Performance Evaluation of Volcanic Stone Pad Used in Evaporative Cooling System

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

In this paper, the authors investigated the effectiveness of volcanic stone as an innovative material for evaporative cooling pads. The work is certainly relevant as it aims to identify methods to improve the efficiency of the cooling process. The strength of this paper is the presence of an experiment, but there are some weaknesses, which will be discussed next.

In section 1, the authors provide a literature review and define the purpose of the study. However, the authors did not specifically state what is the scientific novelty?

In section 2, the authors describe the design of the experiment in which two substrate thicknesses of 10 cm and 15 cm were tested. The rates of addition of water and air were different. Measurements were made with different measuring instruments: humidity sensor, temperature sensor, anemometer, and pressure gauge. Each medium was measured with only one type of instrument. What is the justification for this? In our opinion, in order to average measurements, it is necessary to use several similar devices. Among other things, the authors did not specify how accurate the instruments are? When were the instruments calibrated? It is possible that the instruments have a significant error and distort the result of experiments. How many parallel experiments were there? Did the authors limit themselves to only one experiment? We believe that the experiment planning section is very sparse and should be expanded.

Section 3 describes the statistical analysis very laconically. Why was it necessary to include a separate section? What did the authors want to say? It is recommended that the authors eliminate the section with statistical analysis and combine it with the results and discussion section.

Section 4 describes the results of the experiments. The influence of gasket thickness, air velocity passing through the gasket, and the rate of water addition on the cooling efficiency of the system in our opinion should be demonstrated in the form of regression relationships, given that the authors applied methods of mathematical statistics in processing the experimental results.

In section 5, the authors conclude that the cooling efficiency of volcanic stone pads is very close to that of commercial pads so it is considered more durable, less maintenance and not subject to rot. It is hard to draw such a conclusion here because such experiments come to naught without good preparation for planning the experiment and selecting the measuring instruments.

In science today, one experiment is not enough and often one experiment is not proof of the adequacy of the experiments. Authors are advised to answer the question, why was only one type of experiment conducted? Maybe they should have performed numerical modeling, for example, and compared the results?

Comments on the Quality of English Language

The English could be improved to more clearly express the research.

Author Response

Please see the attachment file

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The topic of the article and its content are interesting. However, the quality of the article could be improved with some specific actions. In particular, I believe that a more complete characterization (description) should be provided for the volcanic stone grain, as the evaporative exchange and optimal thickness of the stone pebbles used in the pad likely depend on it. It is important to stress that the behavior of the 10 cm and 15 cm thick pads tested here is not an absolute truth but depends on many parameters, most of which have not been tested. This is because the scope of the article was to study average use conditions rather than to interpret the physical fundamentals of the system in question.
In particular, I think that the text (especially in the "Results and Discussion" section) should explicitly state that the results depend on the specific conditions of this study and that different granulometric conditions of the stone could lead to different responses to pad thickness.
Additionally, I believe that the references to similar research are neither sufficiently exhaustive nor sufficiently discussed and should therefore be expanded.

More detailed observations follow.
Abstract: It is advisable not to include references in the abstract.
Page 2: "Dry bulb temperature and humidity"—please specify the type of humidity: air moisture content? Absolute humidity? This should be defined.
Page 3, Section 2.1: 
- In "thermal glass wool," "thermal" should be replaced with "insulation" or removed.
- The porosity of the mesh should be provided as an important piece of information.
- The density of the pebbles should also be specified.
Page 4, Section 3: It is essential to define how pad efficiency is measured. Is pad efficiency determined by the absolute temperature reduction percentage? Or by the cooling power inferred from the amount of water consumed? Or by another method? This should be clarified.
Page 6: Figure 2 and Figure 3 seem to present the same information from different perspectives. Either one of them is redundant, or the text should clarify that the two figures illustrate the same data in different ways and explain why this is necessary.
Results and Discussion section: The text often merely restates in numbers what the figures already present graphically. This makes the discussion less insightful than it could be.
Page 14, Section 4.10: The advantage of the tested solution over cellulose pads appears to be in the order of 5% or slightly higher. Thus, additional advantages, such as lower maintenance requirements, should be emphasized as decisive factors for practical use.
Page 15, Conclusions: The "Conclusions" section should not begin with a summary of raw data. It should start by summarizing the main findings. More conceptual discussion is needed, and fewer but more carefully selected numerical results should be presented.

Comments on the Quality of English Language

The text contains numerous small grammatical, syntactic, and lexical errors that should be addressed through more rigorous editing.

Author Response

Please see the attachment file

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

recommended for publication