Experimental Study of a Pump-Driven Microchannel-Separated Heat Pipe System

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

First of all, I would like to thank you very much for choosing our journal for your article. It is a very successful and meticulously prepared article. If you answer the questions I have asked, I would like to read the article again.

- Can you provide more details on how the working fluid was selected for this study? What specific properties or characteristics made it a suitable choice?

- How does the heat flow rate impact the phase change of the working fluid in the evaporator, and what implications does this have for the system’s performance?

- How was the designed heat exchange capacity of 4kW determined, and how does it relate to the intended applications of this heat pipe system?

- How might the heat pipe system’s performance change under different operating conditions or with different working fluids?

- These two studies must be in your introduction section to give an example of cooling and heat pipe devices

Der, O.; Edwardson, S.; Marengo, M.; Bertola, V. Engineered composite polymer sheets with enhanced thermal conductivity. IOP Conf. Ser. Mater. Sci. Eng. 2019, 613, 012008

https://doi.org/10.1088/1757-899X/613/1/012008

- How does the design of this specific heat pipe system compare to existing designs or systems in the literature?

- How might the findings of this study be applied or extended to other types of heat pipe systems or applications?

- Can you provide more details on the previous numerical calculation research mentioned, particularly how it informs the analysis of the phase transition state of the refrigerant working fluid?

- Could you provide more information on the three-process micro channel heat exchanger used as the condenser, particularly how its design and dimensions were determined?

- Can you explain the rationale behind choosing the heat transfer correlation proposed by Kandlikar for the refrigerant side heat transfer coefficient calculation in the evaporator design?

- Could you provide more details on the calculation processes and steps used to determine the total heat transfer area required for the evaporator?

- Why was a vertical multi-stage pump selected, and how were the flow and head requirements determined?

- Were any experimental validations conducted to verify the theoretical findings and design choices made in the study?

- Could you clarify the reason behind letting the system stand for 0.5 hours after vacuuming in the experimental procedure?

- This article must be in your paper to understand in detail condenser design and evaporator design.

Heat transfer and flow visualization of pulsating heat pipe with silica nanofluid: An experimental study

https://doi.org/10.1016/j.ijheatmasstransfer.2021.122100

- You mentioned that the heat transfer performance of the heat pipe system is significantly superior within the range of 75% to 95% liquid filling rate. Can you provide more insights or theories that support this observation?

- Can you discuss any steps taken to minimize measurement errors and ensure the reliability of the experimental results?

- the text mentions a relationship between the heat exchange rate and the superheat degree of the working fluid at the outlet of the evaporator as a function of the mass flow rate, depicted in Fig 6. Can the authors elaborate on the nature of this relationship? Is it linear, exponential, or of another form?

- Can the authors provide more insight into why the superheat at the outlet of the evaporator decreases with an increase in mass flow rate? How does this relate to the internal processes and heat transfer mechanisms within the evaporator?

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The paper investigates a pump driven cooling/heating system. Different parameters are varied and their influence on system performance / heat transfer capacity is evaluated.  An experimental analysis is presented and the topic is in scope of the journal an in general interesting for others. However, from my point of view the paper needs considerable improvement before publication.

The novelty should be elaborated and highlighted clearly in the introduction. What exactly makes the content special and is improved in relation to other studies?

In general, based on the current description it is hard to understand or reproduce experiments. Here, significant improvement is required.

In detail the following point should be addressed:

-          The abstract mentions that a filling rate from 75-95% is optimal. What exactly is a 100% filling rate? How can a filling rate be higher than 100%? Especially in the abstract no reader will know what exactly this means.

-          Section 2.1 should reference to a figure (flow sheet) with correlating numbers (e.g. fig 2), otherwise it is hard to understand this.

-          Table 1: What exactly are qualitative temperatures of condenser and evaporator?

-          For some of the Eq. 5-13 references should be provided. Obviously, some of them are basic, however, for e.g. fin efficiency the user should be pointed to the respective literature.

-          Where exactly in the paper are eqs 5-20 utilised? Why is the detailed calculation of heat transfer required, as experiments are presented later.

-          What exactly are microelements of the HXs in section 2.3?

-          Eq21/22 contains delta T; the text mentions the lowest temperature in the experiment is 20°C. What exactly are you referring to (differences or absolute temps.)? The error propagation calculation seems a bit strange to me. One temperature probe has an error of 0.1°C and you conclude the error is 0.5%. Flow rate is 0.54%. How exactly to you calculate the error of the transferred energy? There is phase change ongoing and with pure sensible heat exchange the error (as you need two temperature probes) should be higher as presented. Following Fig 6 you go as low as 2°K overheating. The error should be way higher here.

-          How exactly do you measure air volume flow?

Comments on the Quality of English Language

English is ok

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

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Comments on the Quality of English Language

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