Design and Investigation of an Effective Solar Still Applicable to Remote Islands

Round 1

Reviewer 1 Report

This manuscript evaluates the performance of solar stills with different designs. It reports daily water production rates with modified passive and active solar stills. However, I do not find a novelty in this manuscript. Authors utilized various designs to improve the water condensation rate, such as adopting fins and wicks without suggesting aimed surface are enhancement or heat transfer coefficient to maximize the solar radiation and to increase the active surface for water condensation/evaporation as well as to enhance heat transfer. Rather, authors combined all factors in the design and named it as ‘modified’ vs ‘unmodified’. It needs to be highlighted if their design is the best compared with literature, or there should be additional experiments or modeling to optimize the structures. Most critically, authors did not observe improved performance in experiments even they designed the modified structures to enhance the water production rate. It implies that only additional heating power from the active design (meaning additional energy input, but it was not considered in the efficiency calculation in the manuscript) could increase the yield. It was mentioned that the reduced productivity is due to the bad solar condition in the testing period. First, in this case, authors should have collected data under proper or controlled environmental conditions. Second, average daily productivity is calculated by total distilled water per total solar energy absorbed (based on Eq1), which implies that the absolute amount of incident solar irradiation should not affect the production rate per performance. In general, I do not recommend it to be published with the current manuscript.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

The present manuscript entitled “Design and Investigation of an Effective Solar Still Applicable to Remote Islands” Alinford Samuel et al., describe the aims to design and fabricate an effective solar still suitable for application in the remote islands with low freshwater sources but easy access to sea water and rich solar irradiance. Integrating a conventional passive double sloped solar still with an evacuated solar water heater, fins and wick material improves heat transfer rate through the brine in the basin and increases effective evaporative surface area. Furthermore, experimental results reveal that the augmentation of fins, wicks and solar water heater influences the overall distillate output of the solar still. The combined use of fins, wicks and solar water heater increases the average daily productivity by 147% and the average daytime hourly productivity by 245% compared to the conventional passive solar still under similar average solar radiation levels. The authors report an interesting approach. The objective and justification of the work are clear, and the experimental work is significant. The study is very accurate and adequate, and thus, I recommend it for publication. However, certain Minor issues are detailed below which need to be addressed before its final acceptance in Water.

I advise the authors to take the following points into account while revising their manuscript.

Comment 1: There are some typographical errors in the manuscript text, so authors need to correct them in the revised manuscript. For e.g. Line 244, Two thermocouples (T_G1, T_G2) should be Two thermocouples (T_G1 and T_G2); Line 246, (T_B1, T_B2, T_B3, T_B4) should be (T_B1, T_B2, T_B3, and T_B4); Line 250, humidity range of 0 %–100 % should be humidity range of 0–100 %; etc.,

Comment 2: The introduction section is too lengthy, it should be revised.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The revised manuscript does not reflect sufficient changes to answer my earlier comments. Although authors claim that they added new experimental sets, there is no change in their conclusions as well as no change in the months of their experiment, but slight changes with a few words. The majority of red-colored parts in the revised manuscript, including equations, are identical to their original manuscript. If the experiments require a longer period to be conducted, authors should spend sufficient time to collect all required data. 'Due to the bad solar condition' (as stated in their manuscript), this manuscript could not deliver concrete conclusions.

Author Response

Response to Reviewer 1 Comments

Dear Reviewer

We appreciate the feedback given and have responded accordingly.

 

Reviewer #1

Comments:     The revised manuscript does not reflect sufficient changes to answer my earlier comments. Although authors claim that they added new experimental sets, there is no change in their conclusions as well as no change in the months of their experiment, but slight changes with a few words. The majority of red-colored parts in the revised manuscript, including equations, are identical to their original manuscript. If the experiments require a longer period to be conducted, authors should spend sufficient time to collect all required data. 'Due to the bad solar condition' (as stated in their manuscript), this manuscript could not deliver concrete conclusions.

 

Reply:                    We will conduct further experiments to obtain more data under various solar irradiation conditions as it is well agreed that the productivity of the solar still is dependent to a certain extent on the amount of solar irradiation received. With this new and sufficient set of data we will develop a correlation with the yield of distillate versus solar irradiation and also seek publication in the future.