Improved Smoke Exhaust Efficiency Through Modification of Ventilation Fan Orientation in Underground Parking Lots

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This study investigates the optimization of installation orientation for ventilation fans and inducer fans to effectively exhaust smoke in underground parking lots during a fire. The authors present CFD simulation results comparing the smoke exhaust performance when the ventilation and inducer fans are arranged primarily in horizontal and vertical orientations. These findings are meaningful as they can provide guidelines for fan installation in underground parking lots. The study aligns well with the scope of Fire Journal, and I believe the paper could be considered for publication after addressing the suggestions outlined below.

 

1. In Figures 4 and 6, the authors explain that the Intake, Fire area, and Exhaust positions correspond to the Upper, Middle, and Lower levels, and they describe the smoke distribution at each location. To improve clarity and reader comprehension, it would be helpful to indicate the regions corresponding to Upper, Middle, and Lower more explicitly in the figures.
2. In this study, the analysis of smoke movement was performed at 200 seconds. Besides the authors’ remark that the smoke distribution is clearly observable at this time, is there any additional reason for selecting 200 seconds? Furthermore, while analyzing the smoke distribution over time after the fire, what was the rationale for choosing 1000 seconds? If the intention was to evaluate smoke distribution after fire extinguishment, it would be helpful to specify the exact extinguishment time and clarify how long after extinguishment the 1000-second mark represents.
3. In the visibility analysis for the PA case, the authors state that the proportion of the blue zone is concentrated in the Upper and Lower regions, while the green zone is evenly distributed across the Upper and Lower regions. However, Tables 4 and 5 suggest that the proportions of the blue zone in the Middle and Lower regions do not differ significantly. Furthermore, for the green zone, the Middle region appears to have a higher proportion than the Lower region. This indicates a discrepancy between the values and the description, and clarification regarding the reason for this difference is needed
4. Regarding the explanation in the section beginning with ‘Furthermore, because overall~’ on page 7, a more detailed justification supported by concrete evidence is needed.

Author Response

Thank you for the valuable comments on our paper. The point-by-point response to the valuable comments is attached.

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

This study employs the Fire Dynamics Simulator (FDS) to investigate smoke exhaust efficiency in underground parking garages. By considering parallel or perpendicular installation of intake and exhaust ports for induced draft fans and ventilation fans, it analyzes the impact of airflow volume at intake and exhaust ports on smoke movement and visibility.

1. The grid size of the FDS model in the paper is 0.3m. The rationale for this selection should be provided and validated to enhance its persuasiveness.
2. Figures 6 and 9 lack the rainbow bars indicating visibility values, making it impossible to accurately display the visibility gradient distribution in the images.
3. This study primarily employed qualitative analysis throughout the research process, making it impossible to precisely quantify the relationship between ventilation efficiency and airflow volume. Furthermore, all findings are based solely on simulation calculations without validation through full-scale or scaled experiments, resulting in a lack of persuasive evidence.
4. Numerous scholars have previously investigated the impact of horizontal versus vertical installation of ventilation inlets and exhaust outlets on ventilation efficiency, and extensive practical applications exist in engineering practice. Consequently, this topic cannot be considered a novel research focus of this paper.
5. The parameters examined in this study lack sufficient detail. For instance, while the variables include the relative position and orientation of ventilation fans and smoke exhaust outlets, the analysis fails to account for the combined effects of varying exhaust outlet areas across different orientations and changes in airflow organization direction. This oversight risks misinterpretation of the conclusions and underlying mechanisms.
6. The innovation of the research methods or theories in this paper is insufficient, and it is suggested to improve.

Author Response

Thank you for the valuable comments which allow us to improve the quality of our paper. The detailed point-by-point response to each valuable comment is attached. Please see the attachment.

Author Response File: Author Response.docx