Study of the Variation of Fuel Pressure to Improve Spraying and the Range of the Injection Jet

Round 1

Reviewer 1 Report

This paper studied the relationship between the variation of the injection pressure of the fuel supply in MPI systems and the performance of improving the spraying and range of the injection jet. The work mathematically defined and then solved the problems. The solution was implemented in practice. The proposed method is novel. The manuscript is well written and the explanation is clear. I recommend acceptance of this submission.

Author Response

Dear reviewer, thank you for your time, the text has been modified according to the suggestions and comments of reviewers 2 and 3.

Kind regards

Reviewer 2 Report

The authors conducted an experimental study to examine the effects of injection pressure, injection pulse, and engine speed on the mass flow rate and spray angle of the fuel supply system on a commercial MPI system. The experimental equipment and approach were described in detail and the results look reasonable. The topic of the current work is relevant to the interests of engine researchers, so it can be published after appropriate revisions.

1. In the introduction, the authors must further highlight the novelty of this work and the reasons to justify why they conducted this research. There should be some other researchers who have performed similar studies. What are their new findings that are significant and different from this work?

2. Language in the first several paragraphs is fine. But thereafter there are many grammar typos and the language is not fluent, making it difficult to understand. To improve the quality of this paper and make it sufficient to be published in the journal, the authors should make more efforts in refining the language of the whole manuscript. There are some grammar software that might help, such as Grammarly (free).

3. Table 1. ‘High pressure pump’ has an overlap issue. Line 147: ‘3.5bar to 4bar’ should be ‘3.5 to 4 bar’. Line 528, ‘this because’ should be ‘this is because’.

4. In section 2.1.2, it is not clear how many injectors the authors used. Is it 4 or 1? Are they measured simultaneously (in total) or sequentially (separately)? In Table 4, 4 injectors are mentioned.

5. In section 2.2, from lines 160 to 162, the authors mentioned ‘In the tests carried out the parameters of the vehicle, emissions, fuel consumption of the engine were obtained, in each test an operation of data measured in the GT-600-PRO bank was established’. But the measured emissions are not reported at all.

6. Line 169, ‘in most of the processes of institutional evaluation of universities’, and line 171 ‘as one more function within the overall evaluation of the institution’ are difficult to understand. Please rephrase the sentences.

7. Is the injection pressure fixed in the real engine (Kia or Hyundai, for instance) or within a specific range?

8. The authors have not reported the details of the control software or ECU type.

9. In fact, the authors may not measure the real injection pressure and injection duration. The reported injection pressure and pulse could be input signals determined by the ECU. Please comment.

10. It is still difficult to understand the difference between the injection and spray angle from Figure 6. Commonly, the spray angle should be the spray-included angle. Is the injection angle indicating the tilted rotation angle of the injector?

11. In equation 1, is there any theoretical explanation of how the authors come up with this kind of correlation? It is challenging to understand why the fuel flow rate has a relation with spray angle…

12. The reviewer could not see the importance of equations 2-8. The authors have not used these equations in their correlation model at all.

13. From Figs. 7 to 10, there are so many points that it is difficult to see which parameters are fixed and which are varied. Please indicate these variables in the corresponding figure. In addition, considering the parameters are varied, why not depict the line plot instead of the scatter plot? In this way, it is easier to identify the law of change.

14. In the discussion section, it is not clear how many points the authors have calculated and their corresponding conditions.

15. Figure 11. Why not just plot the line-symbol figure instead of the bar figure?

16. In fact, the measurement in this work should be quite different from the real engine operating conditions where the intake flow field might have a significant impact on the jet behavior such as the spray angle. Please comment on why the authors have a special interest in the spray angle and they have implemented this variable in Equation 1.

17. Minor suggestion. In the introduction, the authors may consider referencing the following publications regarding the injector model development (Int. J. Engine Res. 24 (2023) 595-609) and injection modeling (Fuel 331 (2023) 125759).

The English should be carefully re-checked and improved.

Author Response

Dear reviewer, thank you for your time, the text has been modified according to your suggestions and comments. Please see the attachment.

Kind regards

Author Response File: Author Response.pdf

Reviewer 3 Report

Thank you for submitting your manuscript, number energies-2478713, entitled " Study of the Variation of the Injection Pressure of the Fuel Supply in MPI Systems to Improve the Spraying and Range of the Injection Jet". After careful consideration and review of your manuscript, I have found that there are major issues that need to be addressed. The main issue is that this manuscript is presented in a thesis style, not a research paper style. Here are my comments:

• Avoid using unknown or undefined abbreviations in titles or abstracts, such as MPI. At this point, the reader does not recognize what this stands for. Use the word in full.
• The paper title needs to be changed. The paper title is too long. A short, concise title is recommended.
• The abstract (lines 15–27): A very long introductory statement is used. One or two sentences should be enough. The abstract should have the following in this order: An introductory statement (which should present a research challenge and is currently too long) that leads to an objective statement, then a description of the experimental method (currently missing), what are the tested parameters (currently missing), results, and major conclusions (currently missing). Please revise and edit the abstract accordingly.
• Section number "2. Materials and Methods" isn’t in its best form. For example, "2.1 Instrumentation" and "2.2.2. Experimental Design" should all be combined and merged under "experimental setup," which describes in detail the overall setup and also the specs of every component. Also, "experimental conditions" should be described as a single section, but it is somehow missing between "2.3. Measurement Protocol" and "2.4. Data Logging".
• Section "3.1 Mathematical Model with Suggested Statistical Basis" This section should be presented in the methodology section, not "results and discussions."
• Between lines 346–357, why did the authors describe the figure legend within the text? Figure 7 already contains a legend that does the same thing. The same comment applies to lines 406-417.
• All figures in the results and discussion sections are not clear. The scatter symbols are too big and overlapping, and it is hard to draw any conclusions from these graphs.
• The current paper is not in research paper format. It is more like a thesis format, which isn’t acceptable as a research paper. Authors should put this paper in research paper format before considering it for publication.

Based on the previous comments, I don’t recommend this paper for publication in Energies.

The English language needs to be improved

Author Response

Dear reviewer, thank you for your time, the text has been modified according to your suggestions and comments. Please see the attachment.

Kind regards

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The authors have well replied to the reviewers' comments. It can be accepted in the current form.

Reviewer 3 Report

The authors have addressed all comments