figure 10b.

5. The abbreviations should be defined upon first use.

 

6. Please correct some typos, e.g. Table 2: the subscripts in the air parameters section.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This manuscript deals with a simulation of the distribution of porosity and the combined heat and moisture movement during the drying of packed-bed porous media in soybeans. It focuses on the porosity and flow of soybeans with different particle size ratio, and the drying of soybeans with varying particle temperatures. Since the computer aided simulations have also high impact on the chemical operations and processes, this investigation deserves attention.

The manuscript is fairly well written and the results are clearly presented. However, some minor revisions should be made before publication:

 1) p. 1 line 14 The authors use the abbreviations UG, UDF or CFD, but they are not not resolved. You should already express their meanings at the first appearance..

2) p. 1 line 36 You also write that “… (Fleurat-Lessard, 2017) (Jian and Jayas, 2012) (Flinn et al., 2004).”, but this is not the correct form of the citation of references in the main text. Please, check and modify all of them.

3) p. 4 line 113 The authors use the N value, but it was not mentioned previously. However, you also do the D/d_p one_, and it seems these expressions are the same. Furthermore, you also use the N/d_p one in the Figures 1, 4, 5, 8, 10 and 11. You should clarify these confusing marks.

4) pp. 30–32 Style of the references does not meet the requirements of journal Applied Sciences. For example, in case of “BAI, H., THEUERKAUF, J., GILLIS, P. A. & WITT, P. M. 2009. A Coupled DEM and CFD Simulation of Flow Field and Pressure Drop in Fixed Bed Reactor with Randomly Packed Catalyst Particles. Industrial & Engineering Chemistry Research.” you should use it in this form: Bai, H.; Theuerkauf, J.; Gillis, P.A.; Witt, P.M. A Coupled DEM and CFD Simulation of Flow Field and Pressure Drop in Fixed Bed Reactor with Randomly Packed Catalyst Particles. Ind. Eng. Chem. Res. 2009, 48, 4060–4074. Please, check all of them and modify them accordingly.

 

Comments on the Quality of English Language

The English needs slight improvements. There are some, typical grammar or typing mistakes:

p. 15 line 333 „… famous …”  instead of  well-known

p. 22 line 454 and elsewhere „… D/dp …”  instead of  D/d_p

         line 462 and elsewhere „… V₀= …”  instead of  ν₀=

         line 466 and elsewhere „… 300 seconds …”  instead of  300 s

p. 26 line 516 and elsewhere „… 3 hours …”  instead of  3 h

Author Response

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Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The issue of grain storage and drying is an important agricultural and food factor worldwide. The authors decided to investigate the drying processes and the effects acting in terms of temperature and moisture distribution between the soybean particles with aim to publish in scientific journal Applied Sciences.

- What is the similarity between the shape of the soybeans and the simulated "balls" and can be used the performed simulations for other crops as well?

- Were the results verified on a physical model?

- Drying and storage of crops can take place under different conditions. Why and how were the shapes of the cylinders and the thicknesses of the material layers chosen? For what method of drying did the authors anticipate using the results?

- The abstract needs to be edited. Limit general formulations and focus more on supplementing specific results. E.g. basic parameters such as the temperature and humidity of the air, which were considered for the simulation, are not listed. The same applies to other results.

- In the introductory part of the Introduction line 35 and other parts of the text, the authors speak generally about "grain storage", however, the research was focused only on soybeans. How is the research conducted on soybeans (described in this article) applicable to, for example, the drying of grains such as wheat, barley, corn, rice, etc.?

2. Methodology

- In the part of the work focused on methodology, I lack scientific hypotheses that should have been verified.

- The explanation of quantities and units is confused and unsystematic. E.g. In the text, the designation N appears many times, but nowhere is it explained what N means and what its size is. Only on line 313 is stated: tube-to-particle size ratio N, although this does not appear in the preceding formula (10). Similarly, the designation Z is also not mentioned in the opening tables, but is on lines 484 and 515.

- In Table 1, the Cylinder-to-particle size ratio D/dp 4.44/5.6/6.25 is given without the given Unit. In a scientific article, the designation of quantities and their dimensions must be given precisely and unambiguously.

- It is necessary to correct incorrectly entered quantities with indices and units with exponents, e.g. Table 2 shows: ρs, kg/m3; ρf, kg/m3 and there should be kg/m³ ; are wrong: μf, kg/(m·s) and there should be μ_f; similarly for other quantities.

- The continuity of the height and the position of the comparison of the temperature values in Figures 9 and 11 is not clarified.

- There is no clear connection between the temperature indicated on line 513: ventilation temperature of T = 308.15 K and the images in Figure 11.

- The indication of humidity in the pictures and in the text is inconsistent. It is necessary to unify and write correctly.

- The conclusions state only general information that can be arrived at even without conducting research. The Conclusion needs to be reworked in a fundamental way, in particular to state specific results achieved and possibilities of use.

- It is clear from the presented article that the authors tried to use a modern method of calculation, which is interesting, but the necessary results should be primarily useful and beneficial to the field of drying. It is not clear to me from the presented article how and in what way I could use the results.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors revised the manuscript appropriately.

Reviewer 4 Report

Comments and Suggestions for Authors

The article was partially edited according to the reviewer's instructions and the authors' possibilities. I recommend it for publication.