Cooling Potential for Single and Advanced Absorption Cooling Systems in a Geothermal Field in Mexico

Round 1

Reviewer 1 Report

Line 18: T_E de 8deg.C- Please change to English. Also T_E is not in the nomenclature at the end of the manuscript.

Introduction: Please provide citation for the information from the first paragraph

Line 118: Please change the units to fit the rest of the paper (tons of cooling power and deg.F)

Line 178: “solution reach on refrigerant” I do not understand

Line 216: “second-effect” should be “double-effect”

Fig. 5: Could you add a small reference map of Mexico for quick reference where the forest is situated?

Line 240: I think you meant Fig. 6 instead of 7

Fig. 6 doesn’t have legend finished. Also please add information on what the numbers state for (I guess depth in km, but it should be clear).

Line 297: What is SEACS? It was not used earlier in the manuscript.

Line 298: By medium system do you mean single-effect? Or what? It was only used once in the introduction.

As I do not know what the medium system is, it is hard to tell, but generally temperature of 58deg.C is considered too low for LiBr-H2O systems.

Line 301: the text says about the average temperature from 4 wells, while there is only one well described in the table 1.

Line 304: Please also add “(CP)” in the paragraph, so it is not only in the section title.

Eq. (4) and (5): what does the “t” stand for (it is described in the paragraph, but not in the nomenclature)?

Tables 2-5: please check the nomenclature.

Fig. 7: Please refer to it in the text near the figure.

Eq. (6): alpha and v is not in nomenclature.

Line 514: please delete one “between”

Author Response

Letter to the Reviewer No. 1

Dear Reviewer.  

Thank you very much for your invaluable comments and suggestions in order to improve the quality of the paper. 

1. Line 18: T_E de 8°C. Please change to English. And TE is not in the Nomenclature at the end the manuscript.

Thanks. Now is “T_E=8°C” and T_E was added to the nomenclature

2. Introduction: please provide citation for the information from the first paragraph 

Done. Citation [1] and [2] were added in the introduction.

3. Line 118: Please change the units to fit the rest of the paper (tons of cooling power and deg. F)

The units were changed.

4. Line 178: “solution reach on refrigerant” I do not understand

The phrase was changed to “solution with high amount of refrigerant”.

5. Line 216:” second-effect” should be “double-effect”

Thank you for the observation.  The change was done throughout the manuscript.

6. 5. Could you add a small reference map of Mexico for quick reference where the forest is situated?

Taken into account your comment this was done.

7. Line 240 I think you meant Fig 6 instead of 7.

Thanks, we corrected that in the text.

8. 6 doesn’t have legend finished. Also please add information on what the numbers state for (I guess depth in km, but it should be clear)

Thank you again. The legends have been added to Fig. 6.

9. Line 297: What is SEACS? It was not used earlier in the manuscript.

SEACS is short for single-effect absorption system and it was removed from the manuscript.

10. Line 298: By medium system do you mean single effect. Or what? It was only used once in the introduction.

Medium system was changed for half-system throughout the manuscript.

11. As I do not know what the medium system is, it is hard to tell, but generally temperature of 58°C is considered too low for LiBr-H2O system.

The value is correct but taking into account your concerns the following paragraph was added to the manuscript.

“It is important to mention that although a Tm of 58 °C for the half-effect cycle seemed to be a low temperature to drive an absorption cooling system, the double solution circuit used in this cycle (see Fig. 2), allows the system to operate at a such low temperature.”

12. Line 301: The text says about the average temperature from 4 wells, while there is only one well described in the table 1.

This sentence was removed from the manuscript. This article refers only to well PR2. 

13. Line 304: Please also add (CP) in the paragraph, so it is not only I the section title.

It was done.

14. (4) and (5): what does the “t” stand for (it is described in the paragraph, but not in the Nomenclature).

          The “t” is time and was added to nomenclature. Additionally, that sections (3.1-3.3)

            were modified for a better understanding.

15. Tables 2-5: please check the nomenclature

The parameters from tables were added to the nomenclature.

16. 7: Please refer to it in the text near the figure.

The following sentence was added to the manuscript:

“Figure 7 shows a schematic diagram of the underground tube heat exchanger.”   

17. (6): alpha and v is not in nomenclature.

Now Alpha and v are included in nomenclature.

18. Line 514: please delete one between

Thank you the correction was done.

Again, thank you very much for all your comments and suggestions.

 

Author Response File: Author Response.docx

Reviewer 2 Report

This original article is considered a positive contribution to the geothermal field as it assesses the cooling potential derived from the use of a determined geothermal well located in Mexico. It considers a cooling absorption technology and establishes different scenarios varying the technical conditions and the input data. It mainly distinguishes between half-effect, single-effect, double-effect, and triple-effect systems and assesses the most appropriate system based on the cooling capacity that can be obtained from each separately. The paper is considered relevant and innovative; however, the manuscript needs to be improved considerably. The proposed changes are following described:

 

1. Page 1. Abstract. It is mentioned: ‘The development and use of cooling systems driven by renewable energies such as geothermal is very important’. Could you please give the reasons why is important? This way is a contentless expression.
2. Page 1. In the abstract section, the objective of the paper is not described.
3. A thorough revision of the English grammar must be done. They are not severe errors but are quite abundant. Examples:

Page 1. Row 15: The development and use of cooling systems driven by renewable energies such as geothermal are very important, instead of ‘is important.

Page 1. Row 31. Not “consume” but “consumption”.

Page 2. Row 73. At the/an international level, instead of ‘At international level’

Page 2. Row 86. Alternatives, instead of alternative.

Page 13. Row 466. Wells, instead of walls.

 

4. Some important references are missing with the statements present in the manuscript that are not in the result section. Mostly, in the introduction section. For example:

Page 1. Row 28.  ‘Currently, 17% of the total energy produced 28 is consumed by cooling equipment’. In the world, in Mexico? Please, reference and clarify this.

 

Row 37 to 39.  The total heat content of the Earth 37 is estimated to be around 1,013 EJ (1 EJ = 1018 J) and it would take more than 109 years to 38 deplete it, through a current global terrestrial heat flux of 40 million MW. Please, reference this.

 

5. Page 7, row 239. PR2 well is introduced without giving more details concerning the reason, how many other wells there are or any other explanation that makes the reader understand why this one was selected.
6. In Figure 6, patterns present in the legend are missing.
7. The logic pattern is that after every equation, the parameters are explained. The order used here makes it harder to understand the purpose of every equation. Please, consider explaining these after every equation.
8. Page 8, row 321. For this evaluation, a conservative factor of Rf = 12.5% is considered. Please, justify this decision.
9. Page 10 – 12. Tables 2 to 5. Please, reference these equations and justify their usage. For the better of the paper, they could be added in the paper but in an appendix, not in the manuscript.
10. Page 12, row 448. Using a mathematical model. Which one? Please, reference it.
11. Page 15. Row 536. ‘Finally, a "U" tube heat exchanger with a 3'' pipe diameter was considered for the 6 cases’. Please, justify this decision.
12. Page 15. Row 546. ‘The second case, the insulator material was omitted in the simulation’. For a better understanding of the author's intention, it is recommendable to explain why did you decide to do this in this part of the paper. Is this a new scenario considered? After reading the conclusions, it is more or less clear, but not before.
13. Page 19. Conclusions section. As it is draft now, is rather an abstract of the results. More conclusions and discussion over the input and output data are missing. For instance:

-           At a TE = 8 °C, the operating range temperatures were 59-80 °C, 77-110 ºC, 135-162 739 ºC, and 180-187 ºC. What would be the results with other TE? Why Te=8ºC? How would the COP´s  obtained under these conditions?

-           Row 744 – 745. ‘The maximum values of the coefficients of performance were obtained in Autumn and Winter when the ambient temperatures were the lowest’. Is that valid? Can be then considered as a valid option?

-           Page 20. Row 756 – 757. ‘This fact is very important because around the world there are a great among of geothermal wells which can be used for these purposes. Could you please develop ideas of what to do with this potential, pros and cons, where are usually located,…

Author Response

Letter to the Reviewer No. 2 

Dear Reviewer.  

Thank you very much for your invaluable comments and suggestions in order to improve the quality of the paper.

1. Page 1. Abstract it is mentioned: The development and use of cooling systems driven by renewable energies as geothermal is very important. Could you please give the reasons why is important?

Thanks. The following sentence was added in the abstract:

 “The development and use thermally driven cooling systems is very important since they can be activated by renewable energies such as geothermal, and therefore reduce the consumption of electricity produced by fossil fuels”

2. Page 1. In the abstract section, the objective of the paper is not described.

Taking into account your comment the following sentence was also added in the abstract:

“A geothermal field located in the Jalisco state, Mexico, is analyzed with the aim of comparing the performance of different advanced absorption cooling system driven by a geothermal heat source. The analysis includes the influence of water temperature obtained from an abandoned geothermal well, using a U tube heat exchanger inside the well.”

3. A thorough revision of the English grammar must be done. They are not severe errors but are quite abundant. Examples:

Page 1. Row 15: The development and use cooling systems driven by renewable energies as geothermal are very important, instead of is important. 

Done (see answer 1).

• Row 31. Not “consume” but “consumption”
• Page 2. Row 73. At the/an international level, instead “at international level”
• Page 2. Row 86. Alternatives, instead of alternative

Thanks, all done.

• Page 13. Row 466. Wells instead of walls

Walls is correct because we talk about heat exchanger walls of the pipes. We only added “of the pipes”.

4. Some important references area missing with the statements presents in the manuscript that are not in result section. Mostly, in the introduction section. For example:

• Page 1: Row 28 currently 17% of the total energy produced is consumed by cooling equipment. In the world in Mexico? please, reference and clarify this.

Done, and changed to:

 “Currently, 20% of the total electricity consumed in buildings worldwide is for air conditioning [1]”

• 37 to 39 The total heat content of the Earth is estimated to be around 1,013 EJ (1 EJ = 1018 J) and it would take more than 109 years to deplete it, through a current global terrestrial heat flux of 40 million MW. Please, reference this.

Now the text contains the reference clearly:

“The total heat content of the Earth is estimated to be around 1,013 EJ (1 EJ = 1018 J) and it would take more than 109 years to deplete it, through a current global terrestrial heat flux of 40 million MW [4]”

5. Page 7, row 239. PR2 well is introduced without giving more details concerning the reason, how many others wells there are or any other explanation that makes the reader understand why this one was selected.

PR2 well is select due to the availability of the data. This was introduced within the manuscript:

“In the present study, the data of the PR2 well are used. This well was chosen due to all the necessary data for analysis were available”

6. In Figure 6, patterns in the legend are missing.

Done.

7. The logic pattern is that after every equation, the parameters are explained. The order used hare makes it harder to understand the purpose of every equation. Please, considered explaining these after every equation.

Dear reviewer taking into account your comment the most of the paragraphs related with equations were rewritten.

8. Page 8, row 321. For this evaluation, a conservative factor of Rf= 12.5% is considered. Please, Justify this decision.

We added:

“For the present study a Rf of 12.5 and a Fp of 90% were considered since they are typical values reported in the literature [36].”

9. Page 10-12- tables 2 to 5. Please, reference these equations and justify their usage. For the better of the paper, they could be added in the paper but in a appendix, not in the manuscript.

 

Tables were included to appendix A. In the text:

 

 “Appendix A show the tables with the energy balances for each one of the components integrating the four analyzed systems [20]”

 

10. Page 12. Row 448. Using a mathematical model. Which one? Please, reference it.

 

Modified in the text:

 “This computational mathematical method consists of dividing the    study domain into a finite quantity of control volumes. The equation which models the physical phenomena is discretized and solved for each control volume [37].”

 

11. Page 15. Row 536. Finally, a “U” tube heat exchanger with a 3 “pipe diameter was considered for the 6 cases. Please justify this decision.

 

Modified in the text:

“The pipe for the "U" type heat exchanger was set on 3'' due to this is the maximum allowable diameter to cover the largest contact area inside the well”.

12. Page 15. Row 546. The second case, the insulator material was omitted in the simulation. For a better understanding of the authors intention, it is recommendable to explain why you decided to do this in this part of the paper. It is a a new scenario considered. After reading the conclusions, it is more o less clear, but not before.

 

Taking into account your comment, this paragraph was modified as following:

“Due to the base case (first) was done without insulation, and the result showed that the fluid outlet temperature is 60.8 °C. This outlet temperature is enough to be used in a half-effect cooling system and was set as the starting point to compare subse-quent results. Afterward, distinct values of total length, insulator length, insulator thickness, and air velocity were used to analyze their effects on the outlet fluid tem-perature, which is used to drive the absorption systems.”

“For the second case, insulator material was considered with a 1000 m of length and 1’’ of thickness, keeping the remaining parameters as in the first case. The result shows that the fluid outlet temperature was 174.7 °C.”

 

Page 19. Conclusions section. As it is draft now, is rather an abstract of results. More conclusions and discussion over the input and output data are missing. For instance:

 

• At a TE = 8 °C, the operating range temperatures were 59-80 °C, 77-110 ºC, 135-162 ºC and 180-187 ºC. What would be the results with other T_E? Why T_E= 8°C? how would the COP obtained under these conditions?

 

Taking into account your comment, this paragraph was modified as following:

 

 “The value of T_E= 8 °C was chosen since it was the optimum value of the evaporation temperature obtained from the analysis of diverse absorption cooling systems [10]. These authors also reported that the values of CP and COP are directly proportional to TE.  However, higher values of TE were not considered in the present study, since higher temperatures cannot provide good air condition temperatures.”

 

 

 

• Row 744-745. The maximum values of the coefficients of performance were obtained in Autumn and Winter when the ambient temperatures were the lowest. Is that valid? Can be then considered as valid option?

 

Taking into account your comment, the following paragraph was added to the text:

 

“This occurs since at low ambient temperatures, the condenser and absorber temperatures are also lower, thus reducing the operating pressures of the systems. The lower operating pressures cause an increase of the refrigerant production and therefor an in-crease of the coefficients of performance.

 

• Page 20. Row 756-757. This fact is very important because around the word there are a great among of geo-thermal wells which can be used for these purposes. Could you please develop ideas of what to do with this potential, pros and cons, where are usually located.

 

Modified in the text:

“However, the geothermal areas that are currently being exploited in Mexico (hydrothermal) are located far from urban areas; therefore, not all the potential can be exploited. However, it is possible to start taking advantage of it in the installations of geothermal power plants for cooling offices, greenhouses, etc.

Another field of application is to evaluate the use of absorption systems through Enhanced Geothermal Systems (EGS), whose geographical distribution is much wider than that of hydrothermal systems.”

 

Again, thank you very much for all your comments and suggestions.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Thank you for the changes.