Evolution of the Soot-Particle Size Distribution Function in the Cylinder and Exhaust System of Piston Engines: Simulation
, Konstantin A. Avdeev 2, Vladislav S. Ivanov 1,2, Pavel A. Vlasov 2, Fedor S. Frolov 1,2, Ilya V. Semenov 1 and Marina S. Belotserkovskaya 1
Zhao Zhengfeng
Round 1
Reviewer 1 Report
In this paper, the evolution process of soot-particle size distribution function in piston engine cylinder and exhaust system is studied by means of simulation. The research content is enriched and meaningful, and the following suggestions are put forward:
1. Some pictures, such as Figures 5 and 7, need to be improved in clarity, and the layout of Figure 7 needs to be adjusted to make the pictures more readable.
2. The reference should be completely cited, and the reference location is not found in Reference 15.
3. Lack of verification of simulation model accuracy.
Author Response
We are grateful to the reviewer for valuable comments. We made our best to follow all the comments. All changes in the revised manuscript are marked in yellow.
In this paper, the evolution process of soot-particle size distribution function in piston engine cylinder and exhaust system is studied by means of simulation. The research content is enriched and meaningful, and the following suggestions are put forward:
- Some pictures, such as Figures 5 and 7, need to be improved in clarity, and the layout of Figure 7 needs to be adjusted to make the pictures more readable.
We have replotted Figure 5 and improved the quality of Figure 7.
- The reference should be completely cited, and the reference location is not found in Reference 15.
Sorry, the citation of Ref. 15 is missing: it must be cited together with Ref.14 as [14,15].
- Lack of verification of simulation model accuracy.
To address this comment, we have added the following two sentence to the text in Introduction and in Section 2.3.
Introduction:
“This model has been implemented in the MACRON code.”
Section 2.3:
“As was mentioned earlier in this paper, the most important advantage of the MACRON code is that it satisfactorily describes all the available experimental data on the soot yield during pyrolysis and partial oxidation of various hydrocarbons. In view of it, the fact that the log-normal SDF of Eq. (15) approximates satisfactorily the soot-particle SDF predicted by the MACRON-code can be treated as verification of simulation model accuracy.”
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments for author File: Comments.pdf
Author Response
We are grateful to the reviewer for valuable comments. We made our best to follow all the comments. All changes in the revised manuscript are marked in green.
In this work, the soot particle size distribution function in the engine cylinder and a model for simulating the coagulation of soot particles in the exhaust system of a reciprocating engine are developed. The coagulation model includes three coagulation mechanisms i.e., Brownian, turbulent-kinetic, turbulent-diffusion. Results are presented in a very clear way and the subject also fits the scope of the journal of Atmosphere. 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.
- Abstract is not giving information about methodology, results, conclusion, and recommendations as it should be written clearly. I suggest the authors remove generic lines and present the strong statements and novelty of the article. The abstract is written in qualitative sentences. It needs to be modified and written based on the most important quantity results from this research.
To address this comment, we have rewritten the abstract as follows:
“A computational tool for simulating the temporal evolution of the soot-particle size distribution function (SDF) in the internal combustion engine (ICE) and in the attached exhaust pipe is developed and tested against available experimental data on soot-particle SDF at the outlet of the exhaust system. Firstly, a database of soot particle properties (particle mean diameter, dispersion, and total particle number density vs. time for different fuels, fuel-to-air equivalence ratios, temperatures, pressures, and exhaust gas recirculation) is developed based on the thoroughly validated detailed model of soot formation under ICE conditions. The database is organized in the form of look-up tables. Secondly, the soot-particle SDF in the database is approximated by the log-normal SDF, which is directly used in the multidimensional calculations of the ICE operation process. Thirdly, the coagulation model of soot particles is developed, which includes three coagulation mechanisms: Brownian, turbulent-kinetic, and turbulent-diffusion. This model is applied for simulating the evolution of the soot-particle SDF in the exhaust pipe after opening the exhaust valve. Calculations show that the coagulation process of soot particles in the exhaust pipe has a significant effect on the mean size of particles at the outlet of the exhaust system (the mean particle diameter can increase by almost an order of magnitude!), and the dominant mechanism of particle coagulation in the exhaust system of diesel engine is the Brownian mechanism. The objective, approach and the obtained results are the novel features of the study.”
- A great review of the literature is presented in the Introduction. However, many statements are written without citing the actual references. For example Page2, Line 46- 49: “Improving the operation process in ICEs is impossible without deep understanding of all the physical and chemical processes accompanying smoke/soot formation in the engine cylinder. This requires model….”. A few papers can help authors review: 10.1177/1468087416688805, 10.1016/j.applthermaleng.2011.10.027, 10.1016/j.energy.2022.125796, 10.4271/760129
We have added 4 references [2-5] kindly suggested by the reviewer. In view of it, all succeeding references were renumbered.
2.Hiroyasu, H., & Kadota, T. Models for Combustion and Formation of Nitric Oxide and Soot in Direct Injection Diesel Engines. SAE Techn. Paper 760129, 1976. doi:10.4271/760129.
3.Payri, R.; García-Oliver, J. M.; Bardi, M.; Manin, J. Fuel temperature influence on diesel sprays in inert and reacting conditions. Appl. Therm. Eng. 2012, 35, 185–195.
4.Nishida, K.; Zhu, J.; Leng, X.; He, Z. Effects of micro-hole nozzle and ultra-high injection pressure on air entrainment, liquid penetration, flame lift-off and soot formation of diesel spray flame. Int. J. Engine Res. 2017, 18(1-2), 51–65.
5.Samir Chandra Ray, S.; Keiya Nishida, K.; McDonell, V.; Ogata, Y. Effects of full transient injection rate and initial spray trajectory angle profiles on the CFD simulation of evaporating diesel sprays- comparison between single-hole and multihole injectors. Energy 2023, 263(C), 125796, doi:10.1016/j.energy.2022.125796.
- Many equations are presented in the paper (40 in total), and most look OK. However, please check carefully whether all equations are necessary and whether the quantities involved are properly explained.
We have carefully checked all equations and decided to leave them. Otherwise, the clarity of the approach may be lost.
- 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.
We asked a colleague who worked in the UK for a long time to proofread the manuscript. He made some corrections in the text.
- Future scope and current limitations must be discussed, for example, a short paragraph may be included in the conclusion section more explicitly.
To address this comment, we have added a new paragraph to the Conclusions:
“Further model development will be focused on the refinement of the database of soot-particle parameters. Remind that the detailed model of soot formation underlying the current database was validated against the available experimental data on the soot yield during pyrolysis and partial oxidation of various hydrocarbons obtained in kinetic shock tubes rather than in internal combustion engines. The conditions behind reflected shock waves can differ considerably from those in engines.”
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The manuscript looks in a good shape now. Authors have addressed all the suggestions made by this reviewer in a clear and precise manner. However, this reviewer suggests all references should include DOIs. Moreover, authors are advised to use Grammarly software for any possible grammatical and paraphrasing.
