Effects of Different Diesel-Ethanol Dual Fuel Ratio on Performance and Emission Characteristics of Diesel Engine
, Jiangtao Li 1,2, Jie Tian 1,2, Guangling Xie 1, Dongli Tan 2,3, Boying Qin 4, Yuanxing Huang 1,2,* and Shuwan Cui 1Round 1
Reviewer 1 Report
This is an interesting paper addressing an important issue. It can be considered for publication in Processes. However, I have the following comments that the authors should carefully implement in the revised manuscript before publication.
1) Introduction - The authors stressed the importance of developing new fuels to reduce pollutant emissions from diesel engines. However, in the revised Introduction, in order to give a more complete picture, they should better highlight, citing pertinent literature works, also the importance of developing - in parallel to new fuels and new injection strategies - highly performing after-treatment devices, i.e., Diesel Particulate Filters (DPFs) (see, e.g., AIChE Journal, Volume 64, Issue 5, 2018, Pages 1714-1722; AIChE Journal, Volume 63, Issue 8, 2017, Pages 3442-3449).
2) 2.1.6 Three-Dimensional CFD Simulation model - Are the computational results grid-independent? The authors should comment on this key issue.
3) In the discussion, the authors should better highlight the practical impact of the results obtained in this work. This should also be done at the end of the section "Conclusions". The conclusion section cannot be a list of outcomes, and more criticism is needed.
4) Conclusions - The authors should also give an outlook on future research work.
5) Starting form line 267, “Error! Reference source not found.” is found several times.
I’m willing to review the revised manuscript.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The use of alternative and renewable fuels in ICE is really promising direction of work, so presented paper is actual. Authors analyse diesel engine performance and emissions when using ethanol and diesel fuel blends. But in the paper are some inaccurate items in the text and formula writing and description of obtained results.
- There is no description of used models for emissions of NOx, HC, CO and soot calculation. Did they used AVL Fire submodels or their own models? It is hard to believe that chemical mechanism from 34 reactions allows to calculate all mentioned emissions.
- In formula (9) what variable designated as sigma?
- What are Alam, P, C and S in formula (12)?
- What the word «Particle» means in context of fuel spray model?
- Table 1 - Total piston displacement (L), probably “Total engine displacement (L)”?
- Subclause 2.3. Please provide information about engine RPM and used fuel. Did authors validate emission calculation with experimental data?
- Subclause 3.3. Is that correct to use Grey relational analysis (GRA) to analyse simulation results when we know applied mathematical models and theoretical relationship between parameters?
- 580-581. It is not correct to say “the influence of five factors on power is NOx > Cylinder peak pressure > Cylinder peak temperature > Torque > BTE.” We only could say that these parameters have some level of relationship on the base of presented data analysis.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
It is believed that studies have been conducted on combustion and exhaust properties according to the diesel-ethanol mixing ratio.
1. I don't think it's clear what the advantages of this study are.
2. In terms of combustion and exhaust, what is the optimal condition for the mixing ratio of diesel to ethanol?
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
Blends of diesel and ethanol have been studied experimentally in the literature. The difficulty with purely experimental studies is that they are not predictive, but rather representational. If you wish to design a process, it is much better to have a multiphysics predictive model that captures all the relevant physico-chemical processes with adjustable geometries. The assembly of such a model requires experimental validation, and sometimes data assimilation from classes of experiments to be semi-empirically accurate and to be able to extrapolate with confidence outside the limited experimental regimes. As such the aims of this paper are within the scope of the journal Processes, comprising combustion processes and combustion engine design.
There is a systematic but essential flaw in the paper in that the referencing / citation macros did not work in the production of the PDF. This makes it impossible to follow all the logic of the paper, so it should be formally rejected with the invitation to re-submit with proper citations. I was especially interested to learn of the grey correlation analysis, so disappointed that the citation style does not clarify the approach. Mathematically, equation 34 shows a matrix on the RHS and a vector on the LHS, which can only make sense if the components of the vector are themselves row vectors. Perhaps that is stated in the intended citation, but could use clarification.
The other minor concerns are that as written equation (3) has the mass times the specific enthalpy rate of accumulation on the LHS, but specific enthalpy is not defined as a variable (or is this just a typo, h for H?). PM and HC are introduced as abbreviations without prior definition. Sherwood number is defined as Sh but then used as sh. Equations (1)-(4) are summation over "front" where front is never defined. I believe the intention is to be summations over the boundaries of the domain D (sometimes symbolized by \partial D_i ), but it is conventional to express this concept.
Figure 1 gives the computational domain and a relevant mesh. Were mesh resolution studies conducted to show grid independence?
Under the headings feasibility studies and validation, reference [43] is cited as having completed these aspects. Could the authors please clarify how the paper presented here relates to reference [43]? For instance, is the model validated for diesel but modified and used for the blends of diesel and ethanol, in this paper?
The abstract only reports qualitative results as trends. Significant, for instance, is a meaningless word because it implies a judgment -- relative to what benchmark is something insignficant. If 100 ppm of cyanide in beverage kills you, that would be significant. Yet 100ppm cyanide introduced into a fuel will change the product distribution from combustion by less than the error in the chemical analysis of the combustion products. Please use quantitative measures that are benchmarked for the meaning of significant!
In general, this looks to be a well composed paper. The results that are checkable seem very good, and supported by the narrative. It is a shame about the technical flaw in the production, and I would likely be supportive of a clean copy!
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors have addressed my comments in a satisfactory manner. Overall, the manuscript has been improved after revisions. Therefore, it can be accepted for publication in Processes .
Reviewer 2 Report
The paper has been extensively revised and could be published in present form.
Reviewer 4 Report
The authors have addressed all my concerns in their revision.
