Review Reports

Round 1

Reviewer 1 Report

This article focuses on a solar thermal plant with a central solar receiver coupled to a partial cooling cycle, conducting a comparative study, both from a thermal and economic perspective, with the aim of optimising the configuration of the receiver.

It has important scientific research value for solar thermal power plants, however, the readability needs to be improved.

1. A systematic introduction should be given to the process of combining solar thermal power plants with carbon dioxide supercritical cycles, so that readers can have a better understanding of the second section.

2. Reference 14 does not reflect the author's proposed of 'The solar receiver model'.

3. The meanings of variables and their subscripts in Figures 5 and formulas (1) - (3) are not covered, making it difficult for readers to understand their meanings。

4. From Figure 4, it can be seen that the solar receiver is only connected to the carbon dioxide supercritical cycle system through PHE. How can the impact of the solar receiver on the efficiency of PHE be determined?

Author Response

Reviewer 1

This article focuses on a solar thermal plant with a central solar receiver coupled to a partial cooling cycle, conducting a comparative study, both from a thermal and economic perspective, with the aim of optimising the configuration of the receiver.

It has important scientific research value for solar thermal power plants, however, the readability needs to be improved.

1. A systematic introduction should be given to the process of combining solar thermal power plants with carbon dioxide supercritical cycles, so that readers can have a better understanding of the second section.

The introduction has been modified by systematically describing the possible coupling schemes between the supercritical cycle and the central receiver system, referencing the main works for each case (lines 45-60).

2. Reference 14 does not reflect the author's proposed of 'The solar receiver model'.

You are right, reference 14 refers to the calculation programme in which the model has been implemented (Matlab). All the calculation programs used are also referenced: EES [18], NIST [22], SolarPilot [27] and Soltrace [28].

For clarity, an important reference has been added on line 154 (reference [20], which refers to the paper where the authors first used the proposed thermal model:

D’Souza, D., Montes, M.J., Romero, M., González-Aguilar, J., 2023. Energy and exergy analysis of microchannel central solar receivers for pressurised fluids. Applied Thermal Engineering 219, 119638. https://doi.org/10.1016/j.applthermaleng.2022.119638

In that reference, it is also accomplished a validation of the model, in section 3.1.

3. The meanings of variables and their subscripts in Figure 5 and formulas (1) - (3) are not covered, making it difficult for readers to understand their meanings.

You are totally right. Figure 5 has been reviewed, including all the terms appearing in eqs. (1-3)

4. From Figure 4, it can be seen that the solar receiver is only connected to the carbon dioxide supercritical cycle system through PHE. How can the impact of the solar receiver on the efficiency of PHE be determined?

This question is very interesting, and it was analysed by the authors in the article (reference 19 of this paper):

Montes, M.J.; Linares, J.I.; Barbero, R.; Rovira, A. Proposal of a new design of source heat exchanger for the technical feasibility of solar thermal plants coupled to supercritical power cycles. Sol. Energy 2020, 211, 1027–1041, https://doi.org/10.1016/j.solener.2020.10.042

One of the reasons for selecting the partial-cooling sCO₂ cycle is precisely that the PHE conditions are very good (large thermal increment and relatively low average operating temperature) for coupling to a central receiver system. This is precisely the conclusion reached in reference 19.

The study presented in this paper assumes that the nominal operating conditions of the PHE and the solar receiver, as well as their thermal power, are constant for all plants, varying only the receiver configuration. This change affects the dimensions of the heliostat field, but the receiver thermal output, as well as its temperatures, are ideally kept constant for all the configurations, so that the PHE and sCO₂ cycle are not affected.

Reviewer 2 Report

Please see attached file.

Comments for author File: Comments.pdf

The quality of the English language is good and some minor corrections are nedded.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The author's modification has met the reviewer's expectation and is recommended to be accepted.

Reviewer 2 Report

Thanks for your answers.

The quality of English writing is suitable for publication in a scientific journal.