Void Fraction Prediction Method in Gas–Liquid Flow through Channel Packed with Open-Cell Metal Foams
Round 1
Reviewer 1 Report
This study focuses on void fraction in two-phase gas-liquid flow in channels packed with metal foams. The topic interesting. The manuscript is technically sound and is well written. Before accepted for publication. Some revisions are needed. 1.The novelty should be further addressed at the end of the introduction 2. The error bar or uncertainty analysis for the experimental data is needed. As an experimental study, the experiments should be carried out several times to ensure a convincing result. 3. The advance of the new method could be further addressed.Author Response
"Please see the attachment."
Author Response File: 
Author Response.docx
Reviewer 2 Report
This study presents a new method developed to measure the void fraction for an air-water or oil-water two-phase flow, employing a metal foam. The paper seems to present useful results, which could have an engineering impact. However, the language and the way that the results are presented, make it very difficult for the reader to follow the applied method and the final contribution of the article.
The following questions need to be addressed:
- The relative unceratainty of the experiment possibly leads to high unertainty of the results, namely 13%. This means that for an industrial application, in the case that someone uses this method to measure quality of a refrigerant would face high inaccuracy.
- The language needs significant improvement throughout the paper. Possibly the whole articles needs to be rewritten, in order to make it clearer and more precise.
- Equations and tables need improvement. The attached file contains some proposals.
- The current state-of-the-art needs improvement.
In general the paper seems to present acceptable results regarding the method applied, nonetheless the scope of the study is not clear, as well as the presentation needs significant changes. The article should show an experimental method that can be reproduced and give improtant information regarding the void fraction measurement in an industrial application. Therefore, this reviewer would propose to reject the article article in this form and resubmit it after the proposed improvements.
Comments for author File: 
Comments.pdf
Author Response
"Please see the attachment."
Author Response File: Author Response.docx
Reviewer 3 Report
Comments regarding the manuscript entitled:
Void fraction prediction method in gas-liquid flow through channel packed with open-cell metal foams
It is mentioned in the abstract that the obtained error using the proposed method is less than 20% for 86% of the experimental data. The errors between %10 and %20 are considered as high. In Addition to the other 14% higher than 20%. So here the approach proposed by the authors is questionable. Can the authors provide their justifications for choosing this approach?
There are several sentences, in particular in the introduction, that need to be re-written. Please check the English of the manuscript.
What is the novelty of the study? This must be mentioned in the last paragraph of the introduction.
I do suggest that the authors add the error bars in Figures 5 and 6.
The authors did not explain deeply the results obtained in Figures 5 and 6.
The authors have to explain and give the reason why the general tendency of the results of Figure 5 are different from those in Figure 6, in particular with a velocity higher than 0.017 m/s.
Those results need to be compared with other published results.
Figure 9 is not clear.
We need to know: what are the limitations of using the equations presented in Tables 3 and 4.
The authors find that GE Ramp and Zuber-Findlay are the most appropriate models to predict the experimental results. However, the accuracy is very low, and the error is relatively very high.
Author Response
"Please see the attachment."
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
After the revision, this manuscript can be accepted
Reviewer 3 Report
I suggest acceptance of the manuscript in its present form.
