Round  1

Reviewer 1 Report

The authors have focused on the effects of the roof sprinkle process like water flow rate on a greenhouse temperature in hot season with the help of CFD model. They developed the porous media model to study the effects of sprinklers on greenhouse cooling mode. They conducted a  short and shallow literature review which can be improved. Please completely revise these sections and avoid providing the general information. Please also clearly elaborate the research gap and then explain the novelty of your work. Generally, the paper deals with an interesting subject precious of investigation.

Some remarks that could improve the paper are:

- In this study, the validation part is conducted, however, it is not sufficiently interpreted. The difference between simulated results and experimental should be further elaborated.

- What is the effect of increasing the sprinkler water flow rate on the humidity of the greenhouse? Have you included this factor in your simulation?

-The authors should include in the paper the error calculation and also some comparison with experimental and numerical data of other authors. So, your results contribution in comparison to the references should be strengthened.

  - Please clearly indicate the contribution and limitations of the proposed idea in this study. The results should be further elaborated to show how they could be used for real applications.

- Line 13, check the typo (k-epsilon).

- Line 107, please use the same symbol for velocity( compare Eq.1 and Line 107).

- Line 146, 152, 154, check the typo.

-Equation 1: "_k" stands for what??

Author Response

Thanks for your comments on our paper. We have revised the paper according to your comments. We have completely revised the literature review sections and try to provide more information about the research gap and explain the novelty of our work. The main revisions are listed as follows:

1. In the “Introduction” part, we divided this part into 5 parts, include “the purpose and general information of roof cooling”, “the literature review of roof sprinkling”, “the comparison among experimental, mathematical prediction and numerical simulation methods”, “the literature review of solar radiation calculation in numerical simulation” and “the research objective and novelty of our work”.

2. In the “Model validation part”, we added more description about the comparison between the simulation and experimental results. Include the detail calculation methods and comparison with the similar results from other authors.

3. Humidity is one of the important factors for plant growing, and temperature is the most important factor, in this paper we have not discussed the effect of increasing the sprinkler water flow rate on humidity in the greenhouse, so our simulation does not include humidity factor. However, we will investigate the effects of water sprinkling on humidity in greenhouse in the future.

4. In order to elaborate more information about how the results can be used for real application, two pictures (Fig. 1 and Fig. 2) of the overall layout of the greenhouse and the installation of the water pump for roof sprinkle were added.

5. According to “Line 13, check the typo (k-epsilon)”, we checked the related description in the manuscript.

6. According to “Line 107, please use the same symbol for velocity (compare Eq.1 and Line 107)”, we change “U” in to “U” in Line 107.

7. According to “Line 146, 152, 154, check the typo”, we checked the typo and revised.

8. According to “Equation 1: "k" stands for what??”, " k " stands for that h_k is the the kinematic viscosity coefficient under turbulent conditions.

 Author Response File: Author Response.doc

Reviewer 2 Report

This article can be a potential interest to the readers in agricultural studies who wants to validate the temperate changes through heavily developed mathematical models. The simulation approach and several outcomes visual presentation from the model drawn thermodynamics and mathematics were interesting; however, authors can make major improvement in terms of depth of literature review, the novelty of modeling approach and depth of discussion from the simulation outcomes. 

Firstly,  I suggest authors considering adding more intensive discussions on the drawbacks/shortfalls of currently available simulation techniques/models through literature review. The article's introduction section has some, but the more extensive literate review in similar studies/papers to authors' will make the paper more powerful.  

Secondly, the article showed weak discussion on a main academic contribution from their research, the model validation, limitation of the study, future research direction and the main take away from the study outcome. For exmaple, in terms of model validation (from line 190 to line 203), the author's argument that their model simulation results show little gap between simulation value and test values; however, how do we know the author's models were better than other simulation approaches in decreasing differences? Can you provide more discussion/argument? 

Furthermore, more discussion drawn from the results in practice will make the article more interesting. 

Thirdly, the article needs significant improvement in English editing as there are numerous grammatic errors and in writing styles.

In short, I suggest authors need to include more rich discussions on the academic contribution (or usefulness in practice).

Author Response

Thanks for your comments on our paper. We have revised the paper according to your comments. We have completely revised the literature review sections that improved the depth of literature review and added more description for the novelty of modeling approach. Meanwhile, deeper discussions were added in "Results and discussion" part. The main revisions are listed as follows:

1. 9 more literatures and more intensive discussions about the numerical simulation were added in "Introduction" part. We divided this part into 5 parts, include “the purpose and general information of roof cooling”, “the literature review of roof sprinkling”, “the comparison among experimental, mathematical prediction and numerical simulation methods”, “the literature review of solar radiation calculation in numerical simulation” and “the research objective and novelty of our work”.

2. In the “Model validation part”, we added more description about the comparison between the simulation and experimental results. Include the detail calculation methods and comparison with the similar results from other authors. Such as, Eq. (11) and Eq. (12) from Delele et al (2013) and Stefano et al (2016) were added as well as comparison between the results in this paper and other literatures.

3. Some of the results in "Roof film temperature distribution and indoor air flow vector " and " Effect of sprinkler flow rate on temperature distribution" part had been compared with the results from other authors.

4. In order to make the results be more applicable in practice, we added two pictures (Fig. 1 and Fig. 2) of the overall layout of the greenhouse and the installation of the water pump for roof sprinkling to elaborate how to apply the results.

5. In order to improve the language level of this manuscripts, we invited a colleague who is a native English speaker to help for English editing.

Author Response File: Author Response.doc

Reviewer 3 Report

The paper introduced a cooling method for greenhouse. Three models were developed. It provided some interesting results. However, authors ignored the greenhouse effect. That is, the solar energies could penetrate the transparent roof materials than increase the inside temperature. That is the reason that the roof sprinkler method did not be accepted in the greenhouse industry. The common way to cool the inside temperature of greenhouse was the evaporative cooling (pad/fans, misting or fogging). Table 3 and Figure 3 all showed the same results: the cooling ability is limited. The temperature range in greenhouse was 37-40℃. It was meaningless for crops. Most of the crops could not survive in that environment. The fixed error were found between simulation value and measurement values. It indicated that these models had the fixed mistakes. The roof materials of livestock houses or industrial factory are opaque. The only heating source was the heat accumulation of the roof due to the sun radiation. By sprinkling, the roof temperature could be decrease significantly. Then the heat transfer from roof to inside space was reduced.

My suggestion for authors was to change the subject, from greenhouse (transparent roof) to other buildings (roof).  

Author Response

Thanks for your comments on our paper. We have received great inspirations from your advices. The detail responds are listed as follows:

1. According to " the solar energies could penetrate the transparent roof materials than increase the inside temperature. That is the reason that the roof sprinkler method did not be accepted in the greenhouse industry. " :

1) We agree that solar energies could penetrate the transparent roof then increase the inside temperature,  however, Suehrcke et al (2008) pointed that water pond on roof, in which the latent heat of evaporation is applied for cooling, heat dissipation techniques, in which the radiation heat gained by the roof is decreased through reduction of the incident radiation. Water sprinkling will produce a water film on the roof, if the water sprinkling rate is big enough, it can looks as a thin water pond, thus, it may has certain degree effects on reducing incident radiation. Thus, we want to know about how water sprinkling methods to cool the roof and indoor environment of a greenhouse.

2) From literature review, we found little information about how water sprinkling affect the temperature on the roof and indoor temperature of a greenhouse, and CFD methods was proved to be able to present the roof temperature and temperature distribution in the greenhouse after our work. Although the effects of water sprinkling on indoor temperature cooling was not significant after our study, we believe that these models and methods will help to improve the effects of roof cooling methods in all of the buildings which need cooling energy reducing.

2. According to " Table 3 and Figure 3 all showed the same results: the cooling ability is limited. The temperature range in greenhouse was 37-40℃. It was meaningless for crops. Most of the crops could not survive in that environment.":

Although the cooling ability is limited, the effects of roof water sprinkling can reduce the cooling system energy consumption in a certain degree. It is no doubt that such high temperature is not beneficial for crops growing, thus, other cooling methods, such as mechanical ventilation and evaporative cooling, are needed (related discussion was added in "Roof film temperature distribution and indoor air flow vector"). In this paper, we want to know about the independent effects of water sprinkling rate on the cooling effect for a greenhouse . Anyhow, we will change the subject or combine other cooling methods to investigate the cooling effects according to your advices in our future research. 

3. According to "The fixed error were found between simulation value and measurement values. It indicated that these models had the fixed mistakes.":

We added more description about the comparison between the simulation and experimental results. Include the detail calculation methods and comparison with the similar results from other authors. Such as, Eq. (11) and Eq. (12) from Delele et al (2013) and Stefano et al (2016) were added as well as comparison between the results in this paper and other literatures. The comparison above showed that the fixed error in the simulation results of this paper is acceptable.

4. According to " My suggestion for authors was to change the subject, from greenhouse (transparent roof) to other buildings (roof). ":

Thanks for your advice. It is no doubt that the effects of water sprinkling will be much greater in other buildings, however, the experimental facilities (a real building) for the simulation results validation are not satisfied with such research at present. Anyhow, we will try our best to change the subject to other buildings (roof) such as livestock houses or industrial factory in the future.

Author Response File: Author Response.doc

Round  2

Reviewer 2 Report

I acknowledge the authors' effort to improve the paper. 

I would like to suggest a couple of things. 

1) The validation section (2.4) looks better to be put after the results section (3.2), as part of the discussion and take away from the article.

2) I still do not see a strong discussion about main take away and future direction to improve the models. 

Author Response

Thanks for your comments on our paper again. We have revised the paper according to your comments. We put " Model validation" in the "Results and discussion" part. The main revisions are listed as follows:

1.According to "1) The validation section (2.4) looks better to be put after the results section (3.2), as part of the discussion and take away from the article", we put " 2.4 Model validation" in the "Results and discussion" part as " 3.3 Model validation".

2. According to "2) I still do not see a strong discussion about main take away and future direction to improve the models.", we added "3.4 Discussion" part to discuss about the main results and future direction to improve the models, include the limitations and model improvements.   

Author Response File: Author Response.doc

Reviewer 3 Report

The content of revised paper have improved significantly

Author Response

Thanks for your comments on our paper again. We have received great inspirations from your advices. If you have any question about this paper, please don’t hesitate to contact us. 

Author Response File: Author Response.doc