Design and Analysis of a While-Drilling Energy-Harvesting Device Based on Piezoelectric Effect
Round 1
Reviewer 1 Report
Authors provided new energy harvesting devices using piezoelectric effects for downhole instruments during drilling process. However, energy harvesting devices using piezoelectric effect for such applications are very common.
It is hard to determine the novelty of the proposed approaches. Comparison of the high temperatures piezoelectric materials are very limited so authors should show why authors select the materials such as efficiency or flexibility or sensitivity parameters. No bandwidth and total harmonic distortion comparison are shown in the manuscript with your new approaches. Authors need to use professional English service or ask native English colleagues to improve the manuscript because there are some broken English expression. In addition, authors missed some references. Therefore, the manuscript is major revision if authors answer the following comments.
1. Authors should verify the novelty of this approaches in detail with several recent references in the introduction sections.
2. Authors need to use professional English service or ask native English colleagues to improve the manuscript one more time because there are some broken English expression.
3. Authors should provide the reference (This kind of commonly used structure is difficult to be directly applied in drilling borehole due to its limited annular space.)
4. Authors should provide the reference (Due to limitations of the materials, power generation capacity of piezoelectric energy collection device is limited)
5. Authors should provide the reference (In addition, its enclosed shell could not provide flow path for drilling fluid, so the traditional piezoelectric energy harvesting structures need to be modified to make it more suitable for the actual drilling working conditions.)
6. Authors should provide the reference (Compared with turbine power generation, piezoelectric energy collection and harvesting device generates less electricity.)
7 Authors should provide the reference (Under the action of external forces, deformation of such material would result in decrease of bound charge spacing and polarization strength between the internal positive and negative poles.).
8. Authors should provide the reference (However, as the drilling depth increases, the under-ground environment becomes complex and has characteristics of high temperature and high pressure.)
Author Response
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Author Response File: 
Author Response.docx
Reviewer 2 Report
The study reports an interesting analysis on energy harvesting during drilling operation which explores the application of piezoelectric material in the drilling field. Few items are to be addressed before publication. The manuscript can be improved by considering the following:
- Please explain briefly the principle of piezoelectric power generation in the context of the drilling vibration including various piezoelectric materials their advantages and limitations.
- Authors are requested to strengthen the literature review is needed to bring out the need for the present work. Authors need to explain the limitations of existing approaches and the identified research gap to be addressed in this study. Please provide an overview of existing devices related to drilling applications, if any.
- Radial dimension design of the proposed device is well explained. Is it possible to provide a range of dimensions within which this device will work? What will be the sensitivity of these dimensions on electric generation?
- Please clarify the basis for selection of beryllium copper for the cantilever beam. Also, is there any effect of cantilever beam parameters on device efficiency?
- In general, the natural frequency depends on mass and stiffness. Please explain in details the mode generation and how you are selecting the preferred modes.
- Are the inflection points different for the natural frequencies as shown in Fig 6? Please list them.
- What are the truncation/selection criteria for the natural frequencies?
- Why linear fitting models were used for defining the relation between the natural frequency and thickness? Please explain.
- The simulation methodology is insufficient. Please describe in details explaining meshing, boundary conditions, multi-physics coupling, material models etc.
- Please explain if there are constant or variable factors used in the simulation. For example, external circuit load resistance was set to 10 kΩ on which basis.
- Please concise the conclusions point-wise identifying the key points.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Reviewer 3 Report
This paper presents the design of an energy harvesting device based on the piezoelectric effect to address the problem of continuous feeding of downhole equipment. The work has a clear industrial application and may be of interest. I therefore recommend its publication.
Some comments that may help the authors to improve this manuscript are:
- Figures 1 and 2 do not clearly represent the elements. I would recommend redoing them and presenting models in three dimensions.
- In line 78 the spacing is not uniform.
- I recommend that the spacing between numerical figures and units be kept uniform. Example: 4W or 4 W
Author Response
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Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Authors corrected the manuscript with improved English expression and updated the references so the paper can be accepted.
Reviewer 2 Report
The revised manuscript has been improved significantly.
