Heat Transfer Deterioration by the Copper Oxide Layer on Horizontal Subcooled Flow Boiling
, Tomihiro Kinjo 1,3, Ouch Som Onn 1, Toshihiko Saiwai 4, Kenji Takita 4, Kenji Orito 4 and Koji Enoki 1,*
Round 1
Reviewer 1 Report
The authors presented an interesting experimental investigation on the Heat transfer deterioration by the copper oxide layer on horizontal subcooled flow boiling
The introduction is to be extended; recently published papers are to be cited and described.
What is the novelty of the paper?
A photography of the experimental setup is to be added.
The data acquisition system is to be described with more details.
The results of experimental uncertainty study are to be mentioned.
Why is the pressure drop not studied?
physical interpretations are to be added to the discussion
Author Response
"Please see the attachment."
Author Response File: 
Author Response.pdf
Reviewer 2 Report
In table 1, the surface roughness of 0.4um is probably the Ra parameter but is not described. The selection of the roughness parameter would allow for precise indication of the surface development (through roughness). The rest looks very good. I would like to commend you for taking an experimental approach to the problem (instead of literature-based simulations).
Author Response
"Please see the attachment."
Author Response File: Author Response.pdf
Reviewer 3 Report
The article is devoted to a particular issue of boiling heat transfer: the influence of the effect of "aging" of the surface on the heat transfer characteristics. A systematic study of the effect of boiling time has been carried out and the effect of aging has been shown. On the one hand, the effect is well known; on the other hand, researchers usually do not pay attention to it in laboratory experiments, incl. the article will certainly be useful, should attract the attention of readers. Practical recommendations for other surfaces and conditions cannot be generalized, applicability is limited to specific conditions. The article is structured, contains all the necessary sections.
Among the comments that can improve the content of the article should be noted:
1. The section with the measurement error has not been completed. There are no results on the error of heat flux, heat transfer coefficient. It is IMPOSSIBLE to achieve the accuracy of temperature measurement in the stated 0.05 K under experimental conditions! Thermocouples are not terminated according to isotherms, there are no indications of heat losses, etc.
2. In the analysis of boiling with subcooling, the temperature difference between the wall and the average along the flow is used, then there will be no decrease in HTC with increasing q.
3. The methodology for conducting experiments is not clear, was one water inlet temperature and one flow rate used? As q increases, the exit temperature increases, by how much?
4. Why the contact angles of wetting before and after boiling were not measured, the effect of this factor on heat transfer was not evaluated.
Author Response
"Please see the attachment."
Author Response File: Author Response.pdf
Reviewer 4 Report
Author has done good work in the area of boiling heat transfer and reported , an experimental investigation was conducted using a cooper bare surface as a 5 heating surface under a constant mass flux of 600 kg·m−2 ·s −1 of deionized water at a subcooled inlet 6 temperature ∆Tsub of 70 K under atmospheric pressure conditions on a closed-loop. To confirm the 7 heat transfer deterioration, the experiment was repeated thirteen times. On the flow boiling region 8 after thirteen experiments, results show an increase in the wall superheat ∆Tsat of around 26% and a 9 reduction in the heat flux of around 200 kW·m−2 . On the other hand, the effect of oxidation on the 10 single-phase is almost marginal.
Specific comments:
Line number : 2.5 MW·m−2 (author may correct such mistakes) in the entire mistakes
General comments :
Author may add some recent research/review articles on boiling heat transfer to make study more relevent and add some novelty of work and and compare the current study with the existing one.
Author may add some relevent research
some examples are below:
10.3390/en15155759
- https://0-doi-org.brum.beds.ac.uk/10.1080/01457632.2022.2086095
Author may add surface rougness value and effect of contact angle on the boiling study
Author Response
"Please see the attachment."
Author Response File: Author Response.pdf
Round 2
Reviewer 4 Report
Thanks for addressing the comments
