Effect of Nanofluids on Boiling Heat Transfer Performance
Round 1
Reviewer 1 Report
The reviews on this topic are many and there are also recent ones, not mentioned by the authors, which also have some points in common with this paper, such as Sajid MU, Ali HM, Renewable and Sustainable Energy Reviews 103 (2019) 556–592.
Authors should therefore indicate what new and useful information they add to the reviews already published.
Furthermore, English has to be significantly revised since in some points it is also difficult to understand the meaning of the text.
The review then, while containing a lot of information and a general view, is too long but at the same time not discussing some among most important aspects of the subject including the stability of these nanofluids.
Author Response
Response to the comments of Reviewer 1:
Query 1: The reviews on this topic are many and there are also recent ones, not mentioned by the authors, which also have some points in common with this paper, such as Sajid MU, Ali HM, Renewable and Sustainable Energy Reviews 103 (2019) 556–592.
Authors should therefore indicate what new and useful information they add to the reviews already published.
Furthermore, English has to be significantly revised since in some points it is also difficult to understand the meaning of the text.
The review then, while containing a lot of information and a general view, is too long but at the same time not discussing some among most important aspects of the subject including the stability of these nanofluids.
Author reply 1: Thank you for your suggestion. The highlights of the reference (Sajid MU, Ali HM, Renewable and Sustainable Energy Reviews 103 (2019) 556–592.) are as follows.
1.A critical review on applications of nanofluids in heat transfer devices is presented.
2.Radiators, heat exchangers, heat sinks for electronic devices are thoroughly covered.
3.Size and shape of nanoparticles played critical role in heat transfer enhancement.
4. Most studies employed concentration of nanoparticles less than 1% for better enhancement.
5.Higher heat fluxes caused reduction in the stability of nanoparticles in base fluid.
It can be seen from the above highlights, the size, shape and concentration of nanoparticles played critical role in heat transfer enhancement, but the effect of nanfluids on the boiling heat transfer coefficient still exist disagreement ( Reference 22, 23 ). Therefore, the differences in boiling heat transfer coefficients of nanofluids are reviewed in this paper.
Nanofluids have an effect on boiling heat transfer and are currently widely used. However, the boiling heat transfer performance of nanofluids is affected by nanofluids and heated surfaces. In addition, the difference in the device is different for the disturbance of the boiling bubbles. Therefore, this paper reviews the effects of different factors on the boiling heat transfer performance of nanofluids, and further summarizes the reasons for the differences in boiling heat transfer coefficients.
The stability of nanofluids is currently an urgent problem to be solved. In addition, the stability of the nanofluid changes during the boiling process. For example, the higher the heating surface temperature, the more severe the sintering of nanoparticles deposited on the heated surface, and the stability of the nanofluid decreases as the heat flux increases(as described in the literature above). Although the addition of a dispersant can improve the stability of the nanofluid, thereby changing the surface tension of the bubble, the addition of the dispersant increases the sintering of the nanoparticles on the surface. Therefore, this paper considers that the stability of the nanofluid cannot be absolutely guaranteed during the boiling process, so the stability of the nanofluid is optimized by increasing the bubble disturbance by modifying the heating surface (reference 119). Furthermore, the effects of deposition surface on boiling heat transfer are reviewed in detail.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments on “Effect of Nanofluids on Boiling Heat Transfer Performance”
Authored by: Shouguang Yao, Zecheng Teng
1- English must be proofread and typos must be eliminated from the paper.
2- The introduction of the paper is superficial and it is expected that the authors review the state of the art papers and use them to fortify the technical content and also to highlight the current situation of study in the field of boiling of nanofluids. Searching through the literature, following papers are suggested to be read and used:
- Application of spherical copper oxide (II) water nano-fluid as a potential coolant in a boiling annular heat exchanger
- Nucleate pool boiling heat transfer to Al2O3-water and TiO2-water nanofluids on horizontal smooth tubes with dissimilar homogeneous materials
- Sedimentation and convective boiling heat transfer of CuO-water/ethylene glycol nanofluids
- Upward Flow Boiling to DI-Water and Cuo Nanofluids Inside the Concentric Annuli.
- Flow boiling heat transfer to MgO-therminol 66 heat transfer fluid: Experimental assessment and correlation development
- Thermal behavior of aqueous iron oxide nano-fluid as a coolant on a flat disc heater under the pool boiling condition
- Boiling heat transfer of alumina nano-fluids: role of nanoparticle deposition on the boiling heat transfer coefficient
3- The quality of Figure 1 is not sufficient. Please replace with a high-quality one or re-sketch the figure.
4- Boiling is a limiting phenomenon in the heat pipe due to the space limitation and sonic limitation. Authors should discuss this in the paper as well.
5- Figure 3 needs more elaboration. Support the elaboration with the literature.
6- I suggest the authors add a new section and discuss the bubble size and bubble diameter in their paper.
7- Future works is not highlighted in the paper. authors should suggest some new directions for the future research and discuss the potential gaps.
Author Response
Response to the comments of Reviewer 2:
Query 1: English must be proofread and typos must be eliminated from the paper.
Author reply 1: Sorry for the poor English and through careful reading of the manuscript, there is a large number of grammatical errors that have been modified to further improve the English expression, please review.
Query 2: The introduction of the paper is superficial and it is expected that the authors review the state of the art papers and use them to fortify the technical content and also to highlight the current situation of study in the field of boiling of nanofluids. Searching through the literature, following papers are suggested to be read and used:
- Application of spherical copper oxide (II) water nano-fluid as a potential coolant in a boiling annular heat exchanger
- Application of spherical copper oxide (II) water nano-fluid as a potential coolant in a boiling annular heat exchanger
- Sedimentation and convective boiling heat transfer of CuO-water/ethylene glycol nanofluids
- Upward Flow Boiling to DI-Water and Cuo Nanofluids Inside the Concentric Annuli.
- Flow boiling heat transfer to MgO-therminol 66 heat transfer fluid: Experimental assessment and correlation development
- Thermal behavior of aqueous iron oxide nano-fluid as a coolant on a flat disc heater under the pool boiling condition
- Boiling heat transfer of alumina nano-fluids: role of nanoparticle deposition on the boiling heat transfer coefficient
Query 3: The quality of Figure 1 is not sufficient. Please replace with a high-quality one or re-sketch the figure.
Author reply 3: Sorry for the quality of Figure 1 is not sufficient and the Figure 1 has been re-sketched, please review.
Query 4: Boiling is a limiting phenomenon in the heat pipe due to the space limitation and sonic limitation. Authors should discuss this in the paper as well.
Author reply 4: Sorry for the unclear statement and thank for your suggestion. The heat pipe limit theory and formula about hydrodynamic limit, the sonic limit and the boiling crisis limit (references 29, 30) have been added on page 4-5, please review.
At present, in order to solve the problem of heat dissipation of electronic equipment, some scholars have applied heat pipe to heat dissipation of electronic equipment. However, from the point of view of boiling heat transfer research and mechanism, the current research on the boiling heat transfer performance and mechanism of nanofluids is more focused on the saturated pool boiling of large vessels. Therefore, based on the research results and analysis, the reasons for the divergence of boiling heat transfer coefficients of nanofluids are summarized.
Query 5: Figure 3 needs more elaboration. Support the elaboration with the literature.
Author reply 5: Sorry for the unclear statement and thank you for your suggestion. The map of sonic limit is added to the text, so Figure 3 becomes Figure 4. More elaboration about Figure 4 has been added on page 6-7, please review.
In this paper, the extensive application of nanofluids is used to further investigate the mechanism of boiling heat transfer in nanofluids and to review the differences. Therefore, Figure 4 shows the nanofluids studied and applied in different types of collectors, which leads to the effect of the following nanofluid types on boiling heat transfer.
Query 6: I suggest the authors add a new section and discuss the bubble size and bubble diameter in their paper.
Author reply 6: Thank you for your suggestion and the bubble size and bubble diameter have been added in section 5 on page 27-29, please review.
Query 7: Future works is not highlighted in the paper. authors should suggest some new directions for the future research and discuss the potential gaps.
Author reply 7: Thank for your suggestion. Through literature review, we found that the deposition of nanoparticles on the heated surface has a greater impact on the critical heat flux. The influence of the boiling heat transfer coefficient is more affected by the boiling bubble and the physical properties of the nanofluid. However, the difference in physical properties causes a difference in the bubble size and the bubble size. Therefore, in terms of the influence of the physical properties of nanofluids, the influence of micro-motion between mixed nanoparticles and mixed multicomponent solutions on boiling heat transfer is proposed, and the effects of the relative motion between multicomponent solutions and the relative motion between nanoparticles on the stability and heat transfer performance of nanofluids are investigated. Secondly, most of the studies on the influence of nanofluids on boiling heat transfer are focused on the effect of surface deposition on heat transfer. Then, the effects of the deposition of single nanoparticles on the formation and detachment of bubbles on the heating surface are observed and studied, and the effect of bubble formation on boiling heat transfer coefficient is investigated from the boiling mechanism. Finally, the boiling heat transfer test device of nanofluids belongs to the large vessel saturated pool boiling, so it is necessary to study the boiling heat transfer of the external test device of condenser, and then investigate the influence of boiling mechanism including wettability and bubble disturbance on the boiling heat transfer performance.
In this paper, the divergence of boiling heat transfer performance of nanofluids is reviewed, and the further research content of divergence is proposed. Therefore, the potential gap is difficult to predict. However, through our experimental study on boiling heat transfer of nanofluids, it is found that multicomponent solutions and mixed nanoparticles have enhanced heat transfer performance, so the micro-motion between multicomponent solutions and nanoparticle mixtures has aroused our interest. However, the workload is large, which is put forward here for reference. In addition, it is found that the external condenser enhances the boiling heat transfer performance of nanofluids. However, the location of the condensate entrance, the amount of condensate, the wettability to the heated surface and the disturbance mechanism of the bubbles still need a lot of research. The map of the experiment setup is shown in the following figure.
Fig. 1 The map of experimental system
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The paper has been improved and it is now suitable for the publication.
Reviewer 2 Report
In the next version of the manuscript, the authors have improved the quality of English, they have used more relevant literature and hence, the paper has significantly improved for the publication.
Hence, I can recommend the publication of this paper in the journal.
