Phase Change Materials—Applications and Systems Designs: A Literature Review
Round 1
Reviewer 1 Report
Please see the attached pdf.
Comments for author File: 
Comments.pdf
Author Response
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Author Response File: Author Response.pdf
Reviewer 2 Report
Thank you for your confidence in this journal. Your mini review is standard in writing and structure. The authors have summarized both conventional applications and recent applications of PCM-based. The conducted survey research seems necessary. However, the prepared manuscript needs to be revised carefully and after major revision can be considered for publication. Please find the comments as below:
1. Novelty part should be improved appropriately. Obviously, there are a lot of reviews about PCM, and you need to reflect the novelty part of your article as much as possible. Novelty part must cover importance of the work and at the same time represent the best findings of the article. This section is vital part and needs serious attention.
2. The latest research of PCM-based in this review seems incomplete. Therefore, if possible, I hope the author can summarize more in this respect.
3. The proof reading is suggested.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
The work is relatively comprehensive overall, but part of it is not very rigorous. In addition, the article lacks comparison of different methods. There are some minor issues in this study as listed below.
1. The necessary references shall be provided for the subcategories in the technical roadmap or technical classification map, such as Fig.2, 10.
2. Tables 1 and 2 should be summarized, classified, and condensed.
3. The subdirectory is unclear in Section 3.
4. There are three types of encapsulations in Figure 2. However, the third category is not introduced in Section 3.
5. “Nano-capsules containing phase change material n-dodecanol as core and polymethyl methacrylate and copper oxide nanoparticles as shell were synthesized by mini-emulsion polymerization.” Is this nanoencapsulation? Whether it is reasonable to state it in the section of form stable PCMs.
6. The classification is unreasonable, such as, Capsule shape and material selection, capsule material selection.
7. Some conclusions are abrupt, and the text lacks corresponding explanation and discussion, such as “It can be argued, that in theory, any technical system undergoing transient thermal regimes can benefit to various degrees from the application of a PCM-based solution.”
8. Careful proofreading is needed to avoid typos and grammar mistakes.
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
This paper presents study of development of Phase Change Materials applications and products closely related to the market of the renewable energy technologies. Authors provide interesting review focused on examining both conventional applications and recent advances and areas.
Although presented article may be interesting to the readership of this journal, the paper may only be considered for publication after the following concerns have been addressed successfully in a revision:
In general:
1) The title of the manuscript should indicate that this manuscript is a review paper.
2) Introduction of the "nomenclature" part is recommended because there are some abbreviations and markings that should be defined at the beginning of the paper. Including this section would make the article much easier for readers less familiar with specific abbreviations.
3) The whole text in my opinion should be readed once again carefully by a english native speaker and "polished" due to many stylistic mistakes. These are not big problems, but some statements could be better worded without repeating the same phrases over and over again.
Regarding to the "Introduction" part:
4) In my opinion this part needs some improvement. The Introduction should introduce the Readers to the subject and problems related to the research. Now, in my opinion, this condition is not entirely fulfilled. I couldn't find the convincing evidence of the novelity nature of current review. I have read a large amount of this type of papers, and there is nothing new in this to encourage further reading. Classificaton of heat storage systems is insufficient in my opinion to start any deeper analysis of the subject. What is new in this article compared to others of this type? Please make it visible what was the purpose of the study and what made them important. I know that question is obvious, but you need to introduce the Readers to the subject and prove or set up the thesis. And these things have not even been outlined here.
Regarding to the "Phase Change Materials applications" part:
5) This part needs also some improvements. Authors wrote: "...inorganic PCMs are cheaper (word "relatively inexpensive" is by the way far better here), widely available, chemically stable and less flammable than organic ones..." So the question is why the commonly used PCMs are still "...paraffins, fatty acids and esters and salt hydrates..." mentioned few lines below? This example was taken by me to show that this entire paragraph is a conglomerate of various real pieces of information which, given in this way, without any context, can confuse their logical interpretation. Then Authors wrote: "Many studies attempted to develop PCM-based thermal control systems under such constraints..." but show only two examples. So how "many studies" were there? Only those two, or more? "Waste heat recovery" has no references at all. So, why such paragraph is even mentioned? Please read this part critically once again and rewrite it with the logical sense and with all needed references.
Regarding to the "PCM systems design considerations" part:
6) This part needs also improvement. Authors wrote: "Two main containment directions exist: (1) Encapsulation and (2) Form-Stable PCMs...", but there should be explanation that there could be also third option: using materials with high porosity as a carrier of phase-change materials. This is also important and new type of PCMs application in order to maintain "...the design behavior throughout the whole lifecycle. Omitting this important issue (PCM carriers) seems unforgivable from the novelty point of view of the paper.
Minor errors:
7) Figure 1 has not been mentioned in the manuscript. Please check this.
8) References are cited in the wrong order. Starts with [3].
9) Figure 2 is mentioned in part "PCM systems design considerations" but was placed in the "Phase Change Materials applications" part. Please check this.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 4 Report
This paper presents definitely better than before. My previous comments have been correctly addressed in this Review. This paper in its current form may in my opinion be approved for publication.
