Version 1
: Received: 11 November 2022 / Approved: 15 November 2022 / Online: 15 November 2022 (02:59:31 CET)
Version 2
: Received: 8 December 2022 / Approved: 8 December 2022 / Online: 8 December 2022 (03:52:39 CET)
Lee, D.I.; Park, J.; Shin, M.; Lee, J.; Park, S. Characteristics of Real-World Gaseous Emissions from Construction Machinery. Energies2022, 15, 9543.
Lee, D.I.; Park, J.; Shin, M.; Lee, J.; Park, S. Characteristics of Real-World Gaseous Emissions from Construction Machinery. Energies 2022, 15, 9543.
Lee, D.I.; Park, J.; Shin, M.; Lee, J.; Park, S. Characteristics of Real-World Gaseous Emissions from Construction Machinery. Energies2022, 15, 9543.
Lee, D.I.; Park, J.; Shin, M.; Lee, J.; Park, S. Characteristics of Real-World Gaseous Emissions from Construction Machinery. Energies 2022, 15, 9543.
Abstract
In Korea’s air pollutant inventory, construction machinery is a major emission source in the non-road sector. Since 2004, the Korean government has introduced and reinforced emission regulations to reduce the air pollutants emitted from their diesel engines. Since the engine dynamometer test method used in emission regulations has limitations in reflecting emission characteristics under the diverse working conditions of construction machinery, it is necessary to examine the effectiveness of emission regulations and the validity of the emission factors applied as inputs to the air pollutants inventory. This could be done by evaluating engine operation and emission characteristics under real-world working conditions. In this study, 14 units were selected among the excavators, wheel loaders, and forklifts that represent approximately 90% of the registered construction machines in Korea. They were equipped with a portable emission measurement system (PEMS) to measure gaseous emissions and collect engine data under various real-world working conditions. With the reinforcement of emission regulations for the construction machinery from K-tier3 to K-tier4 in Korea, exhaust after-treatment technologies, such as selective catalytic reduction and diesel oxidation catalyst, were applied. Real world NOx were reduced by approximately 83%, and THC 77% and CO by 73%, respectively. Real world NOx + THC of the K-tier3 machines exceeded the laboratory emission limit, but the K-tier4 machines considerably improved despite some differences. The emission factors applied to the air pollutant inventory have been developed using the engine dynamometer test method, but they were considerably underestimated compared with emissions under real-world working conditions. The difference was even larger for the K-tier4 machines. In this study, the possibility of developing emission factor equations that use the engine load factor as a parameter was confirmed by using the engine work 1 g/kW·h segment moving averaging window (MAW) method.
Keywords
construction; machinery; emissions; PEMS
Subject
Engineering, Automotive Engineering
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Received:
8 December 2022
Commenter:
Dong In Lee
Commenter's Conflict of Interests:
Author
Comment:
Response to Reviewer 1 Major Comments 1) Abstract. 1-1) In the abstract, the statement "considerably improved" should be expressed as a specific number, X times or X%, or X value. In the revised manuscript, the abstract has been improved. 2) Introduction. 2-1) In the Introduction, the statement "emission reduction technologies are at a lower level” would be good to be based on the scientific source. The scientific source has been added to the text 2-2) In the Introduction part, it is possible to review more similar scientific studies that examined fuel consumption and their impact on the environment (engine load and GHG dependencies). Moreover, there are articles that are very suitable for the topic discussed by the authors - the dependence of fuel consumption, air pollutants and GHG on engine load. https://doi.org/10.3390/app11188662 In the revised paper, the detailed explanation regarding this comment has been added to the introduction part 3) Methods and Materials. 3-1) If possible, Table 1 should be supplemented with additional parameters - the year of manufacture of the machine and the engine hours worked. These are very important parameters when evaluating machines. If such data is available. We agree with your review. All manufacture years for tested construction equipment have been added to Table 1, while the information of engine hours worked is not provided with owners. 3-2) Abbreviations EGR, SCR, etc. are used in Table 1., which are explained only in the following paragraph after the Table 1. Examining Table 1, it is not clear to a non-specialist what this is. All abbreviations used in the article must first be written in full text, only then shortened and only those abbreviations used later in the article. This applies to all abbreviations throughout the article. In the revised manuscript, all abbreviations have been explained in the part of Methods and Materials part 3-3) Chapter 2. “PEMS system” talks about Ambient temperature and humidity. Do they continue to be used in the study and have they affected the results obtained? If not, then there is no need to talk about them. The same section talks about 2.5 and 3 inches. Wouldn't it be better to use mm and cm? The ambient temperature and humidity in the text have been deleted and inch unit has been changed to mm 3-4) The Materials and methods section lacks the PEMS specification. There could be a separate table with measurement parameters. What gas is measured, what is the resolution of the device for each gas, other, specific information related to the PEMS. All information has been added to the manuscript, as shown in Table 3. 4) Results and discussion 4-1) The upper right image in Figure 2 is untitled. Probably missed the “Fork lift...” Figure 2 has been improved as your comment. 4-2) Real-world is used very often when reading an article. I counted 59 times. There is a need to solve this word combination in some other way. Or to declare at the beginning of the article that "real-world" tests will be carried out and not to repeat it further. Or use some kind of abbreviation. The words, “real-world”, have been properly deleted in the text as your comment. 4-3) On pages 10-11, table 3, the authors talk about CO2 emissions. If other GHG and air pollutants can be reduced by introducing advanced engine technologies, then CO2 depends mostly on the amount of fuel used. This should be noted more clear in the article. Possibilities of reducing fuel consumption (at the same time GHG), dependence of GHG on engine load, use of telematic data are also discussed there: https://doi.org/10.3390/app11188662 and https://doi.org/10.3390/atmos12060674 We agree with your review. The detailed explanation for the relation between CO2 and fuel consumption has been inserted to the text. 4-4) In Table 4, the authors present some of the most important results of their research. It is not clearly highlighted what parameter L is. Engine load? In Table 4, L is represent the engine load factor, which has been inserted in the table 4-5) The formulas presented in Table 4 are a very interesting result of the authors' work. Their biggest drawback is the small sample of tested and investigated machines (14 units). The margin of error is likely to be huge. This allows future research to be carried out by increasing the sample size and refining the formulas. At this stage, I think their credibility is low. The authors, by the way, honestly admit it themselves. We fully agree with your review. The results shows reliability law and a large margin of error. So, the error rate for the formula can be reduced and improved with increasing the number of samples and additional investigation in the future. 5) Conclusion 5-1) The Conclusions section is too broad and long. It should be shortened and leave only the conclusions obtained during the investigation. Make it more concise and specific. There are too many elementary truths in this chapter, such as Tier3 emissions being higher than Tier4. In the conclusions, I think more attention should be paid to the developed formulas (dependence of emissions on engine load), to briefly discuss their scientific novelty and potential benefits. The conclusion has been shortened and improved as your comment. 6) Reference 6-1) In the Reference section, there is a link to the EEA Emission Inventory Guidebook 2016. Although the meanings are essentially the same, the newer 2019 version should be referred to: https://www.eea.europa.eu/publications/emep-eea-guidebook-2019 The reference NO. 36 has been updated
Response to Reviewer 2 Minor Comments 1) Subscript and superscript should be mentioned carefully and uniform in the manuscript, such as equation one “Pa or Pc”. In the revised manuscript, the “Pc” has been corrected. 2) Significance of the relationship between load factor and emission should be included before the Results and discussion section in the manuscript. We agree with your comment. In this study, the significance of the relationship between load factor and emission is for achieving the more realistic emission inventory. We added related sentences in introduction part (page 3) as follows “Load factor the fuel consumption in the real operate condition of construction machine, the gaseous emissions from diesel-fueled construction machines well-known to be mainly related to the fuel consumption, consequently, load factor are attributed to the emissions contains.” 3) The significance of the conformity factor has been mentioned in the manuscript, but the methodology for determination has not been mentioned, the author should include the determination method in the manuscript. CF can be obtained by a/b, a Real working emission (cf. Table 4), b Gaseous emission standard (cf. Table 2) 4) MAW description is not sufficient for the current manuscript. The author should include the methodology and full description of MAW. How the author has applied the MAW to determine the goal? In the revised manuscript, the detailed information regarding the MAW methodology has been added to the text With the lkWh-segmented MAW method, a unit segment corresponding to the window of lkWh, the average values of emissions, power and load factor calculated by real time data in consequence, the highly fluctuated real time curve can be transformed to the stabilized curve, as shown in Figure 2. Figure 3 can be represented with Equation (5) and Equation (6). To compare the results, the MAW method was applied to various construction machines with the number of power ranges.
Received:
9 December 2022
Commenter:
Reno Filla
The commenter has declared there is no conflict of interests.
Comment:
I find it ironic that my previous publication [31] is quoted as "applied the working cycles presented in JCMAS H020(for
excavators) and JCMAS H022(for wheel loaders) provided by the Japan Construction Mechanization Association (JCMA) to evaluate the energy consumption of excavators and wheel loaders".
In fact, I did no such thing. The whole point of paper [31] was to reason about the need for real world testing and to abandon simplistic cycles that can be easily beaten by softare (note that this was even before "Dieselgate"). My paper soundly 'refuted H020 and H022 as a valid way of evaluating energy consumption and exhaust emissions, quote: "overly simplistic test cycles that lead to non-representative or even misleading test results."
Commenter: Dong In Lee
Commenter's Conflict of Interests: Author
Major Comments
1) Abstract.
1-1) In the abstract, the statement "considerably improved" should be expressed as a specific number, X times or X%, or X value.
In the revised manuscript, the abstract has been improved.
2) Introduction.
2-1) In the Introduction, the statement "emission reduction technologies are at a lower level” would be good to be based on the scientific source.
The scientific source has been added to the text
2-2) In the Introduction part, it is possible to review more similar scientific studies that examined fuel consumption and their impact on the environment (engine load and GHG dependencies). Moreover, there are articles that are very suitable for the topic discussed by the authors - the dependence of fuel consumption, air pollutants and GHG on engine load. https://doi.org/10.3390/app11188662
In the revised paper, the detailed explanation regarding this comment has been added to the introduction part
3) Methods and Materials.
3-1) If possible, Table 1 should be supplemented with additional parameters - the year of manufacture of the machine and the engine hours worked. These are very important parameters when evaluating machines. If such data is available.
We agree with your review. All manufacture years for tested construction equipment have been added to Table 1, while the information of engine hours worked is not provided with owners.
3-2) Abbreviations EGR, SCR, etc. are used in Table 1., which are explained only in the following paragraph after the Table 1. Examining Table 1, it is not clear to a non-specialist what this is. All abbreviations used in the article must first be written in full text, only then shortened and only those abbreviations used later in the article. This applies to all abbreviations throughout the article.
In the revised manuscript, all abbreviations have been explained in the part of Methods and Materials part
3-3) Chapter 2. “PEMS system” talks about Ambient temperature and humidity. Do they continue to be used in the study and have they affected the results obtained? If not, then there is no need to talk about them. The same section talks about 2.5 and 3 inches. Wouldn't it be better to use mm and cm?
The ambient temperature and humidity in the text have been deleted and inch unit has been changed to mm
3-4) The Materials and methods section lacks the PEMS specification. There could be a separate table with measurement parameters. What gas is measured, what is the resolution of the device for each gas, other, specific information related to the PEMS.
All information has been added to the manuscript, as shown in Table 3.
4) Results and discussion
4-1) The upper right image in Figure 2 is untitled. Probably missed the “Fork lift...”
Figure 2 has been improved as your comment.
4-2) Real-world is used very often when reading an article. I counted 59 times. There is a need to solve this word combination in some other way. Or to declare at the beginning of the article that "real-world" tests will be carried out and not to repeat it further. Or use some kind of abbreviation.
The words, “real-world”, have been properly deleted in the text as your comment.
4-3) On pages 10-11, table 3, the authors talk about CO2 emissions. If other GHG and air pollutants can be reduced by introducing advanced engine technologies, then CO2 depends mostly on the amount of fuel used. This should be noted more clear in the article. Possibilities of reducing fuel consumption (at the same time GHG), dependence of GHG on engine load, use of telematic data are also discussed there: https://doi.org/10.3390/app11188662 and https://doi.org/10.3390/atmos12060674
We agree with your review. The detailed explanation for the relation between CO2 and fuel consumption has been inserted to the text.
4-4) In Table 4, the authors present some of the most important results of their research. It is not clearly highlighted what parameter L is. Engine load?
In Table 4, L is represent the engine load factor, which has been inserted in the table
4-5) The formulas presented in Table 4 are a very interesting result of the authors' work. Their biggest drawback is the small sample of tested and investigated machines (14 units). The margin of error is likely to be huge. This allows future research to be carried out by increasing the sample size and refining the formulas. At this stage, I think their credibility is low. The authors, by the way, honestly admit it themselves.
We fully agree with your review. The results shows reliability law and a large margin of error. So, the error rate for the formula can be reduced and improved with increasing the number of samples and additional investigation in the future.
5) Conclusion
5-1) The Conclusions section is too broad and long. It should be shortened and leave only the conclusions obtained during the investigation. Make it more concise and specific. There are too many elementary truths in this chapter, such as Tier3 emissions being higher than Tier4. In the conclusions, I think more attention should be paid to the developed formulas (dependence of emissions on engine load), to briefly discuss their scientific novelty and potential benefits.
The conclusion has been shortened and improved as your comment.
6) Reference
6-1) In the Reference section, there is a link to the EEA Emission Inventory Guidebook 2016. Although the meanings are essentially the same, the newer 2019 version should be referred to: https://www.eea.europa.eu/publications/emep-eea-guidebook-2019
The reference NO. 36 has been updated
Response to Reviewer 2
Minor Comments
1) Subscript and superscript should be mentioned carefully and uniform in the manuscript, such as equation one “Pa or Pc”.
In the revised manuscript, the “Pc” has been corrected.
2) Significance of the relationship between load factor and emission should be included before the Results and discussion section in the manuscript.
We agree with your comment. In this study, the significance of the relationship between load factor and emission is for achieving the more realistic emission inventory. We added related sentences in introduction part (page 3) as follows
“Load factor the fuel consumption in the real operate condition of construction machine, the gaseous emissions from diesel-fueled construction machines well-known to be mainly related to the fuel consumption, consequently, load factor are attributed to the emissions contains.”
3) The significance of the conformity factor has been mentioned in the manuscript, but the methodology for determination has not been mentioned, the author should include the determination method in the manuscript.
CF can be obtained by a/b, a Real working emission (cf. Table 4), b Gaseous emission standard (cf. Table 2)
4) MAW description is not sufficient for the current manuscript. The author should include the methodology and full description of MAW. How the author has applied the MAW to determine the goal?
In the revised manuscript, the detailed information regarding the MAW methodology has been added to the text
With the lkWh-segmented MAW method, a unit segment corresponding to the window of lkWh, the average values of emissions, power and load factor calculated by real time data in consequence, the highly fluctuated real time curve can be transformed to the stabilized curve, as shown in Figure 2. Figure 3 can be represented with Equation (5) and Equation (6). To compare the results, the MAW method was applied to various construction machines with the number of power ranges.
Commenter: Reno Filla
The commenter has declared there is no conflict of interests.
excavators) and JCMAS H022(for wheel loaders) provided by the Japan Construction Mechanization Association (JCMA) to evaluate the energy consumption of excavators and wheel loaders".
In fact, I did no such thing. The whole point of paper [31] was to reason about the need for real world testing and to abandon simplistic cycles that can be easily beaten by softare (note that this was even before "Dieselgate"). My paper soundly 'refuted H020 and H022 as a valid way of evaluating energy consumption and exhaust emissions, quote: "overly simplistic test cycles that lead to non-representative or even misleading test results."