Experimental and Numerical Study on the Insulation Performance of a Photo-Thermal Roof in Hot Summer and Cold Winter Areas
Round 1
Reviewer 1 Report
The current paper outlines the thermal insulation performance of a building roof combined with photothermal technology. I have provided some suggestions as following to improve the paper:
- All the symbols and terms in figure 3 and in equations should be defined. The nomenclature has not covered all symbols and terms.
- If you have used any references for developing the equations (which is probably the case), you should cite them. Most of these equations are very well known and you need to provide references. Also, you need to present the equations for calculating the heat transfer coefficients. You can refer to the following book and paper: McAdams, W.H. Heat transmission; Mcgraw-Hill Book Company, Inc.: London, UK, 1954; pp. 165–184. Rad, H.M.; Ameri, M. Energy and exergy study of unglazed transpired collector-2stage. Sol. Energy 2016, 132, 570–586.
- You need to provide a table, and list all the values that you have used for the simulations. For example, what are the values of Tsky, ambient temperature, etc. You should also provide how you have selected the values for the simulation (for example, they are fitting parameters, from references, from experiments…).
- You need to explain clearly how you have solved the Eqs. 1-10 to calculate the temperatures numerically. Under Table 3, you have tried to explain the methodology, but it is not written properly.
- Many English mistakes in writing the paper. Please check the English of the manuscript carefully. I have highlighted a few of them in the Pdf file that is attached.
Comments for author File: 
Comments.pdf
Author Response
We very much appreciate constructive comments and suggestions from editor and reviewers. We have carefully treated your kind suggestions and revised portions are marked in red in the revised manuscript. Please see the attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Poor English samples (Just some examples, thorough revision of the English language is needed)
Line 11: “..which is great significance to realize..”
Line 12: “..in hot summer and cold winter zone..”
Line 13+Line14: “..the experimental and simulation for the thermal performance of the photo-thermal..”
Line 17: “..The water saturation of roof insulation materials is an important..” also referred to insulation material elsewhere
Line 51-52: “..about 120℃ in summer..”
Line 62: “..found that the system has overheating effect in summer when..”
Line 66-67: “..the impact of the photo-thermal system with air gap with the building roof on the building..”
Line 74-75: “..On the basis of this point, this paper studies to the thermal performance..”
Line 86-87: “..The roofs structure from..”
Lines 271-274: “..In the solving process, when the variables residuals of continuity equation, momentum equation, k equation, e equation is less than 10-3 and the variables residual of energy equations and radiation equation is less than 10-6, it is considered convergence of calculation..”
Line 280: “..It can be known from the temperature changed that the..”
Lines 339-340: “..but the peaks and peaks occur time slightly differently over different periods due to fluctuations..”
Paragraph 127
This is a poor assumption since the thickness is about 10% of the panel width so it can not just simply indicate a one-dimensional conduction, the mathematical model should be more accurately represented.
Line 148
How did the authors get the third left-side term in Equation-4?
Line 409
How much was the water flow value set at?
Figure 9 (line 412) Same applies for Figure 11 and 13.
The difference in simulation temperature results re almost 25°C between ordinary and photo-thermal rooftop. That is about 150% more than the maximum shown in the experimental results which indicates a revision of the simulation model is probably needed. The results are good to prove a point but far from the actual results.
Author Response
We very much appreciate constructive comments and suggestions from editor and reviewers. We have carefully treated your kind suggestions and revised portions are marked in red in the revised manuscript. Please see the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The authors need to add references for the equations that they have presented. These equations are very well-known.
Author Response
We very much appreciate constructive comments and suggestions from editor and reviewers. We have carefully treated your kind suggestions and revised portions are marked in red in the revised manuscript. The sources of Eq. (1), (13), (14) and (17) have been added in the revised manuscript. (with marks version)
