The Effect of Geometry on the Yield of Fresh Water from Single Slope Solar Stills
Round 1
Reviewer 1 Report
The manuscript ID: energies-1913188, entitled “The effect of geometry on the yield of fresh water from single slope solar stills”. In this paper, the author explained the relationship between the natural convection, the single slope solar still aspect ratio, the cover angle, and the single slope solar stills’ freshwater production. A single convection cell existed, however by varying the cover angle or aspect ratio it was possible to generate additional cells, which in turn encouraged higher heat transfer from the basin to the cover. Furthermore, it was shown that the effect of these changes could be accounted for in the form of a generalized correlation that included cover angle and aspect ratio.
1) The manuscript presentation was not good and difficult to understand. Many sentences have not been clearly explained. I don’t have a good impression of this manuscript. Therefore, I recommend publication only after major revisions.
2) The abstract in this paper is very lengthy, So the author needs to be done shorter the abstract.
3) The author presented only in terms in all figures, for example in Figure 1, what are Th and Tc. ---
4) The author needs to represent terms that they used in figures and equations.
5) The authors would discuss the overview of better deposition techniques with performance.
6) My major observation is, All the Nomenclature or terms full observation, the author needs to write in the below images or equation, it is very difficult to understand. So, please modify accordingly for better understanding.
7) Please verify each sentence of this paper, Some typo errors.
Author Response
We would like to thank the reviewer for their constructive comments. In response to these we have made a number of changes as suggested.
The manuscript ID: energies-1913188, entitled “The effect of geometry on the yield of fresh water from single slope solar stills”. In this paper, the author explained the relationship between the natural convection, the single slope solar still aspect ratio, the cover angle, and the single slope solar stills’ freshwater production. A single convection cell existed, however by varying the cover angle or aspect ratio it was possible to generate additional cells, which in turn encouraged higher heat transfer from the basin to the cover. Furthermore, it was shown that the effect of these changes could be accounted for in the form of a generalized correlation that included cover angle and aspect ratio.
1) The manuscript presentation was not good and difficult to understand. Many sentences have not been clearly explained. I don’t have a good impression of this manuscript. Therefore, I recommend publication only after major revisions.
- In response to the feedback, we have tried to make several potentially ambiguous sentences a bit clearer.
2) The abstract in this paper is very lengthy, So the author needs to be done shorter the abstract.
- We have shortened the abstract as suggested.
3) The author presented only in terms in all figures, for example in Figure 1, what are Th and Tc. ---
- In response to this feedback we have included a nomenclature to help explain each term used in the paper.
4) The author needs to represent terms that they used in figures and equations.
- As we have noted above, we have included a nomenclature to help explain each term used in the paper.
5) The authors would discuss the overview of better deposition techniques with performance.
- Unfortunately, we weren't sure what was meant by this.
6) My major observation is, All the Nomenclature or terms full observation, the author needs to write in the below images or equation, it is very difficult to understand. So, please modify accordingly for better understanding.
- As suggested, we have included a nomenclature.
7) Please verify each sentence of this paper, Some typo errors.
- As suggested, we have attempted to improve the structure of some sentences to improve the readers understanding.
Reviewer 2 Report
Authors raised one of the important problems in research related to solar stills. The paper is well written and analysed numerically and at lab scale. Therefore, it is important to see the results under real field conditions.
1. Conduct experiments real field conditions under sun and validate the lab results
2. Add impact of incident angle modification due to vapor condensation on the glass cover on parameters discussed in the paper.
Author Response
We would like to thank the reviewer for their kind feedback on our work. Below are our responses to their feedback.
Authors raised one of the important problems in research related to solar stills. The paper is well written and analysed numerically and at lab scale. Therefore, it is important to see the results under real field conditions.
1. Conduct experiments real field conditions under sun and validate the lab results
- Although we did not present on-sun testing of a solar still in this work, we did validate our correlation using independent test data from previous studies. This is outlined in Section 4.4 of the paper. Given that this testing was undertaken independently, we believe it provides a stronger validation of our results.
2. Add impact of incident angle modification due to vapor condensation on the glass cover on parameters discussed in the paper.
- We are somewhat unclear on what is being requested here, as it seems rather different to what our work was attempting to address.
Reviewer 3 Report
This is a solar still related research, which has been well written. My minor comments are as follows.
1. The Abstract should be presented in terms of a single paragraph.
2. Can the authors explain the thermal transmittance fluctuations for the 0 degree tilt angle scenario?
3. It is failed to validate the simulation model by simply observing the discrepancies between the simulated and measured results. Although there is no common standard on simulation validation yet, there are certain guidelines that specify the criteria of allowable errors for simulation models, for instance, ASHRAE 14. Fundamentally, a validation of the computer simulation must refer to the criteria for assessing the acceptability of agreement between simulation and measurement.
Author Response
We would like to thank the reviewer for the time they have taken to look at our work.
This is a solar still related research, which has been well written. My minor comments are as follows.
The Abstract should be presented in terms of a single paragraph.
- As suggested, the abstract has been condensed into a single paragraph.
Can the authors explain the thermal transmittance fluctuations for the 0 degree tilt angle scenario?
- If we understand the reviewer's comments correctly, we have noted in the text that this appears to be due to the multiple Benard cells.
It is failed to validate the simulation model by simply observing the discrepancies between the simulated and measured results. Although there is no common standard on simulation validation yet, there are certain guidelines that specify the criteria of allowable errors for simulation models, for instance, ASHRAE 14. Fundamentally, a validation of the computer simulation must refer to the criteria for assessing the acceptability of agreement between simulation and measurement.
- We are somewhat unclear on what is being said with this comment, we looked at ASHRAE 14 and it did not seem to be relevant to this field. We believe that we have shown a sufficient qualitative and quantitative validation of our CFD, using our PIV data. Similarly, we have shown that our correlation derived from the CFD is generalisable to solar stills that have been reported in the literature, which we believe is a rather strong validation of our results.
Round 2
Reviewer 1 Report
Thank you to the author for addressing all the raised comments from reviewers. The revised version manuscript has been modified and revised properly as per the comments raised by the reviewer. Therefore, I recommend this manuscript for publication in Energies as it is without further modifications.
Author Response
Again, we would like to thank the reviewer for the time they have taken to read and comment on our work. Your input helped us identify several improvements to our work.
Reviewer 2 Report
In previous review round it is suggested to Add impact of incident angle modification due to vapor condensation on the glass cover on parameters discussed in the paper.
It means that whenever solar radiation passes through the glass into the interior of solar still, the vepor condensed on the glass cover hurdles penetration of solar radiation and changes its angle of incidence. Therefore, add the impact of this on thermal behaviour of solar still reported.
Author Response
Again, we would like to thank the reviewer for their feedback on our work.
In response to the comment:
In previous review round it is suggested to Add impact of incident angle modification due to vapor condensation on the glass cover on parameters discussed in the paper.
It means that whenever solar radiation passes through the glass into the interior of solar still, the vepor condensed on the glass cover hurdles penetration of solar radiation and changes its angle of incidence. Therefore, add the impact of this on thermal behaviour of solar still reported.
The effect that the condensed water has on the IAM is definitely an interesting area, and we note that it has received some recent attention eg: https://doi.org/10.1016/j.jqsrt.2020.107493 and https://doi.org/10.1016/j.jqsrt.2020.107039
However, in the context of our work we do not feel it is relevant. The methodology we have employed, having a hot 'basin' and cold 'cover', allows us to mimic the effect of having solar radiation being absorbed in the still without needing a radiation source. By changing the temperature difference, we have examined the effect of differing solar flux values (which could occur as a result of what you have mentioned). As such, we have isolated the effect that geometry has on the natural convection (the transport mechanism that determines the yield) from the incoming energy and have characterized it in a controlled manner.
