Simulation Study on Gas Leakage Law and Early Warning in a Utility Tunnel

Round 1

Reviewer 1 Report

 In this paper, based on the utility tunnels of Beijing Winter Olympic Games, the Fluent simulation software is used to establish the simulation model through the relevant fluid mechanics theory, and the physical relationship of relevant parameters is demonstrated theoretically. Several results are found as: (1) When gas leakage occurs from the gas pipeline of the utility tunnel, it is a dynamic process. (2) When the ventilation system of the gas chamber is natural ventilation without accidents, if a leakage accident occurs, even 12 ventilation operations per hour cannot guarantee that the gas concentration in the chamber is lower than 20 percent of the lower explosion limit. Therefore, the gas chamber must maintain daily mechanical ventilation at least 6 times per hour. (3) If the gas in the gas chamber leaks, corresponding measures need to be taken in time to reduce disaster losses. When the leakage does not exceed 20 percent of the lower limit of the gas explosion, workers can be sent directly into the chamber to make repairs such as welding. When the leakage is between the upper and lower limits of the gas ex-plosion, it is necessary to turn off the gas source and turn on the emergency ventilation system to remove the gas. But there have no field survey data to compare in the paper, it is the biggest drawback for the research. Beside this, there are many type mistakes which should be removed before accepted to be published.

1)     There are many Chinese square brackets “【33】”, which should be replaced by English Chinese square bracket in page 1 to Page 3.

2)     Literature review should be presented according to developing relationship of simulation method, focusing point, or others, rather than list results one by one.

3)     Figures and tables should be illustrated unified, fig.13 is larger than figure 12.

4)     Fig.15 has been missed.

5)     Language should be improved before published.

 In this paper, based on the utility tunnels of Beijing Winter Olympic Games, the Fluent simulation software is used to establish the simulation model through the relevant fluid mechanics theory, and the physical relationship of relevant parameters is demonstrated theoretically. Several results are found as: (1) When gas leakage occurs from the gas pipeline of the utility tunnel, it is a dynamic process. (2) When the ventilation system of the gas chamber is natural ventilation without accidents, if a leakage accident occurs, even 12 ventilation operations per hour cannot guarantee that the gas concentration in the chamber is lower than 20 percent of the lower explosion limit. Therefore, the gas chamber must maintain daily mechanical ventilation at least 6 times per hour. (3) If the gas in the gas chamber leaks, corresponding measures need to be taken in time to reduce disaster losses. When the leakage does not exceed 20 percent of the lower limit of the gas explosion, workers can be sent directly into the chamber to make repairs such as welding. When the leakage is between the upper and lower limits of the gas ex-plosion, it is necessary to turn off the gas source and turn on the emergency ventilation system to remove the gas. But there have no field survey data to compare in the paper, it is the biggest drawback for the research. Beside this, there are many type mistakes which should be removed before accepted to be published.

1)     There are many Chinese square brackets “【33】”, which should be replaced by English Chinese square bracket in page 1 to Page 3.

2)     Literature review should be presented according to developing relationship of simulation method, focusing point, or others, rather than list results one by one.

3)     Figures and tables should be illustrated unified, fig.13 is larger than figure 12.

4)     Fig.15 has been missed.

5)     Language should be improved before published.

Author Response

Dear reviewer：

Thank you for your letter dated October 3. We thank the reviewers for the time and effort that they have put into reviewing the previous version of the manuscript. Their suggestions have enabled us to improve our work. Based on the instructions provided in your letter, we uploaded the file of the revised manuscript. Appended to this letter is our point-by-point response to the comments raised by the reviewers. We would like also to thank you for allowing us to resubmit a revised copy of the manuscript. We hope that the revised manuscript is accepted for publication in the Journal of Sustainability.

1)There are many Chinese square brackets “【33】”, which should be replaced by English Chinese square bracket in page 1 to Page 3.

Thank you for your suggestion on the reference numbering, and we apologize that we mistakenly used Chinese brackets for it before. We have changed all of them to English format in the new revised version.

2)Literature review should be presented according to developing relationship of simulation method, focusing point, or others, rather than list results one by one.

In the literature review section, we have redescribed the literature review according to the logical progression of advantages and disadvantages (risks) of utility tunnels, gas accidents and gas leakage patterns. Unnecessary literature has been simplified and the process of forming ideas for writing the text has been highlighted.

3)Figures and tables should be illustrated unified, fig.13 is larger than figure 12.

In response to the layout style of the journal, we have harmonized the images and formulas of the original manuscript to make them more compatible with the current layout presentation.

4)     Fig.15 has been missed.

We were really sorry for our careless mistakes. Thank you for your reminder.  Based on the reviewers' suggestions, we have added the missing analyzed Figure 15.

5)     Language should be improved before published.

Thanks for your suggestion. We invited a friend of us who is a native English speaker from the USA to help polish our article.

Finally, we would like to thank you again for your careful review. And we hope the revised manuscript could be acceptable for you.

Best wishes to you!

Ru Wang

Reviewer 2 Report

1. The equation and figure should be adjusted to the clear.

2. What the difference the utility tunnel with the simulaton model?

3. How did you define the leakage time?

4. How did you deal with the equation with the transition of the critical flow?

5. The results should be futher decrease to three critical points. 

Minor English should be changed, especially in the grammar. 

Author Response

Dear reviewer：

Thank you for your letter dated October 3. We thank the reviewers for the time and effort that they have put into reviewing the previous version of the manuscript. Their suggestions have enabled us to improve our work. Based on the instructions provided in your letter, we uploaded the file of the revised manuscript. Appended to this letter is our point-by-point response to the comments raised by the reviewers. We would like also to thank you for allowing us to resubmit a revised copy of the manuscript. We hope that the revised manuscript is accepted for publication in the Journal of Sustainability.

1)The equation and figure should be adjusted to the clear.

In response to the layout style of the journal, we have harmonized the images and formulas of the original manuscript to make them more compatible with the current layout presentation. We apologize that previously the images in the first manuscript did not correspond to the numbering of the images, causing problems with understanding. We have recoded the full text images and formulas and corresponded them to the appropriate content.

2)What the difference the utility tunnel with the simulaton model?

For the relationship between the real utility tunnel and the simulation model we have also redescribed it in the paper. The simulation model is an abstract simplification of the real object and is a virtual approach to reality in order to categorize and analyze certain factors more easily. The representation of the real utility tunnel is realized by means of relevant assumptions in order to quantify the calculation of the indicators.

3)How did you define the leakage time?

In this paper, leakage time is defined as the time from the moment of rupture of the gas pipe wall, including the subsequent continuous leakage process, and is calculated using seconds as the unit.

4)How did you deal with the equation with the transition of the critical flow?

Since the critical flow process flow rate will be much faster and have a greater impact on the gas cabin, this paper mainly analyzes the critical flow process of leakage when the leakage process is studied. It is also due to the fact that although the subcritical flow lasts for a long time, the logistic parameters at each point in the process do not change much. From the perspective of the overall process to consider the change is negligible, so the actual process is simulated and analyzed in line with the critical flow logistics relationships.

5)The results should be futher decrease to three critical points.

We have streamlined the original conclusions to three, which are organized from three perspectives: leakage patterns, ventilation patterns, and sensor deployment. The practical implications of each conclusion are elaborated in order to make the conclusions clearer as a whole.

Finally, thank you again for your careful review. And hope that the correction will meet with approval.

Best wishes to you!

Ru Wang

Reviewer 3 Report

Overall, your paper shows promise, but there are some areas that could be improved for a more focused and technically sound presentation:

Excessive Figures: Consider reducing the number of figures in your paper. For instance, figures from Fig 14 to Fig 30 may not all be necessary. Additionally, ensure that all figures are relevant to your paper's core message.

Missing Figures: Some critical figures appear to be missing, and their inclusion would enhance the paper's comprehensiveness.

Introduction Length: The introduction appears quite lengthy. While the length itself isn't an issue, it's essential to maintain relevance. Ensure that all information in the introduction directly relates to the paper's field and topic.

Conclusion: The conclusion section needs to be expanded. It should provide a more comprehensive summary of the paper's key findings and their significance.

Technical Presentation: Aim for a more technical presentation throughout the paper. While the topic is interesting, refining the technical aspects of your writing will make it more accessible to an audience of experts in the field.

By addressing these points, you can elevate the quality and impact of your paper. Keep in mind the need for clarity and precision throughout the document.

Author Response

Dear reviewer：

Thank you for your letter dated October 3. We thank the reviewers for the time and effort that they have put into reviewing the previous version of the manuscript. Their suggestions have enabled us to improve our work. Based on the instructions provided in your letter, we uploaded the file of the revised manuscript. Appended to this letter is our point-by-point response to the comments raised by the reviewers. We would like also to thank you for allowing us to resubmit a revised copy of the manuscript. We hope that the revised manuscript is accepted for publication in the Journal of Sustainability.

1)Excessive Figures: Consider reducing the number of figures in your paper. For instance, figures from Fig 14 to Fig 30 may not all be necessary. Additionally, ensure that all figures are relevant to your paper's core message.

Thank you very much for the reminder, and we apologize that the numbering in our last version of the manuscript regarding Fig 14- Fig 30 did not correspond to the contents of the figures, thus causing some misunderstanding. We have re-examined all the images and formulas and have made a one-to-one correspondence with the content. In response to the layout style of the journal, we have harmonized the images and formulas of the original manuscript to make them more compatible with the current layout presentation.

2)Missing Figures: Some critical figures appear to be missing, and their inclusion would enhance the paper's comprehensiveness.

We were really sorry for our careless mistakes. Thank you for your reminder. Based on the reviewers' suggestions, we have added the missing analyzed Figure 15.

3)Introduction Length: The introduction appears quite lengthy. While the length itself isn't an issue, it's essential to maintain relevance. Ensure that all information in the introduction directly relates to the paper's field and topic.

In response to the problem that the introduction of the previous version of the manuscript was long and lacked a certain logic, we have reduced the original introduction by removing and re-describing unnecessary content and highlighting the logic of the writing.

4)Conclusion: The conclusion section needs to be expanded. It should provide a more comprehensive summary of the paper's key findings and their significance.

We have streamlined the original conclusions to three, which are organized from three perspectives: leakage patterns, ventilation patterns, and sensor deployment. To make the conclusions clearer and more meaningful, we have enriched each conclusion with practical implications.

5)Technical Presentation: Aim for a more technical presentation throughout the paper. While the topic is interesting, refining the technical aspects of your writing will make it more accessible to an audience of experts in the field.

In order to make the article read more professionally, we have described the meshing and simulation modeling process in more detail in the original content and replaced the original images.

Finally, thank you again for your careful review. And we hope the revised manuscript could be acceptable for you.

Best wishes to you!

Ru Wang

Round 2

Reviewer 1 Report

No more comments

No more comments