Study of Thermal Inertia in the Subsoil Adjacent to a Civil Engineering Laboratory for a Ground-Coupled Heat Exchanger

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

There is a lot of interest in ground heat exchangers and this paper is part of that. A lot of experimental measurements were made which is useful but they could be better presented. However it was not clear to me what the paper was trying to achieve, and the presentation was poor in places - see notes in attached MS. Is it about thermal soil behaviour with depth, or the design of an air heat exchanger for this building? Some conclusions seem highly specific to this site - there happens to be clay at 3 m depth which is good for heat exchange but that is not of much general use. Overall it needs a much clearer story - what is the main purpose of the research and the main findings useful to others?

Some specific points:

- need to describe the modelling and validiation in more detail

- charts 13, 14, 15 need more explanation of what exactly they represent.

- choice of days/periods to chart seem rather random or need exlaining

- intro says 'seasonal behaviour' but study only considers 4 1/2 months so not really 'seasonal' just late summer/autumn, so how can you use this for a whole year?

- the theory section needs to be clearer - a lot comes at the end Tables 5 - 9 not linked to the text

- the discussion section is completely missing! text from template?

Comments for author File: Comments.pdf

Comments on the Quality of English Language

There are some minor wording errors and use of the wrong word in a few places, see annotated MS. Mostly the English is good.

Author Response

 "Please see the attachment." 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

While this study provides valuable experimental data and relevant methodology, certain gaps have been observed, and below are some remarks for the authors to consider :

1.      The novelty and originality of this study should be clearly stated, and the authors should also highlight the advantages of their research compared to existing knowledge in the field. This will enhance the public's understanding.

2.      The discussion of the obtained results and the interpretation of the graphs are not sufficiently detailed. The authors should provide more in-depth explanations and compare the performance with other studies on the same topic.

3.      Figure 10, which presents the temperature evolution, has insufficient image quality. Please replace it with a more legible version.

4.      There is an error in equation 1, which concerns the sizing of the buried heat exchanger. Please correct it.

5.      It would be preferable to present the values of certain properties when they are affected by another parameter, rather than simply referring to previous studies. For example, in the case of the effect of water quantity on thermal conductivity and diffusivity, this should be clearly illustrated in line 418.

6.      It is essential to properly correlate experimental data with simulation data to consistently select a single layer choice.

7.      Obviously, temperature decreases with depth. Is it possible, therefore, that a rigorous design of the heat exchanger, independently of the soil properties, will make it possible to exploit an even greater depth than the one you have chosen?

Author Response

 "Please see the attachment." 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you for making the changes suggested in the text I sent, which does improve the text and clarity.

I attach another annotated MS with a few more things to look at.

However most of my general comments still stand - it is not very clear what the research value is which could be used elsewhere. The results are presented in terms of temperatures but do they meet the required building loads? This is hardly mentioned in the results; what loads are delivered in reality or in simulations.  Also the soil layers are quite specific to the site. Liquid (water/glycol) rather than air is much more commonly used in ground system because smaller pipes are used; perhaps use of air needs more explanation. The value as research to the wider community needs to be a lot clearer, in my view. 

Comments for author File: Comments.pdf

Comments on the Quality of English Language

English is good, just a few minor points.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 3

Reviewer 1 Report

Comments and Suggestions for Authors

Thanks for improving the MS and adding information on loads, and further context around use of air. A couple of minor things on Figure 22: x axis time format could be simplified e.g. to whole hours; certainly don't need seconds. Caption: correct 'the august 18th' to 'August 18th'. P22 'with only a ½ HP blower' replace with 'with only a ?? watt fan'.

Comments on the Quality of English Language

Standard of English is very good.

Author Response

Dear reviewer,

We appreciate the insightful feedback. Subsequent to your recommendations, we have refined Figure 22 by configuring the x-axis to portray whole hours instead of seconds. Additionally, we have rectified the caption to accurately read 'August 18th.'

Your discerning suggestions have been duly noted. In response, we have revised page 22 to replace the phrase 'with only a ½ HP blower' with 'with only a 370 watt fan.'