Numerical Simulation Study on Flow Heat Transfer and Stress Distribution of Shell-and-Tube Superheater in Molten Salt Solar Thermal Power Station

Round 1

Reviewer 1 Report

Information is organized in well-constructed paragraphs. Only minor language check required.

Clear aims. Works cover new territory. Citations support the paper content. 

Methodology is appropriate. More attempts should be made to justify for decisions taken and assumptions made. Limitations to the methodology is somewhat mentioned.

Results displayed clearly using appropriate visuals. Limitations of results are discussed. Error analysis not sufficient.

Conclusion summarized findings. Future work not identified or not relevant. 

 

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

Please see the attached reviewer's comments file.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

Major comments

• I would make the concept of the problem being explored more clear to have a schematic of a typical solar thermal power system with energy storage; this schematic could be used to identify the location and role of the superheater in a system like this
• Thermal conductivity is denoted by lambda in Table 2, but is identified by k in Eq. 3 and then referred to as the heat transfer coefficient (line 136, page 4). As given in Eq (3), this is the thermal conductivity and has SI units of W/mK (not W/m²K) [again line 136]
• There are several issues with Eq. 2
  • I believe that the first derivative in each line is supposed to be the partial derivative with respect to time, not y
  • The second term cannot be expressed as a divergence; this term should be ∂(ρu u-vec)/∂x + ∂(ρv u-vec)/∂y + ∂(ρw u-vec)/∂z
  • Each of the pressure gradient terms should have a negative sign in front of them (since the pressure acts inward)
  • The partial derivatives of the shear stresses should be separated by plus signs; these terms are added, not multiplied
• There is insufficient detail about the model; Is this an in-house or commercial code? Is this a CFD or FEA model or a multiphysics coupling of the two; There is a lot of detail on the mesh and the equations are shown, but the specifics about how the equations are implemented is missing; the mention of the turbulence model (line 195, page 6) suggests CFD for the fluid flows
• There is a bit of confusion on the definition of the heat exchange efficiency. The only way that the heat gained by the vapor is not equal to the heat lost by the molten salt is if there is heat loss to the ambient. Is heat loss to the ambient considered? Or is the value quoted the heat exchanger effectiveness or some other standard metric?
•  It looks like the headers in columns 2 and 3 in Table 6 may not match the numbers: 340 looks more like an inlet temperature than the heat transfer efficiency
• Figure 15 only shows a plot of the Heat Exchange Efficiency but the caption also refers to an outlet temperature plot; either add the temperature plot or revise the caption

Minor comments

• Clarify what is meant by the "stable condition" on line 20, page 1
• Flow rate is quoted in m/s at various points throughout the paper; this would correspond to an average velocity; these values should be converted to kg/s or m³/s to reference either mass or volumetric flow rate
• It is not clear what is meant by "the superheater has the advantages of solid structure, strong adaptability, ..." Advantages compared to what? Consider revising wording
• The term "control body" is not familiar (line 127, page 4). Do you mean control volume?
• Figure 4 is never directly referenced in the text; it appears that this should happen somewhere between lines 210-212 on page 6
• When comparing Figure 6 and 7, it would be helpful to have the matching cases in the same location in the figures (i.e. water vapor in the tube side as (a) in both Fig. 6 and 7
• Run-on sentence between 267-274 on page 9; revise to make the meaning more clear. Incomplete sentence just after this (line 274); also revise
• Sentence add-on "so the thermal economy of the integrated steam generation system" doesn't fit with portion preceding it; revise
• Figure 14 is lacking a color bar; what is the meaning of color in this figure?
• Better to quote the flow rate in terms of mass flow rate (lines 395-396, page 13) rather than velocity; for steady conditions, the mass flow rate will be constant through each side of the heat exchanger; velocity will change as the density changes (with temperature change) through the heat exchanger
• Uncertain meaning of "the gravity with increasing gradually" on line 438 of page 14; possibly a typo; revise

Typos

• "When" should be capitalized on line 15, page 1
• "The" on line 270 of page 9 should not be capitalized unless it is the start of a new sentence (and then there should be a period before it)
• Unneeded period between Figure and 15 in line 425, page 14

Author Response

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Author Response File: Author Response.docx