Experimental Study of Simultaneous Charging and Discharging Process in Thermocline Phase Change Heat Storage System Based on Solar Energy
Round 1
Reviewer 1 Report
The manuscript is well-presented overall. Two major problems should be addressed:
1. Many citation problems in Introduction, especially the misuse of given and family name for Chinese authors.
2. What's the main novelty and motivation of this work? They are not explained well. "Not studied" is not a good motivation nor novelty.
Author Response
Thanks for the reviewer’s comments.
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The author presents an experimentally study on the interesting topic of solar thermal storage with the help of phase change materials. The work is really interesting and current but some of results are questionable requiring more explanation and clarification :
1. You Should add more references about the topic.
2. You Should add more detail about utilization Rate (UR).
3. It would be interesting to test different phase change materials and not just paraffin.
4. Add a table with the percent comparison among the three different case.
5. Figure 5- I would use the same colors and different types of lines (for example dotted) to identify the different cases (intensity of solar radiation and discharge)
6. With Regard to the result more details should be discussed:
· the efficiency of the system,
· production of domestic hot water (with regard to standard usage profile)
7. Add future developments
Author Response
Thanks for the reviewer’s comments.
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
The study examined the experimental study of simultaneous charging and discharging process in thermocline phase change heat storage system based on solar energy. In the paper, solar energy is used as the heat source, water is used as the heat transfer fluid, and encapsulated paraffin is used as the phase change heat storage material in this experimental system. The effects of different discharging flow rates on the temperature field, the evolution of the thermocline and the utilization rate in the tank under simultaneous charging/discharging conditions were studied.
The following need to be attended to to improve the manuscript:
The term (TC, out) should be defined first before using it as abbreviation especially in the abstract.
The statement “many researchers have conducted in-depth experimental studies and numerical simulations in this field” needs citations to back it up. In general, more references are needed in the introduction of the manuscript. The last paragraph of the introduction should include the outline of the study.
ERROR: Under Experimental system, this statement “the heat source of to heat the recharge water or 107 the cold water from the bottom of the tank,” should be checked for grammar error. Also “a orifice plate which is made of 112 stainless steel is fixed at the bottom of the tank” should also be checked.
RESULT WITH ANALYSIS: “the solar radiation intensity is recorded every 176 10 minutes, and since the thermocouple is recorded every 10 seconds, the charging power 177 is also changed every 10 seconds” What informed the decision to use the interval. A reference will suffice.
In the discussion of the result, authors should give a valid reference of previous studies that their result compares with.
The conclusion of the study seem one sided. It should include areas for future studies and recommendations.
Author Response
Thanks for the reviewer’s comments.
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 4 Report
The article is technical in nature. The article needs improvement, my recommendation is to reject the article, there is no scientific contribution, here are my observations:
1. There is a lack in relating the obtained results and analysis to the current state of knowledge.
2. No indication in the summary of what the authors consider a scientific achievement.
3. The article should be expanded in terms of analysis and generalized conclusions.
4. The text also needs an editorial overhaul
5. The topics of the article (energy storage) are timely and important. 6. The conditions and duration of the experiments were not precisely defined. Why are the durations of case 1, 2 and 3 different? (180) The intensity of solar radiation over time is usually different every day. It depends on atmospheric conditions and the season. The results presented here correspond to a special case. Please explain how to draw generalized conclusions in such a case. 7. (291) UR began to decline after 15:00 only in Case 3. (Fig. 9) In Case 2 UR began to decline after 15:45. 8. (293-294) In each of the cases studied, radiation intensity at 3pm had a different value. (Fig. 5) 9. (306) Please think about the proposal: "There is no obvious quantitative relationship between solar radiation intensity and charging power" 10. Solar radiation intensity of 535 W/m2 appears for the first time in line 294, and turns out to be a key parameter in the conclusions despite not being in earlier analyses. 11. There are no generalized conclusions or recommendations from the study. 12. What do the authors consider a scientific achievement? 13. Separation of number and unit at the end of the lines (16, 119, 206, 248) 14. The caption of figure 8 from page 11 is on page 12. 15. Comparing the temperature fields in Figure 8 would be easier if the same temperature color coding were used. is currently e.g.: Fig. 8(a) 70℃ - light green 8(b) 70℃ - orange 8(c) 70℃ - red
Author Response
Thanks for the reviewer’s comments.
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 4 Report
The paper has addressed the reviewer's suggestions in a proper manner.
