Thermal Management of Fuel Cells Based on Diploid Genetic Algorithm and Fuzzy PID
Round 1
Reviewer 1 Report
The manuscript reported a diploid genetic algorithm for the thermal management of the PEMFC applications in order to optimize the membership function of the controller and improve the adaptability of the control system. The manuscript takes the inner layer of PEMFC as the foothold, through the analysis of the heat change and material flow between layers, the model can reflect the temperature change of various components. Moreover, a fuzzy PID controller is used to control the cooling water flow to achieve a cooling effect. The work reported in this manuscript can overcome the low efficiency and instability of haploid genetic algorithms in solving dynamic optimization problems.
I consider the content of this manuscript meets the reading interests of the readers of the journal. However, there are certain English spelling and grammar issues, and also the discussion and explanation should be further improved. I suggest giving a minor revision and the authors need to clarify some issues or supply some more experimental data to enrich the content.
1. For grammar issues, it is suggested that the author double-check the small grammar errors in the full text, especially the lack of and redundant use of definite articles.
2. For the Keywords, ‘temperature change’, ‘control strategy’, and ‘diploid’ should be added in order to attract a broader readership.
3. Page 1, ‘As a new energy technology, hydrogen fuel cell (HFC) has attracted attention due to its high energy density and no greenhouse gas output in the context of global energy crisis and environmental crisis.’ For no greenhouse gas emissions and to solve the global energy/environmental crisis, renewable energy sources are also desirable. What are the advantages of HFC over these energy sources? For the substitution of conventional fossil fuels, where are the hydrogen sources from? It should be explained a bit.
For example, renewable energy sources are unstable and intermittent during generation, and the generated energies are difficult to apply continuously and stably. The additional employment of energy storage systems are needed to improve the utilization rate and stability (ChemSusChem, 2022, 15(1): e202101798). Green hydrogen can be another solution since it can be produced by using the excess renewable energy sources, and later fuel cells can produce electricity with hydrogen when the energy generation by renewable energy sources is not sufficient (Sustainable Energy & Fuels, 2021, 5(4): 1085-1094).
‘If the temperature is too low, the battery may be flooded, and the activity of the molecules involved in the reaction will decrease, and the battery cannot give full play to its performance.’ The description of this sentence is inconsistent. If the activity of the reaction is low, and the battery does not reach its best performance, the water generation should be limited. Hence, how is it possible that the battery may be flooded?
‘If the temperature is too high, the water content of the proton exchange membrane will decrease’. That is true, but what is the relation between the water content of the PEM and the performance of the fuel cell? It is not described and the causal relationship is not very clear. Reduce the amount of water uptake/content in the membrane will lower the proton conductivity of the membrane, hence the limited proton conduction will restrain the electron transfer due to the charge conservation principle (Electrochimica Acta, 2021, 378: 138133). Hence, the PEMFC cannot operate at high current densities.
4. Page 2, ‘ The inside of the fuel cell is divided into five layers -- negative/positive end plate layer, negative/positive plate layer, MEA layer, and the temperature calculation of each layer are different [12].’ Why is the MEA layer not further divided into the membrane, GDL, MPL, and CL? It seems it is not a very accurate structure by dividing into only five layers [ETransportation, 2020, 5: 100075].
5. Page 7, ‘The target temperature of the proton exchange membrane is set at 70℃.’ How about the operating conditions and materials of the PEMFC? More details should be provided. As far as I know, for PEMFC assembled with different membranes, the target temperature should be different. How is the temperature of 70 degrees determined?
6. Page 12, ‘In this paper, the NEDC working condition is taken as the simulation condition to test whether the thermal management...’ What is the ‘NEDC working condition’? It should be clarified.
‘Set the target temperature to 343.15K. The input gas temperature is set at 373.15K. ’ Why is the temperature of input gas much higher than the target temperature? Is this really practical or just an assumed condition?
7. Page 13, ‘The smaller the evaluation index is, the higher the control precision of the system is. In the simulation process, the ITAE index is recorded for each simulation cycle. The smaller the evaluation index is, the higher the control precision of the system is.’ At the beginning and the end, the same sentence appears twice, which should be refined.
Author Response
Dear editor and reviewer：
Thank you very much for your suggestions and views. Your opinions are of great help to the improvement of the quality and readability of this paper, and also play an important role in guiding our research. We have studied comments carefully and have made correction which we hope meet with approval. There are revised papers in the attachment. Revised portions are marked in red in the paper. The main corrections in the paper and the responds to the reviewer’s comments are as follows:
Reply 1:
Thank you for your suggestions on grammar issues in this paper. We have corrected some grammatical errors.
Reply 2:
Thank you for some additions on keywords. We have added them to the keyword field.
Reply 3:
Thank you for your suggestions on expanding the illustration of HFC energy advantages in this paper, and for providing a way of thinking through examples. Based on your examples and literature, we have revised our presentation of the prospect of fuel cells. See Chapter 1, Section 1.1 for details.
Thank you for your question about ‘ the battery may be flooded ’. I'm sorry we didn't put it right on this sentence. What we mean is ‘If the temperature is too low, the vapor agglutination of the gas diffusion layer and the bipolar plate runner cannot volatilize, resulting in too much water. The volume of water will crowd out the volume of the reaction gas and affect the participation of the gas in the reaction. ’.It's like being in water and not being able to breathe.
At the same time, your explanation of the principle that "the excessively high temperature of the reactor leads to the decrease of the power generation capacity" is very correct. We have revised and added it to the paper according to your opinion. Make the paper more substantial.
Please refer to Section 1.2 of Sheet 1 for details of the paper modification.
Reply 4:
Your description of the internal structure of the fuel cell is correct. We tried to establish fuel cell structures including membrane, GDL and CL at the initial stage of model building, but the simulation results were poor. By analyzing the reasons, we believe that the material flow between membranes, GDL and CL is complex and cannot be simply quantified by a model. However, they will be integrated into one - MEA, the relationship between the layers will more understand. At the same time, the temperature of membrane, GDL and CL is similar, which is representative of MEA layer modeling. We finally adopted MEA modeling. The reasons have been sorted into the paper.
Reply 5:
I am very sorry that we have made a mistake here. It should be: 'Target temperature of MEA layer'. We have made many corrections to the paper and promised not to repeat them.
What you said about 'target temperature setting needs to be based' is very reasonable. We by reference [https://doi.org/10.1016/j.enconman.2021.114842]. In this paper, the real-time optimal operating temperature of vehicle fuel cells is tracked and obtained between 65 and 80℃.We set it at 70 degrees Celsius. At the same time, the materials and working parameters of fuel cells are attached in the paper. See Chapter 3, Section 3.1 for details. Refer to the end of Chapter 2 for material parameters.
Reply 6:
New European Driving Cycle——NEDC
Reply 7:
Thank you for correcting the errors in the paper. This error has been corrected.
According to the suggestion of a reviewer, we modified the model parameters and changed the data graph.
Finally, thank you for reviewing the paper and making suggestions on it. Every suggestion you have on the paper is very valuable to us.
Author，Zhao Ruikang
2022.12.22
Author Response File: 
Author Response.docx
Reviewer 2 Report
In this study, the Authors proposed thermal management of fuel cells based on a diploid Genetic algorithm and fuzzy PID and compared it with unoptimized fuzzy PID. It is an impressive study that can guide the future design of fuel cell systems to enhance their commercialization and make the stack works at regulated conditions with no damage. This topic could attract a large readership of researchers in the field of fuel cells. Corrections to be made in this study before publishing are listed below:
Point 1: I suggest that the authors divide the introduction section into several subsections, which would make it more readable.
The following subdivision for example:
1.1 Motivations, where the authors explain the problem they want to solve.
1.2 State of the arts, in which the authors describe and directly compare existing solutions highlighting where they intend to contribute.
1.3 Contributions, in which the authors make an explicit list of the contributions that this work introduces with respect to the state of the art.
Point 2: In the study, it appears that there are many improperly spaced punctuations. Please added spaces.
Point 3: In the study, many abbreviations were used in the text. Some of these abbreviations were never defined and some were used without definition for instance proton exchange membrane fuel cells (PEMFC). All abbreviations should be defined beforehand, and a list of abbreviations can be added.
Point 4: In some places, language should be improved (mostly in the Abstract and the Introduction). Reference style should be corrected from "For instance, in [4], [...]" to "For instance, in Zhiming Zhang et al. [4], [...]".
Point 5: There is no description or values of the parameters of equations (1 to 18). Please add a table of the parameters of the previous equations also a reference should be added for each equation.
Point 6: The literature survey needs improvement; please expand it. Additional related papers can be found in the applied sciences journal, as well as in other energy and fuel cells related publications.
Point 7: Simulink model figures are blurry please improve it.
Point 8: Use separated spaces between paragraphs, also between tables and paragraphs.
Point 9: The First letter in Figures X and Y labels should be in capital letters.
Point 10: There are two figures 13 please confirm.
Point 11: Relevant recent literatures about fuel cells should be cited such as Actuators. https://doi.org/10.3390/act9040105; Energies. https://doi.org/10.3390/en13174317; Sustainability. https://doi.org/10.3390/su13042360; Processes. https://doi.org/10.3390/pr10030450; Electronics: https://doi.org/10.3390/electronics11162610
Point 12: The references part needs to be carefully checked and revised. Please, check the guide for authors /or some papers from applied sciences journal.
Author Response
Dear editor and reviewer：
Thank you very much for your suggestions and views. Your opinions are of great help to the improvement of the quality and readability of this paper, and also play an important role in guiding our research. We have studied comments carefully and have made correction which we hope meet with approval. There are revised papers in the attachment. Revised portions are marked in red in the paper. The main corrections in the paper and the responds to the reviewer’s comments are as follows:
Reply 1:
Thank you for your thoughts on Chapter 1 division. We have divided Chapter 1 into four summaries according to the content.
Reply 2:
We have corrected the punctuation interval in the paper according to your suggestion.
Reply 3:
We are very sorry that we failed to produce the acronym list as you requested. We promise to attach an acronym list to our next submission.
Reply 4:
The reference format has been modified according to your suggestion.
Reply 5:
A table of parameter constants has been made according to your suggestion. See the end of Chapter 2 for details.
Reply 6:
According to your suggestion, we have made some expansion to the literature survey.
Reply 7:
According to your suggestion, we have changed the picture source of simulink picture.
Reply 8:
According to your suggestion, we have adjusted the gap between partial paragraphs and paragraphs and between paragraphs in the table.
Reply 9:
According to your suggestion, we capitalize the data graph label. At the same time, the format of data graph is optimized to make it more beautiful.
Reply 10:
This is an oversight on our part, and we are very sorry. We reconfirmed the drawing number.
Reply 11:
The paper you provided has been cited.
Reply 12:
The literature section has been re-entered according to your suggestion.
According to the suggestion of a reviewer, we modified the model parameters and changed the data graph.
Finally, thank you for reviewing the paper and making suggestions on it. Every suggestion you have on the paper is very valuable to us.
Author，Zhao Ruikang
2022.12.22
Author Response File: Author Response.docx
Reviewer 3 Report
This paper displays an interesting work for the optimization of a fuzzy PID using diploid genetic algorithm for the control of thermal fuel cells. The authors show an adequate development. However, aspects to review and improve are:
1. It is recommended to review the title as it is confusing.
2. In the introduction, please clarify the paper difference from similar works.
3. It is suggested to include a graphic abstract in the introduction.
4. A paragraph should be included in the introduction indicating the organization of the document.
5. Please expand the explanation of diagram in Figure 1.
6. What is the motivation to use Integral of Time and Absolute Error (ITAE) as the fitness function?
7. The selection of parameters of the genetic algorithm must be justified.
8. A statistical summary of all performed runs of the genetic algorithm should be displayed. In this regard, a statistical analysis can also be performed to validate the optimization process achieved with the genetic algorithm.
9. It is recommended to expand the explanation, analysis, and discussion of Figures 12 to 15.
10. It is important to include a discussion section addressing the limitations and aspects not covered.
11. It is suggested to separate the conclusions into paragraphs according to the aspects to highlight.
12. It is recommended to use the form provided in the template to cite the bibliography.
13. A general revision of the article is suggested to improve the writing. Some typos are identified; for example, see lines 9, 11, 14, 17, 26, 29, 33, and so on for the rest of the document. Also review lines 302, and 309.
Author Response
Dear editor and reviewer：
Thank you very much for your suggestions and views. Your opinions are of great help to the improvement of the quality and readability of this paper, and also play an important role in guiding our research. We have studied comments carefully and have made correction which we hope meet with approval. There are revised papers in the attachment. Revised portions are marked in red in the paper. The main corrections in the paper and the responds to the reviewer’s comments are as follows:
Reply 1:
Some titles have been revised according to your comments.
Reply 2:
Based on your and other reviewers' comments, the paper content and differences are concentrated in Chapter 1, Section 1.4.
Reply 3:
We regret that we were unable to complete your proposal in time. We promise to complete the chart summary by the next submission.
Reply 4:
According to your suggestions, we have added the general content of the article in Chapter 1, Section 1.4.
Reply 5:
Based on your suggestions, we have added the description of Figure 1. See Chapter 1, Section 2.1 for details.
Reply 6:
The loop time we simulated was long. Taking ITEA index as fitness, it can not only show the instantaneous error, but also not ignore the error accumulated over time. For each driving cycle duration, the algorithm records a fitness and is associated with the genetic information expressed at this time, which serves as an important basis for selection operators to screen excellent genes.
The explanation of your opinion is also summarized in Chapter 3, Section 3.2.2.
Reply 7:
According to your comments, we have explained in detail the origin of genetic algorithm optimization parameter setting.
‘Because the membership function is triangular, the fuzzy subsets NB and PB can be represented by 2 parameters at the membership function boundary, while the other fuzzy subsets need to be represented by 3 parameters, and each membership function has 19 optimization parameters.’
The explanation of your opinion is also summarized in Chapter 3, Section 3.2.1.
Reply 8:
According to your comments, we have made certain refinement of the 100 times overlapping representation. The excellent number, good number, bad number, maximum value and minimum value of 0~20, 21~40, 41~60, 61~80 and 81~100 were counted respectively. The causes of some phenomena are analyzed.
Reply 9:
According to your suggestions, we have expanded the discussion and analysis of Figure 12~16.
Reply 10:
Based on your suggestions, we have divided discussion sections, focusing on some of the phenomena in simulation, the reasons for the phenomena, and the limitations of the article.
Reply 11:
According to your suggestions, the conclusion is divided into two parts: the summary of this paper and the simulation results.
Reply 12:
According to your suggestion, refer to the literature for re-entry.
Reply 13:
According to your suggestion, some typos in the article have been changed.
According to the suggestion of a reviewer, we modified the model parameters and changed the data graph.
Finally, thank you for reviewing the paper and making suggestions on it. Every suggestion you have on the paper is very valuable to us.
Author，Zhao Ruikang
2022.12.22
Author Response File: Author Response.docx
Reviewer 4 Report
[1] Lots of typing errors are found in the manuscript, the authors should check the whole manuscript very carefully. Some of examples are shown below.
[1-a] Abstract, line 9 -- “cells.On the model,…..”, A space between “cells.” and “On” is missed.
[1-b] Abstract, line 11 -- “Assembly).In..…. ”, ” A space between “Assembly)s.” and “In” is missed.
[1-c] Page 1, line 37--- “Zhiming Zhang et al….” Please add references in this sentence.
[1-d] Page 1, line 41---- “…..GDL are revealed[4].Mohanty…..” A space between “revealed[4].” and “Mohanty..” is missed.
[1-e] Page 2, line 46---- “Dongxu Li et al. established…..” Please add references in this sentence.
[1-7] page 2, line 53 ---- “…..simulink.Martin et al…..” A space between “simulink.” and “Martin” is missed.
[2] Page 5, Table 1 ---- Usually, the area of MEA is smaller than that of polar plate, the area of polar plate is smaller than that of end plate. However, in Table 1, the areas of MEA, polar plate, and end plate are same. The areas of the three plates shown in Table 1 are unreasonable.
[3] In Eq. (1), why the heat loss term “QL1“ is not count in the energy conservation, i.e.,
(ρL1 AL1 hL1 cp,L1)(dTL,1/dt)= Qair + QL2 – QL1
Similarly, in Eq. (4) (bipolar plate model) and Eq. (15) (MEA model), why the heat flow out terms were not counted in the equations?
Author Response
Dear editor and reviewer：
Thank you very much for your suggestions and views. Your opinions are of great help to the improvement of the quality and readability of this paper, and also play an important role in guiding our research. We have studied comments carefully and have made correction which we hope meet with approval. There are revised papers in the attachment. Revised portions are marked in red in the paper. The main corrections in the paper and the responds to the reviewer’s comments are as follows：
Reply 1:
Thank you for your suggestions on the format of the paper. It has been modified according to your suggestions.
Reply 2:
The model parameters have been modified according to your suggestion. The area of MEA layer is 0.0036m2, the area of bipolar plate is 0.0049m2 and the area of end plate is 0.0064m2. At the same time, re-simulation, update data graph.
Reply 3:
The end layer temperature is always higher than the outside temperature. So, the calculation result of Qair is negative. Similarly, in Eq. (15) of MEA layer, the positive and negative values of QL2, QL2R, QL4 and QL4R depend on the temperature relationship between MEA layer and bipolar plate.
Finally, thank you for reviewing the paper and making suggestions on it. Every suggestion you have on the paper is very valuable to us.
Author，Zhao Ruikang
2022.12.22
Author Response File: Author Response.docx
Reviewer 5 Report
I have attached the file to this email.
Comments for author File: Comments.docx
Author Response
Dear editor and reviewer：
Thank you very much for your suggestions and views. Your opinions are of great help to the improvement of the quality and readability of this paper, and also play an important role in guiding our research. We have studied comments carefully and have made correction which we hope meet with approval. There are revised papers in the attachment. Revised portions are marked in red in the paper. The main corrections in the paper and the responds to the reviewer’s comments are as follows:
Reply 1:
Some syntax errors have been corrected according to your suggestions.
Reply 2:
According to your suggestion, the comparison with other workers is concentrated in Chapter 1, Section 1.4.
Reply 3:
According to your suggestion, the source of figure 2, 8 and 9 has been changed.
Reply 4:
According to your suggestions, describe the calculation process of the figure.See the beginning of Chapter 3 for details.
Reply 5:
According to your suggestion, the function of each parameter of the equation is described in detail.
Reply 6:
Based on your suggestions and those of other reviewers, the paper's work is expanded in the conclusion chapter while the discussion chapter is divided.
Reply 7:
At your suggestion, some of the findings have been described in the abstract.
Reply 8:
The literature you provided has been cited.
According to the suggestion of a reviewer, we modified the model parameters and changed the data graph.
Finally, thank you for reviewing the paper and making suggestions on it. Every suggestion you have on the paper is very valuable to us.
Author，Zhao Ruikang
2022.12.22
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
The paper was already well presented, so I don't feel like giving another major for the latest shortcomings.
However, there are some points that need improvement before the final submission:
Point 1: The abbreviation PEMFC, MEA, and GA are mentioned in the keyword but not defined in the abstract. proton exchange membrane (PEMFC), membrane electrode assembly (MEA), and genetic algorithm (GA).
Point 2: Many improperly spaced punctuations in the paper are not corrected. For instance, in the abstract:
-, efficiency and power output of fuel cells.On the model,
- control strategy reduce by 27.9%.Compared with
Same for the parts in the introduction for instance:
- different countries.Academic
- in recent years.Among them
- reaction.At the same
- reaction.The water
- too high.The conductivity
Please revise all the paper and added spaces.
Point 3: There are two same titles:
1.3. Advances in fuel cell research and 1.4. Advances in fuel cell research. Please confirm.
Author Response
Dear editor and reviewer：
Thank you for your approval of this paper and for your suggestions on it. According to your suggestions, we have made the following modifications:
Reply 1:
We annotated the abbreviations and added a list of abbreviations at the end of chapter 1.
Reply 2:
We have corrected the punctuation errors according to your suggestions and corrected the punctuation errors in the whole text.
Reply 3:
We have revised the title of Section 1.4 of Chapter 1 according to your reminder. The title is "Research content of this paper."
Thank you again for reviewing this paper and suggesting revisions.
Author，Zhao Ruikang
2022.12.28
Author Response File: Author Response.docx
Reviewer 3 Report
The authors have successfully addressed all the comments and clarification is satisfied from the authors.
Finally to have a continuity in reading, it is suggested to add an introductory paragraph in Section 1.
Author Response
Dear editor and reviewer：
Thank you for your approval of this paper and for your suggestions on it. According to your suggestions, we have made the following modifications:
In accordance with your suggestions, we supplement the introduction of fuel cell system composition, different types of thermal management and different control methods in Chapter 1, Section 1.1.
We have also corrected punctuation errors in the whole text and spelling errors in some words.
Thank you again for reviewing this paper and suggesting revisions.
Author，Zhao Ruikang
2022.12.28
Author Response File: Author Response.docx
Reviewer 4 Report
The manuscript can be published in the present form.
Author Response
Dear editor and reviewer：
Thank you for your approval of this paper and for your suggestions on it. Your opinion is very helpful to improve the quality of the paper.
It's my honor to have this paper reviewed by you.
Author，Zhao Ruikang
2022.12.28
Author Response File: Author Response.docx
Reviewer 5 Report
The Authors have correctly made all the required changes.
Author Response
Dear editor and reviewer：
Thank you for your approval of this paper and for your suggestions on it. According to your suggestions, we have made the following modifications:
We have corrected the punctuation errors in the whole article and corrected some spelling mistakes.
Thank you again for reviewing this paper and suggesting revisions.
Author，Zhao Ruikang
2022.12.28
Author Response File: Author Response.docx
