Numerical Simulation and Development of a Continuous Microwave-Assisted Pilot Plant for Shelled Almond Processing

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This manuscript developed computer simulation models to design a semi-industrial scale microwave system for almond disinfection. The manuscript showed promising results, but the authors need to address the following questions and comments for clarification.

 

1. the used frequency needs to be shown in the abstract

2. Line 95: Is “flow” a good term?

3. Line 162: for the complex permittivity values of mixture, there are several mixture theory very well developed and widely evaluated in the literature (e.g., Complex Refractive Index mixture equation (CRIME), Landau and Lifshitz, Looyenga equation (LLLE), Böttcher equation (BE), and Lichtenecker equation (LE)). Why did the authors use a simple average equation for volume fraction?

4. The geometric details of the system needs to be provided in addition to the current limited information? The boundary conditions of the microwave port and other boundaries are needed.

5. How is the movement of the almonds simulated? The reviewer has a concern/question about the thermal results: Why does the temperature seem uniform at different locations of the chamber and not increase along with the movement of the sample in the chamber?

Author Response

Dear Reviewer,

thanks for the comment and suggestion to improve the paper. All the authors accepted and implemented the revision in the attached papaer.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The method used in this paper to desing and validate a microwave applicator that can disinfect shelled almonds to a maximum temperature of 60 ºC is really noteworthy. Before I can suggest publication, though, I need to see a lot more data, citations, flow charts outlining the methodology, dimensions of scenarios, and justifications for the simulation methods (particularly for temperature computation). It is my goal that the remarks and recommendations I provide may enhance the quality and comprehension of the authors' work.

SECTION 1:

-   The introduction section omits several important references about mode stirrers, sample movement, multifeeding, and dielectric moldings inside microwave applicators to enhance heating uniformity. These ought to be mentioned and examined because the paper is centered around this subject.

SECTION 2:

-        Please  provide a number for the Material and Methods section's headline.

-        Please provide the initial and end moisture content of the almonds used in the experiments in this section. This would give background knowledge to support the decision to exclude evaporation processes from the heat equation.

-        It is not clear in the text whether the relative permittivity data in equations (2-3) is used in simulations or not. Please explain this in detail.

-        A more accurate schematic of the microwave applicator should be supplied, as Figure 1 does not accurately depict its geometry. For reproducibility considerations, please include the cavity shape and primary dimensions, the location and dimensions of the microwave sources, etc. in that scheme. It is imperative for authors to always remember that solid research techniques must provide sufficient data to enable other researchers to replicate their findings. This is currently not achievable with the simulation scenario's provided data.

-        Kindly provide the honeycomb filter's layout and dimensions, together with the appropriate lettering (W, L, etc.) as indicated in Table 1.

- Please include the relative permittivity data for the propylene tube used in simulations.

- I've missed a crucial detail in the technique description since the almonds are moving: how is this movement accounted for in the temperature calculation? Please update the text with the technique and an explanation. It would be really appreciated if there was a diagram for the electric field and temperature computation together. This point should be covered in its own section. Appropriate references must also be given. The literature contains a number of articles that consider sample movement or mobile stirrers. Please contrast these methods with the one you explain.

 The suggested method appears to average the almonds' temperature in a static manner, but the correct method should take into account the electric field at each location and the temperature increments that have come before it while calculating the temperature. There are other legitimate methods that compute an average electric field earlier on. This has to be discussed with the appropriate references. The suggested approach appears to be effective in determining the mean temperature, but it appears to be ineffective in estimating the temperature variance. Please talk about potential explanations in the appropriate section.

- Please list the primary features of the thermal camera (uncertainty, pixel number, etc.) in section 2.5 along with the distance at which the thermal pictures were captured.

-Kindly make the text on lines 288–290 better.

SECTION 3:

-        It is recommended to test the honeycomb filters both with and without almonds. Would you kindly let us know in the text if you tested them under both circumstances?

-        A crucial piece of information missing from simulations for multiport feeding is what the various ports' crosscoupling and matching are. You may get this crucial information straight from CST MW Studio Suite. This information is needed to prevent magnetron malfunction and overheating. This also shows the system's overall efficiency, which is a crucial indicator for the product's commercialization. Please supply information about this using appropriate figures and/or tables.

-        The authors don't elaborate on how they introduce the metallic helix axis without causing leaks or overheating the bearing balls. Please make note of the introduction of the metallic axis in microwave cavities in the text and cite the appropriate sources.

-        The authors state on lines 409–411 that they utilize a PLC to keep an eye on the process's temperature. Kindly explain this under the sections on appropriate material and methods. What kind of sensor is used for temperature within the microwave oven, and where are these sensors located?

-        Table 3's results demonstrate that, although the simulation methodology accurately forecasts the average temperature, it is unable to anticipate the variance of the microwave heating. Please make a note about this in the table 3 description.

-        Figure 12 shows a very poor quality. For instance, the temperature colorbars cannot be read. Please improve it.

SECTION 4:

-        Authors indicate in line 490: “…proves to be highly effective by yielding temperature values closely correlated with experimental data. Furthermore, the proposed modeling approach proves beneficial for quantifying and predicting the uniformity of MW-induced heat concerning various physical and geometric properties, as well as operational parameters.” That being said, I would argue that while the suggested methodology is accurate in calculating the average temperature, it is not successful in forecasting the uniformity indicators. Kindly rewrite this text correctly. This conclusion section should offer some justification for this circumstance.

-        The authors provide no results regarding efficiency enhancement, however they do mention it in the findings. Both the results and the conclusions in this section should include efficiency and cross coupling information.

With these changes I think that the contribution would be valuable for publication.

Comments on the Quality of English Language

The paper reads well although some errata have been found and minor edition is required:

-        Line 97: please change “an almonds temperatures of up to 60°C.” into “almonds temperatures of up to 60°C.”

-        Line 265: please change “An experimental test plans were carried..” into “Experimental test were carried…”

-        Table 2: please change “1 MW sources” into “1 MW source”

-        Line 398: I would say "providing a much more uniform distribution of the electromagnetic field for the almonds"

-        In line 475 authors write “Finally, the study demonstrated that the simulation results are in good agreement 475 with the experimental findings.” This is only true for the average temperature. Please be more specific in the text.

Author Response

Dear Reviewer,

thanks for the comment and suggestion to improve the paper. All the authors accepted and implemented the revision in the attached papaer.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Design work involving the development of an almond disinfection plant based on numerical methods. The topics correspond well to those of Applied System Innovation. The manuscript has been prepared in a manner that meets editorial requirements and, in my opinion, can be accepted for publication with minor corrections:

Lack of paragraph number before “Materials and method”

Materials and method: I suggest presenting the next steps of the research in graphical form, e.g. a flow chart.

Please edit equation 2 - 12 so that it is aligned with the text (font size and type) and numbered according to the guidelines i.e. at the end of the line

The captions of Figure 2 are not clear, also Table 3 captions should be edited.

In conclusion, the authors should emphasise the advantages of the developed system over commercially used chemical and thermal methods.

Author Response

Dear Reviewer,

thanks for the comment and suggestion to improve the paper. All the authors accepted and implemented the revision in the attached papaer.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

If the movement of the sample was not considered in the model, why did lines 210-215 discuss the movement parameters? 

Author Response

The parameters of the movement were discussed as the use of the metal spiral at different rotation speeds regulated the residence time of the almonds inside the treatment chamber and consequently the mass flow rate and outlet temperature.
Finally, the mixing resulting from the advancement of the almonds resulted in greater uniformity of heating, as already demonstrated in other scientific works.
Given the importance of the movement parameters, it was deemed necessary to carry out an adequate discussion.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This is the second iteration of the study on heating almonds in a continuous microwave applicator using one or more sources. The paper's quality has increased and the majority of the earlier comments have been taken into consideration. Nevertheless, before I can suggest that the work be accepted, a few adjustments need to be made:

The new references in [26–29] seem more appropriate for sample movement than for mode stirrers; please change the paragraph or the references. I am still missing in the introduction section contributions on mode stirrers and the use of dielectric molds. Please improve this.

Regarding Figure 1, other researchers would still not be capable of reproducing the simulation scenarios. Please provide at least the magnetrons' location, polypropilene tube position, inclined plane angle, etcetera. Another option would be to provide step or other 3D models for the simulated scenarios in the additional data for this paper.

Regarding Table 1, there are some values that cannot be read well. Please include the loss factor or loss tangent of polypropilene in this table.

- While I agree with the authors' discussion about temperature calculation in the cover letter, a summary of this discussion should be included in the text to clarify the employed methodology.

The Port 1 label is missing in Table 2.

The authors indicate that they have added new information about the PLC temperature monitoring, but I have not been able to find it. I include my previous request: "The authors state on lines 409–411 that they utilize a PLC to keep an eye on the process's temperature. Kindly explain this under the sections on appropriate material and methods. What kind of sensor is used for temperature within the microwave oven, and where are these sensors located?" Please include this information in the contribution.

 

I hope that these comments can help authors improve their contributions.

 

Author Response

Dear Reviewer, here attached response to comment received

Author Response File: Author Response.pdf