Modeling and Control of a Multiple-Heat-Exchanger Thermal Management System for Conventional and Hybrid Electric Vehicles

Round 1

Reviewer 1 Report

This paper explores the use of multiple radiators to adapt the cooling system operations to driving demands. The findings contribute to improving the overall performance of the powertrain.

1.       The importance and innovation of this research need to be further emphasized in the introduction.

2.       The mechanism behind good performance needs to be explained in depth.

3.       The service stability of a multiple heat exchanger thermal management system for conventional and Hybrid electric vehicles needs to be demonstrated.

4.       Figure 1 requires normalization, especially for lines.

5.       The reference format needs to be standardized and consistent.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Manuscript ID: designs-2124088

Title: Modeling and control of a Multiple heat exchanger thermal management system for conventional and Hybrid electric vehicles

In this study, system dynamic modeling, controller design, and experimental research has been done on a scalable multi-radiator thermal management system concept. The subject is in the scope of the journal. The following minor and major comments should be addressed before the final decision.

  ·         Explain the novelty of the study in more detail.

·         Recently, the use of ultrasonic vibrations has been introduced as another way to control heat transfer in thermal systems. It is suggested to mention this in the introduction for readers’ information. Referring to the following articles will be helpful: Doi:10.1016/j.icheatmasstransfer.2022.106098; Doi: 10.3390/w14244000.

·         The author should state the difference between the current research with the following previous one in the introduction section:

Z. Syed, R. Miller and J. Wagner, "Multiple heat exchangers for automotive systems - A design tool," in SAE

Techncical Paper No. 2022-01-0180, Detroit, 2022.

·         Fig 2: Why the heat removal is less for twin configuration in some periods of time?

·         Enrich the abstract and conclusion sections with more quantitative data from the research.

·         A validation benchmark must be presented to ensure the accuracy of the thermal results.

·         According to the experimental tests, has the uncertainty analysis been done?

·         Has the repeatability of the experiments been checked?

 

·         It is necessary to explain the characteristics of the test equipment in more detail.

Author Response

Please see attachment

Author Response File: Author Response.pdf

Reviewer 3 Report

In order to improve the overall quality of the article, authors are requested to address the following comments:

1. Manuscript must be thoroughly reviewed to and grammatical/typographical errors should be removed. A few examples:

A. Section 4: Lines 151 to 154 are copied from the manuscript template and should be removed

B. Font size in lines 194 to 201 is same as the figure captions. It must be fixed.

 

2. The conclusion of the article should be improved to include technical comparison through data. Novel contributions made by the study and magnitude of energy savings should be explicitly mentioned.

3. While inclusion of an additional radiator results in ~4.5% reduction in fan energy consumption, it is not clear how much more energy is consumed by the pump. Unless the energy consumption of the pump is included, the energy analysis cannot be considered complete. 

4. Authors have stated a bigger pump was utilized for the study. Is it due to the higher volumetric flow rate of coolant needed for the multi radiator setup? What was the difference in overall volumetric flow rate of coolant between the two architectures.

5. How much weight increase of the vehicle is expected due to the additional radiator and more coolant volume? Does that offset the energy savings from the fan?

6. Can authors comment on the overall contribution of the ambient temperature in this study? Will conclusions change at much lower ambient conditions?

Author Response

Please see attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

All the comments are addressed.

Author Response

The authors thank the reviewers for the helpful comments. We are glad all the comments were addressed.

Reviewer 3 Report

Dear Authors,

Thank you for providing your responses. I think some of the answers provided to the questions were inadequate. For instance, comment number 4 clearly asks for difference in Volumetric flow rates of coolant between the two strategies, to which authors refer to their response to comment number 3, which does not discuss anything related to volumetric flow rate difference between the two strategies.

Comment number 5 is a straightforward question on weight of the two small HXs versus one big HX. To this, authors state that the weight increase is insignificant. Authors must provide the actual numbers and let readers and reviewers be able to deliberate over the claims. 

Regarding comment 6, what about higher ambient temperatures? Is this strategy worth looking at by the automotive companies.

 

Author Response

The authors are grateful to the reviewer for the helpful comments and suggestions to improve the quality and presentation of the paper. We have earnestly considered each comment and modified the paper.

Comment 1: Comment number 4 clearly asks for difference in Volumetric flow rates of coolant between the two strategies, to which authors refer to their response to comment number 3, which does not discuss anything related to volumetric flow rate difference between the two strategies. (Authors have stated a bigger pump was utilized for the study. Is it due to the higher volumetric flow rate of coolant needed for the multi radiator setup? What was the difference in overall volumetric flow rate of coolant between the two architectures.)

Response: No, the bigger pump was already in the system which was used for an earlier project. As for the volumetric flow rate, the pump was calibrated to provide 0-1.5 kg/s of coolant flow within the circuit. The change in configuration did not impact the volumetric flow rate. However, by activating the second radiator in parallel, the overall fluid resistance is expected to reduce a bit (due to an additional pathway being opened). From our observations, we have noticed a ~10% increase in flow rate when second radiator is activated.

Comment 2: Comment number 5 is a straightforward question on weight of the two small HXs versus one big HX. To this, authors state that the weight increase is insignificant. Authors must provide the actual numbers and let readers and reviewers be able to deliberate over the claims.

Response: The larger radiator weighs ~8 kg. This was replaced with 2 smaller radiators of ~6 kg each. Considering a vehicle weighs 1500+ kg, we believe the added weight of about 4-8 kg (including any additional peripherals) would be insignificant. We can provide the spec sheets to the reviewer if needed.

Comment 3: Regarding comment 6, what about higher ambient temperatures? Is this strategy worth looking at by the automotive companies.

Response: Yes, further research may be beneficial to the field. At higher temperatures, a single radiator may not be sufficient, but some energy savings may still be achieved with optimal controls.

Round 3

Reviewer 3 Report

thank you for the answers. I do not have any other questions at this time.