Design and Implementation of a MHz Frequency Transformer with a Ferromagnetic Fluid Core
Round 1
Reviewer 1 Report
From my point of view, the topic paper is quite interesting but some questions should be answered or clarified:
1- the differet iron losses should be estudied: Kh, Hf and Ke (histeresis, foucalt and excess).
2- structure has some mistakes: figure 2 ("lm is moved"), equations from 11 to 14 are moved, etc.
3- I wolud like to see the B-H curve.
4- I would likr to see the comparation of MUMPS.
5- Table 1. I would like to know the origin of that parameters.
6- The quality of figure 4 should be improved.
Author Response
REVIEWER 1:
Q1. The different iron losses should be studied: Kh, Hf and Ke (histeresis, foucalt and excess).
R1. As mentioned in the provided research the fluid core enables access to low conductivity and super paramagnetic features in order to decrease the eddy currents and core losses encountered in the conventional transformers. In current research the simulation and practical processes for designing the transformer operating with magnetic fluid core has been investigated. Implementation and analyzing the performance of the system in terms of various losses happening in the transformer, is one of the very basic objectives of the authors of this article that is planned to be studied as the achievement in the next paper as future work. To conclude all parameters cannot be explored in a single paper. We have 44 pages in double lines already and different iron losses are another issue which depends on different iron matter.
Q2. Structure has some mistakes: figure 2 ("lm is moved"), equations from 11 to 14 are moved, etc.
R2. Figure 2 and equations are corrected in accordance with the reviewer’s comments.
Q3. I would like to see the B-H curve.
R3. The magnetization curve generated for various concentration rates of the magnetic fluid which is located inside the transformer core is provided in Figure 11. Since he relationship for B (magnetic flux density) can be written in the equivalent form B = μ0(H + M), H (magnetic field strength) and M (magnetization of the material) will have the same units, amperes/meter. Hence the B-H curve can be obtained according to the coefficient mentioned. Thus, there is no need to draw another curve since we have already given the M-H curve (Fig. 11) in that regard.
Q4. I would like to see the comparison of MUMPS.
R4. The problem is non-linear. At first step the determined equation is proper for the Coil Geometry Analysis. A time dependent study is needed for transient solving. The settings needed to arrange the convergence due to the nonlinearity in addition to achieve a reduction in computing processes. Hence the stationary equations one should utilize the previous study results. For the transient study in time dependent solver, in order to configure the solver, the time stepping taken by the solver is selected as intermediate. The solver method is in direct type and Mumps. The convergence plot is presented below:
Of course one should check these calculation plots in order to be at the safe side for the simulation results.
Q5. Table 1. I would like to know the origin of that parameters.
R5. The parameters given in Table 1 are in accordance with the simulation study. The numerical value for some of these parameters (Dynamic viscosity (Pa s), Heat capacity at constant pressure (J/(kg K)), Thermal conductivity (W/mK), Electrical conductivity [MS/m]) are detected automatically by default as the considered parameter which decided to be used as the core is introduced to the program as a material. Comsol multi-physics simulation packet does not offer a capability of presenting the exact properties of practically achieved mixture (solution) by directly asking for the chemical properties. Hence, the parameters are formed separately. The remaining parameters (Chemical composition of magnetic particle, Magnetic particle mean radius (μm), Magnetic particles weight concentration, Density (g/), Operating frequency (MHz)) are defined by the researchers with respect to the circumstances of the tests in various cases of simulation study. One has to be parallel with the earlier works on the magnetic materials, thereby by using these material parameters, we found our model close to the experimental work.
Q6. The quality of figure 4 should be improved.
R6. The quality of Figure 4 is improved.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This manuscript presents the design and practical implementation of transformer. Below, are my comments for improving.
1) The novelty of manuscript must be clarified.
2) The text and description of manuscript must be improved.
3) The number of references is high. The authors must select the most important and up-to-date ones.
4) One comparison table must be added with the recently published papers.
5) The structure is straightforward. The authors must improve the structure with the novelty of performance.
Author Response
REVIEWER 2:
Q1. The novelty of manuscript must be clarified.
R1. For the novelty we have added sentences to the end of the Introduction as follows:
“The main innovation of the present work is that we aim to design and construct a transformer working with a very cheap ferro-fluid structure combined with iron dusts and engine oil in its core having special geometry, which has not been worked experimentally and theoretically before. In this context, we explore the characteristic features of the new transformer for the first time to our knowledge and prove that it gives both solid and liquid features depending on the mass fraction of the ferromagnetic material. It will be also proven that there exist a certain mass fraction leading the maximum power at the terminals of secondary windings. Besides, for the first time to our knowledge, we operate the transformer under MHz range and find that the transformer works very well under such a high frequency.”
Q2. The text and description of manuscript must be improved.
R2. We have improved the text and manuscript by consolidating to a native English speaker. The journal itself has also an editing service for all papers too. Thus, the paper is ready in that regard.
Q3. The number of references is high. The authors must select the most important and up-to-date ones.
R3. The number of References is reduced to the most important and up-to-date ones as the reviewer recommends.
Q4. One comparison table must be added with the recently published papers.
R4. A comparison table (Table 5) has been added in order to assert an evaluation of the current paper and compare the previous applications that have utilized similar methods and materials with various operating frequencies.
Q5. The structure is straightforward. The authors must improve the structure with the novelty of performance.
R5. We have added the importance and innovative part of the structure at the end of Introduction section. Also, we have proven that the new transformer works well under high frequencies in MHz range. The structure has been improved with a very cheap new fluid core mixture by iron dust and engine oil. Therefore, core structure is not considered as straightforward since we have explored various components with different ferromagnet fraction ratio which is not encountered in previous works.
Author Response File: Author Response.pdf
Reviewer 3 Report
Dear authors, I have read your paper entitled "Design and Implementation of an MHz Frequency Transformer with a Ferromagnetic Fluid Core", I found the paper well structured and organized. This work is well supported with theory, simulations, and experiments. I found a good agreement with these results. My comments are:
1. The quality of Figures 7 and 8 must be improved.
2. Table 4 must be corrected.
Author Response
REVIEWER 3:
Q1. The quality of Figures 7 and 8 must be improved.
R1. The qualities of Figures 7 and 8 have been improved.
Q2. Table 4 must be corrected.
R2. Table 4 is corrected in accordance with the reviewers’ comments.
Author Response File: Author Response.pdf
Reviewer 4 Report
The authors sought to expand their earlier published work ( 10.30521/jes.1123925 ). The novelty has worn off and is not merged with an original research article. In my judgement, this work cannot be published in Sustainability journal
Author Response
REVIEWER 4:
Q1. The authors sought to expand their earlier published work (10.30521/jes.1123925). The novelty has worn off and is not merged with an original research article. In my judgement, this work cannot be published in Sustainability journal.
R1. Our transformer works for different frequency regime with an easier magnetofluid. Therefore, we do not agree that our work is similar to the earlier ones. Our magnetofluid structure is not complicated. Also, we introduce a mass ratio variable which varies all the electromagnetic results of the transformers. Before the current study, in the literature there exists no such a detailed study for an easy-constructed magneto fluid core. Even it is too cheap compared to the other studies. The mathematical model and the numerical simulations of the transformer with copper windings are analyzed in (10.30521/jes.1123925). There is no experimental work in the mentioned previous paper. The reviewer should be careful on what was included in the previous publication. The mentioned research is concerned with different electric powering schemes providing the operational conditions considered and 3D models are used to compute the magnetic field, the magnetic fluid core flow, and magnetic parameters of the magnetic fluid core transformer by simulation program. However, the current paper specifies the practical study and the experimental processes of a ferrofluid core transformer with varying the percentage of magnetic nanoparticles’ mass fraction for the first time to our knowledge in the literature. For lower and higher values of mass fraction, voltage and power at the secondary windings are varied. Besides, it has been observed that the electrical properties and output power and voltage characteristics of the designed transformer in the prototype environment are similar to those of industrially used transformers at high frequency values.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
It is recommended to authors to plot all the figures with one style.
Reviewer 4 Report
As I stated before, I found a sort of "recycling fraud" and the The authors' explanations about the differences are not convincing and sufficient, hence, in my opinion this work cannot be published in Sustainability journal.
