Performance Optimization and Knock Investigation of Marine Two-Stroke Pre-Mixed Dual-Fuel Engine Based on RSM and MOPSO
Round 1
Reviewer 1 Report
The paper investigates the Performance of marine dual fuel engine based on RSM and MOPSO. Some comments ca be considered during the revision as follows:
1. This type of methodology has been previously used in several papers, the authors need to clarify the novelty of the work.
2. Figure 1 needs improvement.
3. Figures 7-10 for which operating point?
4. English language needs improvements
5. The authors need to clarify and describe more if they perform optimization using RSM or direct coupling with the software. Did the authors see a high accuracy results using RSM?
6. It will be interesting to predict the engine performance along the engine load diagram and not only 3-4 operating points.
7. I think it will be interesting to add the computation of exhaust emissions (CO2, NOx, Sox)
8. Why the authors use particle swarm optimization and not another optimizer?
9. The authors can describe more about the combustion process, including the Wiebe function, HRR, etc.
10. The authors can describe more about the injection process, like the injection profile, injection timing, and fuel rate for main and pilot fuel.
11. What are the characteristics of the fuel used?
12. The authors can present more information about the volume of the intake and exhaust system, manifold, and ports, Scavenge, How they collected these data and what are the values?
13. The authors as well can present more information about the turbocharger and maps of the turbo as well as the Air cooler.
14. What is the software used to perform optimization procedures?
Author Response
Dear Reviewer,
We would like to thank you for giving us constructive suggestions which would help us both in English and in depth to improve the quality of the paper. We resubmit a new version of our manuscript with the title “Performance optimization and knock investigation of marine two-stroke pre-mixed dual-fuel engine based on RSM and MOPSO”, which has been modified for the suggestions made.
The modified contents of the revision have been marked in green color. Detailed responses are listed in the attachment "Rasponse for reviewer1", and we really appreciate your valuable comments.
Please see the attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Manuscript ID: jmse-1916549
Manuscript title: Performance optimization and knock investigation of marine 2 two-stroke pre-mixed dual-fuel engine based on RSM and 3 MOPSO
Comments
The manuscript deals with an interesting topic - multi-objective optimization of four fuel injection parameters on the performance of a dual fuel engine. However, the research methodology, especially the engine simulation method, lacks sufficient scientific soundness. Some subjects should be addressed, as commented below.
1. Figure 1 should be should be moved to the section ‘Modeling Methodology’.
2. In Table 1 the number of cylinders is 7, while only 6 cylinders are involved in the firing sequence. In addition, engines with 7 cylinders are rarely found in practice.
3. The Vibe empirical combustion model was used for performance simulation of a dual fuel engine and investigation of the effect of fuel injection parameters. However, the Vibe model is insufficient to capture the combustion characteristics of dual-fuel engines and the effect of injection parameters on combustion. Because the constants of the Vibe model have to be changed with injection parameters variation to reproduce combustion process close to real ones. For the combustion process of a dual fuel engine, the interaction between diffusion combustion of pilot fuel and premixed combustion of gas fuel, which is out of the capabilities of the Vibe model, must be considered. The author should consider applying another 1-D combustion model (such as DI-jet combined with Si-turb model in GT-power) and CFD combustion model (such as ECFM-3Z, chemical kinetics).
4. Engine simulation model was only calibrated for net diesel operating mode and gas operating mode. It is very interesting, whether the constant values in the simulation models for net diesel operating mode and gas operating mode are the same?
5. How was the gas fuel injected? Port injection, direct injection? How was the adjustment of gas injection pressure realized during simulations?
6. RI model must be calibrated!
7. In Fig. 5, are the ranges of the two left horizontal coordinates the same?
8. In Fig. 7, how can SOC be in g/kw∙h?
9. In line 263 “ignition delay period became longer with the advance of SOC”. Does the author mean SOC or SOI? SOC – start of combustion. SOI – start of injection.
10. What is ‘terminal mixture’ in line 269? The author should use accepted technical terms.
11. In lines 270-271, ‘ignition area in the cylinder will increase so that the cylinder pressure will fluctuate violently and the knocking intensity increases’. The Vibe model cannot capture the variation of ignition area.
12. In lines 273-274, ‘The higher natural gas pressure will increase the turbulent kinetic energy of the mixed gas in the cylinder, which is conducive to more uniform fuel-air mixing, making…’. An unreasonable explanation is given for the obtained simulation results. The Vibe model cannot take into account the influence of turbulence on the flame speed.
Author Response
Dear Reviewer,
We would like to thank you for giving us constructive suggestions which would help us both in English and in depth to improve the quality of the paper. We resubmit a new version of our manuscript with the title “Performance optimization and knock investigation of marine two-stroke pre-mixed dual-fuel engine based on RSM and MOPSO”, which has been modified for the suggestions made.
The modified contents of the revision have been marked in green color. Detailed responses are listed in the attachment "Response for reviewer 2", and we really appreciate your valuable comments.
Please see the attachment.
Author Response File: Author Response.docx
Reviewer 3 Report
The studies presented in the publication related to the knocking phenomena and engine performance optimization of marine 2-stroke dual-fuel engines. The topic is relevant and fully corresponds to the subject matter of the “Journal of Marine Science and Engineering” journal.
The material of the article is presented in a logical sequence; in general, adhering to the recommendations of the journal, the research results are highlighted clearly and reasonably.
At the same time, some separate structural additions and a number of clarifications of technological aspects of the article material should be made:
- Novelty: The authors partly stated what motivated the idea portrayed in this study, what then does this study offer beyond the recent advances made on the combined approaches? I would advise the authors to carefully carry out a close comparison as well in the discussion section to enumerate the advantages this study offers over other related works.
- Most of the ideas written were already described in many literatures. The Authors tried to compile it but lack of the enhancement of the interrelation analysis between the references. It is advised that the authors give a deeper analysis of how these ideas become more applicative strategies so that they can contribute to the next step of implementation.
- Introduction provides a great overview and introduces the topic. However, it misses the aim of the study or what is going to be done in this study. Please state clearly the aims and what this study does. However, highlight those innovative technologies and alternative fuels in combination with advanced combustion concepts could be used also to improve efficiency and performance. Please take a look at the work performed by J. Turner, G. Di Blasio and C. Mueller on alternative fuels, Dual Fuel (CNG-diesel) and advanced combustion fuel systems. It is worth mentioning their contribution. The authors could extend the introduction discussion reporting that innovative technologies could give a potential boost to the CI engine fuel economy and engine-out emissions reduction.
- More in-depth analysis of the author's contribution to this paper is in the introduction section. I would like to see more discussion of the literature so that I can clearly identify the article relates to competing ideas.
- The motivation of the paper is unclear, but it should be eye-catching to make more sense. In this regard, a separate section on motivation and contribution should be included.
- The results of the study are not to a small extent dependent on the accuracy class of the measuring equipment used. Please complete the methodology section with appropriate information.
- How many repeat experiments were performed at each point? Comment on repeatability. How did the authors establish/estimate the uncertainties in the measurements documented in this research?
- The language of the manuscript is fair; I would advise consulting a language editor to further polish the language of the manuscript. There are several grammatical mistakes. Please work closely with a native English speaker to refine the language of this paper.
- Please reduce the number of plots and extend the detailed discussion.
- Challenges and future directions to improve and implement these technologies with big data analytics should be discussed.
- Further explanation of the advantages of the suggested approach should be added. What are the main positive and negative points of this approach?
- In my opinion, there are several up-to-date approaches to the idea. Authors should look for these approaches, compare the results and prove their idea. This is a major concern.
- Conclusions should be summarised.
Author Response
Dear Reviewer,
We would like to thank you for giving us constructive suggestions which would help us both in English and in depth to improve the quality of the paper. We resubmit a new version of our manuscript with the title “Performance optimization and knock investigation of marine two-stroke pre-mixed dual-fuel engine based on RSM and MOPSO”, which has been modified for the suggestions made.
The modified contents of the revision have been marked in green color. Detailed responses are listed in the attachment "Response for reviewer 3", and we really appreciate your valuable comments.
Please see the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Accepted
Reviewer 3 Report
The Manuscript has been revised and it can be considered for publication.
