Numerical Analysis of the Effects of Ship Motion on Hydrogen Release and Dispersion in an Enclosed Area

Round 1

Reviewer 1 Report

The authors presented a numerical study of the release and dispersion of hydrogen enclosed in a rectangular box, taking into account the conditions of the ship’s motion. The CFD code FLUENT is used as a numerical tool. The governing equations include the continuity, momentum, energy, species transport, turbulent kinetic energy and dissipation rate equations of turbulent kinetic energy. The effectiveness of the numerical analysis was verified by comparing the experimental and numerical results in a steady state. A vent was located on the left side of the ceiling of the experimental box to ensure constant pressure conditions. Hydrogen was released through a tube from the right side of the enclosure. Seven hydrogen sensors were employed to measure the hydrogen concentration. It is shown that the 
experimental and numerical results predicted similar hydrogen concentrations. 
Then the hydrogen concentration for each sensor location was investigated using the ship motion type, period, and motion direction as variables for analyzing the effect of ship motion on the hydrogen dispersion behavior. The calculations presented show that hydrogen leakage diffusion changes significantly under various ship motion conditions. 
The studies performed are necessary to ensure the safe operation of ships using hydrogen energy. The subject of this manuscript is within the aims and scope of journal “Applied Sciences” but the manuscript may be acceptable after minor revision. 
Reviewer’s remark: 
1) On p. 8 (line 232), definition of the value ‘d’ should be given.

Author Response

[January 18, 2022]

Dear Editor:

We wish to re-submit the manuscript titled “Numerical analysis of the effect of ship motion on hydrogen release and dispersion in an enclosed area.” The manuscript ID is [applsci-1545603].

We thank you and the reviewers for your thoughtful suggestions and insights. The manuscript has benefited from these insightful suggestions. I look forward to working with you and the reviewers to move this manuscript closer to publication in the Applied Science.

The manuscript has been rechecked and the necessary changes have been made in accordance with the reviewers’ suggestions. Revised text has been highlighted in blue in the manuscript. The responses to all comments have been prepared and attached herewith.

Thank you for your consideration. I look forward to hearing from you.

 

Sincerely,

Kwang-Il Hwang

Affiliation: Korea Maritime and Ocean University

Address: 727, Taejong-ro, Yeongdo-gu, Busan 49112, Korea

Tel.: +82-51-410-4368

E-mail: [email protected]

 

Author Response File: Author Response.pdf

Reviewer 2 Report

The title of the paper is appropriately selected. Summary is clear. Introduction is sufficiently detailed with appropriate references. Figures and tables are suitable size and resolution and well described. The used units are correct. Calls to figures, tables and references are clear.
The work is well structured, with well-chosen names of chapters. Results and discussion are elaborated in detail and are very promising for further implementation. Conclusion is clear, also.

One global note, which runs through most of the text, is the syntax that should clearly state what Ship motion types (roll and pitch) are, which is fine (Figure 1), but should also be clearly indicated in the second part of the paper, for example in Table 2 should be replaced by type of ship motion instead of description.

The second global note refers to the Direction of ship motions, which is a term within seakeeping analysis reserved for the direction of ship motion in relation to the waves (180 deg are waves in the bow), which is here characterised as clockwise and counter clockwise and which is fine. Thus, it should be clearly indicated that this is the local direction of motion of a particular cross-section (longitudinal or transverse) and not the global motion of the ship.

Page 6, maybe number of grids such as 490000 grids are elements (not grids) in sense of domain meshing?

Page 8; are 15000 tons are deadweight or displacement tons?

Figure 7 c and 8 c should be a bit larger

Within text, instead movements it should be appropriate term motions in sense of naval architecture nomenclature.

Figure 11 title should be Longitudinal cross-section… as well as Figure 12 Transversal cross-section… in order to distinguish ship planes, inspite showed data Y=0.0m and X=0.0m

Author Response

Please see the attachment.

Author Response File: Author Response.pdf