Review Reports

Round 1

Reviewer 1 Report

In this paper, the load characteristics of different filter media on particulate matter in oil were studied by two-stage filtration method. The relationship between the two-stage filters is very interesting. There are several issues that need to be explained here.

1. In figure 5, how the limited value of 500Pa determined?

2. What is the definition of DHC and how is it calculated?

3. The list of acronyms are needed.

4. Whether particle size distribution or morphology in the liquid phase is more likely to indicate filtration characteristics.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

In this paper, the authors evaluated the effects of oil content on the loading performance of single-stage and two-stage filtration systems. The study finds that a slight amount of oil can increase the Dust Holding Capacity (DHC) of filter media by forming a more porous cake, but an excess amount of oil can reduce DHC by forming impermeable liquid films on the solid skeleton. The study also finds that the use of a pre-stage filter media can unintentionally deteriorate the service lifetime of the main-stage filter media when challenged with certain oil-coated contaminants, due to the unique loading behaviors of oil-solid mixed particles. The study suggests that the feasibility of using a pre-stage in the filtration system requires comprehensive evaluations based on the specific properties of the oil-coated contaminants.

The methods of this study are well established, and the results are clearly presented. The findings of this work are informative and can be helpful to the readers of Atmosphere. Therefore, publication of this work is recommended after minor revisions. Please see my comments below.

1. Abstract the first sentence, it may be helpful to specify the types of practical applications in which filter media are used (e.g., industrial, automotive, household).

2. Information about the viscosity of DEHS oil may be helpful for future researchers.

3. I may interpret this wrong. The average diameter of G4 is about 26 micrometers, whereas in Figure 3 the particle mobility size of majority portion of coarse and fine particles is less than 10 micrometers. Would this influence the effectiveness of G4 in this study?

4. In Figure 6, when DEHS:A2 is 50%, the loading behavior of F7 and E11 looks similar, whereas F9 seems quite different. What could possibly be the reason for this?

5. Please improve the written English of the manuscript, including figure captions. Please revise all the typos, tense and grammar issues before this article is ready for publication.

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

This is a well-designed study in understanding the effectiveness of the pre-stage filter media. Some of the findings presented in the study would certainly help the industry develop better filtration systems especially for aerosols containing oils residue. I recommend accepting this manuscript in the current form.

Author Response

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Author Response File: Author Response.docx

Reviewer 4 Report

The english grammar needs significant work.

 

I will list a few examples, but the entire paper needs to be carefully reviewed.

Line 35-abstract- should be contaminants  not contaminates

Line 130 – should be contact angle not contactor

Line 188-190 ; Figures 6 (a-c) depict the pressure drop evolution of F7 cellulose, F9 melt-blown and 188 E11 PTFE membrane-coated filter media in a single-stage configuration when loaded with 189 different oil-coated particles. When loaded with different oil-coated particles, As the oil 190 content increased from 0%, 25%, 50%, 75% to 100%, the growth rate of each curve for filter 191 media varied significantly.

Line 290 should read: “However, further particle accumulation caused the long chains to collapse and particles to pack densely, due to the  heavy gravity and air force in the longitudinal direction.”

 

There are many cases of incorrect tense.

Line 129 should read “images of filter media samples are shown…”

Line 214 – “Fig 7 shows…”

Line 277 - … “(F7 cellulose and E11 PTFE membrane-coated filter media are not presented here because the formed cake  layers are too thin to measure accurately in some solid-oil mixed cases).

 

Sentences that don’t make sense or are hard to understand

Line 162- “As the mass concentration of DEHS oil increase, the mixed particles were transit from pure solid particle to that pure oil particle.”? 

Line 238 should read “A cake layer forms as particles are captured on the surface of high efficiency filter media and contributes to the increase of pressure drop.”

Line 353 would be improved as:” When pure oil particles were loaded, the G4 pre-stage  filter media only prolonged the service lifetime of F9 main-stage filter media by 5%.”

Line 368: “The pre-stage filter media  loading curve in two-stage loading configurations was deleted in order to compare the  results intuitive (???), and the replacement of pre-stage filter was marked by arrows.

Lines 391-396 would be better as:  “With the fraction of oil continuing to increase, i.e., the 75% oil case, it can be seen from Figure 12(d), the pressure drop of the F9 melt- blown main-stage filter media increased more slowly in the two-stage configuration than in the corresponding single-stage configuration. This was because the existing solid particles are sufficient to serve as a skeleton,  permitting rapid formation of an oil film without the pre-stage filter media.“

Line 435 – better as “The filtration performance of filter media is significantly affected by oil-solid mixtures with different oil proportions. Therefore, the impact of different oil-solid mixtures effects on the filtration of single-stage and  two-stage was thoroughly investigated in this work. “ 

Simple errors

Line 176 – should be fine oil generator

Line 177 – should be sensor

Line 426 – should be “25% oil-coated”

 

Technical questions

Figure 3 – how was “particle mobility” determined? Is this the particle size distribution?

Figure 7 – How was DHC determined? This should be detailed in the experimental section

Author Response

Please see the attachment.

Author Response File: Author Response.docx