Refrigerant Charge Prediction of Vapor Compression Air Conditioner Based on Start-Up Characteristics
Round 1
Reviewer 1 Report
Dear authors,
The paper proposes a method to evaluate the refrigerant charge of a refrigeration system based on start-up tests. The paper is interesting and worth of investigation. In general the paper is good, but the reviewer thinks that there are some aspects which must be improved:
Introduction: Authors can make reference to a recent published article that quantifies the impact of under-charged refrigerant systems to highlight the importance of refrigerant charge (see: https://www.sciencedirect.com/science/article/pii/S0140700720302528 )
2.1. Experimental setup: Authors mention that they measure compressor rotational speed with a power meter. Please, indicate how you measure this variable.
Table 2. It is strange authors were able to maintain the outdoor/indoor temperature without oscillations, and also it is strange that the refrigerant charge was exact. Authors should include the experimental deviations of outdoor temperature. Also, they must indicate the charge procedure of the system and the uncertainty of the charge amount. It is very important in this paper to indicate how the system is charged (100g, then +100g,…) and evaluate the uncertainty of the charge, since then, the refrigerant charge is used for model validation.
3.2.. I think the referenced figures do not match with the real figures/captions, please, revise them.
Page 9: Authors indicate that they use compression rotational speed as predicting variable, however, it is not clear how it is measured and it is not indicated in Table 2. Please, check.
Although authors propose a method to estimate the charge characteristics of an air conditioning system and the are able to validate the model, the reviewer ask for more applicability or generalization of the model. How can other researchers implement the proposed model. The reviewer thinks that more information about the method should be given.
Reviewer ask for another question: The proposed model is valid for this system, which regulation was fixed (by manufacturer?). What would happen if the system is run at different regulation parameters, such as different superheating degree at evaporator? Authors must explain a little bit the applicability of the method.
Author Response
Please see the attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
This is an interesting paper and subject.
There are some minor English grammar mistakes which can be corrected using a grammar checker.
The Figures need renumbering (from figure 3 onwards). Please check that figure references are referring to the correct figure.
Please show uncertainty bars on experimental data points on all charts. Please also state how these uncertainties were calculated/established.
Looking forward to review the revised version of the paper.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Dear authors,
Thank you for considering the suggestions to improve the quality of the paper and for the answers given to my comments. Now I think it is ready to be accepted.
