Design and Evaluation of a Novel Efficient Air-Assisted Hollow-Cone Electrostatic Nozzle

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This study designed a novel air-assisted hydraulic hollow-cone electrostatic spray nozzle and optimized the parameters of the annular induction electrode based on the morphological characteristics of the hollow-cone liquid film to achieve higher charge-to-mass ratio and better application quality. The paper analyzed the influence of the hollow-cone liquid film on spatial electric field distribution, compared the droplet charge-to-mass ratio and application quality before and after electrode optimization, and proposed universal principles for electrode optimization. To further improve the quality of the paper, several issues need to be addressed:

1) The manuscript mentions the distortion effect of the hollow-cone liquid film on the spatial electric field. What is the underlying cause of this distortion effect?

2) The electric field simulation adopts a steady-state approach, without considering the dynamic processes of liquid film rupture and fluctuation. Could these factors affect the results?

3) In the simulation, the liquid medium is tap water (Line 224), whereas in actual pesticide applications, the medium consists of various types of pesticides. Would this discrepancy significantly affect the spatial electric field distribution?

4) Please check the heading at Line 348, it should be "3.3" instead of "3.2".

5) Why is the electrode cross-sectional width set equal to the liquid film length (Lines 392–396)? Please explain the basis for doing so in detail.

6) Could the influence of corona discharge on the charge-to-mass ratio be further elaborated?

7) The droplet deposition experiment lacks detailed environmental conditions (e.g., temperature, humidity). Please include these parameters in the experimental setups.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Dear authors, congratulations on your work. I learned from reading it. I made some small observations that I recommend you adjust if you do not have a justification for keeping it.

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript presents the design and evaluation of a new air-assisted hollow cone electrostatic nozzle. Based on the adopted methodology, the authors designed the nozzle, used high-speed imaging techniques to characterize the dynamic behavior of liquid films from hollow cone nozzles, obtaining critical parameters describing the course of liquid film morphology. According to literature reports, charged droplet clouds in the atomization zone affect the charging efficiency. The authors' experiments seem to be reliable, revealing the mechanism of induction of electrostatic spray breakup, which can improve the uniformity of spray application on plant surfaces. The manuscript is scientifically correct. The article is clear, should be better developed methodologically (no information on the materials used for the construction of nozzles and electrodes), but is comprehensive and relevant to the field, suitable for publication in the journal Agriculture. The manuscript requires the following corrections.

Abstract: the significance and essence of the research for practice should be emphasized at the end.

1. Introduction

The review is concise and comprehensive, the objectives are discussed quite clearly.

2. Materials and Methods

a) There is no information about the geometric parameters of the designed nozzle (diameters, lengths of tapered flow channels).

b) What liquid was tested exactly?

c) It should be justified what material the electrodes are made of. What is the expected service life of the electrodes and how are they protected against corrosion?

d) It should be added in the text of the manuscript how the authors view the safety aspects of work and use of such nozzles in real conditions of a field sprayer. What dangers can a person face when using such a spraying system (voltage 3 kV).

3. Results

a) Illegible descriptions in Figures 10, 11. Spatial graphs are too small, need to be improved to increase size and readability.

4. Conclusions

They are consistent with the assumed goals. Emphasize the practical significance of the research at the end.

References

The cited references are important, but are somewhat outdated. Supplement newer items and remove those older than 10 years.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The article titled "Design and Evaluation of a Novel Efficient Air-assisted Hollow-cone Electrostatic Nozzle" presents the design and comprehensive evaluation of a high-efficiency electrostatic spray nozzle combining hydraulic and pneumatic atomization with electrostatic droplet charging. The work demonstrates a high level of scientific rigor and originality by introducing a novel nozzle structure and an integrated methodology involving structural design, high-speed imaging for liquid film morphology analysis, electric field simulation, parameter optimization using Particle Swarm Optimization (PSO), and experimental validation using a realistic spraying platform with soybean plants. The methodological framework is well-structured and allows for a detailed analysis of how the electrode's spatial position and geometric dimensions influence droplet charging performance. The authors reference relevant literature and provide a clear rationale for the optimization criteria applied.

However, the manuscript contains numerous linguistic and grammatical inaccuracies, such as typographical errors (e.g., "electrostaic" instead of "electrostatic"), inconsistent punctuation, misuse of hyphens, and repetitive phrases that affect the clarity of the text. While the technical terminology is appropriate, the manuscript would benefit significantly from thorough language polishing to enhance its readability and academic tone. From a methodological perspective, the key weakness lies in the insufficient reporting of experimental replication and the lack of statistical analysis (e.g., standard deviations, significance levels). Additionally, although the authors use a 2D axisymmetric model to simulate the electric field—a reasonable simplification—they fail to discuss its limitations or justify the absence of a 3D approach. Moreover, there is no direct performance comparison with existing commercial electrostatic or hydraulic nozzles, which would strengthen the practical relevance of the work.

The conclusions are logically derived and well-supported by the results. The authors successfully demonstrate that optimizing the electrode configuration leads to improved charge-to-mass ratios and more uniform droplet coverage, particularly on the abaxial surfaces of leaves—an important factor for crop protection efficiency. The proposed nozzle design and simulation-guided optimization offer valuable insights and hold clear potential for practical application in precision agriculture. However, the manuscript lacks discussion on durability, maintenance, and cost-related aspects of the nozzle, which are crucial for evaluating its real-world applicability.

In summary, this article presents a valuable contribution to the field of agricultural spraying technologies and introduces a promising approach to electrostatic nozzle design. It is recommended for publication after moderate revisions. The authors should improve the language and consistency of the manuscript, include more detailed experimental data with statistical validation, and address practical limitations of the proposed nozzle while comparing its performance with existing solutions.

Comments on the Quality of English Language

The manuscript contains numerous linguistic and grammatical inaccuracies, such as typographical errors (e.g., "electrostaic" instead of "electrostatic"), inconsistent punctuation, misuse of hyphens, and repetitive phrases that affect the clarity of the text. While the technical terminology is appropriate, the manuscript would benefit significantly from thorough language polishing to enhance its readability and academic tone.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf