Phase-Change-Material-Impregnated Wood for Potential Energy-Saving Building Materials
Round 1
Reviewer 1 Report
In the present contribution, the authors present a throughout thermal characterization of Oriental spruce sapwood coupled with three different PCMs. This characterization is done in order to derive DSC curves, i. e. heat capacity for both phases and melting temperatures, thermogravimetric analysis, and so on. The authors showed that these PCM presents both good thermal stability and resistance to wood-destroying fungi. The reviewer thinks that this is an interesting paper about the characterization of a material, that could be really useful for whom wants to use this material in engineering applications like building thermal management and not only. Therefore, it is suggested to consider this contribution after addressing the following points.
- The paper introduction is well presented but actually, since this paper essentially deals with the thermal characterization of a PCM, some more effort are required from the authors. For instance, the authors should mention that, within the energy efficiency framework, these materials can be also used as thermal energy storage systems for hot water production [1, 2] or also for wall-type heat recovery systems [3]. In order to remark some potential applications of this work - that would not be only referred to building energy efficiency - the authors should mention all this within the paper introduction
- Including some pictures of the samples investigated could be a good idea
- In table 1, please use J/kg instead of j/kg for the enthalpy; furthermore, some units (for instance, specific heat) are missing within the table
- Within all the DSC curves shown through the manuscript, are the authors able to provide some more details about liquidus/solidus temperatures, i. e. temperatures at which some phase change starts to arise?
- In Figs. 5 and 6, please report the scale for the y-axis
- Please improve equations graphics. For instance, in Eq. 1, the authors could use some subscript, as well as some equation tools like Word Equation, Mathtype, or similar
- The DSC curve for PCM2W looks quite weird. If there aren't any results, why did the authors include this within Fig. 7?
- The authors present here a throughout characterization of phase change materials. However, did they check what happens in terms of thermal hysteresis if more heating/cooling cycles are considered? This would be interesting for future studies
- In the reviewer's opinion, it seems that there is no reference about the uncertainties of either instruments employed or measurements performed. Could the authors please provide some more details about this?
- It is suggested to use bullet points for the conclusions; furthermore, please report some potential future plans for this study
[1] Fragnito, A., Bianco, N., Iasiello, M., Mauro, G. M., & Mongibello, L. (2022). Experimental and numerical analysis of a phase change material-based shell-and-tube heat exchanger for cold thermal energy storage. Journal of Energy Storage, 56, 105975.
[2] Pekdogan, T., Tokuç, A., Ezan, M. A., & BaÅŸaran, T. (2021). Experimental investigation on heat transfer and air flow behavior of latent heat storage unit in a facade integrated ventilation system. Journal of Energy Storage, 44, 103367.
Author Response
Dear Reviewer,
We would like to thank you for carefully reading our manuscript and offering your insightful comments/remarks to improve our work. We have taken them into consideration in preparing the revised form of the manuscript. Our point-by-point responses to your comments are given below. The appropriate corrections and modifications to the revised manuscript have been made using the Track changes function of MS Word.
In the present contribution, the authors present a throughout thermal characterization of Oriental spruce sapwood coupled with three different PCMs. This characterization is done in order to derive DSC curves, i. e. heat capacity for both phases and melting temperatures, thermogravimetric analysis, and so on. The authors showed that these PCM presents both good thermal stability and resistance to wood-destroying fungi. The reviewer thinks that this is an interesting paper about the characterization of a material, that could be really useful for whom wants to use this material in engineering applications like building thermal management and not only. Therefore, it is suggested to consider this contribution after addressing the following points.
- The paper introduction is well presented but actually, since this paper essentially deals with the thermal characterization of a PCM, some more effort are required from the authors. For instance, the authors should mention that, within the energy efficiency framework, these materials can be also used as thermal energy storage systems for hot water production [1, 2] or also for wall-type heat recovery systems [3]. In order to remark some potential applications of this work - that would not be only referred to building energy efficiency - the authors should mention all this within the paper introduction
A: Yes, that's correct. Within the context of energy efficiency, materials such as phase change materials (PCMs) can be utilized as thermal energy storage systems for hot water production or for wall-type heat recovery systems. PCMs have the ability to store and release thermal energy as they change from solid to liquid and vice versa, which makes them useful in a variety of applications related to energy efficiency and storage. In the case of hot water production, PCMs can be incorporated into tanks or other storage containers to store heat generated from solar panels or other sources, which can then be used to produce hot water as needed. In wall-type heat recovery systems, PCMs can be used to store heat generated within a building and release it later, helping to regulate indoor temperature and reduce heating and cooling costs. These are just a few examples of the many potential applications of PCMs within the energy efficiency framework, and research into their use is ongoing as scientists and engineers look for new and innovative ways to harness their unique properties to create more energy-efficient systems.
Phase change materials (PCMs) are substances that can store and release thermal energy as they change from solid to liquid and vice versa. Owing to this property, they can be used in a variety of applications, including: 1) Building insulation: PCMs can be used to help regulate indoor temperatures and reduce heating and cooling costs in buildings; 2) Thermal energy storage: PCMs can be used in thermal energy storage systems to store and release excess heat generated by renewable energy sources such as solar panels.; 3) Refrigeration and air conditioning: PCMs can be used to improve efficiency and reduce energy consumption in refrigeration and air conditioning systems; 4) Clothing and textiles: PCMs can be incorporated into clothing and textiles to provide people working in hot or cold environments with comfortable, temperature-regulating clothing; 5) Packaging: PCMs can be used in packaging to help temperature-sensitive products, such as food and pharmaceuticals, to maintain their temperature; 6) Electronics: PCMs can be used to regulate temperatures and reduce the risk of overheating in electronics such as laptops and smartphones; and 7) These are just a few of the many potential applications of PCMs, and research into their use is ongoing as scientists and engineers seek new and innovative ways to leverage their unique properties.
- Including some pictures of the samples investigated could be a good idea
A: Thank you for this comment. Unfortunately, it is not possible for us to take pictures at the moment, as the samples were used in the experiments.
- In table 1, please use J/kg instead of j/kg for the enthalpy; furthermore, some units (for instance, specific heat) are missing within the table
A: Thank you, the recommended corrections have been made.
- Within all the DSC curves shown through the manuscript, are the authors able to provide some more details about liquidus/solidus temperatures, i. e. temperatures at which some phase change starts to arise?
A: The details are provided as follow: “In addition, when the figure 7 is examined, it is seen that PCM1 begins to melt at 18 ºC, solidifies at 20 ºC, PCM2 begins to melt at 15 ºC and solidifies at 20 ºC, and PCM3 begins to melt at 23 ºC and solidifies at 38 ºC. Similarly, it is seen that PCM1W material begins to melt at 15º C, begins to solidify at 20 ºC, and PCM3W begins to melt at 20 ºC and solidifies at 24 ºC.”
- In Figs. 5 and 6, please report the scale for the y-axis
A: Thank you, the recommended corrections have been made.
- Please improve equations graphics. For instance, in Eq. 1, the authors could use some subscript, as well as some equation tools like Word Equation, Mathtype, or similar
A: Thank you for this comment. The equations graphic has been made:
- The DSC curve for PCM2W looks quite weird. If there aren't any results, why did the authors include this within Fig. 7?
A: Thank you for this comment. No results were obtained for PCM2W. It was included just for a comparison.
- The authors present here a throughout characterization of phase change materials. However, did they check what happens in terms of thermal hysteresis if more heating/cooling cycles are considered? This would be interesting for future studies
A: Thank you for this insightful comment. You are quite right, but we did not look at the long-term cycle. Maybe we can do it in future studies. In addition, doing these 500 cycles requires a high budget.
- In the reviewer's opinion, it seems that there is no reference about the uncertainties of either instruments employed or measurements performed. Could the authors please provide some more details about this?
A: Thank you for this comment. The washing test was carried out according to a certain standard. In other analyses, a certain standard was not used.
- It is suggested to use bullet points for the conclusions; furthermore, please report some potential future plans for this study
A: Thank you for this comment. The Conclusions section has been reworked accordingly.
[1] Fragnito, A., Bianco, N., Iasiello, M., Mauro, G. M., & Mongibello, L. (2022). Experimental and numerical analysis of a phase change material-based shell-and-tube heat exchanger for cold thermal energy storage. Journal of Energy Storage, 56, 105975.
[2] Pekdogan, T., Tokuç, A., Ezan, M. A., & BaÅŸaran, T. (2021). Experimental investigation on heat transfer and air flow behavior of latent heat storage unit in a facade integrated ventilation system. Journal of Energy Storage, 44, 103367.
A: Thank you for this comment. The recommended references have been added in the revised version of the manuscript.
Thank you very much for your time and consideration!
Reviewer 2 Report
Dear authors,
A very interesting approach to using Oriental Spruce impregnated with PCM.
The methods of this study have been presented in detail.
A very well-organised manuscript. In the concluding chapter, I would expect to see a more analytical approach presenting the findings based on the previous chapters and also suggest future steps to your approach which is very little investigated up to now.
More comments within the attached manuscript
Comments for author File: 
Comments.pdf
Author Response
Dear Reviewer,
We would like to thank you for carefully reading our manuscript and offering your insightful comments/remarks to improve our work. We have taken them into consideration in preparing the revised form of the manuscript. Our response to your comments are given below. The appropriate corrections and modifications to the revised manuscript have been made using the Track changes function of MS Word.
Dear authors,
A very interesting approach to using Oriental Spruce impregnated with PCM.
The methods of this study have been presented in detail.
A very well-organised manuscript. In the concluding chapter, I would expect to see a more analytical approach presenting the findings based on the previous chapters and also suggest future steps to your approach which is very little investigated up to now.
More comments within the attached manuscript
Kindly enhance this sentence by noticing the results that were drawn from the previous tests.
Authors’ response: Thank you for this comment. The Conclusions section of the manuscript has been revised accordingly to better reflect the content of the paper.
Thank you very much for your time and consideration!
Reviewer 3 Report
Comments
In this article The biological properties, hygroscopic and thermal performance of the PCM-impregnated wood were examined. The topic of this research is very interesting I would suggest the publication of this article if the following minor issues are addressed.
- - In the introduction (line50), more recent works related to the use of PCM to store energy for buildings applications, should be added.
Authors may include the closely related work such as:
1- Ben Khedher, N. 2018. “Numerical Study of the Thermal Behavior of a Composite Phase Change Material (PCM) Room”. Engineering, Technology & Applied Science Research 8 (2). Greece:2663-67. https://doi.org/10.48084/etasr.1824.
- - Equation (1) should be typed with mathtype or any math editor as well please choose a conventional symbol ΔHm for latent heat of melting.
- - Figure 7, the temperature axis the ticks are missing. Please add the missing temperature ticks in all figures.
- - Table1, the thermo-physical properties of three PCMs (paraffins) should be given separately and in a clearer way (three columns for three PCMs). Their commercial name should be given or their chemical formula if available.
- Line 162, there is a big difference in the weight percentage gain achieved for PCM1, PCM2, and PCM3 especially for PCM. Could you please justify this especially the same operational conditions were kept and for the same wood and the same density of PCMs.
- -Leaching and decay test were performed at ambient temperature 20⸰C. However PCM-impregnated wood samples (PCMW) will be exposed to higher outdoor temperatures that will cause the melting of PCMs and consequently the leakage of PCMs. It is recommended the use of encapsulated PCM.
- Line 314, “No results were obtained in PCM2W samples (Table 30)” why the results are missing for PCM2W.
- - The choice of these particular PCMs should be justified since their properties are almost the same why not different PCMs with different thermo-physical properties to confirm the best performing PCM type for this type of wood.
Author Response
Dear Reviewer,
We would like to thank you for carefully reading our manuscript and offering your insightful comments/remarks to improve our work. We have taken them into consideration in preparing the revised form of the manuscript. Our point-by-point responses to your comments are given below. The appropriate corrections and modifications to the revised manuscript have been made using the Track changes function of MS Word.
In this article The biological properties, hygroscopic and thermal performance of the PCM-impregnated wood were examined. The topic of this research is very interesting I would suggest the publication of this article if the following minor issues are addressed.
- - In the introduction (line50), more recent works related to the use of PCM to store energy for buildings applications, should be added.
Authors may include the closely related work such as:
1- Ben Khedher, N. 2018. “Numerical Study of the Thermal Behavior of a Composite Phase Change Material (PCM) Room”. Engineering, Technology & Applied Science Research 8 (2). Greece:2663-67. https://doi.org/10.48084/etasr.1824.
A: Thank you for this comment. The relevant part has been corrected. The suggested reference has been added in the revised version of our manuscript.
- - Equation (1) should be typed with mathtype or any math editor as well please choose a conventional symbol ΔHm for latent heat of melting.
A: Thank you for this comment. Equation 1 has been revised:
- - Figure 7, the temperature axis the ticks are missing. Please add the missing temperature ticks in all figures.
A: Thank you for this comment. Fig. 7 has been edited accordingly.
- - Table1, the thermo-physical properties of three PCMs (paraffins) should be given separately and in a clearer way (three columns for three PCMs). Their commercial name should be given or their chemical formula if available.
A: Thank you for this comment. Only the melting and solidification temperatures of the phase change materials used differ. All other features are the same.
- Line 162, there is a big difference in the weight percentage gain achieved for PCM1, PCM2, and PCM3 especially for PCM. Could you please justify this especially the same operational conditions were kept and for the same wood and the same density of PCMs.
A: Thank you for this comment. Yes, all the conditions you mentioned are the same. Low weight gains were obtained in the samples belonging to the PCM2W group. This is also seen in the DSC analysis. The low weight percent gain after the modification of wood can have several reasons, some of which are:
Incomplete Impregnation: If the wood was not thoroughly impregnated with the modifying agent, it can result in low weight percent gain. Environmental Factors: The temperature, humidity, and other environmental conditions during the modification process can also impact the weight percent gain. It's important to note that weight percent gain is not the only factor that determines the effectiveness of wood modification. Other factors, such as changes in the mechanical and physical properties of the wood, should also be considered.
- -Leaching and decay test were performed at ambient temperature 20⸰C. However PCM-impregnated wood samples (PCMW) will be exposed to higher outdoor temperatures that will cause the melting of PCMs and consequently the leakage of PCMs. It is recommended the use of encapsulated PCM.
A: Thank you for this comment. Yes, PCMs materials that are used at higher temperatures should be protected by encapsulation and leaching problems should be minimized. However, the purpose of the leaching test in this study is completely different. The purpose of this is to determine the leaching rate of the samples when exposed to water before the decay test. The main purpose is to determine how resistant the samples leached with water will be to the decay test.
- Line 314, “No results were obtained in PCM2W samples (Table 30)” why the results are missing for PCM2W.
A: Thank you for this comment. It was probably due to the low weight gain (20%) and we chose to include it for comparison purpose.
- - The choice of these particular PCMs should be justified since their properties are almost the same why not different PCMs with different thermo-physical properties to confirm the best performing PCM type for this type of wood.
A: Thank you for this insightful comment. Yes, we wanted to use PCM with the same thermo-physical properties. We wanted to find out how PCMs with the same property behave at different temperatures.
Thank you for your time and consideration!
Round 2
Reviewer 1 Report
The paper can be accepted as it is in the revised form
