Assessment of Efficiency of Heat Transportation in Indirect Propane Refrigeration System Equipped with Carbon Dioxide Circulation Loop
Round 1
Reviewer 1 Report
The authors have presented a systematic and comprehensive development of an analytical model for indirect propane refrigeration system with CO2 circulation loop. The authors have presented the application of the model for refrigeration system design, performance evaluation as well as shown validation of the model by comparing with data from previous literatures.
11. Abstract requires modification and correction. For example the term “perspective configuration“ should be replaced. Similarly, “literature available experimental studies“ should have been written as “available in literatures“. Abbreviations such as “app“ should not be used in abstract. Also, “natural circulated“ should be "naturally circulated“.
22. Overall, the whole manuscript is riddled with grammatical errors, typos, and complex/long running sentences. For example, page 3 alone has around 10 errors. The manuscript should be thoroughly proof read.
33. Weber number has been written has 'Webber' in the nomenclature. Please fix this in Nomenclature and throughout the manuscript as well.
44. In the introduction, the authors talk about the changes in regulations regarding refrigeration systems which is related to Kigali amendment. Please cite appropriate references for the corresponding discussions.
55. The Figure texts are blurry. Please enhance the resolution of the figures.
66. Please fix y axis title in Fig 3 and Fig 4 to manuscript standard, “kg/(m2s)“.
77. For consistency and to avoid ambiguity use the term “mass flux“ throughout the manuscript.
88. In page 13, the last sentence of section 3.1. is ambiguous. Please rephrase.
99. In page 14, the authors mention: “However, obtained results may be assessed as corresponding to order of magnitude of pressure drops of the plate heat exchangers in application to evaporator and condenser.“ The authors need to provide justification or reference for this assumption. In a research article assumptions cant be made without proper scientific explanation or reference.
110. In Table 2, comparison of the model has been made with experimental results from previous literature for R134a refrigerant.
Referring to the data in Table 2 the authors mention that the methods are similar. Later on the authors again state that the model overpredicts the height. These are counter intuitive statements.
In the end of this section the authors mention, “However, the provided data may be thought as sufficiently positive validation of the proposed modelling approach that will be applied in the analysis presented in the next section. “
This is a big assumption without any logical explanation. Table 2 compares the data for R134a and shows large difference. Hence, the assumption that these data (Table 2) are sufficient to validate the proposed model for a CO2 system does not make sense at all.
111. Please provide a reference for the parameters chosen for Table 3.
112. In the Conclusions section, the usage of "proprietary analytical model“ may not be a proper term to be used in a research article meant for scientific community. I would recommend rephrasing the term.
Author Response
Dear Reviewer,
Thank you very much for the review of our paper. Our responses are attached in pdf file. With kind regards,
Dariusz Butrymowicz
Author Response File: 
Author Response.pdf
Reviewer 2 Report
In this paper a analytical model is proposed and a close attention has been paid to the analytical modelling of operation of the carbon dioxide circulation loop. The model was formulated to determine the optimum height of the liquid downcomer based on the determination of flow resistance occurring in the flow as well as heat transfer rate in evaporation and condensation processes.the model is validated with with literature available experimental studies of two-phase flow structures predictions and thermal performance predictions has been performed. The authors were able to generate results . the results indicate that the indirect cooling systems with natural circulated CO2 as heat transfer fluid should be designed for operation at maximum refrigeration capacity. The selection of problem is appropriate, language is good and organization of the manuscript is as per required standards. The publication of this paper will be beneficial for a large community of researchers
Comments
Comment No. 1: You should add same recently references in (2022)
Comment No. 2: added some quantitative results in the conclusion
Author Response
Dear Reviewer,
Thank you very much for the review of our paper. Our responses are attached in pdf file. With kind regards,
Dariusz Butrymowicz
Author Response File: Author Response.pdf
Reviewer 3 Report
Dear authors,
The discussions blend multitude aspects related to the assessment of heat transportation in the indirect propane refrigeration system. The modelling concept explains the influence of various parameters affecting the system efficiency and also accounts for the previously established reports. The listed comments may be considered which might improve our understanding about the work.
Major comments
(1) The modelling to validate the previous results is indeed appreciable. However, authors must also propose their viewpoints on further improvement in the system capacity.
Minor comments
Abstract
(1) Expand ‘COP’ before abbreviating it.
(2) The quantity of propane generation may be indicated.
(3) The merit of the adopted protocol may be briefly emphasized.
Section 2.0
(1) Figure 1: The dimension of the components may be specified.
Section 3.0
(1) Most of the discussions run without literature support, which may be taken care off.
(2) The optimized diameter of the pipeline and the threshold volume of the working fluid for significant mass flow rate needs to be provided for more understanding. At present, the phrase is much generalized.
Author Response
Dear Reviewer,
Thank you very much for the review of our paper. Our responses are attached in pdf file. With kind regards,
Dariusz Butrymowicz
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors have addressed all of my concerns.
