Study on the Influence of EGR on the Combustion Performance of Biofuel Diesel at Different Ambient Simulated Pressures

Round 1

Reviewer 1 Report

The contents of the mauscript are very interesting and the results presented in a clear and rigorous way. I recommend it for publication with some comments to improve its quality:

• Introduction must be absolutely improved. An overview of the state of the art on the use of EGR technology should be included. Furthermore, I recommend inserting a flow-chart that better summarizes the experimental program of this work

• Can the authors specify how they determined the physicochemical properties of the fuels? Datasheet or experimentally evaluated?

• "r/min" is not suitable unit of measure. Please, use "rpm"

• The results are presented in a very clear and orderly manner. Well done! Just two observations:
  1) The dotted legends of the histograms (Figures 9-10-11-12) are very similar when comparing "100kPa 16% ERG", "81kPa 0% ERG" and "81 kPa 16% ERG". I recommend changing them.
  2) To get an idea of the performance of the technology, it might be useful to insert technical reference indicators that indicate the quality of the fuels. According to the purposes of "Sustainability"  journal, this aspect should be emphasized, especially in terms of emissions.

• What are the future developments of the work? please implement the conclusions

Author Response

Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Study on the Influence of EGR on the Combustion Performance of Biomass Diesel at Different Altitudes”. (1272050). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval. Revised portion are marked in blue in the paper.

With respect to other reviewer’s comments and the main corrections in the paper are as flowing:

Author Response File: Author Response.pdf

Reviewer 2 Report

Dear Authors,

The reviewed manuscript entitled “Study on the Influence of EGR on the Combustion Performance of Biomass Diesel at Different Altitudes” contains analyses related to the evaluation of the influence of EGR rate and atmospheric pressure on the environmental and operating parameters of a compression ignition engine.

The article is interesting, but I believe that the manuscript in its current version should not be accepted for publication. I recommend that the reviewed paper be accepted for publication after major revisions. In order to improve the quality of the article, I propose to take into account detailed remarks:

• Abstract: It should emphasize the novelty of the manuscript.
• Introduction: The paper lacks adequate literature analysis and reference of the presented results to the works of other authors. The problem of research on biofuel powered diesel engines is presented in a very large number of scientific articles. It would be beneficial to refer to their results.
• Experimental equipment and methods: Please provide a more detailed description of the CEM101 device. What is its purpose. Provide a precise description of the measurement methodology.
• Experimental equipment and methods: How was the change in ambient pressure implemented? Was the pressure value of 100 kPa actually the ambient pressure value or was it simulated? This question should be clarified. If the ambient pressure value was simulated, it should be clearly described in the body of the article. The simulation does not fully represent the parameters obtained by the engine as in conditions of real change of ambient pressure. In this case, the conclusions concerning the influence of the atmospheric pressure on the analyzed parameters are incorrect and need to be corrected. Moreover, the title of the article should also be corrected as the tests were not carried out, for example, in a mobile laboratory allowing tests at different altitudes.
• Experimental equipment and methods: What is the measurement accuracy of the analyzed quantities. For example, how was the emission of pollutants measured - are the values presented in the graphs averaged for a given point of engine operation and a given time? What is the uncertainty of their measurement?
• Experimental equipment and methods: What was the reason for adopting an EGR factor of 16%? This is the only value adopted for the analysis, and it is also very low. It would be more beneficial to present results for larger differences in the EGR ratio, then its effect on the studied parameters would be clear.
• Experimental equipment and methods: What was the composition of the fuel tested? The description in lines 61 and 62 is incomprehensible: "The blended fuel consisted of 0# diesel oil, 99.5% ethanol, biodiesel (made from waste cooking oil) and B15E5".
• Line 62: What does "0# diesel oil" mean?
• Experimental equipment and methods: What was the reason for accepting fuel of the given composition? Why comparative tests were not carried out when powering the engine with ON? One could compare the results and indicate possible advantages of using a mixture of ON and adopted bio-components.
• Table 3: Were fuel parameters measured by the authors? If yes, on what apparatus? If not, please provide the source of the data.
• Table 1 shows the engine specifications, including the value of maximum engine torque of 260 Nm at 1800 rpm. So how can the authors explain the measured torque values (Figures 1 and 2) above 300 Nm?
• Results and discussions: Due to the lack of stated measurement uncertainty associated with the measured quantities (results), it is difficult to interpret test results correctly. In many cases, the differences between the results are so small that they are certainly within the limits of measurement error.
• The manuscript contains numerous linguistic, stylistic, and editorial errors (e.g. Line 47: „the the”; Table 2: „m3”; Figure 1 and 2: description of the vertical axis “Toqure”; Line 123: “at big load” and “economical degradation of the engine”; Figures 5,6,7 and 8: “Crank angel”). Proofreading of manuscript is required.
• In the manuscript, the authors use the term "Biomass". In my opinion the term "biofuel" would be more appropriate. In addition, the term "r/min" should be replaced by "rpm".
• Conclusions: It is expedient, on the basis of the conducted research, to present the advantages associated with the use of the analyzed fuel in relation to diesel fuel.

Best regards

Author Response

Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Study on the Influence of EGR on the Combustion Performance of Biomass Diesel at Different Altitudes”. (1272050). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval. Revised portion are marked in blue in the paper.

With respect to other reviewer’s comments and the main corrections in the paper are as flowing:

Author Response File: Author Response.pdf

Reviewer 3 Report

Notes are provided in the Annex

Comments for author File: Comments.pdf

Author Response

Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Study on the Influence of EGR on the Combustion Performance of Biomass Diesel at Different Altitudes”. (1272050). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval. Revised portion are marked in blue in the paper.

With respect to other reviewer’s comments and the main corrections in the paper are as flowing:

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Dear Authors,

The reviewed manuscript entitled “Study on the Influence of EGR on the Combustion Performance of Biofuel Diesel at Different Altitudes” in its current version should not be accepted for publication. I recommend that the reviewed paper be accepted for publication after minor revisions. In order to improve the quality of the article, I propose to take into account detailed remarks:

1. After the explanation of ambient pressure simulation as a measure of altitude, it is advisable to change the title of the article. This is because the simulation of ambient pressure cannot be accepted as equivalent to the change in altitude above sea level (it is about air composition - oxygen content). Therefore, an adequate title is: Study on the Influence of EGR on the Combustion Performance of Biofuel Diesel at Different Ambient Simulated Pressures.
2. The parameters of the engine are still in some doubt. On the website of the manufacturer Kunming Yunnei Power Co., Ltd. there is no YN38 series engine with the parameters presented in the manuscript - why? The engines of the specified series have different values of parameters such as: capacity, piston diameter and stroke, maximum power, maximum torque, etc. Due to these doubts it is advisable to attach to the manuscript as additional material - confirmation of the engine data in the form of manufacturer's data sheet.
3. Table 2 - shouldn't the Air mass flow rate 0-800 m³/h be expressed in kg/h?
4. The torque values in Figure 2 are incorrect - they exceed the maximum torque value given for this engine in Table 1, given a speed of 2200 rpm.
5. The legend description in Figures 2 and 3 is missing.
6. The engine torque values in Figure 3 exceed the maximum value given in Table 1.
7. The captions for Figures 2 and 3 should refer to torque and not power performance.
8. Axis descriptions in Figures 6, 7, 8 and 9 are still wrong - "cranck angel".
9. Lines 358 through 362 - sources should be moved to the literature list.
10. Proofreading of the article is advisable.

Best regards

Author Response

Dear Editors and Reviewers,

On behalf of my co-authors, we thank you very much for giving us an opportunity to revise our manuscript again. We are very sorry that there are many small mistakes in our manuscript, we appreciate editor and reviewers very much for their positive and constructive comments and suggestions on our manuscript entitled “Study on the Influence of EGR on the Combustion Performance of Biomass Diesel at Different Ambient Simulated Pressures”. (1272050).

We have studied reviewers' comments carefully and have made revision. We have tried our best to revise our manuscript according to the comments. According to the revised requirements, the revisions have been marked up using the “Track Changes” function. Please find the attached revised version, which we would like to submit for your kind consideration. 

We would like to express our great appreciation to you and reviewers for comments on our paper. Looking forward to hearing from you.

Thank you and best regards.

Yours sincerely,

Zefei Tan (on behalf of co-authors)

E-mail: [email protected]

Author Response File: Author Response.pdf

Reviewer 3 Report

I have no comments to the authors

Author Response

Dear Editors and Reviewers,

On behalf of my co-authors, we thank you very much for giving us an opportunity to revise our manuscript again. We are very sorry that there are many small mistakes in our manuscript, we appreciate editor and reviewers very much for their positive and constructive comments and suggestions on our manuscript entitled “Study on the Influence of EGR on the Combustion Performance of Biomass Diesel at Different Ambient Simulated Pressures”. (1272050).

We have studied reviewers' comments carefully and have made revision. We have tried our best to revise our manuscript according to the comments. According to the revised requirements, the revisions have been marked up using the “Track Changes” function. Please find the attached revised version, which we would like to submit for your kind consideration. 

We would like to express our great appreciation to you and reviewers for comments on our paper. Looking forward to hearing from you.

Thank you and best regards.

Yours sincerely,

Zefei Tan (on behalf of co-authors)

E-mail: [email protected]

Author Response File: Author Response.pdf