Hydraulic Characteristics Analysis of Double-Bend Roadway of Abandoned Mine Pumped Storage
Round 1
Reviewer 1 Report
Abandoned mines have the inherent advantage of building underground energy storage power plants. Rational development of mine resources using abandoned mine pumped storage technology, can not only realize the secondary development and utilization of resources, and enhance the peaking capacity of the power grid, also provide a strategic path for the transformation and sustainable development of abandoned mine enterprises. With the common double-bend structure of abandoned mine roadway as research object, this study selected two typical underground double curved roadways to establish three-dimensional models, and used Fluent software to conduct numerical simulation of various models to analyze the fluid velocity field and pressure field under different tunnel geometric characteristics, as well as the influence of tunnel geometric characteristics on energy storage efficiency. The motivation behind the problem investigated in this manuscript is meaningful, and the relevant results can provide certain reference for the underground space planning and utilization of pumped storage in abandoned mines, however, there are critical issues, as detailed in the follows:
(1) The innovation and content in the paper are limited, and key concepts are not explained precisely. For example, what’s the operating condition simulated in this study? Are there any effects of different operating conditions, such as turbine operating condition and pump operating condition, on the simulation results? How to consider the effect of bend section spacing on the model? Related research work needs to be continued in depth.
(2) The analysis of paper is insufficient, there are new discoveries, but they are not well refined and sublimated, as well as raised to the theoretical height.
(3) The authors should clearly stated the limitations of the study.
(4) There exist errors in the use of punctuation, Chinese symbols, capital and lower-case letter, as well as the lack of necessary spaces between words.
(5) The paper has a high repetition rate, and the control equations in section 2.2 are all referenced from other studies, however, the relevant literature is not cited.
(6) The drawing is blurry, and the necessary textual information is missing in Fig. 1, Fig. 2 and Fig. 6. In addition, a brief description of the overall structure for underground cavern in abandoned mine should be given.
(7) Fig. 3, Fig. 4 and Fig. 5 have low resolution, which is difficult to distinguish the fluid velocity, flow lines and pressure distributions.
(8) The meanings of the characters in formula are not explained clearly, such as ρ and ρp. What does Y mean, and why is it set to 1.3?
(9) Quite a few errors in the language expression of the manuscript are existed, with prominent grammatical errors and serious colloquialism. The overall level of language needs to be further improved.
Author Response
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Reviewer 2 Report
The present manuscript describes the study of selected two typical underground double-curved roadways to establish three-dimensional models and used Fluent software to conduct a numerical simulation of various models to analyze the fluid velocity field and pressure field under different tunnel geometric characteristics, as well as the influence of tunnel geometric characteristics on energy storage efficiency. A manuscript has a practical application and also provides important theoretical for the next studies. The paper can be accepted for publication after providing the corrections mentioned below.
Point 1. The abstract section is too short, that is why an abstract needs to be enhanced with more descriptive details.
Point 2. Please use words not combinations of words or phrases. Keywords need to be modified.
Point 3. The introduction section is too short. In the introduction section, an enhanced literature review is required. It will be great if the authors show some description in context – why it is so important to provide this study.
Point 4. In case to provide in-deep literature review (according to Point 3) please consider the suggested research (comes from, Ukraine and Germany) in your paper when enhancing the introduction section. I believe they are worth considering in your paper.
Rudakov, D., & Westermann, S. (2021). Analytical modeling of mine water rebound: Three case studies in closed hard-coal mines in Germany. Mining of Mineral Deposits, 15(3), 22-30. https://doi.org/10.33271/mining15.03.022
Rudakov, D., & Inkin, O. (2022). Evaluation of heat supply with maintaining a safe mine water level during operation of open geothermal systems in post-coalmining areas. Mining of Mineral Deposits, 16(1), 24-31. https://doi.org/10.33271/mining16.01.024
Point 5. How Can the expected result be used or implemented within other abandoned mines?
Point 6. What are the limitations of your research?
Point 7. Can you provide more information about the Longdong Mine?
Point 8. Can you add some important geometrical parameters to Figure 1?
Point 9. Why was the SolidWorks software used?
Point 10. Does Bernoulli equation (4) is modified?
Point 11. Why have you used “H2O” but not “water” across the text?
Point 12. Please delete (1)-(4) in the conclusion section.
Point 13. The novelty of the paper must be highlighted in the conclusions section or an abstract.
Author Response
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Reviewer 3 Report
The research presented in the paper is at the level of a project done by a Bachelor level student. The significance of the knowledge resulting from the work is very low. The Authors proved that bends in the flow increase the energy losses. This is obvious for any engineer that deals with fluid flows.
The goal of the work is not clearly defined. If the Authors wanted to prove, what I cited above about the losses in a flow, then any engineering book would have been sufficient. If this work is a part of a larger research for example of an optimization of the underground storage system, then the whole work would be interesting, not just a small part of it.
Specific comments:
1.
The fluid is not clearly defined in the beginning of the paper. In is described in the section 2.3 that water and air are applied to the numerical model. However there are no further details. Does the water fill the roadways up to some level? What level is it then? If it is compressed air, then what are its parameters, the pressure and the temperature? The inlet pressure described in the section 2.3 is 300 mH2O, which is about 3 MPa but what is the general setup of the storage system?
2.
Figures 1 and 2.
Figure 1 shows that there is a quite large distance between the two corners (bends). At least it is considerably larger than the width of the roadway. In figure 2 and also in the numerical model the bends are located within a distance that is rather small - at most two or three times the width of the roadway. The question is: what is the real arrangement of the roadways? Is it closer to the figure 1 or 2?
3.
The governing equations should be totally removed from the paper, unless the Authors modified the FLUENT software via a scripting method of some sort. The Authors probably used the software as most of the engineers do - as users. In this case it doesn’t make sense to describe the equations. In the software they are used in an averaged form with some other transformations.
4.
What is Y = 1.3 m mentioned in the section 3.1? Is it the distance between the bends? Or the width of the roadways?
5.
The graphs in the fig. 7 should include a mark to show the location of the bends along the curve.
Author Response
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Round 2
Reviewer 1 Report
The present quality of the paper can be considered for publication.
Author Response
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Reviewer 2 Report
Dear authors, I am satisfied with the revisions provided by you.
Author Response
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Reviewer 3 Report
Technically the paper is correct. The text and figures are improved. Yet I did not change my opinion that the research value of the paper is very, very low, even though it is correctly described. It is up to the Editor to decide whether the level of the research is acceptable for the journal.
Author Response
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