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Peer-Review Record

Influence of Disc Temperature on Ultrafine, Fine, and Coarse Particle Emissions of Passenger Car Disc Brakes with Organic and Inorganic Pad Binder Materials

Atmosphere 2020, 11(10), 1060;
Reviewer 1: Anonymous
Reviewer 2: Anonymous
Reviewer 3: Anonymous
Atmosphere 2020, 11(10), 1060;
Received: 14 September 2020 / Revised: 28 September 2020 / Accepted: 29 September 2020 / Published: 5 October 2020
(This article belongs to the Special Issue Advancements in the Reduction of Submicron Particle Concentrations)

Round 1

Reviewer 1 Report

Atmosphere – comments and suggestions for authors

The topic – emissions from braking – is certainly important and actual. Method for its study suggested in this manuscript sounds quite appropriate: good experimental equipment for both simulation braking process, and also for detection of emitted particles and scheme of experiments look nice. A little bit worse is experimentation itself; it seems that it is not so easy to keep suggested brake pads temperature during braking events repeatedly, which results in large data scatter and in difficulties of data interpretation. It mainly concerns with last paragraph on p. 10 and interpretation of the data in Figure 9. Nevertheless, five tasks postulated in the beginning were solved.

Remarks in chronological order:

r.141 “the influence of organic binder material” organic should be omitted, because also pads with inorganic binder material were tested,

Figure 2                                there is APS 3321 instead of CPC 3776,

Figures 4, 8, 9 and possibly also 10 and 11             it would be useful to distinguish ascending and descending points by different shape of markers (e.g. spherical and triangular), because distinction only by color is especially in Figure 9 insufficient

r. 267-279 this paragraph is written that way that it is very difficult to understand it. From Figure 9 it does not seem that PM10-data points are scattered randomly (r. 271) nor that µ-data point are distributed horizontally after the apex of the first triangle (r. 271-272) – there is clear hysteresis. And there are not two regimes in the dependence mOPC on µ (r. 272 – r 276). There is one regime, mOPS is gradually increasing with µ over the entire range of µ.

Figure 10 and Figure 11  there are missing scales on the right hand side of the figures,

r. 337-345 may be this should by explained in more detail. Do the authors mean decomposition and evaporation of all available material, or decomposition mostly to less volatile material, possibly with worse braking properties?

r. 454 possibly, there should be “the area below” instead of “the are below”

Comments for author File: Comments.docx

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

            The article deals with the problem of  ultrafine and PM10 particles generation during the braking process of passenger cars. The emphasis was placed on the assessment of the influence of brake disc temperature on particle emission for two different types of brake pads.

   The manuscript  is generally well written. The introduction is well presented and points out with clarity the aims of the study. Overall, the study objectives, the experimental design and the obtained results are very interesting and represent an advancement of the current state of knowledge.   The work is useful  and surely  will find readers not only among a  group of specialists but among a wider community so it should be more comprehensible.  There are some aspects regarding the terminology, ways of presenting the results and the interpretation of dataset that are not clear. In order to make for a stronger paper, I suggest  some   revisions   to improve its  transparency.

  1. Please standardize the terminology: Fine particles have an aerodynamic diameter of 2.5 µm or less (PM5). The fine particles which are smaller than 0.1 µm are referred to as ultrafine particles (PM0.1). PM10 is particulate matter with an aerodynamic diameter of up to 10 µm, i.e. the fine and coarse particle fractions combined. In the title (and partly in the text)there are fine particles and this actually concerns PM10.
  2. In Abstract, instead of literature information, there should be more information about the methodology used.
  3. Symbols used in figures should be explained either in the text or in figure captions.
  4. What do the pages in parentheses next to some citations mean? (e.g. 43, l. 46, l.61, etc.).
  5. 2 - Please indicate particle size in case of CPS.
  6. Figure 4 is most likely readable to a specialist, but contains too much information for the wider public. I would suggest simplifying it and possibly making two drawings and describe them in a more understandable way.
  7. Why are the research results and their interpretation presented in a different way for the second pads material? I think that the same method of presentation should be adopted for better comparison. You can transfer some material to attachments.
  8. 229 – should be PM10 particles........instead of Fine particles.....
  9. Why are the regimes not marked in Fig. 9, similar to Fig. 8? They are mentioned in the text.
  10. 278-279 - This explanation should be described in more detail in the methodology
  11. 284 – see p.8.
  12. Please pay attention to the references. Many references contain incomplete bibliographic information, e.g. 6, 11, 12, 14, 19, 22, 24.


Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

The manuscript is difficult to read. This is mainly due to many long sentences which should be broken into shorter sentences. Otherwise the method and results are sound

Below are some suggestion to improve the readability of the manuscript

(1) Line 15-16: Change "According to estimations 21% of total traffic related PM10 emissions.."  to "It is estimated that 21% of total traffic related PM10 emissions.."

(2) Line 41-44: This sentence has been used in the abstract.

(3) Line 62: "The investigation..." should be "Their investigation..."

(4) Line 88-102: These 3 paragrphs can be merged into a single paragraph.

(5) Line 133: "according to the PM10 convention.." changed to "as defined to be in PM10"

(6) Line 138: " the institute of environmental and energy technology.." should be "...the Institute of Environmental and Energy Technology..". 

(7) Figure 10 and 11: Color bar does not have scale

(8) Line 316: "Whether" should be "Neither"

(9) Line 333: "takes already place" should be "already takes place"

(10) Line 355: ", which suggests..." should be a new sentence ". This suggests..."

(11) Line 367: "Nevertheless it is not sure..." should be "Nevertheless it is not certain..."

(12) Line 369: ", but the correlation..." , make this a new sentence ". But the correlation..."

(13) Line 370: ", that is..." make this a new sentence ". This is ..."

(14) Line 371: which argumentation ? Please clarify or rephrase the text to make this clear.

(15) Line 372: "Both with..." should be "With both..."

(16) Line 385-386: I don't understand this sentence

"By means of a triangular temperature test signal the investigation independently from other influencing factors as velocity, pressure and friction history was enabled."

Please clarify.

(17) Line 387: ", which allows...". Make into a new sentence ". This allows..."

(18) Line 414: change "in accordance with other previous studies of the authors" to "corresponding with other previous studies"

(19) Line 429: "...on the topic of influencing parameters" change to "...on the topic of influencing parameters on emission"







Author Response

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Author Response File: Author Response.docx

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