Experimental Evaluation of the Influence of the Diameter of the Outlet Nozzle Bore of a Gas Injector on Its Flow Characteristic
Round 1
Reviewer 1 Report
The authors investigated the flow characteristics of differently designed low-pressure gas-phase injectors. The work is systematic and well-reasoned. The introduction gives a comprehensive view on the need for such studies. A few sentences on the possible impact of injector and it's flow characteristics on performance and emissions will tie the introduction nicely. Similarly, the results and discussion section address the differences well.
Author Response
Reviewer#1
Thank you for evaluation of the manuscript. We appreciated the constructive criticisms of the reviewers. We have addressed each of their concerns as outlined below. The paper has been revised .The corrections were with yellow highlighting indicating changes.
Reviewer#1, Concern#0: The authors investigated the flow characteristics of differently designed low-pressure gas-phase injectors. The work is systematic and well-reasoned. The introduction gives a comprehensive view on the need for such studies. A few sentences on the possible impact of injector and it's flow characteristics on performance and emissions will tie the introduction nicely. Similarly, the results and discussion section address the differences well.
Author response: Thank you for your positive review. We have tried to take into account the comments of all reviewers.
Author action: None.
Reviewer 2 Report
Comments for author File: 
Comments.pdf
Author Response
Reviewer#2
Thank you for evaluation of the manuscript. We appreciated the constructive criticisms of the reviewers. We have addressed each of their concerns as outlined below. The paper has been revised .The corrections were with yellow highlighting indicating changes.
Reviewer#2, Concern#0: In this work, the flow characteristics of three injectors operating at a certain frequency and time are determined. The operating temperature is the same; however, the opening and closing timings for each of them are different. Results are presented in a very clear way and the subject also fits the scope of the journal of Applied Sciences. However, some clarifications are required. Below are some suggestions and comments which may help the authors to revise this work. The authors are also encouraged to seek a careful editorial review of the manuscript.
Author response: Thank you for reviewing the manuscript. We have tried to take into account the comments of all reviewers, both from the substantive side as well as from the editorial and linguistic side.
Author action: The manuscript has been revised taking into account the suggestions of all reviewers.
Reviewer#2, Concern#1: Abstract mostly talks about the background and results. However, the objectives and methodology should also be written clearly. I suggest the authors remove generic lines and present the strong statements and novelty of the article.
Author response: Thank you for the suggestion.
Author action: Abstract and generic lines have been changed.
Reviewer#2, Concern#2: A great review of the literature is presented in the Introduction. However, many important pieces of research are ignored. Below books/papers can help authors to polish the literature review part: https://doi.org/10.1201/9781315120911; https://doi.org/10.1016/j.energy.2022.125796; https://doi.org/10.4271/2001-01-1294
Author response: Thank you for the suggestion. We believe that the literature review is extensive as it stands, but we would be happy to add brief descriptions as indicated by the Reviewer.
Author action: The text has been completed.
Reviewer#2, Concern#3: In Figure 12, different pressure waveforms at the outlet of the injector nozzle are seen. Is it possible, in the future, to make the same pressure waveform for each of the injectors to compare the flow characteristics more comprehensively? This paper can help: 10.1016/j.icheatmasstransfer.2021.105184 4. Can authors comment on the spray characteristics of these injectors?
Author response: Thank you for the suggestion and for pointing out the literature source. Figure 12 shows the pressure waveforms at the nozzles of the tested injectors measured with a special sensor (https://doi.org/10.1016/j.measurement.2018.01.045) at the same supply pressure. The differences in waveforms are due to the operation of the injector, that is, the opening and closing times and the instantaneous flow area inside the valve.
Author action: None.
Reviewer#2, Concern#4: Can authors comment on the spray characteristics of these injectors?
Author response: Thank you for your suggestion. For the moment, we are running CFD calculations and ultimately plan to compare this with an experiment. Unfortunately, due to the fact that the research is conducted with air, it is necessary to introduce dye as a boundary.
Author action: None.
Reviewer#2, Concern#5: The language of the manuscript is fair; however, I would advise consulting a language editor to further polish the language of the manuscript. There are several grammatical mistakes and instances “a”, “an” and “the” should be used with utmost care. Please work closely to a native English speaker to refine the language of this paper.
Author response: We apologize for our oversights and grammatical errors.
Author action: The text has undergone a thorough linguistic correction.
Reviewer#2, Concern#6: This reviewer wants to see more about the injector specifications. L/D ratio, Sac Chamber Volume?
Author response: Thank you for your suggestion. Unfortunately, manufacturers do not provide such parameters as plunger stroke, head valve diameter or chamber volumes in the technical data. The flow value here is determined by the diameter of the outlet nozzle. Hence the addressing of this topic in the manuscript.
Author action: None.
Reviewer#2, Concern#7: Is it possible to do an internal flow simulation of these injectors to also compare the internal flow characteristics?
Author response: Thank you for your suggestion. Regarding CFD calculations, preliminary attempts have already been made for another type of injector (https://doi.org/10.3390/s21010234). Ultimately, it is planned to carry out calculations for the injectors presented in the study for comparison in future publications.
Author action: None.
Reviewer 3 Report
The research manuscript entitled “Experimental evaluation of the influence of the diameter of the 2-outlet nozzle bore of a gas injector on its flow characteristic” is not written in proper manner. Needs to be restructure. More explanation is required while interpreting the details given literature to strengthen the background of the work. The physics behind the gas flow needs to be discussed in detail. The novelty of the work needs to be mentioned in the manuscript. As the research work conducted on air flow through the injector, why gas has been included in the Title of the manuscript?
Line 22: Differences in opening times where differences of 29.3% and 36.6% were obtained were identified as one of the reasons for this condition- Restructure the sentence.
Avoid the grouping of References [5-7], [32-34], [35-37].
What was the basis of selecting low pressure injector? Needs to be mentioned in the manuscript.
Line 106: The last…… Restructure the sentence.
Line 128: What was the pressure of compressed air?
It is suggested that Section 3 &4 should be combined.
Line 127: As the test were conducted with air instead of gas, how the obtained results may be claimed for operation of injector with gas?
What changes will be observed if the same experimentation carried out with gas?
How the author have optimized injection pressure? As it is very important parameter, it must be explained in detail at appropriate place in the manuscript.
Have you varied the injection timing to maintain the desired output? If it is, what was the injection pressure?
The influence of change in nozzle diameter on the performance and flow characteristics needs to be discussed in detail manner.
I feel, the title and keywords are not perfectly matching the present research work.
General Comments on entire manuscript: Call all the Figures/ Tables in text while discussion. Many sentences are grammatically wrong, needs to be restructure. Avoid irrelevant references.
Author Response
Reviewer#3
Thank you for evaluation of the manuscript. We appreciated the constructive criticisms of the reviewers. We have addressed each of their concerns as outlined below. The paper has been revised .The corrections were with yellow highlighting indicating changes.
Reviewer#3, Concern#0: The research manuscript entitled “Experimental evaluation of the influence of the diameter of the outlet nozzle bore of a gas injector on its flow characteristic” is not written in proper manner. Needs to be restructure. More explanation is required while interpreting the details given literature to strengthen the background of the work. The physics behind the gas flow needs to be discussed in detail. The novelty of the work needs to be mentioned in the manuscript. As the research work conducted on air flow through the injector, why gas has been included in the Title of the manuscript?
Author response: Thank you for reviewing the manuscript. We have tried to take into account the comments of all reviewers, both from the substantive side as well as from the editorial and linguistic side. Indicating more details in the introduction will significantly increase the volume of the paper, which is not a review. Theoretical descriptions are required for numerical identification or mathematical modeling, which is not the subject of the manuscript. Gas appears in the title because it is a gas injector, and testing is done in the air for safety reasons.
Author action: The manuscript has been revised taking into account the suggestions of all reviewers.
Reviewer#3, Concern#1: Line 22: Differences in opening times where differences of 29.3% and 36.6% were obtained were identified as one of the reasons for this condition- Restructure the sentence.
Author response: Thank you for your suggestion.
Author action: Corrections have been made in the text.
Reviewer#3, Concern#2: Avoid the grouping of References [5-7], [32-34], [35-37].
Author response: Thank you for drawing attention in this regard. Unfortunately, referring to each work individually would significantly increase the volume of the manuscript. In our opinion, the inclusion of a maximum of 3 references in a single reference is not an abuse in this regard, since they represent the same scope.
Author action: None.
Reviewer#3, Concern#3: Line 106: The last…… Restructure the sentence.
Author response: Thank you for your suggestion..
Author action: Corrections have been made in the text.
Reviewer#3, Concern#4: Line 128: What was the pressure of compressed air?
Author response: Thank you for your question. The supply pressure was 1×10^5 Pa, as described in lines 158-161..
Author action: None.
Reviewer#3, Concern#5: Line 127: As the test were conducted with air instead of gas, how the obtained results may be claimed for operation of injector with gas?
Author response: Thank you for your question. In the simplest variant, you can rely on density differences. LPG has a very different composition, so testing is done on air, as it is safe, cheap and available.
Author action: None.
Reviewer#3, Concern#6: What changes will be observed if the same experimentation carried out with gas?
Author response: Thank you for your question. Conducting an experiment on gas is dangerous. It requires special gas expansion systems at the input and chambers with nitrogen at the output. Further, the gas must be burned. Differences in this case will be mainly due to differences in the density of LPG and air and additives in LPG, which can determine the flow and change the boundary layer.
Author action: None.
Reviewer#3, Concern#7: How the author have optimized injection pressure? As it is very important parameter, it must be explained in detail at appropriate place in the manuscript.
Author response: Thank you for your question. Below Table 2 is an explanation of the choice of study parameters - analysis of literature data.
Author action: None.
Reviewer#3, Concern#8: Have you varied the injection timing to maintain the desired output? If it is, what was the injection pressure?
Author response: Thank you for your insights. In sequential vapor phase LPG injection systems, there is no concept of injection pressure, only supply pressure regulated by the regulator. In our case, we kept both supply pressure and injection timing constant.
Author action: None.
Reviewer#3, Concern#9: The influence of change in nozzle diameter on the performance and flow characteristics needs to be discussed in detail manner.
Author response: Thank you for the suggestion, but the effect of nozzle diameter on volumetric flow rate has been described in each case by equations 1, 2 and 3 and additionally from the conclusions.
Author action: None.
Reviewer#3, Concern#10: I feel, the title and keywords are not perfectly matching the present research work.
Author response: Thank you for your suggestion.
Author action: Corrections have been made in keywords.
Reviewer#3, Concern#11: General Comments on entire manuscript: Call all the Figures/ Tables in text while discussion. Many sentences are grammatically wrong, needs to be restructure. Avoid irrelevant references.
Author response: We apologize for our oversights and grammatical errors.
Author action: The text has been thoroughly revised in terms of content and language.
Reviewer 4 Report
The authors conducted a series of measurements of three sets of injectors to study the effect of outlet bore diameter on the injector flow features. Mathematical correlations have been conducted. Metrics such as mass flow rate and opening and closing timings were taken as the research targets. A lot of work has been done. But there are some points that should be addressed before publishing.
1. The background knowledge is not well established. The reviewer was expecting the injector studied in this work could be implemented in marine engine combustion as a fuel gas supply or fuel gas injection. However, it is not clear where these injectors studied in this work could be used. Throughout the paper, the gas was injected at only 1 bar most likely. Please indicate where these injectors can be used, which is a significant point for the readers.
2. Line 203. What is the relative error?
3. Tables 2 and 3. The first letter of the first-column word should be capitalized.
4. The authors have formulated various correlations between the measured mass flow rate and don’. However, there were very few explanations why they exhibited in this way. Especially, when there existed a plateau at a large don’.
5. Is there any advice on which kind of injector is the best for practical applications regarding the response time and peak mass flow rate? Also, how about their cost?
6. In fact, the injector flow feature is highly related to its respective inflow geometry. Providing such a kind of information might be helpful to explain the measured data.
7. The authors mostly measured the injection data at around 1 bar. Have they tested higher injection pressures? Would the high pressure be used in practical applications?
Author Response
Reviewer#4
Thank you for evaluation of the manuscript. We appreciated the constructive criticisms of the reviewers. We have addressed each of their concerns as outlined below. The paper has been revised .The corrections were with yellow highlighting indicating changes.
Reviewer#3, Concern#0: The authors conducted a series of measurements of three sets of injectors to study the effect of outlet bore diameter on the injector flow features. Mathematical correlations have been conducted. Metrics such as mass flow rate and opening and closing timings were taken as the research targets. A lot of work has been done. But there are some points that should be addressed before publishing.
Author response: Thank you for reviewing the manuscript. We have tried to take into account the comments of all reviewers, both from the substantive side as well as from the editorial and linguistic side.
Author action: The manuscript has been revised taking into account the suggestions of all reviewers.
Reviewer#1, Concern#1: The background knowledge is not well established. The reviewer was expecting the injector studied in this work could be implemented in marine engine combustion as a fuel gas supply or fuel gas injection. However, it is not clear where these injectors studied in this work could be used. Throughout the paper, the gas was injected at only 1 bar most likely. Please indicate where these injectors can be used, which is a significant point for the readers.
Author response: Thank you for your suggestion. The tested injectors are commonly used in alternative car power systems. An addendum is included before Table 1.
Author action: Corrections have been made in the text.
Reviewer#4, Concern#2: Line 203. What is the relative error?
Author response: Thank you for your insightful analysis. In line 203 was written Root Mean Square Error – RMSE = sqrt (sum (Dates - Scores)^2) / Dates.
Author action: None.
Reviewer#4, Concern#3: Tables 2 and 3. The first letter of the first-column word should be capitalized.
Author response: Thank you for pointing out this editing detail.
Author action: Corrections have been made in the tables.
Reviewer#4, Concern#4: The authors have formulated various correlations between the measured mass flow rate and don’. However, there were very few explanations why they exhibited in this way. Especially, when there existed a plateau at a large don’.
Author response: Thank you for your insightful analysis. A description of the possible cause is provided under Table 6.
Author action: None.
Reviewer#4, Concern#5: Is there any advice on which kind of injector is the best for practical applications regarding the response time and peak mass flow rate? Also, how about their cost?
Author response: Thank you for your question. Of course, the best injector would be the one with the shortest opening and closing time. With a magnetic coil drive, the coil would have to be large, or a high control voltage and a stiff compression spring. As another example, piezoelectric drive can be used. Of course, a "high-speed" insertion device will be very expensive and will require specific electrical supply conditions..
Author action: None.
Reviewer#4, Concern#6: In fact, the injector flow feature is highly related to its respective inflow geometry. Providing such a kind of information might be helpful to explain the measured data.
Author response: Thank you for your suggestion. Unfortunately, manufacturers do not provide such parameters as plunger stroke, head valve diameter or chamber volumes in the technical data. The flow value here is determined by the diameter of the outlet nozzle. Hence the addressing of this topic in the manuscript.
Author action: None.
Reviewer#4, Concern#7: The authors mostly measured the injection data at around 1 bar. Have they tested higher injection pressures? Would the high pressure be used in practical applications?
Author response: Thank you for your question. The pressure of 1 bar was chosen because of the use of this type of insertion in automotive power systems. Table 1 shows the limiting conditions of gas supply. As shown in many publications, the higher the gas pressure, the longer the opening time and the shorter the closing time (https://doi.org/10.2478/ama-2020-0026).
Author action: None.
Round 2
Reviewer 2 Report
Accept in present form.
Reviewer 3 Report
Accept
