Research on Energy Savings of an Air-Source Heat Pump Hot Water System in a College Student’s Dormitory Building

Round 1

Reviewer 1 Report

This paper conducted an analysis on the energy saving performance of centralized hot water systems and emphasizes the advantages of air source heat pump hot water systems in achieving sustainable and environmentally friendly heating solutions. Through one year of practical operation testing and simulation analysis, this article demonstrates the high-efficiency energy-saving characteristics of air source heat pump hot water systems and their important role in reducing energy consumption. Several remarks and questions are suggested to be considered before the final manuscript:

(1) The importance and the novelty of this work should be addressed.

(2) What about the error analysis for the experimental study?

(3) Fig. 7 presents the results of “direct heat mode” and “circulation mode”, and Fig. 8 shows the data for “Direct heat water production mode” and “Circulation heat preservation mode”. The authors are required to provide the definition of these different modes.

(4) In section 4: The optimized system was studied by simulation or experimental measurement? Is there any validation process?

It would be better if the language could be more concise and precise.

Author Response

Thank you very much for your suggestion.Please see the attachment about my response.Please see the attachment about my revised manuscript.

Author Response File: Author Response.docx

Reviewer 2 Report

It is believed that the article concerns a very interesting and important topic like the energy saving of hot water systems.

 

The role of the optimization  operation for centralized plants for hot water of the building   in the different energy  scenario and different climate situation  is one the aspects very important both as a relationship with  Heating systems, and for health needs and the comfort of the people but also for energy saving.

the new international political orientation on environment It increases systems for the use of renewable sources on buildings. Many heating   systems of the water work at low temperature and require the use of performing removable energy systems

 

Said this, However, it is believed that paper he need an little review and integration of the bibliography before its publication to better consider the different types of optimizations and integrations now present on the market

The Bibliography both at the general level that in the introductory part, and in the various chapters must be integrated.

 

In this regard, It is suggested to the authors to insert in the introduction some references for example:

 

" Potential for Building Façade-Integrated Solar Thermal Collectors in a Highly Urbanized Context"

https://doi.org/10.3390/en13215801

 

 

 

 

 

Final comment

The work deals with an interesting and current topic.

Next at the changes required the work is believed to be publishable.

No particular comment

Author Response

Thank you very much for your suggestion. Please see the attachment about revised manuscript.Please see the attachment about my response.

Author Response File: Author Response.docx

Reviewer 3 Report

Manuscript ID: sustainability-2381988

Research on Energy Saving of Air-source Heat Pump Hot Water System in a College Student's Dormitory Building

 

To editor/authors:

Submitted manuscript deals with investigation and improvement of centralized hot water system based on air source heat pump. Authors conducted experimental monitoring of the system and developed numerical model of the system in TRNSYS. Good agreement between the two is reported. In the end, authors showed that by means of so-called time-sharing control strategy it is possible to improve energy performance of the system. Topic itself fits the journal scope. Still there are some major shortcomings that need to be addressed prior to the consideration of manuscript publication.

1) Technically the manuscript is not ready for publication. Writing must be improved in detail. There are numerous mistakes in the text like missing spaces, references in titles, occasional use of bold text for units, figures are not unified with in terms of style and font, text in figures is too small, repeated sentences describing figure 6 etc.

2) Listing of the references must be done correctly, some references are multiplied (14 and 18), there is unknown mark [J] in almost all references in the list, writing of authors names must be unified.

3) Some figures and data are not fully described or do not follow the description. For example, Figure 5 has 3 temperature points that are not explained. Figures 16 and 22 show significantly different values of COP difference and plotted error. In figure 13 unit kWh is used for power, it should be kW etc.

4) Heating seasonal factor performance is introduced in the text, still there is missing an exact description on how is it calculated. Commonly, seasonal efficiency is calculated as ratio of useful delivered energy (not power) over energy consumed.

5) Authors provided clear ideas and motivation for the research, but I do not find scientific novelty in the approach or in the results. Novelty must be clearly defined and highlighted based on the literature review.

6) Time-sharing control strategy is introduced in the manuscript but there are no explicit details on what really is that kind of control strategy and how it differs from standard one.

7) Last part of the manuscript deals with the optimization of performance of DHW system. Optimization procedure implies the definition of optimization function that needs to be minimized or maximized to achieve some goal. In this manuscript, there is no such approach. From my understanding, authors prescribed working hours of the system based on monitored data. I would call this improvement of control strategy, not optimization. On the other hand, I wonder, what happens with system performance when environmental conditions or conditions on user side differ significantly from the typical days recorded during the monitoring year.

Writing must be improved, numerous technical errors in the text.

Author Response

Thank you very much for your suggestion. Please see the attachment about revised manuscript.Please see the attachment about my response.

Author Response File: Author Response.docx

Reviewer 4 Report

1. In order to facilitate the reader's reading and understanding, it is suggested that the first occurrence of the acronym "COP" be expressed in its full form, and that the acronym "COP" be used only in the subsequent text, without repeated explanation.

2. In "1. Introduction", the word "CO2" is suggested to be changed to "CO₂".

3. There are many irregularities in the article, such as "°C" in the article, "mm", "W", "kW" in Table 1, etc., which are not separated by spaces between units and values, "It is recommended to read and amend them carefully.

4. In "Figure 3.", it is recommended that spaces be used to separate the serial numbers (b), (c), (d) and (e) from the specific notes.

5. In "2.3. Testing Procedure", the first line of the paragraph is not indented. In addition, it is more appropriate to use "where" in the formula paragraph for the description of the formula.

6. It is recommended that all parentheses in the article be in English.

7. In "Figure 8.", between "Figure 8." and "COP", and between ". " and "(b)" are separated by a space.

8. In sub-section "2.4.4.", it is proposed to amend "87878 kWh" and "22176 kWh" to "87. 878 kWh" and "22,176 kWh" and "114,397 kWh" to "114,397 kWh" in sub-section 3.2 (2). kWh".

9. There are several writing formatting problems in the text, such as two spaces after M in equations (5) and (6), two spaces after "The simulated results in" in subsection 3.2(2), and two spaces after "The simulated results in" in subsection 4.4.  goals.Overall " has no space at the end of the sentence, and two commas appear in " systems, ,as ".

Author Response

Thank you very much for your suggestion. Please see the attachment about revised manuscript. Please see the attachment about my response.

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

Authors responded to raised questions. Technically manuscript is improved. Some clarifications are added to the manuscript thus improving the understanding. I still feel that scientific novelty is not clearly enough highlighted compared to available scientific literature.

In point 7 authors provided more information on the applied optimization procedure for the control of DHW system. I still believe that it would be more appropriate to name that section as Improvement of controls than optimization as I find the optimization procedure to be more detail and more evidence based than it is the case in the manuscript.

English is improved.

Author Response

Thank you very much for your suggestion. Please see the attachment about my response. Please see the attachment about revised manuscript.

Author Response File: Author Response.docx