Modeling and Efficiency Analysis of an Immersed Heat Exchanger for Solar-Powered Industrial Heat Processes: A Case Study on Wool Washing

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

• The literature review should provide some quantitative values from selected cited studies, so that readers can better understand the key findings of the referenced works and how they relate to the present study.
• Regarding Figure 1, please indicate the flow direction and include diagrams or annotations showing the location and type of sensors used at each point, particularly if any experimental data were used as input or for validation purposes.
• Please elaborate on the validation of the model.
• Please justify the use of the k-ε turbulence model, and explain why alternative models were not considered or were deemed less appropriate for the case under study.
• A dedicated section detailing the boundary conditions should be included. These conditions must be clearly defined for each case analysed, where applicable.
• The quality of all images and figures needs to be significantly improved. Some figures contain large unused areas; these should be cropped or zoomed to focus on the relevant regions. Please update the images accordingly for better clarity and presentation.
• It is unclear from the manuscript which cross-sectional plane the results are taken from, nor is there any justification for selecting only a single plane to represent the thermal behaviour of the entire 3D system. Please include a diagram of the control volume, clearly indicating where temperature and other data are extracted. A similar schematic should be provided for the plane in which tube temperature data were recorded.
• The results focus solely on the temperature distribution within the water tank under steady-state conditions. However, the solar system itself has not been included in the analysis, nor has the study addressed the transient behaviour associated with solar energy variability. Please justify.
• To properly assess the feasibility of the solar system, in line with the conclusions presented, the system should be analysed under transient operating conditions. The current steady-state assumptions are insufficient to support the claims made regarding the system applicability. Please justify.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript is very interesting. However, it is extremely hard to analyze the text due to the low quality of all the figures. Special focus should be put on the presentation of CFD results. The introduction should be revised. The literature gap should be better stressed. The conclusions should be prepared more carefully, with emphasis on the main bullet points of the results. The recommendations for future scientists should be noted. 

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Comments on the Quality of English Language

The English quality is sufficient. 

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript presents the numerical analysis of heat transfer in a heat exchanger between different thermal fluids, for comparison, and the water used for wool washing. The thermal fluid is heated by means of solar energy, thus increasing the thermal efficiency and reducing the environmental impact.

The authors point in their manuscript to a solution for industrial hot water needs. The  manuscript can be published after performing several corrections according to the following comments and suggestions:

1) Line 152: it would be useful to provide a description of Thermia B, in addition to the commercial name. What kind of oil is it?

2) Line 170: if the parameters refer to water, this should be mentioned.

3) Line 182-185: the heat transfer is performed by conduction and convection, not only by conduction; convective boundary conditions are recommended at the interface fluid-solid.

4) Lines 194-195: the sentence is not clear and must be rephrased.

5) The quantities occurring in equations 1-16 must be described.

6) Lines 235 and 244: a suggestion is to replace thermal power with rate of heat.

7) Fig 5a: the title is incomplete

8) Some sentences begin with "Where", such as in Lines 265-267, making the text unclear.

9) Line 290: Fig. 6a instead of Fig. 7

10) Line 354: Fig. 9 instead of Fig. 8

11) The numerical results should be compared with similar results existing in the literature. It is not enough to just indicate the reference. A discussion would be useful.

In general, an English language revision is required.

 

 

Comments on the Quality of English Language

Some sentences are difficult to understand. The English language revision is required.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The reviewer is satisfied with the improvements made to the document.