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Thermofluid design and analysis of centrifugal compressors for a 50 MWe concentrated solar power supercritical CO₂ Brayton power cycle

Thesis (MEng)--Stellenbosch University, 2026.

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Main Author: De Villiers, Caroline Michelle
Other Authors: Laubscher, Ryno
Format: Thesis
Language:English
Published: Stellenbosch : Stellenbosch University 2026
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access_status_str Open Access
author De Villiers, Caroline Michelle
author2 Laubscher, Ryno
author_browse De Villiers, Caroline Michelle
Laubscher, Ryno
author_facet Laubscher, Ryno
De Villiers, Caroline Michelle
author_sort De Villiers, Caroline Michelle
collection Thesis
dc_rights_str_mv Stellenbosch University
description Thesis (MEng)--Stellenbosch University, 2026.
format Thesis
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institution Stellenbosch University (South Africa)
language English
last_indexed 2026-06-10T12:43:57.159Z
license_str Other — see source repository
provenance_str_mv Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository
publishDate 2026
publishDateRange 2026
publishDateSort 2026
publisher Stellenbosch : Stellenbosch University
publisherStr Stellenbosch : Stellenbosch University
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source_str SUNScholar — Stellenbosch University Repository
spelling oai:scholar.sun.ac.za:10019.1/135733 Thermofluid design and analysis of centrifugal compressors for a 50 MWe concentrated solar power supercritical CO₂ Brayton power cycle De Villiers, Caroline Michelle Laubscher, Ryno Rousseau, Pieter Pretorius, Johannes Stellenbosch University. Faculty of Engineering. Dept. of Mechanical & Mechatronic Engineering. Thesis (MEng)--Stellenbosch University, 2026. De Villiers, C. M. 2026. Thermofluid design and analysis of centrifugal compressors for a 50 MWe concentrated solar power supercritical CO₂ Brayton power cycle. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/7b05c32a-1702-479a-8ec1-8b3f9bdb44e9 Brayton power cycles employing supercritical CO₂ (sCO₂) as the working fluid are attracting growing interest for use in concentrated solar power (CSP) plants. The primary motivation is to enhance the efficiency of the power block and reduce overall system costs by utilising the high efficiency, compact layout, and reduced turbomachinery size achievable with sCO₂. This study presents the design and simulation of three centrifugal compressors for a 50 MWe CSP sCO₂ Brayton power cycle. To accomplish this, a one-dimensional (1-D) mean line design methodology was developed for preliminary design and optimisation purposes. The methodology employs Latin Hypercube Sampling combined with an exhaustive search strategy to systematically explore the design space and identify optimal compressor configurations based on isentropic efficiency. A 1-D mean line simulation model was then developed to perform design point and off-design performance predictions. The model was validated using data from literature and thereafter used to simulate each of the designed compressors over a range of mass flow rates at the design rotational speed. Further validation was done using 3-D computational fluid dynamics (CFD) simulations conducted at the design point, as well as 90% and 105% mass flow conditions. The results of the 1-D simulation model and the 3-D CFD show good agreement. The findings reveal that compressors with lower rotor tip diameter ratios and meridional velocity ratios generally exhibit higher efficiencies, although values below 0.7 result in excessive diffusion within the blade passages. Optimal flow and work coefficients were found to depend on the specific thermodynamic requirements of each compressor stage. The final high-pressure compressor (HPC) design achieved the highest isentropic efficiency and the low-pressure compressor (LPC) the lowest. Skin friction was identified as the predominant aerodynamic loss mechanism within the rotor. The exhaustive search mean line preliminary design approach provided valuable insights into the influence of different parameters on the performance of each of the machines, while the good agreement between the 1-D and 3-D CFD models provides confidence in the prediction capability of the mean line approach. The methodology applied here can be improved further by incorporating the parasitic work into the preliminary design tool, as well as an equation of state (EOS) capable of handling two-phase flow. To further optimize compressor performance the effects of blade profile and entropy generation can also be examined in more detail. Masters 2026-04-09T06:23:56Z 2026-04-09T06:23:56Z 2026-03 Thesis https://scholar.sun.ac.za/handle/10019.1/135733 en Stellenbosch University 132 pages : ill. application/pdf Stellenbosch : Stellenbosch University
spellingShingle De Villiers, Caroline Michelle
Thermofluid design and analysis of centrifugal compressors for a 50 MWe concentrated solar power supercritical CO₂ Brayton power cycle
title Thermofluid design and analysis of centrifugal compressors for a 50 MWe concentrated solar power supercritical CO₂ Brayton power cycle
title_full Thermofluid design and analysis of centrifugal compressors for a 50 MWe concentrated solar power supercritical CO₂ Brayton power cycle
title_fullStr Thermofluid design and analysis of centrifugal compressors for a 50 MWe concentrated solar power supercritical CO₂ Brayton power cycle
title_full_unstemmed Thermofluid design and analysis of centrifugal compressors for a 50 MWe concentrated solar power supercritical CO₂ Brayton power cycle
title_short Thermofluid design and analysis of centrifugal compressors for a 50 MWe concentrated solar power supercritical CO₂ Brayton power cycle
title_sort thermofluid design and analysis of centrifugal compressors for a 50 mwe concentrated solar power supercritical co₂ brayton power cycle
url https://scholar.sun.ac.za/handle/10019.1/135733
work_keys_str_mv AT devillierscarolinemichelle thermofluiddesignandanalysisofcentrifugalcompressorsfora50mweconcentratedsolarpowersupercriticalco2braytonpowercycle