Aircraft-engine particulate matter emissions from conventional and sustainable aviation fuel combustion: comparison of measurement techniques for mass, number, and size

Corbin, Joel C.; Schripp, Tobias; Anderson, Bruce E.; Smallwood, Greg J.; LeClercq, Patrick; Crosbie, Ewan C.; Achterberg, Steven; Whitefield, Philip D.; Miake-Lye, Richard C.; Yu, Zhenhong; Freedman, Andrew; Trueblood, Max; Satterfield, David; Liu, Wenyan; Oßwald, Patrick; Robinson, Claire; Shook, Michael A.; Moore, Richard H.; Lobo, Prem

doi:https://doi.org/10.5194/amt-15-3223-2022

Articles | Volume 15, issue 10

https://doi.org/10.5194/amt-15-3223-2022

© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/amt-15-3223-2022

© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 15, issue 10

Research article

|

30 May 2022

Research article |

| 30 May 2022

Aircraft-engine particulate matter emissions from conventional and sustainable aviation fuel combustion: comparison of measurement techniques for mass, number, and size

Joel C. Corbin, Tobias Schripp, Bruce E. Anderson, Greg J. Smallwood, Patrick LeClercq, Ewan C. Crosbie, Steven Achterberg, Philip D. Whitefield, Richard C. Miake-Lye, Zhenhong Yu, Andrew Freedman, Max Trueblood, David Satterfield, Wenyan Liu, Patrick Oßwald, Claire Robinson, Michael A. Shook, Richard H. Moore, and Prem Lobo

Download

Final revised paper (published on 30 May 2022)
Preprint (discussion started on 03 Jan 2022)

Interactive discussion

Status: closed

RC1:
'Comment on amt-2021-320', Anonymous Referee #2, 23 Jan 2022

See attached pdf document for general review along with major and minor comments.

Citation: https://doi.org/10.5194/amt-2021-320-RC1
- AC1: 'Reply on RC1', J. C. Corbin, 11 Mar 2022
  
  Please see the attached document.
  
  Citation: https://doi.org/10.5194/amt-2021-320-AC1
RC2:
'Comment on amt-2021-320', Anonymous Referee #3, 24 Jan 2022
I struggle with the assessment of this work: while the all the methods and results presented are of respectable scientific quality , I think there is a lack of focus in terms of relevance and scope for AMT. There is no novelty in concepts or data treatment and it is not clear what the real scientific value of the study is. For regulatory purposes there is little value due to the non-compliant sampling system, non- existent pre experiment calibration etc. The scientific value is also limited – I understand the argument for connecting ground measurements to cruise at altitude data, but for that purpose, a more focused effort with a better experimental design that would allow tracking down sampling/ conditioning from instrument issues would be beneficial. With the current manuscript one gets the impression that it is a side product of a bigger effort and was not carefully thought through when the experiment was conducted – which is not necessarily a problem if the reader does not get this impression, but I currently do.

Major comments:

The comparison of the mass measurement is somewhat biased experimentally (due to distance to the engine, dilution, detection limits and long lines etc.) to higher thrust levels. At these thrust levels it is not a major surprise that there is not much variability in instrument responses (little OC, larger aggregate sizes, soot properties less influenced by fuel type etc.). I also tend to disagree with the authors conclusion that a 30-50% difference is a “comparable” especially for the near real time in situ instruments such as MSS LII and CAPS. Would be good to point this out to the reader, or even split the discussion for cruising relevant (i.e. 50 -70% thrust) and near idle thrusts this might improve the lack of relevance pointed out above.

It would beneficial to show the comparison of measured concentration as a function of CO2 ( at least in the SI)

SMPS EIm derivation: this work makes the impression that an SMPS measures the volume size distribution with high precision and there is furthermore no need to apply a size dependent effective density (which I believe is crucial for larger sizes). It would be beneficial for the discussion to elaborate on this based on previous experiences on helicopter or jet engines
Citation: https://doi.org/10.5194/amt-2021-320-RC2
- AC2: 'Reply to RC2', J. C. Corbin, 11 Mar 2022
  
  Please see attached document.
  
  Citation: https://doi.org/10.5194/amt-2021-320-AC2

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload

AR by J. C. Corbin on behalf of the Authors (11 Mar 2022) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (14 Mar 2022) by Albert Presto

RR by Anonymous Referee #2 (30 Mar 2022)

RR by Anonymous Referee #3 (01 Apr 2022)

Suggestions for revision or reasons for rejection

Reviewer report on the manuscript “Aircraft-engine particulate matter emissions from conventional and sustainable aviation fuel combustion: comparison of measurement techniques for mass, number, and size” by Corbin et al.
General: this work compares the response of various PM mass and number instruments when sampling in the near field of a V2527-A5 and a CFM56- 2C1 aircraft engine. The manuscript is well written, and the data processing is of good quality; however, the content is of somewhat limited scientific relevance. The comparison between the real time and filter based mass measurements is of high relevance but is unfortunately hampered see below.
Major:
The drastically reduced flows in the filter based clap and psap are a major concern and make the shown comparison not very useful. While the authors point out the potentially added noise, there are also other problems associated with this e.g. particle losses within the instruments, more undefined spot size, potential dependence on commonly/normally occurring leaking in these type of instruments. The authors discuss this adequately by citing other literature, but it is very important to clearly mention that the instruments were not operated according to their specifications.
Minor:
Ln 28/29 for an easier read I would add “absolute” in front of magnitude of emissions
Ln 44: albedo is albedo in plural (CAPS PMSSAs) therefore I would remove the s but would add “instruments” for an easier read
Ln 47 to 49. The use of integrative seems to be a little misleading in general (different things are integrated in the two techniques). The main difference is for the filter measurements is that they are not performed in situ
Ln 122/123 As in the PMP, the catalytic stripper is not the key requirement an evaporation tube could also be used as stripper. The key is the additional dilution step after the stripper to prevent re nucleation
Ln 128 There is also a more recent publication by Durdina Empa?
Ln 376: I do not think one can call them “low cost”… and “portable” as mentioned in the response to reviewers. They are long term monitoring devices with great sensitivity (10 -100x better than a LII) but with a limited temporal resolution. Theoretically, they should actually work really well for low SSA/ strongly absorbing aerosol as measured here if operated correctly, but only with low filter loadings…
Ln 512: please clarify wording what has the turbine/ fan speed to do with thrust? Isn’t the low-pressure turbine linked to the fan?
Ln 771 to 783: Valuable discussion see major comment above – please clearly mention that the instruments were not operated according to their specification
Ln 802 to 806: Since the instruments were not operated according to their specs, this correction is definitely not valid and should not be done – please delete this paragraph.
Ln 824 might be typical for SAC combustors but not for other engine technologies
Ln 862 more crystalline structure (e.g. A. Liati ES&T or Papers from Vander Wal group),
Figure 8. Could this high variability in the integrated SMPS data also be explained by the fast scanning (45s) which pushes the limits of Scanning DMAs transfer functions theory etc…

Hide

ED: Publish subject to minor revisions (review by editor) (03 Apr 2022) by Albert Presto

AR by J. C. Corbin on behalf of the Authors (19 Apr 2022) Author's response Author's tracked changes Manuscript

ED: Publish as is (02 May 2022) by Albert Presto

AR by J. C. Corbin on behalf of the Authors (05 May 2022)

Short summary

The combustion of sustainable aviation fuels in aircraft engines produces particulate matter (PM) emissions with different properties than conventional fuels due to changes in fuel composition. Consequently, the response of various diagnostic instruments to PM emissions may be impacted. We found no significant instrument biases in terms of particle mass, number, and size measurements for conventional and sustainable aviation fuel blends despite large differences in the magnitude of emissions.