Experimental Design for the Propagation of Smoldering Fires in Corn Powder and Cornflour

Round 1

Reviewer 1 Report

This research is interesting and has considerable value in adding the required information to the global scholars. The methods used are very clear and understandable. The results are clearly displayed and the conclusion is to the point, except some unnecessary explanation in the first paragraph of the conclusion part.

The research gap has to be further elaborated so as to show the real picture of the problem that this specific research wants to address

Author Response

Response to Reviewer 1 Comments

 

Dear Reviewer,

 

Here we are presenting our explanations for the comments received, which we agree with all. We are also attaching a version of the paper with the highlighted changes since we have kept Word in change-tracking mode.

 

We take this opportunity to thank you for the time and effort you have taken to review our paper. The comments received undoubtedly improved the quality and level of the paper's understanding.

 

We hope this new version is more suitable for publication.

 

Regards,

 

The authors

 

1. This research is interesting and has considerable value in adding the required information to the global scholars. The methods used are very clear and understandable. The results are clearly displayed and the conclusion is to the point, except some unnecessary explanation in the first paragraph of the conclusion part.

Thank you for your comment. Some sentences were removed from this paragraph in order to make it clear and avoid unnecessary explanations.

 

2. The research gap has to be further elaborated so as to show the real picture of the problem that this specific research wants to address

Thank you for your comment. The last paragraph was adjusted to clarify the research gap, and the authors detailed the novelty of the work, which can be seen in line 54.

"Although smoldering combustion is a common hazard in agricultural storage, there are few studies regarding the smoldering propagation phenomena and a lack of studies in agricultural materials, especially on corn grains. Most studies focus on other materials with a higher level of combustibility, such as sawdust, biomass, foam, and coal. This paper aims to fill this gap by developing an upward smoldering reaction in a corn pile. The novelty of this work lies in proposing a framework to develop a design of experiments (DoE) to understand the variables' impact and characterize the smoldering velocity inside the pile. Since the reaction propagation depends on material characteristics and external conditions, this work evaluates the influence of three factors in a full factorial experiment – particle size, moisture content, and air ventilation. The present study investigates how granularity, moisture, and ventilation affect smoldering fire propagation. In order to make the problem reliable and reproducible, DoE was designed and developed via Minitab software, which can offer a statistical representation for the extrapolation of the experiments and provide a mathematical equation with the three dependent variables. Then, allowing the determination of smoldering velocity for different conditions."

 

 

Author Response File: Author Response.docx

Reviewer 2 Report

This manuscript presents an experimental study of the phenomenon of negative combustion of corn flour. It aims to evaluate the effects of particle size, moisture and air ventilation on the smoldering velocity. This study is slightly less innovative, but it provides some theoretical support for the safe storage of cornstarch. During the review of the manuscript, I have the following comments. I hope that these comments would be addressed before the paper is published.

 

1、In the last sentence of the third paragraph of Introduction, the expression "2. Materials and Methods" appears, which seems to be the title of the chapter, so please check and revise it.

 

2、Paragraphs 4, 5, and 6 of the Introduction all express content that is completely irrelevant to the manuscript; they appear to be from the author's guide. This is a major error, please check and revise this.

 

3、The innovation of the study is not evident in the manuscript's exposition; could the authors make this more explicit and clear in the manuscript ?

 

4、Figures 5 and 6 are extremely unclear, please provide a sufficiently clear version in the revision.

 

5、The mathematical expression of Equation 1 seems too complicated and some of the coefficients can be expressed in scientific notation.

Author Response

Response to Reviewer 2 Comments

 

Dear Reviewer,

 

Here we are presenting our explanations for the comments received, which we agree with all. We are also attaching a version of the paper with the highlighted changes since we have kept Word in change-tracking mode.

 

We take this opportunity to thank you for the time and effort you have taken to review our paper. The comments received undoubtedly improved the quality and level of the paper's understanding.

 

We hope this new version is more suitable for publication.

 

Regards,

 

The authors

 

 

This manuscript presents an experimental study of the phenomenon of negative combustion of corn flour. It aims to evaluate the effects of particle size, moisture and air ventilation on the smoldering velocity. This study is slightly less innovative, but it provides some theoretical support for the safe storage of cornstarch. During the review of the manuscript, I have the following comments. I hope that these comments would be addressed before the paper is published.

Thank you for your time reviewing the manuscript.

1、In the last sentence of the third paragraph of the Introduction, the expression "2. Materials and Methods" appears, which seems to be the title of the chapter, so please check and revise it.

Thanks for your comment. The sentence was removed from this paragraph.

2、Paragraphs 4, 5, and 6 of the Introduction all express content that is completely irrelevant to the manuscript; they appear to be from the author's guide. This is a major error, please check and revise this.

Thanks for your comment. The paragraphs were removed.

3、The innovation of the study is not evident in the manuscript's exposition; could the authors make this more explicit and clear in the manuscript ?

Thanks for your comment. The novelty of the work was better explained, and it can be seen in line 54.

"Although smoldering combustion is a common hazard in agricultural storage, there are few studies regarding the smoldering propagation phenomena and a lack of studies in agricultural materials, especially on corn grains. Most studies focus on other materials with a higher level of combustibility, such as sawdust, biomass, foam, and coal. This paper aims to fill this gap by developing an upward smoldering reaction in a corn pile. The novelty of this work lies in proposing a framework to develop a design of experiments (DoE) to understand the variables' impact and characterize the smoldering velocity inside the pile. Since the reaction propagation depends on material characteristics and external conditions, this work evaluates the influence of three factors in a full factorial experiment – particle size, moisture content, and air ventilation. The present study investigates how granularity, moisture, and ventilation affect smoldering fire propagation. In order to make the problem reliable and reproducible, DoE was designed and developed via Minitab software, which can offer a statistical representation for the extrapolation of the experiments and provide a mathematical equation with the three dependent variables. Then, allowing the determination of smoldering velocity for different conditions."

4、Figures 5 and 6 are extremely unclear, please provide a sufficiently clear version in the revision.

Thanks for your comment. Figure 5 and Figure 6 were changed.

5、The mathematical expression of Equation 1 seems too complicated and some of the coefficients can be expressed in scientific notation.

Thanks for your comment. The revised manuscript has an explanation of how the mathematical expression was achieved in order to make it clear. Besides that, the coefficients are now expressed in scientific notation.

 

 

Author Response File: Author Response.docx

Reviewer 3 Report

Three main influencing factors of particle size, moisture content, and air ventilation were investigated by experimental study.
The work is interesting and helpful for giving some suggestions on the storage of some agricultural materials. 
Some suggestions are given below.
1)Generally, it is difficult for me to understand your results. How did you get Figure 8, Figure 9, Figure 10 and Figure 11? What is the meaning of “standardized effect”? Such proper nouns should be explained in the text. 
2) The results on every factor should be presented independently, making the results clear. 
3) In your experiments, only the data about temperature were collected. Did you get other data such as the glue gas compositions for supporting your conclusion?
4) For Eq.1, how did you get it? Can you provide some details or the process for it?
5) The measuring process of the smoldering velocity should be presented in section 3 of this manuscript.

Author Response

Response to Reviewer 3 Comments

 

Dear Reviewer,

 

Here we are presenting our explanations for the comments received, which we agree with all. We are also attaching a version of the paper with the highlighted changes since we have kept Word in change-tracking mode.

 

We take this opportunity to thank you for the time and effort you have taken to review our paper. The comments received undoubtedly improved the quality and level of the paper's understanding.

 

We hope this new version is more suitable for publication.

 

Regards,

 

The authors

 

 

Three main influencing factors of particle size, moisture content, and air ventilation were investigated by experimental study.

The work is interesting and helpful for giving some suggestions on the storage of some agricultural materials.

Some suggestions are given below.

1) Generally, it is difficult for me to understand your results. How did you get Figure 8, Figure 9, Figure 10 and Figure 11? What is the meaning of "standardized effect"? Such proper nouns should be explained in the text.

Thanks for your comment. Figure 8, Figure 9, Figure 10, and Figure 11 were obtained from the software Minitab, where it was developed the Design of Experiments (DOE). In order to clarify this part to the reader, part of the text was rewritten, as indicated in line 397.

"The tests were performed, varying the selected factors according to the values specified. After running the tests and calculating smoldering velocity in each case, all data were inserted in Minitab to continue with DOE analysis. Afterward, it was possible to produce some graphs in this software to analyze the influencing factors and smoldering velocity."

Regarding the term "standardized effect" is a well-known term related to the Pareto analysis. The Pareto chart of the standardized effects compares the relative magnitude and the statistical significance of both main and interaction effects. Basically, it compares the t-statistic from each factor to the value corresponding to the error. However, this was also briefly explained in this revised manuscript, as seen in line 426.

"Figure 9 shows the Pareto Chart of the standardized effects that evaluate the effects of each influencing factor on smoldering velocity, which compares the relative magnitude and the statistical significance of both main and interaction effects. The standardized effect compares the t-statistic from each factor to the value corresponding to the error."

 

2) The results on every factor should be presented independently, making the results clear.

Thanks for your comment. From the Pareto Chart, each factor's influence can be verified independently. The following graphs provided by the software Minitab are always presented to observe the impact of more than one factor on the response, which can be verified in line 431.

"This graph evaluates the effects of each factor alone and the effects of more than one factor acting on the process. The factor with the most significant influence on smoldering propagation is the particle diameter, followed by the moisture content of the material. It is worth emphasizing that the impact of the material size is almost twice more significant than the influence of the moisture content. Also, according to Pareto Chart, the effect of two or more factors together is not so relevant."

 

3) In your experiments, only the data about temperature were collected. Did you get other data such as the glue gas compositions for supporting your conclusion?

Thanks for your comment. Since the design of experiments (DOE) was used to plan all the tests to show the influence variables' effects on the temperature inside the pile, only this property was measured. For this reason, only the temperature was measured.

 

4) For Eq.1, how did you get it? Can you provide some details or the process for it?

Thanks for your comment. Some details of the process of achieving equation 1 are provided in this revised manuscript, which can be seen in the following paragraph (line 490).

"Besides the plots, running the experimental design in Minitab provides a linear regression equation (Equation 1) based on the data plugged into the software. The equation represents the contributions of the three influenced factors (Diameter – D, Moisture – M, Air ventilation – V) along with the three two-factor interactions (DM, MV, DV) and one three-factor interaction (DMV). Thus, this linear regression equation provided by the full-factorial experiment can be used to represent the smoldering process."

 

 

5) The measuring process of the smoldering velocity should be presented in section 3 of this manuscript.

Thanks for your comment. The measuring process of the smoldering velocity is presented more clearly in this revised manuscript, which can be seen in the following paragraph (line 328).

"The velocity at which smoldering propagates was defined according to the data gathered from the temperature evolution graphs. First, for each thermocouple positioned along the central axis of the fuel bed, it was verified the time taken to reach a temperature of 350 °C. Then, with all the points of each thermocouple, a regression line was built, and the slope of the regression line quantifies the smoldering velocities. This process was repeated for each test, allowing us to achieve each condition's smoldering velocity."

 

 

 

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Nice work.

Reviewer 3 Report

I have no questions about the revised manuscript.